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Diffstat (limited to 'html/drivers')
39 files changed, 4002 insertions, 0 deletions
diff --git a/html/drivers/driver1.html b/html/drivers/driver1.html new file mode 100644 index 0000000..5933483 --- /dev/null +++ b/html/drivers/driver1.html @@ -0,0 +1,64 @@ +<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> + +<html> + + <head> + <meta name="generator" content="HTML Tidy, see www.w3.org"> + <title>Undisciplined Local Clock</title> + <link href="../scripts/style.css" type="text/css" rel="stylesheet"> + </head> + + <body> + <h3>Undisciplined Local Clock</h3> + <hr> + <h4>Synopsis</h4> + <p>Address: 127.127.1.<i>u</i><br> + Reference ID: <tt>LCL</tt><br> + Driver ID: <tt>LOCAL</tt></p> + <h4>Description</h4> + <p>This driver is intended for use in an isolated network where no external source of synchronization such as a radio clock or modem is available. It allows a designated time server to act as a primary server to provide synchronization to other clients on the network. Pick a machine that has a good clock oscillator (Digital machines are good, Sun machines are not) and configure it with this driver. Set the clock using the best means available, like eyeball-and-wristwatch. Then, point all the other machines at this one or use broadcast (not multicast) mode to distribute time.</p> + <p>Another application for this driver is if a particular server clock is to be used as the clock of last resort when all other normal synchronization sources have gone away. This is especially useful if that server has an ovenized oscillator. For this you would configure this driver at a stratum greater than any other likely sources of time (say 3 or 4) to prevent the server taking over when legitimate sources are still available.</p> + <p>A third application for this driver is when an external discipline source is available, such as the NIST <tt>lockclock</tt> program, which synchronizes the local clock via a telephone modem and the NIST Automated Computer Time Service (ACTS), or the Digital Time Synchronization Service (DTSS), which runs on DCE machines. In this case the stratum should be set at zero, indicating a bona fide stratum-1 source. In the case of DTSS, the local clock can have a rather large jitter, depending on the interval between corrections and the intrinsic frequency error of the clock oscillator. In extreme cases, this can cause clients to exceed the 128-ms slew window and drop off the NTP subnet.</p> + <p>In the case where a NTP time server is synchronized to some device or protocol that is not external to the NTP daemon itself, some means should be provided to pass such things as error and health values to the NTP daemon for dissemination to its clients. If this is not done, there is a very real danger that the device or protocol could fail and with no means to tell NTP clients of the mishap. When ordinary Unix system calls like <tt>adjtime()</tt> are used to discipline the kernel clock, there is no obvious way this can be done without modifying the code for each case. However, when a modified kernel with the <tt>ntp_adjtime()</tt> system call is available, that routine can be used for the same purpose as the <tt>adjtime()</tt> routine and in addition provided with the estimated error, maximum error, and leap-indicator values. This is the preferred way to synchronize the kernel clock and pass information to the NTP clients.</p> + <p>In the default mode the behavior of the clock selection algorithm is modified when this driver is in use. The algorithm is designed so that this driver will never be selected unless no other discipline source is available. This can be overridden with the <tt>prefer</tt> keyword of the <tt>server</tt> configuration command, in which case only this driver will be selected for synchronization and all other discipline sources will be ignored. This behavior is intended for use when an external discipline source controls the system clock. See the <a href="../prefer.html">Mitigation Rules and the <tt>prefer</tt> Keyword</a> page for a detailed description of the exact behavior.</p> + <p>The stratum for this driver is set at 5 by default, but can be changed by the <tt>fudge</tt> configuration command and/or the <tt>ntpdc</tt> utility. The reference ID is <tt>LCL</tt> by default, but can be changed using the same mechanisms. <b>*NEVER*</b> configure this driver to operate at a stratum which might possibly disrupt a client with access to a bona fide primary server, unless the local clock oscillator is reliably disciplined by another source. <b>*NEVER NEVER*</b> configure a server which might devolve to an undisciplined local clock to use multicast mode.</p> + <p>This driver provides a mechanism to trim the local clock in both time and frequency, as well as a way to manipulate the leap bits. The <tt>fudge time1</tt> parameter adjusts the time (in seconds) and the <tt>fudge time2</tt> parameter adjusts the frequency (in parts per million). Both parameters are additive and operate only once; that is, each command (as from <tt>ntpdc</tt>) adds signed increments in time or frequency to the nominal local clock time and frequency.</p> + <h4>Operation with an External Reference Source</h4> + <p>There are special provisions for this driver to operate in conjunction with an external reference source, such as the <tt>LOCKCLOCK</tt> scheme used by the NIST time servers. In such schemes the system clock is disciplined by a source external to NTP, in the <tt>LOCKCLOCK</tt> case an ACTS telephone modem. To support <tt>LOCKCLOCK</tt> the NTP distribution should be built with the <tt>--enable-nist</tt> parameter in the configuration phase of the build procedure. This changes the system behavior as follows:</p> + <ol> + <li>The system clock is not disciplined in any way other than to call the <tt>ntp_adjtime()</tt> system call to obtain the kernel leap code, which becomes the driver leap code and. If the kernel leap code is 11 (not synchronized), the driver stratum is infinity; otherwise the stratum is set by the <tt>stratum</tt> subcommand on the <tt>fudge</tt> command applying to the driver. + <li>The NTP algorithms operate in the normal fashion with this driver and possibly other drivers and servers; however, the local clock driver as the <tt>prefer</tt> peer will always be selected, even if declared falseticker by the selection algorithm or fails to survive the clustering algorithm. + <li>If the driver leap code is 11, the system leap code is 11, system stratum infinity and system reference identifier <tt>DOWN</tt>. This provides a definitive status condition to dependent clients. + </ol> + <p>The local clock driver should be configured something like this:</p> + <p><tt>server 127.127.1.1 prefer</tt></p> + <p><tt>fudge 127.127.1.1 stratum 0 refid NIST</tt></p> + <p>The <tt>prefer</tt> keyword forces the driver to discipline the clock, even if other servers are configured and running correctly. This is convenient when a number of servers watch each other for monitoring and statistics gathering. In particular, the <tt>peerstats</tt> data and <tt>sysstats</tt> data can be collected at each server, aggregated for daily or weekly reports and sent by electric mail to a monitoring site. In addition, the full suite of cryptographic authentication algorithms is avialable to other servers and dependent clients.</p> + <h4>Monitor Data</h4> + <p>No <tt>filegen clockstats</tt> monitor data are produced by this driver.</p> + <h4>Fudge Factors</h4> + <dl> + <dt><tt>time1 <i>time</i></tt> + <dd>Specifies the time offset calibration factor, in seconds and fraction, with default 0.0. + <dt><tt>time2 <i>time</i></tt> + <dd>Specifies the frequency offset calibration factor, in parts per million, with default 0.0. + <dt><tt>stratum <i>number</i></tt> + <dd>Specifies the driver stratum, in decimal from 0 to 15, with default 3. + <dt><tt>refid <i>string</i></tt> + <dd>Specifies the driver reference identifier, an ASCII string from one to four characters, with default <tt>LCL</tt>. + <dt><tt>flag1 0 | 1</tt> + <dd>Not used by this driver. + <dt><tt>flag2 0 | 1</tt> + <dd>Not used by this driver. + <dt><tt>flag3 0 | 1</tt> + <dd>Not used by this driver. + <dt><tt>flag4 0 | 1</tt> + <dd>Not used by this driver. + </dl> + <h4>Additional Information</h4> + <p><a href="../refclock.html">Reference Clock Drivers</a></p> + <hr> + <script type="text/javascript" language="javascript" src="../scripts/footer.txt"></script> + </body> + +</html> diff --git a/html/drivers/driver10.html b/html/drivers/driver10.html new file mode 100644 index 0000000..d5692ab --- /dev/null +++ b/html/drivers/driver10.html @@ -0,0 +1,53 @@ +<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> + +<html> + + <head> + <meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1"> + <meta name="GENERATOR" content="Mozilla/4.01 [en] (Win95; I) [Netscape]"> + <title>Austron 2200A/2201A GPS Receivers</title> + <link href="../scripts/style.css" type="text/css" rel="stylesheet"> + </head> + + <body> + <h3>Austron 2200A/2201A GPS Receivers</h3> + <hr> + <h4>Synopsis</h4> + <p>Address: 127.127.10.<i>u</i><br> + Reference ID: <tt>GPS</tt><br> + Driver ID: <tt>GPS_AS2201</tt><br> + Serial Port: <tt>/dev/gps<i>u</i></tt>; 9600 baud, 8-bits, no parity<br> + Features: <tt>tty_clk</tt></p> + <h4>Description</h4> + <p>This driver supports the Austron 2200A/2201A GPS/LORAN Synchronized Clock and Timing Receiver connected via a serial port. It supports several special features of the clock, including the Input Buffer Module, Output Buffer Module, IRIG-B Interface Module and LORAN Assist Module. It requires the RS232 Buffered Serial Interface module for communication with the driver. For operation with multiple computers, it requires the <tt>ppsclock</tt> streams module described in the <a href="../ldisc.html">Line Disciplines and Streams Modules</a> page. The streams module requires a gadget box and 1-PPS level converter, such as described in the <a href="../pps.html">Pulse-per-second (PPS) Signal Interfacing</a> page.</p> + <p>For use with a single computer, the receiver can be connected directly to the receiver. For use with multiple computers, one of them is connected directly to the receiver and generates the polling messages. The other computers just listen to the receiver output directly or through a buffer amplifier. For computers that just listen, <tt>fudge flag2</tt> must be set and the <tt>ppsclock </tt>streams module configured on each of them.</p> + <p>This receiver is capable of a comprehensive and large volume of statistics and operational data. The specific data collection commands and attributes are embedded in the driver source code; however, the collection process can be enabled or disabled using the flag4 flag. If set, collection is enabled; if not, which is the default, it is disabled. A comprehensive suite of data reduction and summary scripts is in the ./scripts/stats directory</p> + of the ntp3 distribution. + <h4>Monitor Data</h4> + <p>When enabled by the <tt>flag4</tt> fudge flag, every received timecode is written as-is to the <tt>clockstats</tt> file.</p> + <h4>Fudge Factors</h4> + <dl> + <dt><tt>time1 <i>time</i></tt> + <dd>Specifies the time offset calibration factor, in seconds and fraction, with default 0.0. + <dt><tt>time2 <i>time</i></tt> + <dd>Not used by this driver. + <dt><tt>stratum <i>number</i></tt> + <dd>Specifies the driver stratum, in decimal from 0 to 15, with default 0. + <dt><tt>refid <i>string</i></tt> + <dd>Specifies the driver reference identifier, an ASCII string from one to four characters, with default <tt>GPS</tt>. + <dt><tt>flag1 0 | 1</tt> + <dd>Not used by this driver. + <dt><tt>flag2 0 | 1</tt> + <dd>Set for computers that listen-only. + <dt><tt>flag3 0 | 1</tt> + <dd>Not used by this driver. + <dt><tt>flag4 0 | 1</tt> + <dd>Enable verbose <tt>clockstats</tt> recording if set. + </dl> + <h4>Additional Information</h4> + <p><a href="../refclock.html">Reference Clock Drivers</a></p> + <hr> + <script type="text/javascript" language="javascript" src="../scripts/footer.txt"></script> + </body> + +</html>
\ No newline at end of file diff --git a/html/drivers/driver11.html b/html/drivers/driver11.html new file mode 100644 index 0000000..9f13f67 --- /dev/null +++ b/html/drivers/driver11.html @@ -0,0 +1,87 @@ +<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> + +<html> + + <head> + <meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1"> + <meta name="GENERATOR" content="Mozilla/4.01 [en] (Win95; I) [Netscape]"> + <title>Arbiter 1088A/B GPS Receiver</title> + <link href="../scripts/style.css" type="text/css" rel="stylesheet"> + </head> + + <body> + <h3>Arbiter 1088A/B GPS Receiver</h3> + <hr> + <h4>Synopsis</h4> + <p>Address: 127.127.11.<i>u</i><br> + Reference ID: <tt>GPS</tt><br> + Driver ID: <tt>GPS_ARBITER</tt><br> + Serial Port: <tt>/dev/gps<i>u</i></tt>; 9600 baud, 8-bits, no parity<br> + Features: <tt>tty_clk</tt></p> + <h4> + <p>Description</p> + </h4> + <p>This driver supports the Arbiter 1088A/B Satellite Controlled Clock. The claimed accuracy of this clock is 100 ns relative to the PPS output when receiving four or more satellites.</p> + <p>The receiver should be configured before starting the NTP daemon, in order to establish reliable position and operating conditions. It does not initiate surveying or hold mode. For use with NTP, the daylight savings time feature should be disables (<tt>D0</tt> command) and the broadcast mode set to operate in UTC (<tt>BU</tt> command).</p> + <p>The timecode format supported by this driver is selected by the poll sequence <tt>B5</tt>, which initiates a line in the following format to be repeated once per second until turned off by the <tt>B0</tt> command.</p> + <p>Format <tt>B5</tt> (24 ASCII printing characters):</p> + <pre><cr><lf>i yy ddd hh:mm:ss.000bbb + +on-time = <cr> +i = synchronization flag (' ' = locked, '?' = unlocked) +yy = year of century +ddd = day of year +hh:mm:ss = hours, minutes, seconds +.000 = fraction of second (not used) +bbb = tailing spaces for fill</pre> + <p>The alarm condition is indicated by a '?' at i, which indicates the receiver is not synchronized. In normal operation, a line consisting of the timecode followed by the time quality character (TQ) followed by the receiver status string (SR) is written to the clockstats file.</p> + <p>The time quality character is encoded in IEEE P1344 standard:</p> + <p>Format <tt>TQ</tt> (IEEE P1344 estimated worst-case time quality)</p> + <pre>0 clock locked, maximum accuracy +F clock failure, time not reliable +4 clock unlocked, accuracy < 1 us +5 clock unlocked, accuracy < 10 us +6 clock unlocked, accuracy < 100 us +7 clock unlocked, accuracy < 1 ms +8 clock unlocked, accuracy < 10 ms +9 clock unlocked, accuracy < 100 ms +A clock unlocked, accuracy < 1 s +B clock unlocked, accuracy < 10 s</pre> + <p>The status string is encoded as follows:</p> + <p>Format <tt>SR</tt> (25 ASCII printing characters)</p> + <pre>V=vv S=ss T=t P=pdop E=ee + +vv = satellites visible +ss = relative signal strength +t = satellites tracked +pdop = position dilution of precision (meters) +ee = hardware errors</pre> + <p>A three-stage median filter is used to reduce jitter and provide a dispersion measure. The driver makes no attempt to correct for the intrinsic jitter of the radio itself.</p> + <h4>Monitor Data</h4> + <p>When enabled by the <tt>flag4</tt> fudge flag, an additional line containing the latitude, longitude, elevation and optional deviation data is written to the <tt>clockstats</tt> file. The deviation data operates with an external pulse-per-second (PPS) input, such as a cesium oscillator or another radio clock. The PPS input should be connected to the B event channel and the radio initialized for deviation data on that channel. The deviation data consists of the mean offset and standard deviation of the external PPS signal relative the GPS signal, both in microseconds over the last 16 seconds.</p> + <h4>Fudge Factors</h4> + <dl> + <dt><tt>time1 <i>time</i></tt> + <dd>Specifies the time offset calibration factor, in seconds and fraction, with default 0.0. + <dt><tt>time2 <i>time</i></tt> + <dd>Not used by this driver. + <dt><tt>stratum <i>number</i></tt> + <dd>Specifies the driver stratum, in decimal from 0 to 15, with default 0. + <dt><tt>refid <i>string</i></tt> + <dd>Specifies the driver reference identifier, an ASCII string from one to four characters, with default <tt>GPS</tt>. + <dt><tt>flag1 0 | 1</tt> + <dd>Not used by this driver. + <dt><tt>flag2 0 | 1</tt> + <dd>Not used by this driver. + <dt><tt>flag3 0 | 1</tt> + <dd>Not used by this driver. + <dt><tt>flag4 0 | 1</tt> + <dd>Enable verbose <tt>clockstats</tt> recording if set. + </dl> + <h4>Additional Information</h4> + <p><a href="../refclock.html">Reference Clock Drivers</a></p> + <hr> + <script type="text/javascript" language="javascript" src="../scripts/footer.txt"></script> + </body> + +</html>
\ No newline at end of file diff --git a/html/drivers/driver12.html b/html/drivers/driver12.html new file mode 100644 index 0000000..242e50b --- /dev/null +++ b/html/drivers/driver12.html @@ -0,0 +1,49 @@ +<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> + +<html> + + <head> + <meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1"> + <meta name="GENERATOR" content="Mozilla/4.01 [en] (Win95; I) [Netscape]"> + <title>KSI/Odetics TPRO/S IRIG Interface</title> + <link href="../scripts/style.css" type="text/css" rel="stylesheet"> + </head> + + <body> + <h3>KSI/Odetics TPRO/S IRIG Interface</h3> + <hr> + <h4>Synopsis</h4> + <p>Address: 127.127.12.<i>u</i><br> + Reference ID: <tt>IRIG</tt><br> + Driver ID: <tt>IRIG_TPRO</tt><br> + TPRO Device: <tt>/dev/tpro<i>u</i></tt><br> + Requires: KSI/Odetics device driver, <tt>/usr/include/sys/tpro.h</tt> header file</p> + <h4>Description</h4> + <p>This driver supports the KSI/Odetics TPRO and TPRO-SAT IRIG-B Decoder, which is a module connected directly to the SBus of a Sun workstation. The module works with the IRIG-B signal generated by several radio clocks, including those made by Arbiter, Austron, Odetics, Spectracom and TrueTime, among others, although it is generally an add- on option. In the case of the TPRO-SAT, the module is an integral part of a GPS receiver, which serves as the primary timing source.</p> + <p>Using the TPRO interface as a NTP reference clock provides precision time only to ntpd and its clients. With suitable kernel modifications, it is possible to use the TPRO as the CPU system clock, avoiding errors introduced by the CPU clock oscillator wander. See the <a href="../kern.html">A Kernel Model for Precision Timekeeping </a>page for further details.</p> + <h4>Fudge Factors</h4> + <dl> + <dt><tt>time1 <i>time</i></tt> + <dd>Specifies the time offset calibration factor, in seconds and fraction, with default 0.0. + <dt><tt>time2 <i>time</i></tt> + <dd>Not used by this driver. + <dt><tt>stratum <i>number</i></tt> + <dd>Specifies the driver stratum, in decimal from 0 to 15, with default 0. + <dt><tt>refid <i>string</i></tt> + <dd>Specifies the driver reference identifier, an ASCII string from one to four characters, with default <tt>IRIG</tt>. + <dt><tt>flag1 0 | 1</tt> + <dd>Not used by this driver. + <dt><tt>flag2 0 | 1</tt> + <dd>Not used by this driver. + <dt><tt>flag3 0 | 1</tt> + <dd>Not used by this driver. + <dt><tt>flag4 0 | 1</tt> + <dd>Not used by this driver. + </dl> + <h4>Additional Information</h4> + <p><a href="../refclock.html">Reference Clock Drivers</a></p> + <hr> + <script type="text/javascript" language="javascript" src="../scripts/footer.txt"></script> + </body> + +</html>
\ No newline at end of file diff --git a/html/drivers/driver16.html b/html/drivers/driver16.html new file mode 100644 index 0000000..96ecdb0 --- /dev/null +++ b/html/drivers/driver16.html @@ -0,0 +1,31 @@ +<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> + +<html> + + <head> + <meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1"> + <meta name="GENERATOR" content="Mozilla/4.6 [en] (Win95; U) [Netscape]"> + <meta name="Author" content="Ganesh Ramasivan"> + <title>Bancomm bc635VME Time and Frequency Processor</title> + <link href="../scripts/style.css" type="text/css" rel="stylesheet"> + </head> + + <body> + <h3>bc635VME/bc350VXI Time and Frequency Processor</h3> + <hr> + <h4>Synopsis</h4> + <p>Address: 127.127.16.<i>u</i><br> + Reference ID: BTFP<br> + Driver ID: GPS_BANCOMM<br> + Bancomm Device <tt>/dev/btfp0</tt><br> + Requires: Bancomm bc635 TFP device module driver for SunOS 4.x/SunOS 5.x</p> + <h4>Description</h4> + <p>This is the clock driver for the Bancomm bc635VME Time and Frequency Processor. It requires the BANCOMM bc635VME bc350VXI Time and Frequency Processor Module Driver for SunOS 4.x/SunOS 5.x UNIX Systems.</p> + <p>Most of this code is originally from refclock_bancomm.c with thanks. It has been modified and tested on an UltraSparc IIi-cEngine running Solaris 2.6. A port for HPUX is not available henceforth.</p> + <h4>Additional Information</h4> + <p><a href="../refclock.html">Reference Clock Drivers</a></p> + <hr> + <script type="text/javascript" language="javascript" src="../scripts/footer.txt"></script> + </body> + +</html>
\ No newline at end of file diff --git a/html/drivers/driver18.html b/html/drivers/driver18.html new file mode 100644 index 0000000..dcd616a --- /dev/null +++ b/html/drivers/driver18.html @@ -0,0 +1,87 @@ +<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> + +<html> + + <head> + <meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1"> + <meta name="GENERATOR" content="Mozilla/4.01 [en] (Win95; I) [Netscape]"> + <title>NIST Modem Time Service</title> + <link href="../scripts/style.css" type="text/css" rel="stylesheet"> + </head> + + <body> + <h3>NIST Modem Time Service</h3> + <hr> + <h4>Synopsis</h4> + <p>Address: 127.127.18.<i>u</i><br> + Reference ID: <tt>NIST</tt><br> + Driver ID: <tt>ACTS_NIST</tt><br> + Serial Port: <tt>/dev/acts<i>u</i></tt>; 1200 baud, 8-bits, no parity<br> + Features: <tt>tty_clk</tt><br> + Requires: <tt>/usr/include/sys/termios.h</tt> header file with modem control</p> + <h4>Description</h4> + <p>This driver supports the NIST Automated Computer Time Service (ACTS). It periodically dials a prespecified telephone number, receives the NIST timecode data and calculates the local clock correction. It designed primarily for use when neither a radio clock nor connectivity to Internet time servers is available. For the best accuracy, the individual telephone line/modem delay needs to be calibrated using outside sources.</p> + <p>The ACTS is located at NIST Boulder, CO, telephone 303 494 4774. A toll call from Newark, DE, costs between three and four cents, although it is not clear what carrier and time of day discounts apply. The modem dial string will differ depending on local telephone configuration, etc., and is specified by the phone command in the configuration file. The argument to this command is an AT command for a Hayes compatible modem.</p> + <p>The driver can operate in either of two modes, as determined by the mode parameter in the server configuration command. In mode 0 the driver operates continuously at intervals determined by the fudge time1 parameter, as described above. In mode 1 the driver is enabled only when no other sources of synchronization are available and when we have gone more than MAXOUTAGE (3600 s) since last synchronized by other sources of synchronization.</p> + <p>The accuracy produced by this driver should be in the range of a millisecond or two, but may need correction due to the delay characteristics of the individual modem involved. For undetermined reasons, some modems work with the ACTS echo-delay measurement scheme and some don't. This driver tries to do the best it can with what it gets. Initial experiments with a Practical Peripherals 9600SA modem here in Delaware suggest an accuracy of a millisecond or two can be achieved without the scheme by using a fudge time1 value of 65.0 ms. In either case, the dispersion for a single call involving ten samples is about 1.3 ms.</p> + <p>For reliable call management, this driver requires a 1200-bps modem with a Hayes-compatible command set and control over the modem data terminal ready (DTR) control line. Present restrictions require the use of a POSIX-compatible programming interface, although other interfaces may work as well. The ACTS telephone number and modem setup string are hard-coded in the driver and may require changes for nonstandard modems or special circumstances.</p> + <p>The fudge time1 parameter represents a propagation-delay correction factor which is added to the value computed by ACTS when the echo-delay scheme is used. This scheme does not work with all modems; for those that don't, fudge flag2 should be set to disable the feature. In this case the fudge time1 parameter represents the total propagation delay due to all causes and must be determined by external calibration.</p> + <p>The ACTS call interval is determined by a counter initially set to the fudge time2 parameter. At each poll interval, minpoll (usually 64 s) is subtracted from the counter. When the counter is equal to or less than zero, the fudge flag1 is set, which causes up to three call attempts to be made to ACTS. The fudge flag1 is reset after a valid clock update has been determined or by a device fault, timeout or manually using <tt>ntpdc</tt>. After a valid clock update, the counter is reset for the next interval. Setting the <tt>fudge time2</tt> parameter to zero disables automatic call attempts. Manual call attempts can be made at any time by setting <tt>fudgeflag1</tt> using ntpdc.</p> + <p>The NIST timecode message is transmitted at 1200 bps in the following format:</p> + <pre> +jjjjj yy-mm-dd hh:mm:ss tt l uuu mmmmm UTC(NIST) * + +jjjjj = modified Julian day +yy-mm-dd = year, month, day +hh:mm:ss = hours, minutes, seconds +tt = DST indicator (see driver listing) +l = leap-second warning (see driver listing) +uuu = DUT1 correction (see driver listing) +mmmmm = modem calibration (see driver listing) +on-time = '*'</pre> + <p>The timecode message is transmitted continuously after a signon banner, which this driver ignores. The driver also ignores all but the yy-mm-dd, hh:mm:ss and on-time character '*' fields, although it checks the format of all fields of the message. A timestamp is captured at the '*' character, as required by the ACTS specification, and used as the reference time of the timecode. If a message with an on-time character of '#' is received, the driver updates the propagation delay. The driver disconnects when (a) ten valid messages have been received, (b) no message has been received for 15 s, (c) an on-time character of '#' is received. These messages are processed by a trimmed-mean filter to reduce timing noise and then by the usual NTP algorithms to develop the clock correction.</p> + <p>Since the accumulated error grows with the interval between calls, it is important that the intrinsic frequency error be minimized. This can be done by observing difference in offsets between two calls placed some hours apart and calculating the uncorrected frequency error. This error, as a fixed-point value in parts-per-million, should be installed in the ntp.drift file before the daemon is started. Some experimentation may be necessary in order to reduce the intrinsic frequency error to the order of 1 ppm.</p> + <p>The behavior of the clock selection algorithm is modified when this driver is in use. The algorithm is designed so that this driver will never be selected unless no other discipline source is available. This can be overridden with the prefer keyword of the server configuration command, in which case only this driver will be selected for synchronization and all other discipline sources will be ignored.</p> + <p>Unlike other drivers, each ACTS call generates one clock correction and that correction is processed immediately. There is no wait to allow the clock filter to accumulate samples. In addition, the watchdog timeout of the local clock algorithm is disabled, so that a correction received from this driver that exceeds CLOCK_MAX (128 ms) causes an immediate step/slew.</p> + <p>Since the interval between updates can be much longer than used with ordinary NTP peers, the local clock procedure has been modified to operate in either of two modes, depending on whether the interval between updates is less than or greater than CLOCK_MAXSEC (1200 s). If less than this value, the local clock procedure operates using the standard NTP phase-lock loop as with other NTP peers. If greater than this value, the procedure operates using a modified frequency-lock loop suggested by Judah Levine in his lockclock algorithm designed specifically for ACTS.</p> + <h4>Call Management</h4> + <p>Since ACTS will be a toll call in most areas of the country, it is necessary to carefully manage the call frequency. This can be done in two ways, by specifying the interval between calls, or by setting a flag bit manually or via a cron job. The call interval is determined by a counter initially set to the fudge time2 parameter. At each poll interval, minpoll (usually 64 s) is subtracted from the counter. When the counter is equal to or less than zero, the fudge flag1 is set, which causes up to three call attempts to be made. The fudge flag1 is reset after ten offset samples have been determined in a single call or by a device fault, timeout or manually using ntpdc. Upon successful completion of a call, the eight samples have been shifted into the clock filter, the local clock updated and the counter reset for the next interval. Setting the fudge time2 parameter to zero disables automatic call attempts.</p> + <p>Manual call attempts can be made at any time by setting fudge flag1 using ntpdc. For example, the ntpdc command</p> + <pre> +fudge 127.127.18.1 flags 1</pre> + <p>will ask for a key identifier and password and, if authenticated by the server, will set flag1. There may be a short delay until the expiration of the current poll timeout.</p> + <p>The flag1 can be set from a cron job in the following way. Construct a file with contents</p> + <pre>keyid 11 +passwd dialup +fudge 127.127.18.1 flags 1 +quit</pre> + <p>Then, run the following program at specified times as required.</p> + <pre>/usr/local/bin/ntpdc <file</pre> + <h4>Monitor Data</h4> + <p>When enabled by the <tt>flag4</tt> fudge flag, every received timecode is written as-is to the <tt>clockstats</tt> file.</p> + <h4>Fudge Factors</h4> + <dl> + <dt><tt>time1 <i>time</i></tt> + <dd>Specifies the time offset calibration factor, in seconds and fraction, with default 0.0. + <dt><tt>time2 <i>time</i></tt> + <dd>Not used by this driver. + <dt><tt>stratum <i>number</i></tt> + <dd>Specifies the driver stratum, in decimal from 0 to 15, with default 0. + <dt><tt>refid <i>string</i></tt> + <dd>Specifies the driver reference identifier, an ASCII string from one to four characters, with default <tt>NIST</tt>. + <dt><tt>flag1 0 | 1</tt> + <dd>Not used by this driver. + <dt><tt>flag2 0 | 1</tt> + <dd>Not used by this driver. + <dt><tt>flag3 0 | 1</tt> + <dd>Not used by this driver. + <dt><tt>flag4 0 | 1</tt> + <dd>Not used by this driver. + </dl> + <h4>Additional Information</h4> + <p><a href="../refclock.html">Reference Clock Drivers</a> </p> + <hr> + <script type="text/javascript" language="javascript" src="../scripts/footer.txt"></script> + </body> + +</html>
\ No newline at end of file diff --git a/html/drivers/driver19.html b/html/drivers/driver19.html new file mode 100644 index 0000000..20dae15 --- /dev/null +++ b/html/drivers/driver19.html @@ -0,0 +1,59 @@ +<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> + +<html> + + <head> + <meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1"> + <meta name="GENERATOR" content="Mozilla/4.01 [en] (Win95; I) [Netscape]"> + <title>Heath WWV/WWVH Receiver</title> + <link href="../scripts/style.css" type="text/css" rel="stylesheet"> + </head> + + <body> + <h3>Heath WWV/WWVH Receiver</h3> + <hr> + <h4>Synopsis</h4> + <p>Address: 127.127.19.<i>u</i><br> + Reference ID: <tt>WWV</tt><br> + Driver ID: <tt>WWV_HEATH</tt><br> + Serial Port: <tt>/dev/heath<i>u</i></tt>; 1200 baud, 8-bits, no parity<br> + Features: <tt>tty_clk</tt><br> + Requires: <tt>/usr/include/sys/termios.h</tt> header file with modem control</p> + <h4>Description</h4> + <p>This driver supports the Heath GC-1000 Most Accurate Clock, with RS232C Output Accessory. This is a WWV/WWVH receiver somewhat less robust than other supported receivers. Its claimed accuracy is 100 ms when actually synchronized to the broadcast signal, but this doesn't happen even most of the time, due to propagation conditions, ambient noise sources, etc. When not synchronized, the accuracy is at the whim of the internal clock oscillator, which can wander into the sunset without warning. Since the indicated precision is 100 ms, expect a host synchronized only to this thing to wander to and fro, occasionally being rudely stepped when the offset exceeds the default CLOCK_MAX of 128 ms.</p> + <p>The internal DIPswitches should be set to operate at 1200 baud in MANUAL mode and the current year. The external DIPswitches should be set to GMT and 24-hour format. It is very important that the year be set correctly in the DIPswitches; otherwise, the day of year will be incorrect after 28 April of a normal or leap year.</p> + <p>In MANUAL mode the clock responds to a rising edge of the request to send (RTS) modem control line by sending the timecode. Therefore, it is necessary that the operating system implement the <tt>TIOCMBIC</tt> and <tt>TIOCMBIS</tt> ioctl system calls and <tt>TIOCM_RTS</tt> control bit. Present restrictions require the use of a POSIX-compatible programming interface, although other interfaces may work as well.</p> + <p>The clock message consists of 23 ASCII printing characters in the following format:</p> + <pre>hh:mm:ss.f dd/mm/yr<cr> + +hh:mm:ss.f = hours, minutes, seconds +f = deciseconds ('?' when out of spec) +dd/mm/yr = day, month, year</pre> + <p>The alarm condition is indicated by '?', rather than a digit, at A. Note that 0?:??:??.? is displayed before synchronization is first established and hh:mm:ss.? once synchronization is established and then lost again for about a day.</p> + <p>A fudge time1 value of .07 s appears to center the clock offset residuals.</p> + <h4>Fudge Factors</h4> + <dl> + <dt><tt>time1 <i>time</i></tt> + <dd>Specifies the time offset calibration factor, in seconds and fraction, with default 0.0. + <dt><tt>time2 <i>time</i></tt> + <dd>Not used by this driver. + <dt><tt>stratum <i>number</i></tt> + <dd>Specifies the driver stratum, in decimal from 0 to 15, with default 0. + <dt><tt>refid <i>string</i></tt> + <dd>Specifies the driver reference identifier, an ASCII string from one to four characters, with default <tt>WWV</tt>. + <dt><tt>flag1 0 | 1</tt> + <dd>Not used by this driver. + <dt><tt>flag2 0 | 1</tt> + <dd>Not used by this driver. + <dt><tt>flag3 0 | 1</tt> + <dd>Not used by this driver. + <dt><tt>flag4 0 | 1</tt> + <dd>Not used by this driver + </dl> + Additional Information + <p><a href="../refclock.html">Reference Clock Drivers</a> </p> + <hr> + <script type="text/javascript" language="javascript" src="../scripts/footer.txt"></script> + </body> + +</html>
\ No newline at end of file diff --git a/html/drivers/driver2.html b/html/drivers/driver2.html new file mode 100644 index 0000000..453374f --- /dev/null +++ b/html/drivers/driver2.html @@ -0,0 +1,67 @@ +<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> + +<html> + + <head> + <meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1"> + <meta name="GENERATOR" content="Mozilla/4.01 [en] (Win95; I) [Netscape]"> + <title>Trak 8820 GPS Receiver</title> + <link href="../scripts/style.css" type="text/css" rel="stylesheet"> + </head> + + <body> + <h3>Trak 8820 GPS Receiver</h3> + <hr> + <h4>Synopsis</h4> + <p>Address: 127.127.2.<i>u</i><br> + Reference ID: <tt>GPS</tt><br> + Driver ID: <tt>GPS_TRAK</tt><br> + Serial Port: <tt>/dev/trak<i>u</i></tt>; 9600 baud, 8-bits, no parity<br> + Features: <tt>tty_clk</tt></p> + <h4>Description</h4> + <p>This driver supports the Trak 8820 GPS Station Clock. The claimed accuracy at the 1-PPS output is 200-300 ns relative to the broadcast signal; however, in most cases the actual accuracy is limited by the precision of the timecode and the latencies of the serial interface and operating system.</p> + <p>For best accuracy, this radio requires the <tt>tty_clk</tt> line discipline, which captures a timestamp at the <tt>*</tt> on-time character of the timecode. Using this discipline the jitter is in the order of 1 ms and systematic error about 0.5 ms. If unavailable, the buffer timestamp is used, which is captured at the <tt>\r</tt> ending the timecode message. This introduces a systematic error of 23 character times, or about 24 ms at 9600 bps, together with a jitter well over 8 ms on Sun IPC-class machines.</p> + <p>Using the menus, the radio should be set for 9600 bps, one stop bit and no parity. It should be set to operate in computer (no echo) mode. The timecode format includes neither the year nor leap-second warning.</p> + <p>In operation, this driver sends a <tt>RQTS\r</tt> request to the radio at initialization in order to put it in continuous time output mode. The radio then sends the following message once each second:</p> + <pre>*RQTS U,ddd:hh:mm:ss.0,q<cr><lf> +on-time = '*' +ddd = day of year +hh:mm:ss = hours, minutes, seconds +q = quality indicator (phase error), 0-6: + 0 > 20 us + 6 > 10 us + 5 > 1 us + 4 > 100 ns + 3 > 10 ns + 2 < 10 ns</pre> + The alarm condition is indicated by <tt>0</tt> at <tt>Q</tt>, which means the radio has a phase error greater than 20 us relative to the broadcast time. The absence of year, DST and leap-second warning in this format is also alarmed. + <p>The continuous time mode is disabled using the <tt>RQTX\r</tt> request, following which the radio sends a <tt>RQTX DONE<cr><lf></tt> response. In the normal mode, other control and status requests are effective, including the leap-second status request <tt>RQLS<cr></tt>. The radio responds with <tt>RQLS yy,mm,dd<cr><lf></tt>, where <tt>yy,mm,dd</tt> are the year, month and day. Presumably, this gives the epoch of the next leap second, <tt>RQLS 00,00,00</tt> if none is specified in the GPS message. Specified in this form, the information is generally useless and is ignored by the driver.</p> + <h4>Monitor Data</h4> + <p>When enabled by the <tt>flag4</tt> fudge flag, every received timecode is written as-is to the <tt>clockstats</tt> file.</p> + <h4>Fudge Factors</h4> + <p></p> + <dl> + <dt><tt>time1 <i>time</i></tt> + <dd>Specifies the time offset calibration factor, in seconds and fraction, with default 0.0. + <dt><tt>time2 <i>time</i></tt> + <dd>Not used by this driver. + <dt><tt>stratum <i>number</i></tt> + <dd>Specifies the driver stratum, in decimal from 0 to 15, with default 0. + <dt><tt>refid <i>string</i></tt> + <dd>Specifies the driver reference identifier, an ASCII string from one to four characters, with default <tt>GPS</tt>. + <dt><tt>flag1 0 | 1</tt> + <dd>Not used by this driver. + <dt><tt>flag2 0 | 1</tt> + <dd>Not used by this driver. + <dt><tt>flag3 0 | 1</tt> + <dd>Not used by this driver. + <dt><tt>flag4 0 | 1</tt> + <dd>Not used by this driver. + <p>Additional Information</p> + <p><a href="../refclock.html">Reference Clock Drivers</a></p> + </dl> + <hr> + <script type="text/javascript" language="javascript" src="../scripts/footer.txt"></script> + </body> + +</html>
\ No newline at end of file diff --git a/html/drivers/driver20.html b/html/drivers/driver20.html new file mode 100644 index 0000000..c387002 --- /dev/null +++ b/html/drivers/driver20.html @@ -0,0 +1,96 @@ +<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> + +<html> + + <head> + <meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1"> + <meta name="GENERATOR" content="Mozilla/4.76 [en] (X11; U; Linux 2.2.16-22 i586) [Netscape]"> + <title>Generic NMEA GPS Receiver</title> + <link href="../scripts/style.css" type="text/css" rel="stylesheet"> + </head> + + <body> + <h3>Generic NMEA GPS Receiver</h3> + <hr> + <h4>Synopsis</h4> + <p>Address: 127.127.20.<i>u</i><br> + Reference ID: <tt>GPS</tt><br> + Driver ID: <tt>GPS_NMEA</tt><br> + Serial Port: <tt>/dev/gps<i>u</i></tt>; 4800 baud, 8-bits, no parity<br> + Features: <tt>tty_clk</tt></p> + <h4>Description</h4> + <p>This driver supports GPS receivers with the <tt>$GPRMC</tt> NMEA output string by default. Alternately the <tt>$GPGGA</tt> or <tt>$GPGLL </tt>may be selected.</p> + <p>The driver expects the receiver to be set up to transmit a <tt>$GPRMC</tt> message every second.</p> + <p>The accuracy depend on the receiver used. Inexpesive GPS models are available with a claimed PPS signal accuracy of 1 <font face="Symbol">m</font>s or better relative to the broadcast signal. However, in most cases the actual accuracy is limited by the precision of the timecode and the latencies of the serial interface and operating system.</p> + <p>If the Operating System supports the PPSAPI, RFC-2783, it will be used.<br> + </p> + <p>The various GPS sentences that this driver recognises look like this:<br> + (others quietly ignored)</p> + <pre><tt>$GPRMC,POS_UTC,POS_STAT,LAT,LAT_REF,LON,LON_REF,SPD,HDG,DATE,MAG_VAR,MAG_REF*CC<cr><lf> +$GPGLL,LAT,LAT_REF,LONG,LONG_REF,POS_UTC,POS_STAT*CC<cr><lf> +$GPGGA,POS_UTC,LAT,LAT_REF,LONG,LONG_REF,FIX_MODE,SAT_USED,HDOP,ALT,ALT_UNIT,GEO,G_UNIT,D_AGE,D_REF*CC<cr><lf> + + POS_UTC - UTC of position. Hours, minutes and seconds [fraction (opt.)]. (hhmmss[.fff]) + POS_STAT - Position status. (A = Data valid, V = Data invalid) + LAT - Latitude (llll.ll) + LAT_REF - Latitude direction. (N = North, S = South) + LON - Longitude (yyyyy.yy) + LON_REF - Longitude direction (E = East, W = West) + SPD - Speed over ground. (knots) (x.x) + HDG - Heading/track made good (degrees True) (x.x) + DATE - Date (ddmmyy) + MAG_VAR - Magnetic variation (degrees) (x.x) + MAG_REF - Magnetic variation (E = East, W = West) + FIX_MODE - Position Fix Mode ( 0 = Invalid, >0 = Valid) + SAT_USED - Number Satellites used in solution + HDOP - Horizontal Dilution of Precision + ALT - Antenna Altitude + ALT_UNIT - Altitude Units (Metres/Feet) + GEO - Geoid/Elipsoid separation + G_UNIT - Geoid units (M/F) + D_AGE - Age of last DGPS Fix + D_REF - Reference ID of DGPS station + CC - Checksum (optional) + <cr><lf> - Sentence terminator.</tt></pre> + Alternate GPS sentences (other than <tt>$GPRMC</tt> - the default) may be enabled by setting the relevent bits of 'mode' in the server configuration line<br> + * server 127.127.20.x mode X<br> + bit 0 - enables RMC ( value = 1)<br> + bit 1 - enables GGA ( value = 2)<br> + bit 2 - enables GLL ( value = 4)<br> + multiple sentences may be selected<br> + <p>The driver will send a <tt>$PMOTG,RMC,0000*1D<cr><lf></tt> message each time a <tt>$GPRMC</tt> string is needed. This is not needed on most GPS receivers because they automatically send the <tt>$GPRMC</tt> string every second and will only work on GPS receivers that understand the <tt>$PMOTG</tt> string. Others will just ignore it.</p> + <h4>Setting up the Garmin GPS-25XL</h4> + Switch off all output with by sending it the following string. + <pre>"$PGRMO,,2<cr><lf>"</pre> + <p>Now switch only $GPRMC on by sending it the following string.</p> + <pre>"$PGRMO,GPRMC,1<cr><lf>"</pre> + <p>On some systems the PPS signal isn't switched on by default. It can be switched on by sending the following string.</p> + <pre>"$PGRMC,,,,,,,,,,,,2<cr><lf>"</pre> + <h4>Monitor Data</h4> + <p>The GPS sentence(s) that is used is written to the clockstats file.</p> + <h4>Fudge Factors</h4> + <dl> + <dt><tt>time1 <i>time</i></tt> + <dd>Specifies the time offset calibration factor, in seconds and fraction, with default 0.0. + <dt><tt>time2 <i>time</i></tt> + <dd>Not used by this driver. + <dt><tt>stratum <i>number</i></tt> + <dd>Specifies the driver stratum, in decimal from 0 to 15, with default 0. + <dt><tt>refid <i>string</i></tt> + <dd>Specifies the driver reference identifier, an ASCII string from one to four characters, with default <tt>GPS</tt>. + <dt><tt>flag1 0 | 1</tt> + <dd>Not used by this driver. + <dt><tt>flag2 0 | 1</tt> + <dd>Specifies the PPS signal on-time edge: 0 for assert (default), 1 for clear. + <dt><tt>flag3 0 | 1</tt> + <dd>Controls the kernel PPS discipline: 0 for disable (default), 1 for enable. + <dt><tt>flag4 0 | 1</tt> + <dd>Not used by this driver. + </dl> + <p>Additional Information</p> + <p><a href="../refclock.html">Reference Clock Drivers</a></p> + <hr> + <script type="text/javascript" language="javascript" src="../scripts/footer.txt"></script> + </body> + +</html>
\ No newline at end of file diff --git a/html/drivers/driver22.html b/html/drivers/driver22.html new file mode 100644 index 0000000..2b871c1 --- /dev/null +++ b/html/drivers/driver22.html @@ -0,0 +1,56 @@ +<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> + +<html> + + <head> + <meta name="generator" content="HTML Tidy, see www.w3.org"> + <title>PPS Clock Discipline</title> + <link href="../scripts/style.css" type="text/css" rel="stylesheet"> + </head> + + <body> + <h3>PPS Clock Discipline</h3> + <hr> + <h4>Synopsis</h4> + <p>Address: 127.127.22.<i>u</i><br> + Reference ID: <tt>PPS</tt><br> + Driver ID: <tt>PPS</tt><br> + Serial or Parallel Port: <tt>/dev/pps<i>u</i></tt><br> + Requires: PPSAPI interface</p> + <p>Note: This driver supersedes an older one of the same name. The older driver operated with several somewhat archaic signal interface devices, required intricate configuration and was poorly documented. This driver operates only with the PPSAPI interface proposed as an IETF standard. Note also that the <tt>pps</tt> configuration command has been obsoleted by this driver.</p> + <h4>Description</h4> + <p>This driver furnishes an interface for the pulse-per-second (PPS) signal produced by a cesium clock, radio clock or related equipment. It can be used to augment the serial timecode generated by a GPS receiver, for example. It can be used to remove accumulated jitter and re-time a secondary server when synchronized to a primary server over a congested, wide-area network and before redistributing the time to local clients. The driver includes extensive signal sanity checks and grooming algorithms. A range gate and frequency discriminator reject noise and signals with incorrect frequency. A multiple-stage median filter rejects jitter due to hardware interrupt and operating system latencies. A trimmed-mean algorithm determines the best time samples. With typical workstations and processing loads, the incidental jitter can be reduced to less than a microsecond.</p> + <p>While this driver can discipline the time and frequency relative to the PPS source, it cannot number the seconds. For this purpose a auxiliary source is required, ordinarily a radio clock operated as a primary reference (stratum 1) source; however, another NTP time server can be used as well. For this purpose, the auxiliary source should be specified as the prefer peer, as described in the <a href="../prefer.html">Mitigation Rules and the <tt>prefer</tt> Keyword</a> page.</p> + <p>The driver requires the PPSAPI interface<sup>1</sup>, which is a proposed IETF standard. The interface consists of the <tt>timepps.h</tt> header file and associated kernel support. Support for this interface is included in current versions of Solaris, FreeBSD and Linux and proprietary versions of Tru64 (Alpha) and SunOS. See the <a href="../pps.html">Pulse-per-second (PPS) Signal Interfacing</a> page for further information.</p> + <p>The PPS source can be connected via a serial or parallel port, depending on the hardware and operating system. The port can be dedicated to the PPS source or shared with another device. A radio clock is usually connected via a serial port and the PPS source connected via a level converter to the data carrier detect (DCD) pin (DB-9 pin 1, DB-25 pin 8) of the same connector. In some systems where a parallel port and driver are available, the PPS signal can be connected directly to the ACK pin (pin 10) of the connector. Whether the PPS signal is connected via a dedicated port or shared with another device, the driver opens the device <tt>/dev/pps%d</tt>, where <tt>%d</tt> is the unit number. As with other drivers, links can be used to redirect the logical name to the actual physical device.</p> + <p>The driver normally operates like any other driver and uses the same mitigation algorithms and PLL/FLL clock discipline incorporated in the daemon. If kernel PLL/FLL support is available, the kernel PLL/FLL clock discipline can be used instead. The default behavior is not to use the kernel PPS clock discipline, even if present. This driver incorporates a good deal of signal processing to reduce jitter using the median filter and trimmed average algorithms in the driver interface. As the result, performance with minpoll and maxpoll configured at the minimum 4 (16s) is generally better than the kernel PPS clock discipline. However, fudge flag 3 can be used to enable this discipline if necessary.</p> + <p>Note that the PPS source is considered valid only if the auxiliary source is the prefer peer, is reachable and is selectable to discipline the system clock. By default the stratum assigned to the PPS source is automatically determined. If the auxiliary source is unreachable or inoperative, the stratum is set to 16. Otherwise it is set to the stratum specified by the <tt>fudge stratum</tt> command, if present, or the auxiliary source stratum if not present. Please note the temptation to masquerade as a primary server by forcing the stratum to zero is decidedly dangerous, as it invites timing loops.</p> + <h4>Fudge Factors</h4> + <dl> + <dt><tt>time1 <i>time</i></tt> + <dd>Specifies the time offset calibration factor, in seconds and fraction, with default 0.0. <dt><tt>time2 <i>time</i></tt> + <dd>Not used by this driver. + <dt><tt>stratum <i>number</i></tt> + <dd>Specifies the driver stratum, in decimal from 0 to 15, with default 0. + <dt><tt>refid <i>string</i></tt> + <dd>Specifies the driver reference identifier, an ASCII string from one to four characters, with default <tt>PPS</tt>. + <dt><tt>flag1 0 | 1</tt> + <dd>Not used by this driver. + <dt><tt>flag2 0 | 1</tt> + <dd>Specifies the PPS signal on-time edge: 0 for assert (default), 1 for clear. + <dt><tt>flag3 0 | 1</tt> + <dd>Controls the kernel PPS discipline: 0 for disable (default), 1 for enable. + <dt><tt>flag4 0 | 1</tt> + <dd>Not used by this driver. + </dl> + <h4>Additional Information</h4> + <p><a href="../refclock.html">Reference Clock Drivers</a></p> + <p>Reference</p> + <ol> + <li>Mogul, J., D. Mills, J. Brittenson, J. Stone and U. Windl. Pulse-per-second API for Unix-like operating systems, version 1. Request for Comments RFC-2783, Internet Engineering Task Force, March 2000, 31 pp. + </ol> + <hr> + <script type="text/javascript" language="javascript" src="../scripts/footer.txt"></script> + </body> + +</html>
\ No newline at end of file diff --git a/html/drivers/driver23.html b/html/drivers/driver23.html new file mode 100644 index 0000000..c8b37be --- /dev/null +++ b/html/drivers/driver23.html @@ -0,0 +1,104 @@ +<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> + +<html> + + <head> + <meta name="GENERATOR" content="Adobe PageMill 3.0 per Windows"> + <meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1"> + <title>PTB Modem Time Service</title> + <link href="../scripts/style.css" type="text/css" rel="stylesheet"> + </head> + + <body> + <h3>PTB Modem Time Service and other European Laboratories Time Services</h3> + <hr> + <h4>Synopsis</h4> + <p>Address: 127.127.23.<i>u</i><br> + Reference ID: <tt>PTB</tt><br> + Driver ID: <tt>ACTS_PTB</tt><br> + Serial Port: <tt>/dev/ptb<i>u</i></tt>; 1200 baud, 8-bits, no parity<br> + Requires: <tt>/usr/include/sys/termios.h</tt> header file with modem control</p> + <h4>Description</h4> + <p>This driver supports the PTB Automated Computer Time Service (ACTS) and it is a modified version of the NIST ACTS driver so see it for more informations..</p> + <p>It periodically dials a prespecified telephone number, receives the PTB timecode data and calculates the local clock correction. It designed primarily for use when neither a radio clock nor connectivity to Internet time servers is available. For the best accuracy, the individual telephone line/modem delay needs to be calibrated using outside sources.</p> + <p>The only change between this driver and the NIST one is the data format. Infact PTB data format is the following:</p> + <p><font size="-1" face="Courier New">Data format<br> + 0000000000111111111122222222223333333333444444444455555555556666666666777777777 7<br> + 0123456789012345678901234567890123456789012345678901234567890123456789012345678 9<br> + 1995-01-23 20:58:51 MEZ 10402303260219950123195849740+40000500 *<br> + A B C D EF G H IJ K L M N O P Q R S T U V W XY Z<CR><LF><br> + A year<br> + B month<br> + C day<br> + D hour<br> + E : normally<br> + A for DST to ST switch first hour<br> + B for DST to ST switch second hour if not marked in H<br> + F minute<br> + G second<br> + H timezone<br> + I day of week<br> + J week of year<br> + K day of year<br> + L month for next ST/DST changes<br> + M day<br> + N hour<br> + O UTC year<br> + P UTC month<br> + Q UTC day<br> + R UTC hour<br> + S UTC minute<br> + T modified julian day (MJD)<br> + U DUT1<br> + V direction and month if leap second<br> + W signal delay (assumed/measured)<br> + X sequence number for additional text line in Y<br> + Y additional text<br> + Z on time marker (* - assumed delay / # measured delay)<br> + <CR>!<LF> ! is second change !<br> + </font></p> + <p>This format is an ITU-R Recommendation (ITU-R TF583.4) and is now available from the primary timing centres of the following countries: Austria, Belgium, Germany, Italy, The Netherlands, Poland, Portugal, Romania, Spain, Sweden, Switzerland, Turkey, United Kingdom. Some examples are:</p> + <ul> + <li>In Germany by Physikalisch-Technische Bundesanstalt (PTB)'s timecode service. Phone number: +49 5 31 51 20 38. + <p>For more detail, see <a href="http://www.ptb.de/english/org/4/43/433/disse.html">http://www.ptb.de/english/org/4/43/433/disse.htm</a></p> + <li>In the UK by National Physical Laboratory (NPL)'s TRUETIME service. Phone number: 0891 516 333 + <p>For more detail, see <a href="http://www.npl.co.uk/npl/ctm/truetime.html">http://www.npl.co.uk/npl/ctm/truetime.html</a></p> + <li>In Italy by Istituto Elettrotecnico Nazionale "Galileo Ferrais" (IEN)'s CTD service. Phone number: 166 11 46 15 + <p>For more detail, see <a href="http://www.ien.it/tf/time/Pagina42.html">http://www.ien.it/tf/time/Pagina42.html</a></p> + <li>In Switzerland by Swiss Federal Office of Metrology 's timecode service. Phone number: 031 323 32 25 + <p>For more detail, see <a href="http://www.ofmet.admin.ch/de/labors/4/Zeitvert.html%20">http://www.ofmet.admin.ch/de/labors/4/Zeitvert.html </a></p> + <li>In Sweden by SP Swedish National Testing and Research Institute 's timecode service. Phone number: +46 33 415783. + <p>For more detail, see <a href="http://www.sp.se/metrology/timefreq/eng/tandf.htm">http://www.sp.se/metrology/timefreq/eng/tandf.htm</a><br> + </p> + </ul> + <h4>Fudge Factors</h4> + <dl> + <dt><tt>time1 <i>time</i></tt> + <dd>Specifies the time offset calibration factor, in seconds and fraction, with default 0.0. + <dt><tt>time2 <i>time</i></tt> + <dd>Not used by this driver. + <dt><tt>stratum <i>number</i></tt> + <dd>Specifies the driver stratum, in decimal from 0 to 15, with default 0. + <dt><tt>refid <i>string</i></tt> + <dd>Specifies the driver reference identifier, an ASCII string from one to four characters, with default PTB. + <dt><tt>flag1 0 | 1</tt> + <dd>Not used by this driver. + <dt><tt>flag2 0 | 1</tt> + <dd>Not used by this driver. + <dt><tt>flag3 0 | 1</tt> + <dd>Not used by this driver. + <dt><tt>flag4 0 | 1</tt> + <dd>Not used by this driver. + </dl> + <h4>Additional Information</h4> + <p>A keyword in the ntp.conf file permits a direct connection to a serial port of source of time like IEN CTD signal. It is sufficient to use the string DIRECT in place of the phone number.</p> + <p>Example:</p> + <p><font face="Courier New">server 127.127.23.1</font></p> + <p><font face="Courier New">phone DIRECT</font></p> + <h4>Additional Information</h4> + <p><a href="../refclock.html">Reference Clock Drivers</a></p> + <hr> + <script type="text/javascript" language="javascript" src="../scripts/footer.txt"></script> + </body> + +</html>
\ No newline at end of file diff --git a/html/drivers/driver24.html b/html/drivers/driver24.html new file mode 100644 index 0000000..8bdf837 --- /dev/null +++ b/html/drivers/driver24.html @@ -0,0 +1,46 @@ +<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> + +<html> + + <head> + <meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1"> + <meta name="GENERATOR" content="Mozilla/4.01 [en] (Win95; I) [Netscape]"> + <title>USNO Modem Time Service</title> + <link href="../scripts/style.css" type="text/css" rel="stylesheet"> + </head> + + <body> + <h3>USNO Modem Time Service</h3> + <hr> + <h4>Synopsis</h4> + <p>Address: 127.127.24.<i>u</i><br> + Reference ID: <tt>USNO</tt><br> + Driver ID: <tt>ACTS_USNO</tt><br> + Serial Port: <tt>/dev/cua<i>u</i></tt>; 1200 baud, 8-bits, no parity<br> + Requires: <tt>/usr/include/sys/termios.h</tt> header file with modem control</p> + <h4>Description</h4> + <p>No information available.</p> + <h4>Fudge Factors</h4> + <dl> + <dt><tt>time1 <i>time</i></tt> + <dd>Specifies the time offset calibration factor, in seconds and fraction, with default 0.0. + <dt><tt>time2 <i>time</i></tt> + <dd>Not used by this driver. + <dt><tt>stratum <i>number</i></tt> + <dd>Specifies the driver stratum, in decimal from 0 to 15, with default 0. + <dt><tt>refid <i>string</i></tt> + <dd>Specifies the driver reference identifier, an ASCII string from one to four characters, with default <tt>USNO</tt>. + <dt><tt>flag1 0 | 1</tt> + <dd>Not used by this driver. + <dt><tt>flag2 0 | 1</tt> + <dd>Not used by this driver. + <dt><tt>flag3 0 | 1</tt> + <dd>Not used by this driver. + <dt><tt>flag4 0 | 1</tt> + <dd>Enable <tt>clockstats</tt> recording if set. + </dl> + <hr> + <script type="text/javascript" language="javascript" src="../scripts/footer.txt"></script> + </body> + +</html>
\ No newline at end of file diff --git a/html/drivers/driver26.html b/html/drivers/driver26.html new file mode 100644 index 0000000..2facea1 --- /dev/null +++ b/html/drivers/driver26.html @@ -0,0 +1,50 @@ +<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> + +<html> + + <head> + <meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1"> + <meta name="GENERATOR" content="Mozilla/4.01 [en] (Win95; I) [Netscape]"> + <title>Hewlett Packard 58503A GPS Receiver</title> + <link href="../scripts/style.css" type="text/css" rel="stylesheet"> + </head> + + <body> + <h3>Hewlett Packard 58503A GPS Receiver</h3> + <hr> + <h4>Synopsis</h4> + <p>Address: 127.127.26.<i>u</i><br> + Reference ID: <tt>GPS</tt><br> + Driver ID: <tt>GPS_HP</tt><br> + Serial Port: <tt>/dev/hpgps<i>u</i></tt>; 9600 baud, 8-bits, no parity</p> + <h4>Description</h4> + <p>This driver supports the HP 58503A Time and Frequency Reference Receiver. It uses HP SmartClock (TM) to implement an Enhanced GPS receiver. The receiver accuracy when locked to GPS in normal operation is better than 1 usec. The accuracy when operating in holdover is typically better than 10 us per day. It receiver should be operated with factory default settings. Initial driver operation: expects the receiver to be already locked to GPS, configured and able to output timecode format 2 messages.</p> + <p>The driver uses the poll sequence <tt>:PTIME:TCODE?</tt> to get a response from the receiver. The receiver responds with a timecode string of ASCII printing characters, followed by a <cr><lf>, followed by a prompt string issued by the receiver, in the following format:</p> + <pre>T#yyyymmddhhmmssMFLRVcc<cr><lf></pre> + The driver processes the response at the <cr> and <lf><cr> and <lf>, so what the driver sees is the prompt from the previous poll, followed by this timecode. The prompt from the current poll is (usually) left unread until the next poll. So (except on the very first poll) the driver sees this: + <pre>T#yyyymmddhhmmssMFLRVcc<cr><lf></pre> + <p>The T is the on-time character, at 980 msec. before the next 1PPS edge. The # is the timecode format type. We look for format 2. Without any of the CLK or PPS stuff, then, the receiver buffer timestamp at the <cr>y is 24 characters later, which is about 25 msec. at 9600 bps, so the first approximation for fudge time1 is nominally -0.955 seconds. This number probably needs adjusting for each machine / OS type, so far: -0.955000 on an HP 9000 Model 712/80 HP-UX 9.05 -0.953175 on an HP 9000 Model 370 HP-UX 9.10</p> + <h4>Fudge Factors</h4> + <dl> + <dt><tt>time1 <i>time</i></tt> + <dd>Specifies the time offset calibration factor, in seconds and fraction, with default 0.0. + <dt><tt>time2 <i>time</i></tt> + <dd>Not used by this driver. + <dt><tt>stratum <i>number</i></tt> + <dd>Specifies the driver stratum, in decimal from 0 to 15, with default 0. + <dt><tt>refid <i>string</i></tt> + <dd>Specifies the driver reference identifier, an ASCII string from one to four characters, with default <tt>GPS</tt>. + <dt><tt>flag1 0 | 1</tt> + <dd>Not used by this driver. + <dt><tt>flag2 0 | 1</tt> + <dd>Not used by this driver. + <dt><tt>flag3 0 | 1</tt> + <dd>Not used by this driver. + <dt><tt>flag4 0 | 1</tt> + <dd>Not used by this driver. + </dl> + <hr> + <script type="text/javascript" language="javascript" src="../scripts/footer.txt"></script> + </body> + +</html>
\ No newline at end of file diff --git a/html/drivers/driver27.html b/html/drivers/driver27.html new file mode 100644 index 0000000..ab406a6 --- /dev/null +++ b/html/drivers/driver27.html @@ -0,0 +1,249 @@ +<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> + +<html> + + <head> + <meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1"> + <meta name="GENERATOR" content="Mozilla/4.01 [en] (Win95; I) [Netscape]"> + <title>Arcron MSF Receiver</title> + <link href="../scripts/style.css" type="text/css" rel="stylesheet"> + </head> + + <body> + <h3>Arcron MSF Receiver</h3> + <hr> + <h4>Synopsis</h4> + <p>Address: 127.127.27.<i>u</i><br> + Reference ID: <tt>MSFa</tt> / <tt>MSF</tt> / <tt>DCF</tt> / <tt>WWVB</tt><br> + Driver ID: <tt>MSF_ARCRON</tt><br> + Serial Port: <tt>/dev/arc<i>u</i></tt>; 300 baud, 8-bits, 2-stop, no parity<br> + Features: <tt>tty_clk</tt></p> + <h4>Description</h4> + <p>This driver supports the Arcron MSF, DCF and WWVB receivers. The clock reports its ID as ``<tt>MSFa</tt>'', ``<tt>MSF</tt>'', ``<tt>DCF</tt>'' or ``<tt>WWVB</tt>'' to indicate the time source.</p> + <p>This documentation describes v1.3 (2003/2/21) of the source and has been tested against ntpd 4.1.0 on linux x86. Changes from v1.1 and v1.2 include patches to work with the new ntp-4 code, clock support for DCF and WWVB configurable via mode flag, an option to ignore resync request (for those of us at the fringes of the WWVB signal, for instance), averaging of the signal quality poll and several bug fixes, code cleanup and standardizations. In all other respects, the driver works as per v1.1 if a mode is not specified.</p> + <p>To use the alternate modes, the mode flag must be specified. If the mode flag is 0, or unspecified, the original MSF version is assumed. This should assure backwards compatibility and should not break existing setups.</p> + + <p>The previous documentation described version V1.1 (1997/06/23) of the source and had been tested (amongst others) against ntpd3-5.90 on Solaris-1 (SunOS 4.1.3_U1 on an SS1 serving as a router and firewall) and against ntpd3-5.90 on Solaris-2.5 (on a SS1+ and TurboSPARC 170MHz). That code will claimed increased stability, reduced jitter and more efficiency (fewer context switches) with the <tt>tty_clk</tt> discipline/STREAMS module installed, but this has not been tested. For a to-do list see the comments at the start of the code.</p> + <p>This code has been significantly slimmed down since the V1.0 version, roughly halving the memory footprint of its code and data.</p> + <p>This driver is designed to allow the unit to run from batteries as designed, for something approaching the 2.5 years expected in the usual stand-alone mode, but no battery-life measurements have been taken.</p> + <p>Much of this code is originally from the other refclock driver files with thanks. The code was originally made to work with the clock by <a href="mailto:derek@toybox.demon.co.uk">Derek Mulcahy</a>, with modifications by <a href="mailto:d@hd.org">Damon Hart-Davis</a>. Thanks also to <a href="mailto:lyndond@sentinet.co.uk">Lyndon David</a> for some of the specifications of the clock. <a href="mailto:palfille@partners.org">Paul Alfille</a> added support for the WWVB clock. <a href="mailto:cprice@cs-home.com">Christopher Price</a> added enhanced support for the MSF, DCF and WWVB clocks.</p> + <p>There is support for a Tcl/Tk monitor written by Derek Mulcahy that examines the output stats; see the <a href="http://www2.exnet.com/NTP/ARC/ARC.html">ARC Rugby MSF Receiver</a> page for more details and the code. Information on the WWVB version is available from <a href="http://www.arctime.com">Atomic Time</a> as their <a href="http://www.atomictime.com/Product17.html">Atomic Time PC</a>.</p> + <p>Look at the notes at the start of the code for further information; some of the more important details follow.</p> + <p>The driver interrogates the clock at each poll (ie every 64s by default) for a timestamp. The clock responds at the start of the next second (with the start bit of the first byte being on-time). In the default or original MSF mode, the time is in `local' format, including the daylight savings adjustment when it is in effect. The driver code converts the time back to UTC. In modes 1-3 the driver can be configured for UTC or local time depending on the setting of flag1.</p> + <p>The clock claims to be accurate to within about 20ms of the broadcast time, and given the low data transmission speed from clock to host, and the fact that the clock is not in continuous sync with MSF, it seems sensible to set the `precision' of this clock to -5 or -4, -4 being used in this code, which builds in a reported dispersion of over 63ms (ie says ``This clock is not very good.''). You can improve the reported precision to -4 (and thus reduce the base dispersion to about 31ms) by setting the fudge <tt>flag3</tt> to <tt>1</tt>.</p> + <p>Even a busy and slow IP link can yield lower dispersions than this from polls of primary time servers on the Internet, which reinforces the idea that this clock should be used as a backup in case of problems with such an IP link, or in the unfortunate event of failure of more accurate sources such as GPS.</p> + <p>By default this clock reports itself to be at stratum 2 rather than the usual stratum 0 for a refclock, because it is not really suited to be used as other than a backup source. The stratum reported can be changed with the <tt>stratum</tt> directive to be whatever you like. After careful monitoring of your clock, and appropriate choice of the <tt>time1</tt> fudge factor to remove systematic errors in the clock's reported time, you might fudge the clock to stratum 1 to allow a stratum-2 secondary server to sync to it.</p> + <p>In default mode, the driver code arranges to resync the clock to MSF at intervals of a little less than an hour (deliberately avoiding the same time each hour to avoid any systematic problems with the signal or host). Whilst resyncing, the driver supplements the normal polls for time from the clock with polls for the reception signal quality reported by the clock. If the signal quality is too low (0--2 out of a range of 0--5), we chose not to trust the clock until the next resync (which we bring forward by about half an hour). If we don't catch the resync, and so don't know the signal quality, we do trust the clock (because this would generally be when the signal is very good and a resync happens quickly), but we still bring the next resync forward and reduce the reported precision (and thus increase reported dispersion).</p> + <p>If we force resyncs to MSF too often we will needlessly exhaust the batteries the unit runs from. During clock resync this driver tries to take enough time samples to avoid <tt>ntpd</tt> losing sync in case this clock is the current peer. By default the clock would only resync to MSF about once per day, which would almost certainly not be acceptable for NTP purposes.</p> + <p>The driver does not force an immediate resync of the clock to MSF when it starts up to avoid excessive battery drain in case <tt>ntpd</tt> is going to be repeatedly restarted for any reason, and also to allow enough samples of the clock to be taken for <tt>ntpd</tt> to sync immediately to this clock (and not remain unsynchronised or to sync briefly to another configured peer, only to hop back in a few poll times, causing unnecessary disturbance). This behaviour should not cause problems because the driver will not accept the timestamps from the clock if the status flag delivered with the time code indicates that the last resync attempt was unsuccessful, so the initial timestamps will be close to reality, even if with up to a day's clock drift in the worst case (the clock by default resyncs to MSF once per day).</p> + <p>When alternate modes 1-3 are selected, the driver can be configured to ignore the resync requests by setting <tt>flag2</tt> to 1. This allows clocks at the fringe of the signal to resync at night when signals are stronger.</p> + <p>The clock has a peculiar RS232 arrangement where the transmit lines are powered from the receive lines, presumably to minimise battery drain. This arrangement has two consequences:</p> + <ul> + <li>Your RS232 interface must drive both +ve and -ve + <li>You must (in theory) wait for an echo and a further 10ms between characters + </ul> + <p>This driver, running on standard Sun and x86 hardware, seems to work fine; note the use of the <tt>send_slow()</tt> routine to queue up command characters to be sent once every two seconds.</p> + <p>Three commands are sent to the clock by this driver. Each command consists of a single letter (of which only the bottom four bits are significant), followed by a CR (ASCII 13). Each character sent to the clock should be followed by a delay to allow the unit to echo the character, and then by a further 10ms. Following the echo of the command string, there may be a response (ie in the case of the <tt>g</tt> and <tt>o</tt> commands below), which in the case of the <tt>o</tt> command may be delayed by up to 1 second so as the start bit of the first byte of the response can arrive on time. The commands and their responses are:</p> + <dl> + <dt><tt>g</tt> CR + <dd>Request for signal quality. Answer only valid during (late part of) resync to MSF signal. The response consists of two characters as follows: + <ol> + <dl compact> + <dt>bit 7 + <dd>parity + <dt>bit 6 + <dd>always 0 + <dt>bit 5 + <dd>always 1 + <dt>bit 4 + <dd>always 1 + <dt>bit 3 + <dd>always 0 + <dt>bit 2 + <dd>always 0 + <dt>bit 1 + <dd>always 1 + <dt>bit 0 + <dd>= 0 if no reception attempt at the moment, = 1 if reception attempt (ie resync) in progress + </dl> + <dl compact> + <dt>bit 7 + <dd>parity + <dt>bit 6 + <dd>always 0 + <dt>bit 5 + <dd>always 1 + <dt>bit 4 + <dd>always 1 + <dt>bit 3 + <dd>always 0 + <dt>bit 2--0 + <dd>reception signal quality in the range 0--5 (very poor to very good); if in the range 0--2 no successful reception is to be expected. The reported value drops to zero when not resyncing, ie when first returned byte is not `3'. + </dl> + </ol> + <dt><tt>h</tt> CR + <dd>Request to resync to signal. Can take up from about 30s to 360s. Drains batteries so should not be used excessively. After this the clock time and date should be correct and the phase within 20ms of time as transmitted from the source signal (remember to allow for propagation time). By default the clock resyncs once per day in the late evening/early morning (presumably to catch transitions to/from daylight saving time quickly). This driver code, by default, resyncs at least once per hour to minimise clock wander. + <dt><tt>o</tt> CR + <dd>Request timestamp. Start bit of first byte of response is on-time, so may be delayed up to 1 second. Note that the driver will convert time to GMT, if required. The response data is as follows: + <ol> + <li>hours tens (hours range from 00 to 23) + <li>hours units + <li>minutes tens (minutes range from 00 to 59) + <li>minutes units + <li>seconds tens (seconds presumed to range from 00 to 60 to allow for leap second) + <li>seconds units + <li>day of week 1 (Monday) to 7 (Sunday) + <li>day of month tens (day ranges from 01 to 31) + <li>day of month units + <li>month tens (months range from 01 to 12) + <li>month units + <li>year tens (years range from 00 to 99) + <li>year units + <li>BST/UTC status (Ignored in WWVB version) + <dl compact> + <dt>bit 7 + <dd>parity + <dt>bit 6 + <dd>always 0 + <dt>bit 5 + <dd>always 1 + <dt>bit 4 + <dd>always 1 + <dt>bit 3 + <dd>(MSF) always 0<br> + (WWVB) Leap year indicator bit<br> + 0 = non-leap year<br> + 1 = leap year + <dt>bit 2 + <dd>= (MSF) 1 if UTC is in effect (reverse of bit 1)<br> + (WWVB) Leap second warning bit + <dt>bit 1 + <dd>= (MSF)1 if BST is in effect (reverse of bit 2)<br> + = (WWVB) 0 if ST is in effect, 1 if DST is in effect, 1 if transition from ST with bit 0 is set to 0 + <dt>bit 0 + <dd>= (MSF)1 if BST/UTC change pending<br> + = (WWVB) 0 if ST is in effect, 1 if DST is in effect, 0 if transition from DST with bit 1 is set to 0 + </dl> + <li>clock status + <dl compact> + <dt>bit 7 + <dd>parity + <dt>bit 6 + <dd>always 0 + <dt>bit 5 + <dd>always 1 + <dt>bit 4 + <dd>always 1 + <dt>bit 3 + <dd>= 1 if low battery is detected + <dt>bit 2 + <dd>= 1 if last resync failed (though officially undefined for the MSF clock, officially defined for WWVB) + <dt>bit 1 + <dd>= 1 if at least one reception attempt was successful<br> + (MSF) since 0230<br> + (DCF) since 0300<br> + (WWVB) resets if not successful between 0300-0400 + <dt>bit 0 + <dd>= 1 if the clock has valid time---reset to zero when clock is reset (eg at power-up), and set to 1 after first successful resync attempt. + </dl> + </ol> + <p>The driver only accepts time from the clock if the bottom three bits of the status byte are <tt>011</tt> or <tt>flag2</tt> is set to 1 to ignore resync requests. For the MSF clock, if the UK parliament decides to move us to +0100/+0200 time as opposed to the current +0000/+0100 time, it is not clear what effect that will have on the time broadcast by MSF, and therefore on this driver's usefulness.</p> + </dl> + <p>A typical <tt>ntp.conf</tt> configuration file for this driver might be:</p> + <pre># hostname(n) means we expect (n) to be the stratum at which hostname runs. + +#------------------------------------------------------------------------------ +# SYNCHRONISATION PARTNERS +# ======================== + +# Default configuration (Original MSF mode)s... +server 127.127.27.0 mode 333 # ARCRON MSF radio clock +# Fudge stratum and other features as required. +# ADJUST time1 VALUE FOR YOUR HOST, CLOCK AND LOCATION! +fudge 127.127.27.0 stratum 1 time1 0.016 flag3 1 +# WWVB users should change that line to: +server 127.127.27.0 mode 3 # ARCRON WWVB radio clock +fudge 127.127.27.0 stratum 1 time1 0.030 flag1 1 flag3 1 + +peer 11.22.33.9 # tick(1--2). +peer 11.22.33.4 # tock(3), boot/NFS server. + +# This shouldn't get swept away unless left untouched for a long time. +driftfile /var/tmp/ntp.drift + +#------------------------------------------------------------------------------ +# RESTRICTIONS +# ============ + +# By default, don't trust and don't allow modifications. Ignore in fact. +restrict default ignore notrust nomodify + +# Allow others in our subnet to check us out... +restrict 11.22.33.0 mask 255.255.255.0 nomodify notrust + +# Trust our peers for time. Don't trust others in case they are insane. +restrict 127.127.27.0 nomodify +restrict 11.22.33.4 nomodify +restrict 11.22.33.9 nomodify + +# Allow anything from the local host. +restrict 127.0.0.1</pre> + There are a few <tt>#define</tt>s in the code that you might wish to play with: + <dl> + <dt><tt>ARCRON_KEEN</tt> + <dd>With this defined, the code is relatively trusting of the clock, and assumes that you will have the clock as one of a few time sources, so will bend over backwards to use the time from the clock when available and avoid <tt>ntpd</tt> dropping sync from the clock where possible. You may wish to undefine this, especially if you have better sources of time or your reception is ropey. However, there are many checks built in even with this flag defined. + <dt><tt>ARCRON_MULTIPLE_SAMPLES</tt> + <dd>When is defined, we regard each character in the returned timecode as at a known delay from the start of the second, and use the smallest (most negative) offset implied by any such character, ie with the smallest kernel-induced display, and use that. This helps to reduce jitter and spikes. + <dt><tt>ARCRON_LEAPSECOND_KEEN</tt> + <dd>When is defined, we try to do a resync to MSF as soon as possible in the first hour of the morning of the first day of the first and seventh months, ie just after a leap-second insertion or deletion would happen if it is going to. This should help compensate for the fact that this clock does not continuously sample MSF, which compounds the fact that MSF itself gives no warning of an impending leap-second event. This code did not seem functional at the leap-second insertion of 30th June 1997 so is by default disabled. + <dt><tt>PRECISION</tt> + <dd>Currently set to <tt>-4</tt>, but you may wish to set it to <tt>-5</tt> if you are more conservative, or to <tt>-6</tt> if you have particularly good experience with the clock and you live on the edge. Note that the <tt>flag3</tt> fudge value will improve the reported dispersion one notch if clock signal quality is known good. So maybe just leave this alone. + </dl> + <h4>Monitor Data</h4> + <p>Each timecode is written to the <tt>clockstats</tt> file with a signal quality value appended (`0'--`5' as reported by the clock, or `6' for unknown).</p> + <p>Each resync and result (plus gaining or losing MSF sync) is logged to the system log at level <tt>LOG_NOTICE</tt>; note that each resync drains the unit's batteries, so the syslog entry seems justified.</p> + <p>Syslog entries are of the form:</p> + <pre>May 10 10:15:24 oolong ntpd[615]: ARCRON: unit 0: sending resync command +May 10 10:17:32 oolong ntpd[615]: ARCRON: sync finished, signal quality 5: OK, will use clock +May 10 11:13:01 oolong ntpd[615]: ARCRON: unit 0: sending resync command +May 10 11:14:06 oolong ntpd[615]: ARCRON: sync finished, signal quality -1: UNKNOWN, will use clock anyway +May 10 11:41:49 oolong ntpd[615]: ARCRON: unit 0: sending resync command +May 10 11:43:57 oolong ntpd[615]: ARCRON: sync finished, signal quality 5: OK, will use clock +May 10 12:39:26 oolong ntpd[615]: ARCRON: unit 0: sending resync command +May 10 12:41:34 oolong ntpd[615]: ARCRON: sync finished, signal quality 3: OK, will use clock</pre> + <h4>Fudge Factors</h4> + <p></p> + <dl> + <dt><tt>mode 0 | 1 | 2 | 3</tt></dt> + <dd>Specifies the clock hardware model. This parameter is optional, it defaults to the original mode of operation. + <dd>Supported modes of operation: + <dd>0 - Default, Original MSF + <dd>1 - Updated MSF + <dd>2 - New DCF77 + <dd>3 - New WWVB + <dt><tt>time1 <i>time</i></tt> + <dd>Specifies the time offset calibration factor, in seconds and fraction, with default 0.0. On a Sun SparcStation 1 running SunOS 4.1.3_U1, with the receiver in London, a value of 0.020 (20ms) seems to be appropriate. + <dt><tt>time2 <i>time</i></tt> + <dd>Not currently used by this driver. + <dt><tt>stratum <i>number</i></tt> + <dd>Specifies the driver stratum, in decimal from 0 to 15, with default 2. It is suggested that the clock be not be fudged higher than stratum 1 so that it is used a backup time source rather than a primary when more accurate sources are available. + <dt><tt>refid <i>string</i></tt> + <dd>Specifies the driver reference identifier, an ASCII string from one to four characters, with default <tt>MSFa</tt>. When used in modes 1-3, the driver will report either <tt>MSF</tt>, <tt>DCF</tt>, or <tt>WWVB</tt> respectively. + <dt><tt>flag1 0 | 1</tt> + <dd>(Modes 1-3) If set to 0 (the default), the clock is set to UTC time. If set to 1, the clock is set to localtime. + <dt><tt>flag2 0 | 1</tt> + <dd>(Modes 1-3) If set to 0 (the default), the clock will be forced to resync approximately every hour. If set to 1, the clock will resync per normal operations (approximately midnight). + <dt><tt>flag3 0 | 1</tt> + <dd>If set to 1, better precision is reported (and thus lower dispersion) while clock's received signal quality is known to be good. + <dt><tt>flag4 0 | 1</tt> + <dd>Not used by this driver. + </dl> + <h4>Additional Information</h4> + <p><a href="../refclock.html">Reference Clock Drivers</a><br> + <a href="http://www2.exnet.com/NTP/ARC/ARC.html">ARC Rugby MSF Receiver</a></p> + <hr> + <script type="text/javascript" language="javascript" src="../scripts/footer.txt"></script> + </body> + +</html> + diff --git a/html/drivers/driver28.html b/html/drivers/driver28.html new file mode 100644 index 0000000..5013ae3 --- /dev/null +++ b/html/drivers/driver28.html @@ -0,0 +1,76 @@ +<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> + +<html> + + <head> + <meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1"> + <meta name="GENERATOR" content="Mozilla/4.01 [en] (Win95; I) [Netscape]"> + <title>Shared memoy Driver</title> + <link href="../scripts/style.css" type="text/css" rel="stylesheet"> + </head> + + <body> + <h3>Shared Memory Driver</h3> + <hr> + <h4>Synopsis</h4> + <p>Address: 127.127.28.<i>u</i><br> + Reference ID: <tt>SHM</tt><br> + Driver ID: <tt>SHM</tt></p> + <h4>Description</h4> + <p>This driver receives its reference clock info from a shared memory-segment. The shared memory-segment is created with owner-only access for unit 0 and 1, and world access for unit 2 and 3</p> + <h4>Structure of shared memory-segment</h4> + <pre>struct shmTime { + int mode; /* 0 - if valid set + * use values, + * clear valid + * 1 - if valid set + * if count before and after read of + * values is equal, + * use values + * clear valid + */ + int count; + time_t clockTimeStampSec; /* external clock */ + int clockTimeStampUSec; /* external clock */ + time_t receiveTimeStampSec; /* internal clock, when external value was received */ + int receiveTimeStampUSec; /* internal clock, when external value was received */ + int leap; + int precision; + int nsamples; + int valid; + int dummy[10]; +};</pre> + <h4>Operation mode=0</h4> + <p>When the poll-method of the driver is called, the valid-flag of the shared memory-segment is checked:</p> + <p>If set, the values in the record (clockTimeStampSec, clockTimeStampUSec, receiveTimeStampSec, receiveTimeStampUSec, leap, precision) are passed to ntp, and the valid-flag is cleared.</p> + <p>If not set, a timeout is reported to ntp, nothing else happend</p> + <h4>Operation mode=1</h4> + <p>When the poll-method of the driver is called, the valid-flag of the shared memory-segment is checked:</p> + <p>If set, the count-field of the record is remembered, and the values in the record (clockTimeStampSec, clockTimeStampUSec, receiveTimeStampSec, receiveTimeStampUSec, leap, precision) are read. Then, the remembered count is compared to the count now in the record. If both are equal, the values read from the record are passed to ntp. If they differ, another process has modified the record while it was read out (was not able to produce this case), and failure is reported to ntp. The valid flag is cleared.</p> + <p>If not set, a timeout is reported to ntp, nothing else happend</p> + <h4>Fudge Factors</h4> + <dl> + <dt><tt>time1 <i>time</i></tt> + <dd>Specifies the time offset calibration factor, in seconds and fraction, with default 0.0. + <dt><tt>time2 <i>time</i></tt> + <dd>Not used by this driver. + <dt><tt>stratum <i>number</i></tt> + <dd>Specifies the driver stratum, in decimal from 0 to 15, with default 0. + <dt><tt>refid <i>string</i></tt> + <dd>Specifies the driver reference identifier, an ASCII string from one to four characters, with default <tt>SHM</tt>. + <dt><tt>flag1 0 | 1</tt> + <dd>Not used by this driver. + <dt><tt>flag2 0 | 1</tt> + <dd>Not used by this driver. + <dt><tt>flag3 0 | 1</tt> + <dd>Not used by this driver. + <dt><tt>flag4 0 | 1</tt> + <dd>Not used by this driver. + <h4>Additional Information</h4> + <p><a href="../refclock.html">Reference Clock Drivers</a></p> + </dl> + <hr> + <script type="text/javascript" language="javascript" src="../scripts/footer.txt"></script> + </body> + +</html>
\ No newline at end of file diff --git a/html/drivers/driver29.html b/html/drivers/driver29.html new file mode 100644 index 0000000..65600bf --- /dev/null +++ b/html/drivers/driver29.html @@ -0,0 +1,797 @@ +<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> + +<html> + + <head> + <meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1"> + <title>Trimble Palisade Receiver</title> + <link href="../scripts/style.css" type="text/css" rel="stylesheet"> + </head> + + <body bgcolor="#FFFFFF" text="#000000" link="#0000FF" vlink="#800080" alink="#FF0000"> + <h1><font size="+2">Trimble Palisade Receiver</font> + <hr> + </h1> + <h2><img src="../pic/driver29.gif" nosave height="100" width="420"></h2> + <h2><font size="+1">Synopsis</font></h2> + <table> + <tr> + <td> + <div align="right"> + <tt>Address: </tt></div> + </td> + <td><b>127.127.29.<i>u</i></b></td> + </tr> + <tr> + <td> + <div align="right"> + <tt>Reference ID:</tt></div> + </td> + <td><a name="REFID"></a><b>GPS</b></td> + </tr> + <tr> + <td> + <div align="right"> + <tt>Driver ID:</tt></div> + </td> + <td><b>GPS_PALISADE</b></td> + </tr> + <tr> + <td> + <div align="right"> + <tt>Serial Port:</tt></div> + </td> + <td><b>/dev/palisade<i>u</i></b></td> + </tr> + <tr> + <td> + <div align="right"> + <tt><font size="+1">Serial I/O:</font></tt></div> + </td> + <td><b>9600 baud, 8-bits, 1-stop, odd parity</b></td> + </tr> + </table> + <h2><font size="+1">Description</font></h2> + The <b>refclock_palisade</b> driver supports <a href="http://www.trimble.com/products/ntp">Trimble Navigation's Palisade Smart Antenna GPS receiver</a>.<br> + Additional software and information about the Palisade GPS is available from: <a href="http://www.trimble.com/oem/ntp">http://www.trimble.com/oem/ntp</a>.<br> + Latest NTP driver source, executables and documentation is maintained at: <a href="ftp://ftp.trimble.com/pub/ntp">ftp://ftp.trimble.com/pub/ntp</a> + <p>This documentation describes version 7.12 of the GPS Firmware and version 2.46 (July 15, 1999) and later, of the driver source.<br> + </p> + <h2><font size="+1">Operating System Compatibility</font></h2> + The Palisade driver has been tested on the following software and hardware platforms:<br> + + <center> + <table> + <tr> + <td valign="CENTER" width="23%">Platform</td> + <td valign="CENTER">Operating System</td> + <td>NTP Sources</td> + <td>Accuracy</td> + </tr> + <tr> + <td valign="CENTER" width="23%">i386 (PC) </td> + <td valign="CENTER">Linux</td> + <td>NTP Distribution</td> + <td>10 us</td> + </tr> + <tr> + <td>i386 (PC) </td> + <td>Windows NT</td> + <td><a href="ftp://ftp.trimble.com/pub/ntp">ftp://ftp.trimble.com/pub/ntp</a></td> + <td>1 ms</td> + </tr> + <tr> + <td valign="CENTER" width="23%">SUN</td> + <td valign="CENTER">Solaris 2.x</td> + <td>NTP Distribution</td> + <td>50 us</td> + </tr> + <tr> + <td valign="CENTER" width="23%">Hewlett-Packard</td> + <td valign="CENTER">HPUX 9, 10, 11</td> + <td><a href="http://us-support.external.hp.com">http://us-support.external.hp.com</a></td> + <td>50 us</td> + </tr> + <tr> + <td>Various</td> + <td>Free BSD</td> + <td>NTP Distribution</td> + <td>20 us</td> + </tr> + </table> + </center> + <h2><font size="+1">GPS Receiver</font></h2> + The Palisade GPS receiver is an 8-channel smart antenna, housing the GPS receiver, antenna and interface in a single unit, and is designed for rooftop deployment in static timing applications. + <p>Palisade generates a PPS synchronized to UTC within +/- 100 ns. The Palisade's external event input with 40 nanosecond resolution is utilized by the Palisade NTP driver for asynchronous precision time transfer.</p> + <p>No user initialization of the receiver is required. This driver is compatible with the following versions of Palisade:<br> + </p> + <center> + <table> + <tr> + <td valign="CENTER"> + <center> + Version</center> + </td> + <td valign="TOP"> + <center> + Event Input</center> + </td> + <td valign="CENTER"> + <center> + Trimble Part Number</center> + </td> + </tr> + <tr> + <td valign="CENTER"> + <center> + 7.02</center> + </td> + <td valign="TOP"> + <center> + No</center> + </td> + <td valign="CENTER"> + <center> + 26664-00</center> + </td> + </tr> + <tr> + <td align="CENTER" valign="CENTER"> + <center> + 7.02E</center> + </td> + <td valign="TOP"> + <center> + Yes</center> + </td> + <td valign="CENTER"> + <center> + 26664-10</center> + </td> + </tr> + <tr> + <td valign="CENTER"> + <center> + 7.12</center> + </td> + <td valign="TOP"> + <center> + Yes</center> + </td> + <td valign="CENTER"> + <center> + 38158-00</center> + </td> + </tr> + </table> + </center> + <dl> + <dl> + Note: When using Palisade 26664-00, you must set fudge flag2 to 1 in <b>ntp.conf</b>. See <a href="#Configuration">configuration</a>. + </dl> + <dl> + <h3><font size="+1">GPS <a name="Installation"></a>Installation</font></h3> + A location with unobstructed view of the horizon is recommended. Palisade is designed to be securely mounted atop standard 3/4 inch threaded pipe. + <p>The 12 conductor (dia. 10 mm) power and I/O cable must be routed from the rooftop site to the NTP server and properly strain relieved.</p> + <h3><font size="+1">GPS <a name="Connection"></a>Connection</font></h3> + The Palisade is equipped with dual (A & B) RS-422 serial interfaces and a differential TTL PPS output. An RS-232 / RS-422 Interface Module is supplied with the Palisade NTP Synchronization Kit. Palisade <a href="#PortA">port A</a> must be connected to the NTP host server. Maximum antenna cable length is 500 meters. See the <a href="#Pinouts">pinouts</a> table for detailed connection Information. + <p>Palisade's <a href="#PortB">port B</a> provides a TSIP (Trimble Standard Interface Protocol) interface for diagnostics, configuration, and monitoring. Port B and the PPS output are not currently used by the Palisade NTP reference clock driver.<br> + </p> + </dl> + </dl> + <h2><font size="+1">O/S Serial Port Configuration</font></h2> + The driver attempts to open the device <b><tt><a href="#REFID">/dev/palisade<i>u</i></a></tt></b> where <b><i>u</i></b> is the NTP refclock unit number as defined by the LSB of the refclock address. Valid refclock unit numbers are 0 - 3. + <p>The user is expected to provide a symbolic link to an available serial port device. This is typically performed by a command such as:</p> + <blockquote> + <tt>ln -s /dev/ttyS0 /dev/palisade0</tt></blockquote> + Windows NT does not support symbolic links to device files. COM<b>x</b>: is used by the driver, based on the refclock unit number, where unit 1 corresponds to COM<b>1</b>: and unit 3 corresponds to COM3:<br> + + <h2><a name="Configuration"></a><font size="+1">NTP Configuration</font></h2> + Palisade NTP configuration file <b><tt>"ntp.conf"</tt></b> with event polling:<br> + <tt>#------------------------------------------------------------------------------</tt><br> + <tt># The Primary reference</tt><br> + <tt>server 127.127.29.0 # Trimble Palisade GPS Refclock Unit #0</tt><br> + <tt>peer terrapin.csc.ncsu.edu # internet server</tt><br> + <tt># Drift file for expedient re-synchronization after downtime or reboot.</tt><br> + <tt>driftfile /etc/ntp.drift</tt><br> + <tt>#------------------------------------------------------------------------------</tt> + <p>Configuration without event polling:<br> + <tt>#------------------------------------------------------------------------------</tt><br> + <tt># The Primary reference</tt><br> + <tt>server 127.127.29.0 # Trimble Palisade GPS (Stratum 1).</tt><br> + <tt># Set packet delay</tt><br> + <tt><a href="#time1">fudge 127.127.29.0 time1 0.020</a></tt><br> + <tt># and set flag2 to turn off event polling.</tt><br> + <tt><a href="#flag2">fudge 127.127.29.0 flag2 1</a></tt><br> + <tt>#------------------------------------------------------------------------------</tt><br> + </p> + <h2><a name="TimeTransfer"></a><font size="+1">Time Transfer and Polling</font></h2> + Time transfer to the NTP host is performed via the Palisade's comprehensive time packet output. The time packets are output once per second, and whenever an event timestamp is requested. + <p>The driver requests an event time stamp at the end of each polling interval, by pulsing the RTS (request to send) line on the serial port. The Palisade GPS responds with a time stamped event packet.</p> + <p>Time stamps are reported by the Palisade with respect to UTC time. The GPS receiver must download UTC offset information from GPS satellites. After an initial UTC download, the receiver will always start with correct UTC offset information.<br> + </p> + <h2><font size="+1">Run NTP in Debugging Mode</font></h2> + The following procedure is recommended for installing and testing a Palisade NTP driver: + <ol> + <li>Perform initial checkout procedures. Place the GPS receiver outdoors; with clear view of the sky. Allow the receiver to obtain an UTC almanac. + <li>Verify presence of timing packets by observing the 1 Hz (PPS) led on the interface module. It should flash once per second. + <li>Connect Palisade's port A to the NTP host. + <li>Configure NTP and the serial I/O port on the host system. + <li>Initially use <tt><a href="#flag2">fudge flag2</a></tt> in <b><a href="#Configuration">ntp.conf</a>,</b> to disable event polling (see configuration). + <li>Run NTP in debug mode (-d -d), to observe Palisade_receive events. + <li>The driver reports the <a href="#TrackingStatus">tracking status of the receiver</a>. Make sure it is tracking several satellites. + <li>Remove fudge flag2 and restart <b>ntpd</b> in debug mode to observe palisade_receive events. + <li>If event polling fails, verify the <a href="#Pinouts">connections</a> and that the host hardware supports RTS control. + </ol> + <h2><font size="+1">Event Logging</font></h2> + System and Event log entries are generated by NTP to report significant system events. Administrators should monitor the system log to observe NTP error messages. Log entries generated by the Palisade NTP reference clock driver will be of the form: + <blockquote> + <pre>Nov 14 16:16:21 terrapin ntpd[1127]: Palisade #0: <i>message</i></pre> + </blockquote> + <h2><font size="+1">Fudge Factors</font></h2> + <dl> + <dt><a name="time1"></a><tt><font size="+1"><a href="#Configuration">time1 <i>time</i></a></font></tt> + <dd>Specifies the time offset calibration factor, in seconds and fraction, with default 0.0. If event capture is not used, time1 should be set to 20 milliseconds to correct serial line and operating system delays incurred in capturing time stamps from the synchronous packets. + <dt><tt><font size="+1">stratum <i>number</i></font></tt> + <dd>Specifies the driver stratum, in decimal from 0 to 15, with default 0. + <dt><tt><font size="+1"><a href="#REFID">refid <i>string</i></a></font></tt> + <dd>Specifies the driver reference identifier, <b>GPS</b>. + <dt><a name="flag2"></a><tt><font size="+1"><a href="#Configuration">flag2 0 | 1</a></font></tt> + <dd>When set to 1, driver does not use hardware event capture. The synchronous packet output by the receiver at the beginning of each second is time stamped by the driver. If triggering the event pulse fails, the driver falls back to this mode automatically. + </dl> + <h2><font size=+1>Mode Parameter</font></h2> + <dl> + <dt><tt><font size=+1>mode <i>number</i></font></tt></dt> + <dd>The mode parameter to the server command specifies the specific hardware this driver is for. The default is 0 for a normal Trimble Palisade. The only other option at this time is 1 for a Endrun Praecis in Trimble emulation mode. + </dl> + <h2><font size="+1">DEFINEs</font></h2> + The following constants are defined in the driver source code. These defines may be modified to improve performance or adapt to new operating systems.<br> + + <center> + <table border> + <tr> + <td><b>Label</b></td> + <td>Definition</td> + <td>Default Value</td> + </tr> + <tr> + <td>DEVICE</td> + <td>The serial port device to be used by the driver</td> + <td>/dev/palisade<b><i>u</i></b></td> + </tr> + <tr> + <td>PRECISION</td> + <td>Accuracy of time transfer</td> + <td>1 microsecond</td> + </tr> + <tr> + <td>CURRENT_UTC</td> + <td>Valid GPS - UTC offset</td> + <td>13</td> + </tr> + <tr> + <td>SPEED232</td> + <td>Host RS-232 baud rate</td> + <td>B9600</td> + </tr> + <tr> + <td>TRMB_MINPOLL </td> + <td>Minimum polling interval</td> + <td>5 (32 seconds)</td> + </tr> + <tr> + <td>TRMB_MAXPOLL</td> + <td>Maximum interval between polls</td> + <td>7 (128 seconds)</td> + </tr> + </table> + </center> + <h2><a name="DataFormat"></a><font size="+1">Data Format</font></h2> + Palisade port A can output two synchronous time packets. The NTP driver can use either packet for synchronization. Packets are formatted as follows: + <h3><b><font size="+0">Packet 8F-AD (Primary NTP Packet)</font></b></h3> + <center> + <table> + <tr> + <td>Byte</td> + <td>Item</td> + <td>Type</td> + <td>Meaning</td> + </tr> + <tr> + <td>0</td> + <td>Sub-Packet ID</td> + <td>BYTE</td> + <td>Subcode 0xAD</td> + </tr> + <tr> + <td>1 - 2</td> + <td>Event Count</td> + <td>INTEGER</td> + <td>External event count recorded (0 = PPS)</td> + </tr> + <tr> + <td>3 - 10</td> + <td>Fractional Second</td> + <td>DOUBLE</td> + <td>Time elapsed in current second (s)</td> + </tr> + <tr> + <td>11</td> + <td>Hour</td> + <td>BYTE</td> + <td>Hour (0 - 23)</td> + </tr> + <tr> + <td>12</td> + <td>Minute</td> + <td>BYTE</td> + <td>Minute (0 - 59)</td> + </tr> + <tr> + <td>13</td> + <td>Second</td> + <td>BYTE</td> + <td>Second (0 - 59; 60 = leap)</td> + </tr> + <tr> + <td>14</td> + <td>Day</td> + <td>BYTE</td> + <td>Date (1 - 31)</td> + </tr> + <tr> + <td>15</td> + <td>Month</td> + <td>BYTE</td> + <td>Month (1 - 12)</td> + </tr> + <tr> + <td>16 - 17</td> + <td>Year</td> + <td>INTEGER</td> + <td>Year (4 digit)</td> + </tr> + <tr> + <td>18</td> + <td>Receiver Status</td> + <td>BYTE</td> + <td>Tracking Status</td> + </tr> + <tr> + <td>19</td> + <td>UTC Flags</td> + <td>BYTE</td> + <td>Leap Second Flags</td> + </tr> + <tr> + <td>20</td> + <td>Reserved</td> + <td>BYTE</td> + <td>Contains 0xFF</td> + </tr> + <tr> + <td>21</td> + <td>Reserved</td> + <td>BYTE</td> + <td>Contains 0xFF</td> + </tr> + </table> + </center> + <blockquote> + <h4>Leap Second Flag Definition:</h4> + Bit 0: (1) UTC Time is available<br> + Bits 1 - 3: Undefined<br> + Bit 4: (1) Leap Scheduled: Leap second pending asserted by GPS control segment.<br> + Bit 5: (1) Leap Pending: set 24 hours before, until beginning of leap second.<br> + Bit 6: (1) GPS Leap Warning: 6 hours before until 6 hours after leap event<br> + Bit 7: (1) Leap In Progress. Only set during the leap second. + <h4><a name="TrackingStatus"></a>Tracking Status Flag Definitions:</h4> + </blockquote> + <center> + <table width="712" border="0" cellspacing="0"> + <tr> + <td valign="CENTER" width="5%">Code</td> + <td valign="CENTER" width="59%">Meaning</td> + <td>Accuracy</td> + <td>Receiver Mode</td> + </tr> + <tr> + <td>0</td> + <td>Receiver is Navigating</td> + <td>+/- 1 us</td> + <td>Self Survey</td> + </tr> + <tr> + <td valign="CENTER" width="5%">1</td> + <td valign="CENTER" width="59%">Static 1 Sat. Timing Mode </td> + <td>+/- 1 us</td> + <td>1-D Timing</td> + </tr> + <tr> + <td valign="CENTER" width="5%">2</td> + <td valign="CENTER" width="59%">Approximate Time</td> + <td>20 - 50 ms</td> + <td>Acquisition</td> + </tr> + <tr> + <td valign="CENTER" width="5%">3</td> + <td valign="CENTER" width="59%">Startup</td> + <td>N/A</td> + <td>Initialization</td> + </tr> + <tr> + <td valign="CENTER" width="5%">4</td> + <td valign="CENTER" width="59%">Startup</td> + <td>N/A</td> + <td>Initialization</td> + </tr> + <tr> + <td valign="CENTER" width="5%">5</td> + <td valign="CENTER" width="59%">Dilution of Position too High </td> + <td>5 ppm</td> + <td>Self Survey</td> + </tr> + <tr> + <td valign="CENTER" width="5%">6</td> + <td valign="CENTER" width="59%">Static 1 Sat. Timing: Sat. not usable</td> + <td>5 ppm</td> + <td>1-D Timing</td> + </tr> + <tr> + <td valign="CENTER" width="5%">7</td> + <td valign="CENTER" width="59%">No Satellites Usable</td> + <td>N/A</td> + <td>Self Survey</td> + </tr> + <tr> + <td valign="CENTER" width="5%">8</td> + <td valign="CENTER" width="59%">Only 1 Satellite Usable</td> + <td>20 - 50 ms</td> + <td>Self Survey</td> + </tr> + <tr> + <td valign="CENTER" width="5%">9</td> + <td valign="CENTER" width="59%">Only 2 Satellite Usable</td> + <td>20 - 50 ms</td> + <td>Self Survey</td> + </tr> + <tr> + <td valign="CENTER" width="5%">10</td> + <td valign="CENTER" width="59%">Only 3 Satellites Usable</td> + <td>20 - 50 ms</td> + <td>Self Survey</td> + </tr> + <tr> + <td valign="CENTER" width="5%">11</td> + <td valign="CENTER" width="59%">Invalid Solution</td> + <td>N/A</td> + <td>Error</td> + </tr> + <tr> + <td valign="CENTER" width="5%">12</td> + <td valign="CENTER" width="59%">Differential Corrections </td> + <td>N/A</td> + <td>N/A</td> + </tr> + <tr> + <td valign="CENTER" width="5%">13</td> + <td valign="CENTER" width="59%">Overdetermined Fixes</td> + <td>+/- 100 ns</td> + <td>Timing Steady State</td> + </tr> + </table> + </center> + <h3><b><font size="+0">Packet 8F-0B (Comprehensive Timing Packet)</font></b></h3> + <center> + <table border="0" cellspacing="0"> + <tr> + <td valign="CENTER" width="9%">Byte</td> + <td valign="CENTER" width="27%">Item</td> + <td valign="CENTER" width="16%">Type</td> + <td valign="CENTER" width="48%">Meaning</td> + </tr> + <tr> + <td valign="CENTER" width="9%">0</td> + <td valign="CENTER" width="27%">Sub-Packet ID</td> + <td valign="CENTER" width="16%">BYTE</td> + <td valign="CENTER" width="48%">Subcode 0x0B</td> + </tr> + <tr> + <td valign="TOP" width="9%">1 - 2</td> + <td valign="TOP" width="27%">Event Count</td> + <td valign="TOP" width="16%">INTEGER</td> + <td valign="TOP" width="48%">External event count recorded (0 = PPS)</td> + </tr> + <tr> + <td valign="TOP" width="9%">3 - 10</td> + <td valign="TOP" width="27%">UTC / GPS TOW</td> + <td valign="TOP" width="16%">DOUBLE</td> + <td valign="TOP" width="48%">UTC / GPS time of week (seconds)</td> + </tr> + <tr> + <td valign="CENTER" width="9%">11</td> + <td valign="CENTER" width="27%">Date</td> + <td valign="CENTER" width="16%">BYTE</td> + <td valign="CENTER" width="48%">Day of Month</td> + </tr> + <tr> + <td valign="CENTER" width="9%">12</td> + <td valign="CENTER" width="27%">Month</td> + <td valign="CENTER" width="16%">BYTE</td> + <td valign="CENTER" width="48%">Month of Event</td> + </tr> + <tr> + <td valign="CENTER" width="9%">13 - 14</td> + <td valign="CENTER" width="27%">Year</td> + <td valign="CENTER" width="16%">INT</td> + <td valign="CENTER" width="48%">Year of event</td> + </tr> + <tr> + <td valign="TOP" width="9%">15</td> + <td valign="TOP" width="27%">Receiver Mode</td> + <td valign="TOP" width="16%">BYTE</td> + <td valign="TOP" width="48%">Receiver operating dimensions: <br> + 0: Horizontal (2D) <br> + 1: Full Position (3D) <br> + 2: Single Satellite (0D) <br> + 3: Automatic (2D / 3D) <br> + 4: DGPS reference <br> + 5: Clock hold (2D) <br> + 6: Over determined Clock</td> + </tr> + <tr> + <td valign="CENTER" width="9%">15 - 17</td> + <td valign="CENTER" width="27%">UTC Offset</td> + <td valign="CENTER" width="16%">INTEGER</td> + <td valign="CENTER" width="48%">UTC Offset value (seconds)</td> + </tr> + <tr> + <td valign="CENTER" width="9%">18 - 25</td> + <td valign="CENTER" width="27%">Oscillator Bias</td> + <td valign="CENTER" width="16%">DOUBLE</td> + <td valign="CENTER" width="48%">Oscillator BIAS (meters)</td> + </tr> + <tr> + <td valign="TOP" width="9%">26 - 33</td> + <td valign="TOP" width="27%">Oscillator Drift Rate</td> + <td valign="TOP" width="16%">DOUBLE</td> + <td valign="TOP" width="48%">Oscillator Drift (meters / second)</td> + </tr> + <tr> + <td valign="CENTER" width="9%">34 - 37</td> + <td valign="CENTER" width="27%">Bias Uncertainty</td> + <td valign="CENTER" width="16%">SINGLE</td> + <td valign="CENTER" width="48%">Oscillator bias uncertainty (meters)</td> + </tr> + <tr> + <td valign="CENTER" width="9%">38 - 41</td> + <td valign="CENTER" width="27%">Drift Uncertainty</td> + <td valign="CENTER" width="16%">SINGLE</td> + <td valign="CENTER" width="48%">Oscillator bias rate uncertainty (m / sec)</td> + </tr> + <tr> + <td valign="CENTER" width="9%">42 - 49</td> + <td valign="CENTER" width="27%">Latitude</td> + <td valign="CENTER" width="16%">DOUBLE</td> + <td valign="CENTER" width="48%">Latitude in radians</td> + </tr> + <tr> + <td valign="CENTER" width="9%">50 - 57</td> + <td valign="CENTER" width="27%">Longitude</td> + <td valign="CENTER" width="16%">DOUBLE</td> + <td valign="CENTER" width="48%">Longitude in radians</td> + </tr> + <tr> + <td valign="CENTER" width="9%">58 - 65</td> + <td valign="CENTER" width="27%">Altitude</td> + <td valign="CENTER" width="16%">DOUBLE</td> + <td valign="CENTER" width="48%">Altitude above mean sea level, in meters</td> + </tr> + <tr> + <td valign="CENTER" width="9%">66 - 73</td> + <td valign="CENTER" width="27%">Satellite ID</td> + <td valign="CENTER" width="16%">BYTE</td> + <td valign="CENTER" width="48%">SV Id No. of tracked satellites</td> + </tr> + </table> + </center> + <h2><a name="Pinouts"></a><font size="+1">Pinouts</font></h2> + <a href="#Connection">The following connections are required when connecting Palisade with a host:</a><br> + <br> + + <center> + <table> + <tr> + <td><u>Description</u></td> + <td><b>Host</b></td> + <td></td> + <td></td> + <td><b>Palisade </b></td> + <td></td> + <td></td> + </tr> + <tr> + <td><a name="PortA"></a><b>Port A</b></td> + <td><u>DB-9</u></td> + <td><u>DB-25</u></td> + <td></td> + <td><u>RS-232</u></td> + <td><u>RS-422</u></td> + <td><u>Palisade Pin</u></td> + </tr> + <tr> + <td>Receive Data </td> + <td>2</td> + <td>3</td> + <td><--></td> + <td>Green</td> + <td>Green / Blue</td> + <td>8 (T-) & 10 (T+)</td> + </tr> + <tr> + <td>Request to Send</td> + <td>7</td> + <td>4</td> + <td><--></td> + <td>Gray</td> + <td>Gray / White</td> + <td>6 (R-) & 7 (R+)</td> + </tr> + <tr> + <td>Signal Ground</td> + <td>5</td> + <td>7</td> + <td><--></td> + <td>Black</td> + <td>Black</td> + <td>9 (GND)</td> + </tr> + <tr> + <td></td> + <td></td> + <td></td> + <td></td> + <td></td> + <td></td> + <td></td> + </tr> + <tr> + <td><a name="PortB"></a><b>Port B</b></td> + <td></td> + <td></td> + <td></td> + <td></td> + <td></td> + <td></td> + </tr> + <tr> + <td>Receive Data </td> + <td>2</td> + <td>3</td> + <td><--></td> + <td>Brown</td> + <td>Brown / Yellow</td> + <td>4 (T-) & 5 (T+)</td> + </tr> + <tr> + <td>Transmit Data</td> + <td>3</td> + <td>2</td> + <td><--></td> + <td>Violet</td> + <td>Orange/ Violet</td> + <td>2 (R-) & 3 (R+)</td> + </tr> + <tr> + <td>Signal Ground</td> + <td>5</td> + <td>7</td> + <td><--></td> + <td>Black</td> + <td>Black</td> + <td>9 (GND)</td> + </tr> + </table> + </center> + <blockquote> + Note: If driving the RS-422 inputs on the Palisade single ended, i.e. using the Green and Gray connections only, does not work on all serial ports. Use of the Palisade NTP Synchronization Interface Module is recommended.</blockquote> + <blockquote> + The 12 pin connector pinout definition:<br> + Face the round 12 pin connector at the end of the cable, with the notch turned upwards.<br> + Pin 1 is to the left of the notch. Pins 2 - 8 wrap around the bottom, counterclockwise to pin 9 on the right of the notch. Pin 10 is just below the notch. Pins 10 (top), 11 (bottom left) and 12 (bottom right) form a triangle in the center of the connector.</blockquote> + <blockquote> + <a name="SIM"></a>Pinouts for the Palisade NTP host adapter (Trimble PN 37070) DB-25 M connector are as follows:</blockquote> + <center> + <table width="682" border="0" cellspacing="0"> + <tr> + <td valign="CENTER" width="12%">DB-25M</td> + <td valign="CENTER" width="31%">Conductor </td> + <td valign="CENTER" width="16%">Palisade</td> + <td valign="CENTER" width="41%">Description</td> + </tr> + <tr> + <td valign="CENTER" width="12%">1 </td> + <td valign="CENTER" width="31%">Red</td> + <td valign="CENTER" width="16%">1</td> + <td valign="CENTER" width="41%">Power</td> + </tr> + <tr> + <td valign="CENTER" width="12%">7 </td> + <td valign="CENTER" width="31%">Black</td> + <td valign="CENTER" width="16%">9</td> + <td valign="CENTER" width="41%">Ground</td> + </tr> + <tr> + <td valign="CENTER" width="12%">9</td> + <td valign="CENTER" width="31%">Black/White</td> + <td valign="CENTER" width="16%">12</td> + <td valign="CENTER" width="41%">PPS -</td> + </tr> + <tr> + <td valign="CENTER" width="12%">10 </td> + <td valign="CENTER" width="31%">Green</td> + <td valign="CENTER" width="16%">8</td> + <td valign="CENTER" width="41%">Transmit Port A (T-)</td> + </tr> + <tr> + <td valign="CENTER" width="12%">11 </td> + <td valign="CENTER" width="31%">Brown</td> + <td valign="CENTER" width="16%">4</td> + <td valign="CENTER" width="41%">Transmit Port B (T-)</td> + </tr> + <tr> + <td valign="CENTER" width="12%">12 </td> + <td valign="CENTER" width="31%">Gray</td> + <td valign="CENTER" width="16%">7</td> + <td valign="CENTER" width="41%">Receive Port A (R+)</td> + </tr> + <tr> + <td valign="CENTER" width="12%">13</td> + <td valign="CENTER" width="31%">Orange</td> + <td valign="CENTER" width="16%">3</td> + <td valign="CENTER" width="41%">Receive Port B (R+)</td> + </tr> + <tr> + <td valign="CENTER" width="12%">21</td> + <td valign="CENTER" width="31%">Orange/White</td> + <td valign="CENTER" width="16%">11</td> + <td valign="CENTER" width="41%">PPS +</td> + </tr> + <tr> + <td valign="CENTER" width="12%">22</td> + <td valign="CENTER" width="31%">Blue</td> + <td valign="CENTER" width="16%">10</td> + <td valign="CENTER" width="41%">Transmit Port A (T+)</td> + </tr> + <tr> + <td valign="CENTER" width="12%">23</td> + <td valign="CENTER" width="31%">Yellow</td> + <td valign="CENTER" width="16%">5</td> + <td valign="CENTER" width="41%">Transmit Port B (T+)</td> + </tr> + <tr> + <td valign="CENTER" width="12%">24</td> + <td valign="CENTER" width="31%">White</td> + <td valign="CENTER" width="16%">6</td> + <td valign="CENTER" width="41%">Receive Port A (R-)</td> + </tr> + <tr> + <td valign="CENTER" width="12%">25</td> + <td valign="CENTER" width="31%">Violet</td> + <td valign="CENTER" width="16%">2</td> + <td valign="CENTER" width="41%">Receive Port B (R-)</td> + </tr> + </table> + </center> + <p></p> + <hr> + <p>Questions or Comments:<br> + <a href="mailto:sven_dietrich@trimble.com">Sven Dietrich</a><br> + <a href="http://www.trimble.com/">Trimble Navigation Ltd.</a></p> + <p>(last updated July 29, 1999)</p> + <hr> + <script type="text/javascript" language="javascript" src="../scripts/footer.txt"></script> + ; + </body> + +</html>
\ No newline at end of file diff --git a/html/drivers/driver3.html b/html/drivers/driver3.html new file mode 100644 index 0000000..7dcc092 --- /dev/null +++ b/html/drivers/driver3.html @@ -0,0 +1,76 @@ +<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> + +<html> + + <head> + <meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1"> + <meta name="GENERATOR" content="Mozilla/4.01 [en] (Win95; I) [Netscape]"> + <title>PSTI/Traconex 1020 WWV/WWVH Receiver</title> + <link href="../scripts/style.css" type="text/css" rel="stylesheet"> + </head> + + <body> + <h3>PSTI/Traconex 1020 WWV/WWVH Receiver</h3> + <hr> + <h4>Synopsis</h4> + <p>Address: 127.127.3.<i>u</i><br> + Reference ID: <tt>WWV</tt><br> + Driver ID: <tt>WWV_PST</tt><br> + Serial Port: <tt>/dev/wwv<i>u</i></tt>; 9600 baud, 8-bits, no parity<br> + Features: <tt>tty_clk</tt></p> + <h4>Description</h4> + <p>This driver supports the PSTI 1010 and Traconex 1020 WWV/WWVH Receivers. No specific claim of accuracy is made for these receiver, but actual experience suggests that 10 ms would be a conservative assumption.</p> + <p>The DIP-switches should be set for 9600 bps line speed, 24-hour day-of-year format and UTC time zone. Automatic correction for DST should be disabled. It is very important that the year be set correctly in the DIP-switches; otherwise, the day of year will be incorrect after 28 April of a normal or leap year. The propagation delay DIP-switches should be set according to the distance from the transmitter for both WWV and WWVH, as described in the instructions. While the delay can be set only to within 11 ms, the fudge time1 parameter can be used for vernier corrections.</p> + <p>Using the poll sequence <tt>QTQDQM</tt>, the response timecode is in three sections totalling 50 ASCII printing characters, as concatenated by the driver, in the following format:</p> + <pre> +ahh:mm:ss.fffs<cr> yy/dd/mm/ddd<cr> +frdzycchhSSFTttttuuxx<cr> + +on-time = first <cr> +hh:mm:ss.fff = hours, minutes, seconds, milliseconds +a = AM/PM indicator (' ' for 24-hour mode) +yy = year (from DIPswitches) +dd/mm/ddd = day of month, month, day of year +s = daylight-saving indicator (' ' for 24-hour mode) +f = frequency enable (O = all frequencies enabled) +r = baud rate (3 = 1200, 6 = 9600) +d = features indicator (@ = month/day display enabled) +z = time zone (0 = UTC) +y = year (5 = 91) +cc = WWV propagation delay (52 = 22 ms) +hh = WWVH propagation delay (81 = 33 ms) +SS = status (80 or 82 = operating correctly) +F = current receive frequency (4 = 15 MHz) +T = transmitter (C = WWV, H = WWVH) +tttt = time since last update (0000 = minutes) +uu = flush character (03 = ^c) +xx = 94 (unknown)</pre> + <p>The alarm condition is indicated by other than <tt>8</tt> at <tt>a</tt>, which occurs during initial synchronization and when received signal is lost for an extended period; unlock condition is indicated by other than <tt>0000</tt> in the <tt>tttt</tt> subfield.</p> + <h4>Monitor Data</h4> + <p>When enabled by the <tt>flag4</tt> fudge flag, every received timecode is written as-is to the <tt>clockstats</tt> file.</p> + <h4>Fudge Factors</h4> + <dl> + <dt><tt>time1 <i>time</i></tt> + <dd>Specifies the time offset calibration factor, in seconds and fraction, with default 0.0. + <dt><tt>time2 <i>time</i></tt> + <dd>Not used by this driver. + <dt><tt>stratum <i>number</i></tt> + <dd>Specifies the driver stratum, in decimal from 0 to 15, with default 0. + <dt><tt>refid <i>string</i></tt> + <dd>Specifies the driver reference identifier, an ASCII string from one to four characters, with default <tt>WWV</tt>. + <dt><tt>flag1 0 | 1</tt> + <dd>Not used by this driver. + <dt><tt>flag2 0 | 1</tt> + <dd>Not used by this driver. + <dt><tt>flag3 0 | 1</tt> + <dd>Not used by this driver. + <dt><tt>flag4 0 | 1</tt> + <dd>Not used by this driver. + </dl> + <h4>Additional Information</h4> + <p><a href="../refclock.html">Reference Clock Drivers</a></p> + <hr> + <script type="text/javascript" language="javascript" src="../scripts/footer.txt"></script> + </body> + +</html>
\ No newline at end of file diff --git a/html/drivers/driver30.html b/html/drivers/driver30.html new file mode 100644 index 0000000..34507f3 --- /dev/null +++ b/html/drivers/driver30.html @@ -0,0 +1,84 @@ +<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> + +<html> + + <head> + <meta http-equiv="Content-Type" content="text/html; charset=iso-8859- 1"> + <meta name="GENERATOR" content="Mozilla/4.06 [en] (X11; I; FreeBSD 3.0-CURRENT i386) [Netscape]"> + <title>Motorola Oncore GPS Receiver</title> + <link href="../scripts/style.css" type="text/css" rel="stylesheet"> + </head> + + <body> + <h3>Motorola Oncore GPS receiver</h3> + <hr> + <h4>Synopsis</h4> + <p>Address: 127.127.30.<i>u</i><br> + Reference ID: <tt>GPS</tt><br> + Driver ID: ONCORE<br> + Serial Port: <tt>/dev/oncore.serial.</tt><i>u</i>; 9600 baud, 8-bits, no parity.<br> + PPS Port: <tt>/dev/oncore.pps.</tt><i>u</i>; <tt>PPS_CAPTUREASSERT</tt> required, <tt>PPS_OFFSETASSERT</tt> supported.<br> + Configuration File: <tt>/etc/ntp.oncore</tt>, or <tt>/etc/ntp.oncore.</tt><i>u</i>, or <tt>/etc/ntp.oncore</tt><i>u</i>.</p> + <h4>Description</h4> + <p>This driver supports most models of the <a href="http://www.mot.com/AECS/PNSB/products">Motorola Oncore GPS receivers</a> (Basic, PVT6, VP, UT, UT+, GT, GT+, SL, M12), as long as they support the <i>Motorola Binary Protocol</i>.</p> + <p>The interesting versions of the Oncore are the VP, the UT+, the "Remote" which is a prepackaged UT+, and the M12 Timing. The VP is no longer available new, and the UT, GT, and SL are at end-of-life. The Motorola evaluation kit can be recommended. It interfaces to a PC straightaway, using the serial (DCD) or parallel port for PPS input and packs the receiver in a nice and sturdy box. Less expensive interface kits are available from <a href="http://www.tapr.org">TAPR</a> and <a href="http://www.synergy-gps.com">Synergy</a>.<br> + </p> + <center> + <table> + <tr> + <td><img src="../pic/oncore_utplusbig.gif" alt="gif" height="124" width="210"></td> + <td><img src="../pic/oncore_evalbig.gif" alt="gif" height="124" width="182"></td> + <td><img src="../pic/oncore_remoteant.jpg" alt="gif" height="188" width="178"></td> + </tr> + <tr> + <td> + <center> + UT+ oncore</center> + </td> + <td> + <center> + Evaluation kit</center> + </td> + <td> + <center> + Oncore Remote</center> + </td> + </tr> + </table> + </center> + <p>The driver requires a standard <tt>PPS</tt> interface for the pulse-per-second output from the receiver. The serial data stream alone does not provide precision time stamps (0-50msec variance, according to the manual), whereas the PPS output is precise down to 50 nsec (1 sigma) for the VP/UT models and 25 nsec for the M12 Timing. If you do not have the PPS signal available, then you should probably be using the NMEA driver rather than the Oncore driver.</p> + <p>The driver will use the "position hold" mode with user provided coordinates, the receivers built-in site-survey, or a similar algorithm implemented in this driver to determine the antenna position.</p> + <h4>Monitor Data</h4> + The driver always puts a lot of useful information on the clockstats file, and when run with debugging can be quite chatty on stdout. When first starting to use the driver you should definitely review the information written to the clockstats file to verify that the driver is running correctly. + <p>In addition, on platforms supporting Shared Memory, all of the messages received from the Oncore receiver are made available in shared memory for use by other programs. See the <a href="oncore-shmem.html">Oncore-SHMEM</a> manual page for information on how to use this option. For either debugging or using the SHMEM option, an Oncore Reference Manual for the specific receiver in use will be required.</p> + <h4>Fudge Factors</h4> + <dl> + <dt><tt>time1 <i>time</i></tt> + <dd>Specifies the time offset calibration factor, in seconds and fraction, with default 0.0. + <dt><tt>time2 <i>time</i></tt> + <dd>Not used by this driver. + <dt><tt>stratum <i>number</i></tt> + <dd>Specifies the driver stratum, in decimal from 0 to 15, with default 0. + <dt><tt>refid <i>string</i></tt> + <dd>Specifies the driver reference identifier, an ASCII string from one to four characters, with default <tt>GPS</tt>. + <dt><tt>flag1 0 | 1</tt> + <dd>Not used by this driver. + <dt><tt>flag2 0 | 1</tt> + <dd>Specifies the PPS signal on-time edge: 0 for assert (default), 1 for clear. + <dt><tt>flag3 0 | 1</tt> + <dd>Controls the kernel PPS discipline: 0 for disable (default), 1 for enable. + <dt><tt>flag4 0 | 1</tt> + <dd>Not used by this driver. + </dl> + <h4>Additional Information</h4> + <p>The driver was initially developed on FreeBSD, and has since been tested on Linux, SunOS and Solaris.</p> + <p><b>Configuration</b></p> + <p>There is a driver specific configuration file <tt>/etc/ntp.oncore</tt> (or <tt>/etc/ntp.oncore.</tt><i>u</i> or <tt>/etc/ntp.oncore</tt><i>u</i> if you must distinguish between more than one Oncore receiver) that contains information on the startup mode, the location of the GPS receiver, an offset of the PPS signal from zero, and the cable delay. The offset shifts the PPS signal to avoid interrupt pileups `on' the second, and adjust the timestamp accordingly. See the driver source for information on this file. The default with no file is: no delay, no offset, and a site survey is done to get the location of the gps receiver.</p> + <p>The edge of the PPS signal that is `on-time' can be set with either flag2 or in the driver specific configuration file with the keywords [ASSERT/CLEAR]. Flag3 (or the word HARDPPS in the driver specific configuration file) will cause the PPS signal to control the kernel PLL.</p> + <p><b>Performance</b></p> + <p>Really good. With the VP/UT+, the generated PPS pulse is referenced to UTC(GPS) with better than 50 nsec (1 sigma) accuracy. The limiting factor will be the timebase of the computer and the precision with which you can timestamp the rising flank of the PPS signal. Using FreeBSD, a FPGA based Timecounter/PPS interface, and an ovenized quartz oscillator, that performance has been reproduced. For more details on this aspect: <a href="http://phk.freebsd.dk/rover.html">Sub-Microsecond timekeeping under FreeBSD</a>.</p> + <hr> + <script type="text/javascript" language="javascript" src="../scripts/footer.txt"></script> + </body> + +</html>
\ No newline at end of file diff --git a/html/drivers/driver32.html b/html/drivers/driver32.html new file mode 100644 index 0000000..18beaaa --- /dev/null +++ b/html/drivers/driver32.html @@ -0,0 +1,38 @@ +<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> + +<html> + + <head> + <meta http-equiv="Content-Type" content="text/html; charset=iso8859-1"> + <title>Chrono-log K-series WWVB receiver</title> + <link href="../scripts/style.css" type="text/css" rel="stylesheet"> + </head> + + <body> + <h3>Chrono-log K-series WWVB receiver</h3> + <hr> + <h4>Synopsis</h4> + <p>Address: 127.127.32.<i>u</i><br> + Reference ID: <tt>CHRONOLOG</tt><br> + Driver ID: <tt>CHRONOLOG</tt><br> + Serial Port: <tt>/dev/chronolog<i>u</i></tt>; 2400 bps, 8-bits, no parity<br> + <br> + Features: <tt>(none)</tt></p> + <h4>Description</h4> + <p>This driver supports the Chrono-log K-series WWVB receiver. This is a very old receiver without provisions for leap seconds, quality codes, etc. It assumes output in the local time zone, and that the C library mktime()/localtime() routines will correctly convert back and forth between local and UTC. There is a hack in the driver for permitting UTC, but it has not been tested.</p> + <p>Most of this code is originally from refclock_wwvb.c with thanks. It has been so mangled that wwvb is not a recognizable ancestor.</p> + <pre> +Timecode format: Y yy/mm/ddCLZhh:mm:ssCL +Y - year/month/date line indicator +yy/mm/dd -- two-digit year/month/day +C - \r (carriage return) +L - \n (newline) +Z - timestamp indicator +hh:mm:ss - local time +</pre> + <!-- hhmts start -->Last modified: Sun Feb 14 11:57:27 EST 1999 <!-- hhmts end --> + <hr> + <script type="text/javascript" language="javascript" src="../scripts/footer.txt"></script> + </body> + +</html>
\ No newline at end of file diff --git a/html/drivers/driver33.html b/html/drivers/driver33.html new file mode 100644 index 0000000..ea77345 --- /dev/null +++ b/html/drivers/driver33.html @@ -0,0 +1,35 @@ +<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> + +<html> + + <head> + <meta http-equiv="Content-Type" content="text/html; charset=iso8859-1"> + <title>Dumb Clock</title> + <link href="../scripts/style.css" type="text/css" rel="stylesheet"> + </head> + + <body> + <h3>Dumb Clock</h3> + <hr> + <h4>Synopsis</h4> + <p>Address: 127.127.33.<i>u</i><br> + Reference ID: <tt>DUMBCLOCK</tt><br> + Driver ID: <tt>DUMBCLOCK</tt><br> + Serial Port: <tt>/dev/dumbclock<i>u</i></tt>; 9600 bps, 8-bits, no parity<br> + Features: <tt>(none)</tt></p> + <h4>Description</h4> + <p>This driver supports a dumb ASCII clock that only emits localtime at a reliable interval. This has no provisions for leap seconds, quality codes, etc. It assumes output in the local time zone, and that the C library mktime()/localtime() routines will correctly convert back and forth between local and UTC.</p> + <p>Most of this code is originally from refclock_wwvb.c with thanks. It has been so mangled that wwvb is not a recognizable ancestor.</p> + <pre> +Timecode format: hh:mm:ssCL +hh:mm:ss - local time +C - \r (carriage return) +L - \n (newline) +</pre> + <hr> + <!-- hhmts start -->Last modified: Sun Feb 14 12:07:01 EST 1999 <!-- hhmts end --> + <hr> + <script type="text/javascript" language="javascript" src="../scripts/footer.txt"></script> + </body> + +</html>
\ No newline at end of file diff --git a/html/drivers/driver34.html b/html/drivers/driver34.html new file mode 100644 index 0000000..dc37f3b --- /dev/null +++ b/html/drivers/driver34.html @@ -0,0 +1,88 @@ +<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> + +<html> + + <head> + <meta http-equiv="Content-Type" content="text/html; charset=iso8859-1"> + <title>Ultralink Clock</title> + <link href="../scripts/style.css" type="text/css" rel="stylesheet"> + </head> + + <body> + <h3>Ultralink Clock</h3> + <hr> + <h4>Synopsis</h4> + Address: 127.127.34.<i>u</i><br> + Reference ID: <tt>WWVB</tt><br> + Driver ID: <tt>ULINK</tt><br> + Serial Port: <tt>/dev/wwvb<i>u</i></tt>; 9600 bps, 8-bits, no parity<br> + <br> + Features: <tt>(none)</tt> + <h4>Description</h4> + <p>This driver supports the Ultralink Model 320 RS-232 powered WWVB receiver. PDF specs available on <a href="http://www.ulio.com">www.ulio.com</a>. This driver also supports the Model 330,331,332 decoders in both polled or continous time code mode. Leap second and quality are supported.</p> + <p>Most of this code is originally from refclock_wwvb.c with thanks. Any mistakes are mine. Any improvements are welcome.</p> + <hr> + <pre> + The Model 320 timecode format is: + + <cr><lf>SQRYYYYDDD+HH:MM:SS.mmLT<cr> + + where: + + S = 'S' -- sync'd in last hour, '0'-'9' - hours x 10 since last update, else '?' + Q = Number of correlating time-frames, from 0 to 5 + R = 'R' -- reception in progress, 'N' -- Noisy reception, ' ' -- standby mode + YYYY = year from 1990 to 2089 + DDD = current day from 1 to 366 + + = '+' if current year is a leap year, else ' ' + HH = UTC hour 0 to 23 + MM = Minutes of current hour from 0 to 59 + SS = Seconds of current minute from 0 to 59 + mm = 10's milliseconds of the current second from 00 to 99 + L = Leap second pending at end of month -- 'I' = inset, 'D'=delete + T = DST <-> STD transition indicators + </pre> + <p>Note that this driver does not do anything with the T flag.</p> + <p>The M320 also has a 'U' command which returns UT1 correction information. It is not used in this driver.</p> + <hr> + <pre> + The Model 33x timecode format is: + + S9+D 00 YYYY+DDDUTCS HH:MM:SSl+5 + + Where: + + S = sync indicator S insync N not in sync + the sync flag is WWVB decoder sync + nothing to do with time being correct + 9+ = signal level 0 thru 9+ If over 9 indicated as 9+ + D = data bit ( fun to watch but useless ;-) + space + 00 = hours since last GOOD WWVB frame sync + space + YYYY = current year + + = leap year indicator + DDD = day of year + UTC = timezone (always UTC) + S = daylight savings indicator + space + HH = hours + : = This is the REAL in sync indicator (: = insync) + MM = minutes + : = : = in sync ? = NOT in sync + SS = seconds + L = leap second flag + +5 = UT1 correction (sign + digit )) + </pre> + <p>This driver ignores UT1 correction,DST indicator,Leap year and signal level.</p> + <hr> + <h4>Fudge factors</h4> + <p>flag1 polling enable (1=poll 0=no poll)</p> + <hr> + <address><a href="mailto:dstrout@linuxfoundary.com">mail</a></address> + <!-- hhmts start -->Last modified: Tue Sep 14 05:53:08 EDT 1999 <!-- hhmts end --> + <hr> + <script type="text/javascript" language="javascript" src="../scripts/footer.txt"></script> + </body> + +</html>
\ No newline at end of file diff --git a/html/drivers/driver35.html b/html/drivers/driver35.html new file mode 100644 index 0000000..20ed717 --- /dev/null +++ b/html/drivers/driver35.html @@ -0,0 +1,47 @@ +<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> + +<html> + + <head> + <title>Conrad parallel port radio clock</title> + <link href="../scripts/style.css" type="text/css" rel="stylesheet"> + </head> + + <body> + <h3>Conrad parallel port radio clock</h3> + <hr> + <h4>Synopsis</h4> + <p>Address: 127.127.35.<i>u</i><br> + Reference ID: <tt>PCF</tt><br> + Driver ID: <tt>PCF</tt><br> + Parallel Port: <tt>/dev/pcfclocks/<i>u</i></tt> or <tt>/dev/pcfclock<i>u</i></tt></p> + <h4>Description</h4> + <p>This driver supports the parallel port radio clock sold by <a href="http://www.conrad-electronic.com/">Conrad Electronic</a> under order numbers 967602 and 642002. This clock is put between a parallel port and your printer. It receives the legal German time, which is either CET or CEST, from the DCF77 transmitter and uses it to set its internal quartz clock. The DCF77 transmitter is located near to Frankfurt/Main and covers a radius of more than 1500 kilometers.</p> + <p>The pcfclock device driver is required in order to use this reference clock driver. Currently device drivers for <a href="http://home.pages.de/%7evoegele/pcf.html">Linux</a> and <a href="http://schumann.cx/pcfclock/">FreeBSD</a> are available.</p> + <p>This driver uses C library functions to convert the received timecode to UTC and thus requires that the local timezone be CET or CEST. If your server is not located in Central Europe you have to set the environment variable TZ to CET before starting <tt>ntpd</tt>.</p> + <h4>Monitor Data</h4> + <p>Each timecode is written to the <tt>clockstats</tt> file in the format <tt>YYYY MM DD HH MI SS</tt>.</p> + <h4>Fudge Factors</h4> + <dl> + <dt><tt>time1 <i>time</i></tt> + <dd>Specifies the time offset calibration factor, in seconds and fraction, with default 0.1725. + <dt><tt>time2 <i>time</i></tt> + <dd>Not used by this driver. + <dt><tt>stratum <i>number</i></tt> + <dd>Specifies the driver stratum, in decimal from 0 to 15, with default 0. + <dt><tt>refid <i>string</i></tt> + <dd>Specifies the driver reference identifier, an ASCII string from one to four characters, with default <tt>PCF</tt>. + <dt><tt>flag1 0 | 1</tt> + <dd>Not used by this driver. + <dt><tt>flag2 0 | 1</tt> + <dd>If set to 1, the radio clock's synchronisation status bit is ignored, ie the timecode is used without a check. + <dt><tt>flag3 0 | 1</tt> + <dd>Not used by this driver. + <dt><tt>flag4 0 | 1</tt> + <dd>Not used by this driver. + </dl> + <hr> + <script type="text/javascript" language="javascript" src="../scripts/footer.txt"></script> + </body> + +</html>
\ No newline at end of file diff --git a/html/drivers/driver36.html b/html/drivers/driver36.html new file mode 100644 index 0000000..2644716 --- /dev/null +++ b/html/drivers/driver36.html @@ -0,0 +1,262 @@ +<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> + +<html> + + <head> + <meta name="generator" content="HTML Tidy, see www.w3.org"> + <title>Radio WWV/H Audio Demodulator/Decoder</title> + <link href="../scripts/style.css" type="text/css" rel="stylesheet"> + </head> + + <body> + <h3>Radio WWV/H Audio Demodulator/Decoder</h3> + <h4>Related Links</h4> + <script type="text/javascript" language="javascript" src="../scripts/links8.txt"></script> + <hr> + <h4>Synopsis</h4> + Address: 127.127.36.<i>u</i><br> + Reference ID: <tt>NONE</tt>, <tt>WV<i>f</i></tt> or <tt>WH<i>f</i></tt><br> + Driver ID: <tt>WWV_AUDIO</tt><br> + Autotune Port: <tt>/dev/icom</tt>; 1200/9600 baud, 8-bits, no parity<br> + Audio Device: <tt>/dev/audio</tt> and <tt>/dev/audioctl</tt> + <h4>Description</h4> + This driver synchronizes the computer time using data encoded in shortwave radio transmissions from NIST time/frequency stations <a href="http://www.bldrdoc.gov/timefreq/stations/wwv.html">WWV</a> in Ft. Collins, CO, and <a href="http://www.bldrdoc.gov/timefreq/stations/wwvh.htm">WWVH</a> in Kauai, HI. Transmissions are made continuously on 2.5, 5, 10 and 15 MHz from both stations and on 20 MHz from WWV. An ordinary shortwave receiver can be tuned manually to one of these frequencies or, in the case of ICOM receivers, the receiver can be tuned automatically by the driver as propagation conditions change throughout the day and night. The performance of this driver when tracking one of the stations is ordinarily better than 1 ms in time with frequency drift less than 0.5 PPM when not tracking either station. + <p>The demodulation and decoding algorithms used by this driver are based on a machine language program developed for the TAPR DSP93 DSP unit, which uses the TI 320C25 DSP chip. The analysis, design and performance of the program running on this unit is described in: Mills, D.L. A precision radio clock for WWV transmissions. Electrical Engineering Report 97-8-1, University of Delaware, August 1997, 25 pp. Available from <a href="http://www.eecis.udel.edu/%7emills/reports.html">www.eecis.udel.edu/~mills/reports.htm</a>. For use in this driver, the original program was rebuilt in the C language and adapted to the NTP driver interface. The algorithms have been modified somewhat to improve performance under weak signal conditions and to provide an automatic station identification feature.</p> + <p>This driver incorporates several features in common with other audio drivers such as described in the <a href="driver7.html">Radio CHU Audio Demodulator/Decoder</a> and the <a href="driver6.html">IRIG Audio Decoder</a> pages. They include automatic gain control (AGC), selectable audio codec port and signal monitoring capabilities. For a discussion of these common features, as well as a guide to hookup, debugging and monitoring, see the <a href="../audio.html">Reference Clock Audio Drivers</a> page.</p> + <p>The WWV signal format is described in NIST Special Publication 432 (Revised 1990). It consists of three elements, a 5-ms, 1000-Hz pulse, which occurs at the beginning of each second, a 800-ms, 1000-Hz pulse, which occurs at the beginning of each minute, and a pulse-width modulated 100-Hz subcarrier for the data bits, one bit per second. The WWVH format is identical, except that the 1000-Hz pulses are sent at 1200 Hz. Each minute encodes nine BCD digits for the time of century plus seven bits for the daylight savings time (DST) indicator, leap warning indicator and DUT1 correction.</p> + <h4>Program Architecture</h4> + <p>As in the original program, the clock discipline is modelled as a Markov process, with probabilistic state transitions corresponding to a conventional clock and the probabilities of received decimal digits. The result is a performance level which results in very high accuracy and reliability, even under conditions when the minute beep of the signal, normally its most prominent feature, can barely be detected by ear with a communications receiver.</p> + <p>The analog audio signal from the shortwave radio is sampled at 8000 Hz and converted to digital representation. The 1000/1200-Hz pulses and 100-Hz subcarrier are first separated using two IIR filters, a 600-Hz bandpass filter centered on 1100 Hz and a 150-Hz lowpass filter. The minute sync pulse is extracted using a 800-ms synchronous matched filter and pulse grooming logic which discriminates between WWV and WWVH signals and noise. The second sync pulse is extracted using a 5-ms FIR matched filter and 8000-stage comb filter.</p> + <p>The phase of the 100-Hz subcarrier relative to the second sync pulse is fixed at the transmitter; however, the audio stage in many radios affects the phase response at 100 Hz in unpredictable ways. The driver adjusts for each radio using two 170-ms synchronous matched filters. The I (in-phase) filter is used to demodulate the subcarrier envelope, while the Q (quadrature-phase) filter is used in a tracking loop to discipline the codec sample clock and thus the demodulator phase.</p> + <p>The data bit probabilities are determined from the subcarrier envelope using a threshold-corrected slicer. The averaged envelope amplitude 30 ms from the beginning of the second establishes the minimum (noise floor) value, while the amplitude 200 ms from the beginning establishes the maximum (signal peak) value. The slice level is midway between these two values. The negative-going envelope transition at the slice level establishes the length of the data pulse, which in turn establish probabilities for binary zero (P0) and binary one (P1). The data values are established by linear interpolation between the pulse lengths for P0 (-1) and P1 (+1). If the driver has not synchronized to the minute pulse, or if the data bit amplitude, signal/noise ratio (SNR) or length are below thresholds, the bit is considered invalid and the data value is ignored.</p> + <p>The difference between the P1 and P0 data values, or likelihood, for each data bit is exponentially averaged in a set of 60 accumulators, one for each second, to determine the semi-static miscellaneous bits, such as DST indicator, leap second warning and DUT1 correction. In this design a data average value larger than a positive threshold is interpreted as +1 (hit) and a value smaller than a negative threshold as a -1 (miss). Values between the two thresholds, which can occur due to signal fades or loss of signal, are interpreted as an erasure and result in no change of indication.</p> + <p>The BCD digit in each digit position of the timecode is represented as four data bits, all of which must be valid for the digit itself to be considered valid. If so, the bits are correlated with the bits corresponding to each of the valid decimal digits in this position. If the digit is invalid, the correlated value for all digits in this position is assumed zero. In either case, the values for all digits are exponentially averaged in a likelihood vector associated with this position. The digit associated with the maximum over all averaged values then becomes the maximum likelihood selection for this position and the ratio of the maximum over the next lower value becomes the likelihood ratio.</p> + <p>The decoding matrix contains nine row vectors, one for each digit position. Each row vector includes the maximum likelihood digit, likelihood vector and other related data. The maximum likelihood digit for each of the nine digit positions becomes the maximum likelihood time of the century. A built-in transition function implements a conventional clock with decimal digits that count the minutes, hours, days and years, as corrected for leap seconds and leap years. The counting operation also rotates the likelihood vector corresponding to each digit as it advances. Thus, once the clock is set, each clock digit should correspond to the maximum likelihood digit as transmitted.</p> + <p>Each row of the decoding matrix also includes a compare counter and the difference (modulo the radix) between the current clock digit and most recently determined maximum likelihood digit. If a digit likelihood exceeds the decision level and the difference is constant for a number of successive minutes in any row, the maximum likelihood digit replaces the clock digit in that row. When this condition is true for all rows and the second epoch has been reliably determined, the clock is set (or verified if it has already been set) and delivers correct time to the integral second. The fraction within the second is derived from the logical master clock, which runs at 8000 Hz and drives all system timing functions.</p> + <p>The logical master clock is derived from the audio codec clock. Its frequency is disciplined by a frequency-lock loop (FLL) which operates independently of the data recovery functions. At averaging intervals determined by the measured jitter, the frequency error is calculated as the difference between the most recent and the current second epoch divided by the interval. The sample clock frequency is then corrected by this amount. When first started, the frequency averaging interval is eight seconds, in order to compensate for intrinsic codec clock frequency offsets up to 125 PPM. Under most conditions, the averaging interval doubles in stages from the initial value to over 1000 seconds, which results in an ultimate frequency precision of 0.125 PPM, or about 11 ms/day.</p> + <p>It is important that the logical clock frequency is stable and accurately determined, since in most applications the shortwave radio will be tuned to a fixed frequency where WWV or WWVH signals are not available throughout the day. In addition, in some parts of the US, especially on the west coast, signals from either or both WWV and WWVH may be available at different times or even at the same time. Since the propagation times from either station are almost always different, each station must be reliably identified before attempting to set the clock.</p> + <p>Station identification uses the 800-ms minute pulse transmitted by each station. In the acquisition phase the entire minute is searched using both the WWV and WWVH matched filters and a pulse gate discriminator similar to that found in radar acquisition and tracking receivers. The peak amplitude found determines a range gate and window where the next pulse is expected to be found. The minute is scanned again to verify the peak is indeed in the window and with acceptable amplitude, SNR and jitter. At this point the receiver begins to track the second sync pulse and operate as above until the clock is set. Once the minute is synchronized, the range gate is fixed and only energy within the window is considered for the minute sync pulse.</p> + <p>It is very important to be able to reliably discriminate between very weak signals in noise and noise alone. The driver very aggresively soaks up every scrap of signal information, but has to be careful to avoid making pseudo-sense of noise alone. The signal quality metric depends on the minute pulse amplitude and SNR together with the data subcarrier amplitude and SNR. If all four values are above defined thresholds a hit is declared, otherwise a miss. The number of hits declared in the last six intervals is the high order bits of the metric value, while the current minute sync pulse amplitude is the low order bits. The metric value is represented on a scale from zero to 100. This is used as a quality indicator and reported in the timecode and also for the autotune function described below.</p> + <h4>Performance</h4> + <p>It is the intent of the design that the accuracy and stability of the indicated time be limited only by the characteristics of the ionospheric propagation medium. Conventional wisdom is that synchronization via the HF medium is good only to a millisecond under the best propagation conditions. The performance of the NTP daemon disciplined by the driver is clearly better than this, even under marginal conditions. Ordinarily, with marginal to good signals and a frequency averaging interval of 1024 s, the frequency is stabilized within 0.1 PPM and the time within 125 <font face="Symbol">m</font>s. The frequency stability characteristic is highly important, since the clock may have to free-run for several hours before reacquiring the WWV/H signal.</p> + <p>The expected accuracy over a typical day was determined using the DSP93 and an oscilloscope and cesium oscillator calibrated with a GPS receiver. With marginal signals and allowing 15 minutes for initial synchronization and frequency compensation, the time accuracy determined from the WWV/H second sync pulse was reliably within 125 <font face="Symbol">m</font>s. In the particular DSP-93 used for program development, the uncorrected CPU clock frequency offset was 45.8±0.1 PPM. Over the first hour after initial synchronization, the clock frequency drifted about 1 PPM as the frequency averaging interval increased to the maximum 1024 s. Once reaching the maximum, the frequency wandered over the day up to 1 PPM, but it is not clear whether this is due to the stability of the DSP-93 clock oscillator or the changing height of the ionosphere. Once the frequency had stabilized and after loss of the WWV/H signal, the frequency drift was less than 0.5 PPM, which is equivalent to 1.8 ms/h or 43 ms/d. This resulted in a step phase correction up to several milliseconds when the signal returned.</p> + <p>The measured propagation delay from the WWV transmitter at Boulder, CO, to the receiver at Newark, DE, is 23.5±0.1 ms. This is measured to the peak of the pulse after the second sync comb filter and includes components due to the ionospheric propagation delay, nominally 8.9 ms, communications receiver delay and program delay. The propagation delay can be expected to change about 0.2 ms over the day, as the result of changing ionosphere height. The DSP93 program delay was measured at 5.5 ms, most of which is due to the 400-Hz bandpass filter and 5-ms matched filter. Similar delays can be expected of this driver.</p> + <h4>Program Operation</h4> + The driver begins operation immediately upon startup. It first searches for one or both of the stations WWV and WWVH and attempts to acquire minute sync. This may take some fits and starts, as the driver expects to see three consecutive minutes with good signals and low jitter. If the autotune function is active, the driver will rotate over all five frequencies and both WWV and WWVH stations until three good minutes are found. + <p>When a minute sync candidate has been found, the driver acquires second sync, which can take up to several minutes, depending on signal quality. At the same time the driver accumulates likelihood values for each of the nine digits of the clock, plus the seven miscellaneous bits included in the WWV/H transmission format. When five repetitions of all nine digits have decoded correctly, which normally takes 15 minutes with good signals and up to an hour when buried in noise, and the second sync alarm has not been raised for two minutes, the clock is set (or verified) and is selectable to discipline the system clock.</p> + <p>As long as the clock is set or verified, the system clock offsets are provided once each second to the reference clock interface, where they are saved in a buffer. At the end of each minute the buffer samples are groomed by the median filter and trimmed-mean averaging functions. Using these functions, the system clock can in principle be disciplined to a much finer resolution than the 125-<font face="Symbol">m</font>s sample interval would suggest, although the ultimate accuracy is probably limited by propagation delay variations as the ionspheric height varies throughout the day and night.</p> + <p>The codec clock frequency is disciplined during times when WWV/H signals are available. The algorithm refines the frequency offset using increasingly longer averaging intervals to 1024 s, where the precision is about 0.1 PPM. With good signals, it takes well over two hours to reach this degree of precision; however, it can take many more hours than this in case of marginal signals. Once reaching the limit, the algorithm will follow frequency variations due to temperature fluctuations and ionospheric height variations.</p> + <p>It may happen as the hours progress around the clock that WWV and WWVH signals may appear alone, together or not at all. When the driver is first started, the NTP reference identifier appears as <tt>NONE</tt>. When the driver has mitigated which station and frequency is best, it sets the reference identifier to the string WV<i>f</i> for WWV and WH<i>f</i> for WWVH, where <i>f</i> is the frequency in megahertz. If the propagation delays have been properly set with the <tt>fudge time1</tt> (WWV) and <tt>fudge time2</tt> (WWVH) commands in the configuration file, handover from one station to the other is seamless.</p> + <p>Once the clock has been set for the first time, it will appear reachable and selectable to discipline the system clock, even if the broadcast signal fades to obscurity. A consequence of this design is that, once the clock is set, the time and frequency are disciplined only by the second sync pulse and the clock digits themselves are driven by the clock state machine. If for some reason the state machine drifts to the wrong second, it would never reresynchronize. To protect against this most unlikely situation, if after two days with no signals, the clock is considered unset and resumes the synchronization procedure from the beginning.</p> + <p>However, as long as the clock has once been set correctly and allowed to converge on the intrinsic codec clock frequency, it will continue to read correctly after a period of signal loss. Assuming the clock frequency can be disciplined within 1 PPM, it can coast without signals for several days without exceeding that NTP step threshold of 128 ms. During such periods the root dispersion increases at 5 <font face="Symbol">m</font>s per second, which makes the driver appears less likely for selection as time goes on. Eventually, when the dispersion due all causes exceeds 1 s, it is no longer suitable for synchronization at all.</p> + <p>To work well, the driver needs a shortwave receiver with good audio response at 100 Hz. Most shortwave and communications receivers roll off the audio response below 250 Hz, so this can be a problem, especially with receivers using DSP technology, since DSP filters can have very fast rolloff outside the passband. Some DSP transceivers, in particular the ICOM 775, have a programmable low frequency cutoff which can be set as low as 80 Hz. However, this particular radio has a strong low frequency buzz at about 10 Hz which appears in the audio output and can affect data recovery under marginal conditions. Although not tested, it would seem very likely that a cheap shortwave receiver could function just as well as an expensive communications receiver.</p> + <h4>Autotune</h4> + <p>The driver includes provisions to automatically tune the radio in response to changing radio propagation conditions throughout the day and night. The radio interface is compatible with the ICOM CI-V standard, which is a bidirectional serial bus operating at TTL levels. The bus can be connected to a serial port using a level converter such as the CT-17.</p> + <p>Each ICOM radio is assigned a unique 8-bit ID select code, usually expressed in hex format. To activate the CI-V interface, the <tt>mode</tt> keyword of the <tt>server</tt> configuration command specifies a nonzero select code in decimal format. A table of ID select codes for the known ICOM radios is given below. Since all ICOM select codes are less than 128, the high order bit of the code is used by the driver to specify the baud rate. If this bit is not set, the rate is 9600 bps for the newer radios; if set, the rate is 1200 bps for the older radios. A missing <tt>mode</tt> keyword or a zero argument leaves the interface disabled.</p> + <p>If specified, the driver will attempt to open the device <tt>/dev/icom</tt> and, if successful will activate the autotune function and tune the radio to each operating frequency in turn while attempting to acquire minute sync from either WWV or WWVH. However, the driver is liberal in what it assumes of the configuration. If the <tt>/dev/icom</tt> link is not present or the open fails or the CI-V bus or radio is inoperative, the driver quietly gives up with no harm done.</p> + <p>Once acquiring minute sync, the driver operates as described above to set the clock. However, during seconds 59, 0 and 1 of each minute it tunes the radio to one of the five broadcast frequencies to measure the sync pulse and data pulse amplitudes and SNR and update the signal metric. Each of the five frequencies are probed in a five-minute rotation to build a database of current propagation conditions for all signals that can be heard at the time. At the end of each probe a mitigation procedure scans the database and retunes the radio to the best frequency and station found. For this to work well, the radio should be set for a fast AGC recovery time. This is most important while tracking a strong signal, which is normally the case, and then probing another frequency, which may have much weaker signals.</p> + <p>Reception conditions for each frequency and station are evaluated according to the signal metric, which uses the minute sync pulse amplitude and SNR and data subcarrier amplitude and SNR. The minute pulse is evaluated at second 0, while the data pulse is evaluated at second 1. In principle, the data pulse in second 58 is usable, but the AGC in most radios is not fast enough for a reliable measurement.</p> + <p>The results are summarized in a scoreboard which drives the mitigation function.</p> + <dl> + <dt><tt>0x0001</tt> + <dd>Minute pulse error. For the minute sync pulse in second 0, either the amplitude or SNR is below threshold (2000 and 20 dB, respectively). + <dt><tt>0x0002</tt> + <dd>Data pulse error. For the data pulse in second 1, either the amplitude or SNR is below threshold (1000 and 10 dB, respectively). + <dt><tt>0x0004</tt> + <dd>Probe pulse error. Two or more decoding errors have occurred for the data pulses in seconds 58, 59 and 1. + </dl> + <p>If none of the scoreboard bits are set, a hit is declared, otherwise a miss. At the end of each probe, the frequency and station with the maximum metric is chosen, with ties going first to the highest frequency and then to WWV in order. During the acquisition phase a station is considered valid only if the metric is above 13; after the clock is synchronized a station is valid only if the metric is above 50. If no stations are valid, the driver ignores all signals and sets the reference ID field to NONE.</p> + <h4>Diagnostics</h4> + <p>The autotune process produces diagnostic information along with the timecode. This is very useful for evaluating the performance of the algorithms, as well as radio propagation conditions in general. The message is produced once each minute for each frequency in turn after minute sync has been acquired.</p> + <p><tt>wwv5 port status agc epoch count wwv wwvh</tt></p> + <p>where <tt>port</tt> and <tt>agc</tt> are the audio port and gain, respectively, for this frequency and <tt>wwv</tt> and <tt>wwvh</tt> are two sets of fields, one each for WWV and WWVH. Each of the two fields has the format</p> + <p><tt>ident score metric sync/snr</tt></p> + <p>where <tt>ident </tt>encodes the station (<tt>C</tt> for WWV, <tt>H</tt> for WWVH) and frequency (2, 5, 10, 15 or 20), <tt>score</tt> is a 32-bit shift register recording the hits (1) and misses (0) of the last 32 probes (hits and misses enter from the right), <tt>metric</tt> is as described above, <tt>sync</tt> is the minute sync pulse amplitude and <tt>snr</tt> is the SNR. An example is:</p> + <p><tt>wwv5 2 110d 111 5753 2 WV20 bdeff 100 8348/30.0/-3 WH20 0000 1 22/-12.4</tt></p> + <p>Here the radio is tuned to 20 MHz and the line-in port AGC is currently 111 at that frequency. The message contains a report for WWV (<tt>WV20</tt>) and WWVH (<tt>WH20</tt>). The WWV report <tt>score</tt> is <tt>bdeff</tt> and the metric is 100, which suggests very good reception conditions, and the minute sync amplitude and SNR are well above thresholds (2000 and 20 dB, respectively). While the message shows solid reception conditions from WWV, this is not the case for WWVH. Both the minute sync amplitude and SNR are below thresholds and the station has not been heard during the last 160 minutes.</p> + <h4>Debugging Aids</h4> + <p>The most convenient way to track the driver status is using the <tt>ntpq</tt> program and the <tt>clockvar</tt> command. This displays the last determined timecode and related status and error counters, even when the driver is not disciplining the system clock. If the debugging trace feature (<tt>-d</tt> on the <tt>ntpd</tt> command line)is enabled, the driver produces detailed status messages as it operates. If the <tt>fudge flag 4</tt> is set, these messages are written to the <tt>clockstats</tt> file. All messages produced by this driver have the prefix <tt>wwv</tt> for convenient filtering with the Unix <tt>grep</tt> command.</p> + <p>In the following descriptions the units of amplitude, phase, probability and likelihood are normalized to the range 0-6000 for convenience. In addition, the signal/noise ratio (SNR) and likelihood ratio are measured in decibels and the words with bit fields are in hex. Most messages begin with a leader in the following format:</p> + <p><tt>wwvn ss stat sigl</tt></p> + <p>where <tt>wwvn</tt> is the message code, <tt>ss</tt> the second of minute, <tt>stat</tt> the driver status word and <tt>sigl</tt> the second sync pulse amplitude. A full explanation of the status bits is contained in the driver source listing; however, the following are the most useful for debugging.</p> + <dl> + <dt><tt>0x0001</tt> + <dd>Minute sync. Set when the decoder has identified a station and acquired the minute sync pulse. + <dt><tt>0x0002</tt> + <dd>Second sync. Set when the decoder has acquired the second sync pulse and within 125 <font face="Symbol">m</font>s of the correct phase. + <dt><tt>0x0004</tt> + <dd>digit sync. Set when the decoder has reliably determined at least one digit of the minute. <dt><tt>0x0008</tt> + <dd>Clock set. Set when the decoder has reliably determined all nine digits of the timecode and is selectable to discipline the system clock. + </dl> + <p>With debugging enabled the driver produces messages in the following formats:</p> + <p>Format <tt>wwv8</tt> messages are produced once per minute by the WWV and WWVH station processes before minute sync has been acquired. They show the progress of identifying and tracking the minute pulse of each station.</p> + <p><tt>wwv8 port agc ident comp ampl snr epoch jitr offs</tt></p> + <p>where <tt>port</tt> and <tt>agc</tt> are the audio port and gain, respectively. The <tt>ident</tt>encodes the station (<tt>C</tt> for WWV, <tt>H</tt> for WWVH) and frequency (2, 5, 10, 15 or 20). For the encoded frequency, <tt>comp</tt> is the hit counter, <tt>ampl</tt> the pulse amplitude, <tt>snr</tt> the SNR, <tt>epoch</tt> the sample number of the minute pulse in the minute, <tt>jitr</tt> the change since the last <tt>epoch</tt> and <tt>offs</tt> the minute pulse offset relative to the second pulse. An example is:</p> + <p><tt>wwv8 2 127 WV15 2 9247 30.0 18843 -1 1</tt><br> + <tt>wwv8 2 127 WH15 0 134 -2.9 19016 193 174</tt></p> + <p>Here the radio is tuned to WWV at 15 MHz, using the line-in port and the AGC is currently 127. The driver has not yet acquired minute sync, the station has been heard for at least two minutes, and WWVH is in the noise. The WWV minute pulse amplitude and SNR are well above the threshold (2000 and 6 dB, respectively) and the minute epoch has been determined -1 sample relative to the last one and 1 sample relative to the second sync pulse. The hit counter has incrmented to two; when it gets to three, minute sync has been acquired.</p> + <p>Format <tt>wwv3</tt> messages are produced after minute sync has been acquired and until the seconds unit digit is determined. They show the results of decoding each bit of the transmitted timecode.</p> + <p><tt>wwv3 ss stat sigl ssnr ampl dsnr like</tt></p> + <p>where <tt>ss</tt>, <tt>stat</tt> and <tt>sigl</tt> are as above, <tt>ssnr</tt> is the seconds sync SNR, <tt>ampl</tt> the subcarrier amplitude, <tt>dsnr</tt> the subcarrier SNR and <tt>like</tt> the bit likelihood. An example is:</p> + <p><tt>wwv3 28 0123 4122 30.0 4286 24.8 -5545</tt></p> + <p>Here the driver has acquired minute and second sync, but has not yet determined the seconds unit digit. However, it has just decoded bit 28 of the minute. The results show the second sync pulse amplitude well over the threshold (500), subcarrier amplitude well above the threshold (1000), good SNR well above the threshold (10 dB). The bit is almost certainly a zero and the likelihood of a zero in this second is very high.</p> + <p>Format <tt>wwv4</tt> messages are produced for each of the nine BCD timecode digits until the clock has been set or verified. They show the results of decoding each digit of the transmitted timecode.</p> + <p><tt>wwv4 ss stat sigl radx ckdig mldig diff cnt like snr</tt></p> + <p>where <tt>ss</tt>, <tt>stat</tt> and <tt>sigl</tt> are as above, <tt>radx</tt> is the digit radix (3, 4, 6, 10), <tt>ckdig</tt> the current clock digit, <tt>mldig</tt> the maximum likelihood digit, <tt>diff</tt> the difference between these two digits modulo the radix, <tt>cnt</tt> the compare counter, <tt>like</tt> the digit likelihood and <tt>snr</tt> the likelihood ratio. An example is:</p> + <p><tt>wwv4 8 010f 5772 10 9 9 0 6 4615 6.1</tt></p> + <p>Here the driver has previousl set or verified the clock. It has just decoded the digit preceding second 8 of the minute. The digit radix is 10, the current clock and maximum likelihood digits are both 9, the likelihood is well above the threshold (1000) and the likelihood function well above threshold (3.0 dB). Short of a hugely unlikely probability conspiracy, the clock digit is most certainly a 9.</p> + <p>Format <tt>wwv2</tt> messages are produced at each master oscillator frequency update, which starts at 8 s, but eventually climbs to 1024 s. They show the progress of the algorithm as it refines the frequency measurement to a precision of 0.1 PPM.</p> + <p><tt>wwv2 ss stat sigl epoch maxrun jitr avinc avint wiggle freq</tt></p> + <p>where <tt>ss</tt>, <tt>stat</tt> and <tt>sigl</tt> are as above, <tt>epoch</tt> the codec clock at the seconds epoch, <tt>maxrun </tt>the maximum run length, <tt>jitr</tt> the jitter counter, <tt>avinc</tt> the increment counter, <tt>avint</tt> the averaging interval, <tt>phase</tt> the phase correction and <tt>freq</tt> the current frequency (PPM). An example is:</p> + <p><tt>wwv2 22 030f 5795 7433 223 0 3 256 0 49.0</tt></p> + <p>Here the driver has acquired minute and second sync and set the clock. The averaging interval has increased to 256 s on the way to 1024 s, has stayed at that interval for 3 averaging intervals and the current frequency is 49.0 PPM.</p> + <p>If the CI-V interface for ICOM radios is active, a debug level greater than 1 will produce a trace of the CI-V command and response messages. Interpretation of these messages requires knowledge of the CI-V protocol, which is beyond the scope of this document.</p> + <h4>Monitor Data</h4> + When enabled by the <tt>filegen</tt> facility, every received timecode is written to the <tt>clockstats</tt> file in the following format: + <pre> + sq yyyy ddd hh:mm:ss ld du lset agc ident metric errs freq cons + + s sync indicator (? or space) + q quality character (see below) + yyyy Gregorian year + ddd day of year + hh hour of day + mm minute of hour + l leap second warning + d DST state + dut DUT sign and magnitude + lset minutes since last set + agc audio gain + ident station identifier and frequency + metric signal metric (0-100) + errs data bit error counter + freq frequency offset + avgt frequency averaging interval +</pre> + The fields beginning with <tt>year</tt> and extending through <tt>dut</tt> are decoded from the received data and are in fixed-length format. The <tt>agc</tt> and <tt>lset</tt> fields, as well as the following driver-dependent fields, are in variable-length format. + <dl> + <dt><tt>s</tt> + <dd>The sync indicator is initially <tt>?</tt> before the clock is set, but turns to space when all nine digits of the timecode are correctly set and the decoder is synchronized to the station within 125 <font face="Symbol">m</font>s. <dt><tt>q</tt> + <dd>The quality character is a four-bit hexadecimal code showing which alarms have been raised. Each bit is associated with a specific alarm condition according to the following: <dl> + <dt><tt>0x8</tt> + <dd>Sync alarm. The decoder is not synchronized to the station within 125 <font face="Symbol">m</font>s. <dt><tt>0x4</tt> + <dd>Error alarm. More than 30 data bit errors occurred in the last minute. + <dt><tt>0x2</tt> + <dd>Symbol alarm. The probability of correct decoding for a digit or miscellaneous bit has fallen below the threshold. + <dt><tt>0x1</tt> + <dd>Decoding alarm. A maximum likelihood digit fails to agree with the current associated clock digit. + </dl>It is important to note that one or more of the above alarms does not necessarily indicate a clock error, but only that the decoder has detected a condition that may eventually result in an error. <dt><tt>yyyy ddd hh:mm:ss</tt> + <dd>The timecode format itself is self explanatory. Since the driver latches the on-time epoch directly from the second sync pulse, the seconds fraction is always zero. Although the transmitted timecode includes only the year of century, the Gregorian year is augmented by 2000. <dt><tt>l</tt> + <dd>The leap second warning is normally space, but changes to <tt>L</tt> if a leap second is to occur at the end of the month of June or December. + <dt><tt>d</tt> + <dd>The DST state is <tt>S</tt> or <tt>D</tt> when standard time or daylight time is in effect, respectively. The state is <tt>I</tt> or <tt>O</tt> when daylight time is about to go into effect or out of effect, respectively. + <dt><tt>dut</tt> + <dd>The DUT sign and magnitude shows the current UT1 offset relative to the displayed UTC time, in deciseconds. + <dt><tt>lset</tt> + <dd>Before the clock is set, the interval since last set is the number of minutes since the driver was started; after the clock is set, this is number of minutes since the decoder was last synchronized to the station within 125 <font face="Symbol">m</font>s. <dt><tt>agc</tt> + <dd>The audio gain shows the current codec gain setting in the range 0 to 255. Ordinarily, the receiver audio gain control or IRIG level control should be set for a value midway in this range. + <dt><tt>ident</tt> + <dd>The station identifier shows the station, <tt>C</tt> for WWV or <tt>H</tt> for WWVH, and frequency being tracked. If neither station is heard on any frequency, the reference identifier shows <tt>NONE</tt>. + <dt><tt>metric</tt> + <dd>The signal metric described above from 0 (no signal) to 100 (best). + <dt><tt>errs</tt> + <dd>The bit error counter is useful to determine the quality of the data signal received in the most recent minute. It is normal to drop a couple of data bits under good signal conditions and increasing numbers as conditions worsen. While the decoder performs moderately well even with half the bits are in error in any minute, usually by that point the metric drops below threshold and the decoder switches to a different frequency. <dt><tt>freq</tt> + <dd>The frequency offset is the current estimate of the codec frequency offset to within 0.1 PPM. This may wander a bit over the day due to local temperature fluctuations and propagation conditions. + <dt><tt>avgt</tt> + <dd>The averaging time is the interval between frequency updates in powers of two to a maximum of 1024 s. Attainment of the maximum indicates the driver is operating at the best possible resolution in time and frequency. + </dl> + <p>An example timecode is:</p> + <p><tt>0 2000 006 22:36:00 S +3 1 115 WV20 86 5 66.4 1024</tt></p> + <p>Here the clock has been set and no alarms are raised. The year, day and time are displayed along with no leap warning, standard time and DUT +0.3 s. The clock was set on the last minute, the AGC is safely in the middle ot the range 0-255, and the receiver is tracking WWV on 20 MHz. Good receiving conditions prevail, as indicated by the metric 86 and 5 bit errors during the last minute. The current frequency is 66.4 PPM and the averaging interval is 1024 s, indicating the maximum precision available.</p> + <h4>Modes</h4> + <p>The <tt>mode</tt> keyword of the <tt>server</tt> configuration command specifies the ICOM ID select code in decimal. A missing or zero argument disables the CI-V interface. Following are the ID select codes for the known radios. These codes are for 9600 baud rate; for 1200 baud rate add 128.</p> + <table width="100%" cols="6"> + <tr> + <td>Radio</td> + <td>Hex</td> + <td>Decimal</td> + <td>Radio</td> + <td>Hex</td> + <td>Decimal</td> + </tr> + <tr> + <td>IC725</td> + <td>0x28</td> + <td>40</td> + <td>IC781</td> + <td>0x26</td> + <td>38</td> + </tr> + <tr> + <td>IC726</td> + <td>0x30</td> + <td>48</td> + <td>R7000</td> + <td>0x08</td> + <td>8</td> + </tr> + <tr> + <td>IC735</td> + <td>0x04</td> + <td>4</td> + <td>R71</td> + <td>0x1A</td> + <td>26</td> + </tr> + <tr> + <td>IC751</td> + <td>0x1c</td> + <td>28</td> + <td>R7100</td> + <td>0x34</td> + <td>52</td> + </tr> + <tr> + <td>IC761</td> + <td>0x1e</td> + <td>30</td> + <td>R72</td> + <td>0x32</td> + <td>50</td> + </tr> + <tr> + <td>IC765</td> + <td>0x2c</td> + <td>44</td> + <td>R8500</td> + <td>0x4a</td> + <td>74</td> + </tr> + <tr> + <td>IC775</td> + <td>0x46</td> + <td>68</td> + <td>R9000</td> + <td>0x2a</td> + <td>42</td> + </tr> + </table> + <h4>Fudge Factors</h4> + <dl> + <dt><tt>time1 <i>time</i></tt> + <dd>Specifies the propagation delay for WWV (40:40:49.0N 105:02:27.0W), in seconds and fraction, with default 0.0. + <dt><tt>time2 <i>time</i></tt> + <dd>Specifies the propagation delay for WWVH (21:59:26.0N 159:46:00.0W), in seconds and fraction, with default 0.0. + <dt><tt>stratum <i>number</i></tt> + <dd>Specifies the driver stratum, in decimal from 0 to 15, with default 0. + <dt><tt>refid <i>string</i></tt> + <dd>Ordinarily, this field specifies the driver reference identifier; however, the driver sets the reference identifier automatically as described above. + <dt><tt>flag1 0 | 1</tt> + <dd>Not used by this driver. + <dt><tt>flag2 0 | 1</tt> + <dd>Specifies the microphone port if set to zero or the line-in port if set to one. It does not seem useful to specify the compact disc player port. + <dt><tt>flag3 0 | 1</tt> + <dd>Enables audio monitoring of the input signal. For this purpose, the speaker volume must be set before the driver is started. + <dt><tt>flag4 0 | 1</tt> + <dd>Enable verbose <tt>clockstats</tt> recording if set. + </dl> + <hr> + <script type="text/javascript" language="javascript" src="../scripts/footer.txt"></script> + </body> + +</html> diff --git a/html/drivers/driver37.html b/html/drivers/driver37.html new file mode 100644 index 0000000..26acbc3 --- /dev/null +++ b/html/drivers/driver37.html @@ -0,0 +1,50 @@ +<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> + +<html> + + <head> + <title>Forum Graphic GPS Dating station</title> + <link href="../scripts/style.css" type="text/css" rel="stylesheet"> + </head> + + <body> + <h3>Forum Graphic GPS Dating station</h3> + <hr> + <h4>Synopsis</h4> + <p>Address: 127.127.37.<i>u</i><br> + Reference ID: <tt>GPS</tt><br> + Driver ID: <tt>GPS</tt><br> + Parallel Port: <tt>/dev/fgclock<i>u</i></tt></p> + <h4>Description</h4> + <p>This driver supports the Forum Graphic GPS Dating station sold by <a href="http://www.emr.fr/gpsclock.html">EMR company</a>.</p> + <p>Unfortunately sometime FG GPS start continues reporting of the same date. The only way to fix this problem is GPS power cycling and ntpd restart after GPS power-up.</p> + <p>After Jan,10 2000 my FG GPS unit start send a wrong answer after 10:00am till 11:00am. It repeat hour value in result string twice. I wroite a small code to avoid such problem. Unfortunately I have no second FG GPS unit to evaluate this problem. Please let me know if your GPS has no problems after Y2K.</p> + <p></p> + <h4>Monitor Data</h4> + <p>Each timecode is written to the <tt>clockstats</tt> file in the format <tt>YYYY YD HH MI SS</tt>.</p> + <h4>Fudge Factors</h4> + <dl> + <dt><tt>time1 <i>time</i></tt> + <dd>Specifies the time offset calibration factor, in seconds and fraction, with default 0.0. + <dt><tt>time2 <i>time</i></tt> + <dd>Not used by this driver. + <dt><tt>stratum <i>number</i></tt> + <dd>Specifies the driver stratum, in decimal from 0 to 15, with default 0. + <dt><tt>refid <i>string</i></tt> + <dd>Specifies the driver reference identifier, an ASCII string from one to four characters, with default <tt>FG</tt>. + <dt><tt>flag1 0 | 1</tt> + <dd>Not used by this driver. + <dt><tt>flag2 0 | 1</tt> + <dd>Not used by this driver. + <dt><tt>flag3 0 | 1</tt> + <dd>Not used by this driver. + <dt><tt>flag4 0 | 1</tt> + <dd>Not used by this driver. + </dl> + <hr> + <address>Dmitry Smirnov (das@amt.ru)</address> + <hr> + <script type="text/javascript" language="javascript" src="../scripts/footer.txt"></script> + </body> + +</html>
\ No newline at end of file diff --git a/html/drivers/driver38.html b/html/drivers/driver38.html new file mode 100644 index 0000000..e32bd71 --- /dev/null +++ b/html/drivers/driver38.html @@ -0,0 +1,138 @@ +<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> + +<html> + + <head> + <meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1"> + <title>hopf clock drivers by ATLSoft</title> + <link href="../scripts/style.css" type="text/css" rel="stylesheet"> + </head> + + <body bgcolor="#FFFFFF" text="#000000" link="#0000FF" vlink="#800080" alink="#FF0000"> + <h1><font face="Arial"><i><blink><font size="5">hopf</font></blink></i><font size="+2"> </font><font size="3">Serial Line Receivers (6021 and kompatible)</font></font></h1> + <hr> + <h2><font size="+1">Synopsis</font></h2> + <table width="100%" border="0" cellspacing cellpadding> + <tr> + <td> + <table border="0" cellpadding="3" bgcolor="#C0C0C0"> + <tr> + <td height="21"> + <div align="right"> + <tt>Address: </tt></div> + </td> + <td><b>127.127.38.<i>X</i></b></td> + </tr> + <tr> + <td height="1"> + <div align="right"> + <tt>Reference ID: </tt></div> + </td> + <td height="1"><a name="REFID"></a><b>.hopf. </b>(default)<b>, GPS, DCF</b></td> + </tr> + <tr> + <td height="21"> + <div align="right"> + <tt>Driver ID: </tt></div> + </td> + <td height="21"><b>HOPF_S</b></td> + </tr> + <tr> + <td height="16"> + <div align="right"> + <tt>Serial Port: </tt></div> + </td> + <td height="16"><b>/dev/hopfclock<i>X</i></b></td> + </tr> + <tr> + <td height="23"> + <div align="right"> + <tt><font size="+1">Serial I/O</font>: </tt></div> + </td> + <td height="23"><b>9600 baud, 8-bits, 1-stop, no parity</b></td> + </tr> + </table> + </td> + <td align="center"><img src="../pic/fg6021.gif" height="207" width="238" border="0"></td> + </tr> + </table> + <hr> + <h2><font size="+1">Description</font></h2> + <p>The <b>refclock_hopf_serial</b> driver supports <a href="http://www.hopf.com">hopf electronic receivers</a> with serial Interface kompatibel 6021.<br> + </p> + <p>Additional software and information about the software drivers is available from: <a href="http://www.ATLSoft.de/ntp">http://www.ATLSoft.de/ntp</a>.<br> + </p> + <p>Latest NTP driver source, executables and documentation is maintained at: <a href="http://www.ATLSoft.de/ntp">http://www.ATLSoft.de/ntp</a></p> + <hr> + <h2><font size="+1">Operating System Compatibility</font></h2> + <p align="left">The hopf clock driver has been tested on the following software and hardware platforms:<br> + </p> + <table bgcolor="#C0C0C0"> + <tr> + <td valign="CENTER" nowrap width="23%"> + <p align="left"><b>Platform</b></p> + </td> + <td valign="CENTER" nowrap> + <p align="left"><b>Operating System</b></p> + </td> + </tr> + <tr> + <td valign="CENTER" nowrap width="23%"> + <p align="left">i386 (PC) </p> + </td> + <td valign="CENTER" nowrap> + <p align="left">Linux</p> + </td> + </tr> + <tr> + <td nowrap> + <p align="left">i386 (PC) </p> + </td> + <td nowrap> + <p align="left">Windows NT</p> + </td> + </tr> + <tr> + <td nowrap> + <p align="left">i386 (PC) </p> + </td> + <center> + <td nowrap>Windows 2000</td> + </center> + </tr> + </table> + <hr> + <h2><font size="+1">O/S Serial Port Configuration</font></h2> + The driver attempts to open the device <b><tt><a href="#REFID">/dev/hopfclock<i>X</i></a></tt></b> where <i><b>X</b></i> is the NTP refclock unit number as defined by the LSB of the refclock address. Valid refclock unit numbers are 0 - 3. + <p>The user is expected to provide a symbolic link to an available serial port device. This is typically performed by a command such as:</p> + <blockquote> + <tt>ln -s /dev/ttyS0 /dev/hopfclock0</tt></blockquote> + Windows NT does not support symbolic links to device files. <br> + <b>COMx</b>: is used by the driver, based on the refclock unit number, where <b>unit 1</b> corresponds to <b>COM1</b>: and <b>unit 3</b> corresponds to <b>COM3</b>:<br> + + <hr> + <h2><font size="+1">Fudge Factors</font></h2> + <dl> + <dt><b><a name="time1"></a><tt><font size="+1"><a href="#Configuration">time1 <i>time</i></a></font></tt></b> + <dd>Specifies the time offset calibration factor, in seconds and fraction, with default 0.0. Should be set to 20 milliseconds to correct serial line and operating system delays incurred in capturing time stamps from the synchronous packets. + <dt><tt><font size="+1"><a href="#REFID"><b>refid <i>string</i></b></a></font></tt> + <dd>Specifies the driver reference identifier, <b>GPS </b><i>or</i> <b>DCF</b>. + <dt><tt><font size="+1"><b>flag1 0 | 1</b></font></tt> + <dd>When set to 1, driver sync's even if only crystal driven. + </dl> + <hr> + <h2><a name="DataFormat"></a><font size="+1">Data Format</font></h2> + <p>as specified in clock manual under pt. <u>[ <span style="font-size:10.0pt;font-family: +Arial;mso-fareast-font-family:"Times New Roman";mso-bidi-font-family:"Times New Roman"; +mso-ansi-language:EN-GB;mso-fareast-language:DE;mso-bidi-language:AR-SA" lang="EN-GB"><b>Data String for NTP</b> ( <b><i>Network Time Protocol </i></b>) </span>]</u></p> + <hr> + <h3>Questions or Comments:</h3> + <p><a href="mailto:altmeier@atlsoft.de">Bernd Altmeier</a><a href="http://www.ATLSoft.de"><br> + Ing.-Büro für Software www.ATLSoft.de</a></p> + <p>(last updated 02/28/2001)<br> + </p> + <hr> + <script type="text/javascript" language="javascript" src="../scripts/footer.txt"></script> + </body> + +</html>
\ No newline at end of file diff --git a/html/drivers/driver39.html b/html/drivers/driver39.html new file mode 100644 index 0000000..10a3d14 --- /dev/null +++ b/html/drivers/driver39.html @@ -0,0 +1,116 @@ +<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> + +<html> + + <head> + <meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1"> + <title>hopf clock drivers by ATLSoft</title> + <link href="../scripts/style.css" type="text/css" rel="stylesheet"> + </head> + + <body bgcolor="#FFFFFF" text="#000000" link="#0000FF" vlink="#800080" alink="#FF0000"> + <h1><font face="Arial"><i><blink><font size="5">hopf</font></blink></i><font size="+2"> </font><font size="3">PCI-Bus Receiver (6039 GPS/DCF77)</font></font></h1> + <hr> + <div align="center"> + <center> + <table width="100%" border="0" cellspacing="0" cellpadding="0"> + <tr> + <td width="50%"> + <h2><font size="+1">Synopsis</font></h2> + <table border="0" cellpadding="3" bgcolor="#C0C0C0"> + <tr> + <td height="21"> + <div align="right"> + <tt>Address: </tt></div> + </td> + <td height="21"><b>127.127.39.<i>X</i></b></td> + </tr> + <tr> + <td height="21"> + <div align="right"> + <tt>Reference ID: </tt></div> + </td> + <td height="21"><a name="REFID"></a><b>.hopf. </b>(default)<b>, GPS, DCF</b></td> + </tr> + <tr> + <td height="21"> + <div align="right"> + <tt>Driver ID: </tt></div> + </td> + <td height="21"><b>HOPF_P</b></td> + </tr> + </table> + </td> + <td align="center" valign="middle"><font face="Arial"><i><blink><font size="5"><img src="../pic/fg6039.jpg" height="140" width="141" border="0"></font></blink></i></font></td> + </tr> + </table> + </center> + </div> + <hr> + <h2><font size="+1">Description</font></h2> + The <b>refclock_hopf_pci </b>driver supports the <a href="http://www.hopf.com">hopf</a> PCI-bus interface 6039 GPS/DCF77.<br> + Additional software and information about the software drivers maybe available from: <a href="http://www.ATLSoft.de/ntp">http://www.ATLSoft.de/ntp</a>.<br> + Latest NTP driver source, executables and documentation is maintained at: <a href="http://www.ATLSoft.de/ntp">http://www.ATLSoft.de/ntp</a> + <hr> + <h2><font size="+1">Operating System Compatibility</font></h2> + <p align="left">The hopf clock driver has been tested on the following software and hardware platforms:<br> + </p> + <table bgcolor="#C0C0C0"> + <tr> + <td valign="CENTER" nowrap width="23%"> + <p align="left"><b>Platform</b></p> + </td> + <td valign="CENTER" nowrap> + <p align="left"><b>Operating System</b></p> + </td> + </tr> + <tr> + <td valign="CENTER" nowrap width="23%"> + <p align="left">i386 (PC) </p> + </td> + <td valign="CENTER" nowrap> + <p align="left">Linux</p> + </td> + </tr> + <tr> + <td nowrap> + <p align="left">i386 (PC) </p> + </td> + <td nowrap> + <p align="left">Windows NT</p> + </td> + </tr> + <tr> + <td nowrap> + <p align="left">i386 (PC) </p> + </td> + <center> + <td nowrap>Windows 2000</td> + </center> + </tr> + </table> + <hr> + <h2><font size="+1">O/S System Configuration</font></h2> + <p><b>UNIX</b></p> + The driver attempts to open the device <b><tt><a href="#REFID">/dev/hopf6039</a></tt></b> . The device entry will be made by the installation process of the kernel module for the PCI-bus board. The driver sources belongs to the delivery equipment of the PCI-board. + <p><b>Windows NT/2000</b></p> + <p>The driver attempts to open the device by calling the function "OpenHopfDevice()". This function will be installed by the Device Driver for the PCI-bus board. The driver belongs to the delivery equipment of the PCI-board.</p> + <hr> + <h2><font size="+1">Fudge Factors</font></h2> + <dl> + <dt><tt><font size="+1"><a href="#REFID"><b>refid <i>string</i></b></a></font></tt> + <dd>Specifies the driver reference identifier, <b>GPS </b><i>or</i> <b>DCF</b>. + <dt><tt><font size="+1"><b>flag1 0 | 1</b></font></tt> + <dd>When set to 1, driver sync's even if only crystal driven. + </dl> + <hr> + <h3>Questions or Comments:</h3> + <p><a href="mailto:altmeier@atlsoft.de">Bernd Altmeier</a><a href="http://www.ATLSoft.de"><br> + Ing.-Büro für Software www.ATLSoft.de</a></p> + <p>(last updated 03/02/2001)<br> + </p> + <hr> + <script type="text/javascript" language="javascript" src="../scripts/footer.txt"></script> + </body> + +</html>
\ No newline at end of file diff --git a/html/drivers/driver4.html b/html/drivers/driver4.html new file mode 100644 index 0000000..2f78eb5 --- /dev/null +++ b/html/drivers/driver4.html @@ -0,0 +1,65 @@ +<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> + +<html> + + <head> + <title>Spectracom 8170 and Netclock/2 WWVB Receivers</title> + <link href="../scripts/style.css" type="text/css" rel="stylesheet"> + </head> + + <body> + <h3>Spectracom 8170 and Netclock/2 WWVB Receivers</h3> + <hr> + <h4>Synopsis</h4> + Address: 127.127.4.<i>u</i><br> + Reference ID: <tt>WWVB</tt><br> + Driver ID: <tt>WWVB_SPEC</tt><br> + Serial Port: <tt>/dev/wwvb<i>u</i></tt>; 9600 baud, 8-bits, no parity<br> + Features: <tt>tty_clk</tt> + <h4>Description</h4> + <p>This driver supports all known Spectracom radio and satellite clocks, including the Model 8170 and Netclock/2 WWVB Synchronized Clocks and the Netclock/GPS GPS Master Clock. The claimed accuracy of the WWVB clocks is 100 usec relative to the broadcast signal. These clocks have proven a reliable source of time, except in some parts of the country with high levels of conducted RF interference. WIth the GPS clock the claimed accuracy is 130 ns. However, in most cases the actual accuracy is limited by the precision of the timecode and the latencies of the serial interface and operating system.</p> + <p>The DIPswitches on these clocks should be set to 24-hour display, AUTO DST off, data format 0 or 2 (see below) and baud rate 9600. If this clock is used as the source for the IRIG Audio Decoder (<tt>refclock_irig.c</tt> in this distribution), set the DIPswitches for AM IRIG output and IRIG format 1 (IRIG B with signature control).</p> + <p>There are two timecode formats used by these clocks. Format 0, which is available with all clocks, and format 2, which is available with all clocks except the original (unmodified) Model 8170.</p> + <p>Format 0 (22 ASCII printing characters):<br> + <cr><lf>i ddd hh:mm:ss TZ=zz<cr><lf></p> + <p>on-time = first <cr><br> + i = synchronization flag (' ' = in synch, '?' = out synch)<br> + hh:mm:ss = hours, minutes, seconds</p> + <p>The alarm condition is indicated by other than ' ' at <tt>i</tt>, which occurs during initial synchronization and when received signal is lost for about ten hours.</p> + <p>Format 2 (24 ASCII printing characters):<br> + lt;cr>lf>iqyy ddd hh:mm:ss.fff ld</p> + <p>on-time = <cr><br> + i = synchronization flag (' ' = in synch, '?' = out synch)<br> + q = quality indicator (' ' = locked, 'A'...'D' = unlocked)<br> + yy = year (as broadcast)<br> + ddd = day of year<br> + hh:mm:ss.fff = hours, minutes, seconds, milliseconds</p> + <p>The alarm condition is indicated by other than ' ' at <tt>i</tt>, which occurs during initial synchronization and when received signal is lost for about ten hours. The unlock condition is indicated by other than ' ' at <tt>q</tt>.</p> + <p>The <tt>q</tt> is normally ' ' when the time error is less than 1 ms and a character in the set <tt>A...D</tt> when the time error is less than 10, 100, 500 and greater than 500 ms respectively. The <tt>l</tt> is normally ' ', but is set to <tt>L</tt> early in the month of an upcoming UTC leap second and reset to ' ' on the first day of the following month. The <tt>d</tt> is set to <tt>S</tt> for standard time <tt>S</tt>, <tt>I</tt> on the day preceding a switch to daylight time, <tt>D</tt> for daylight time and <tt>O</tt> on the day preceding a switch to standard time. The start bit of the first <cr> is synchronized to the indicated time as returned.</p> + <p>This driver does not need to be told which format is in use - it figures out which one from the length of the message. A three-stage median filter is used to reduce jitter and provide a dispersion measure. The driver makes no attempt to correct for the intrinsic jitter of the radio itself, which is a known problem with the older radios.</p> + <h4>Monitor Data</h4> + <p>The driver writes each timecode as received to the <tt>clockstats</tt> file. When enabled by the <tt>flag4</tt> fudge flag, a table of quality data maintained internally by the Netclock/2 is retrieved and written to the <tt>clockstats</tt> file when the first timecode message of a new dayis received.</p> + <h4>Fudge Factors</h4> + <dl> + <dt><tt>time1 <i>time</i></tt> + <dd>Specifies the time offset calibration factor, in seconds and fraction, with default 0.0. + <dt><tt>time2 <i>time</i></tt> + <dd>Not used by this driver. + <dt><tt>stratum <i>number</i></tt> + <dd>Specifies the driver stratum, in decimal from 0 to 15, with default 0. + <dt><tt>refid <i>string</i></tt> + <dd>Specifies the driver reference identifier, an ASCII string from one to four characters, with default <tt>WWVB</tt>. + <dt><tt>flag1 0 | 1</tt> + <dd>Not used by this driver. + <dt><tt>flag2 0 | 1</tt> + <dd>Not used by this driver. + <dt><tt>flag3 0 | 1</tt> + <dd>Not used by this driver. + <dt><tt>flag4 0 | 1</tt> + <dd>Enable verbose <tt>clockstats</tt> recording if set. + </dl> + <hr> + <script type="text/javascript" language="javascript" src="../scripts/footer.txt"></script> + </body> + +</html>
\ No newline at end of file diff --git a/html/drivers/driver40.html b/html/drivers/driver40.html new file mode 100644 index 0000000..0c68081 --- /dev/null +++ b/html/drivers/driver40.html @@ -0,0 +1,99 @@ +<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> + +<html> + + <head> + <meta name="generator" content="HTML Tidy, see www.w3.org"> + <title>JJY Receivers</title> + <link href="../scripts/style.css" type="text/css" rel="stylesheet"> + </head> + + <body> + <h3>JJY Receivers</h3> + <hr> + <h4>Synopsis</h4> + Address: 127.127.40.<i>u</i><br> + Reference ID: <tt>JJY</tt><br> + Driver ID: <tt>JJY</tt><br> + Serial Port: <tt>/dev/jjy<i>u</i></tt>; 9600 baud, 8-bits, no parity, 1 stop bit + <h4>Description</h4> + <p>This driver supports the following JJY receivers sold in Japan.</p> + <ul> + <li>Tristate Ltd. JJY01 <a href="http://www.tristate.ne.jp/rf-clock.html">http://www.tristate.ne.jp/rf-clock.htm</a> (Japanese only)<br> + <dl> + <dt>Time code format + <dd><br> + <table> + <tr> + <td>Command</td> + <td> </td> + <td>Reply</td> + </tr> + <tr> + <td><tt>date<CR><LF></tt></td> + <td> </td> + <td><tt>YYYY/MM/DD WWW<CR><LF></tt></td> + </tr> + <tr> + <td><tt>stim<CR><LF></tt></td> + <td> </td> + <td><tt>HH:MM:SS<CR><LF></tt></td> + </tr> + </table> + <br> + <dt>NTP configuration ( ntp.conf ) + <dd> + <p>server 127.127.40.X mode 1</p> + </dl> + <li>C-DEX Co.,Ltd. JST2000 <a href="http://www.c-dex.co.jp/">http://www.c-dex.co.jp/</a> (Japanese only)<br> + <dl> + <dt>Time code format + <dd><br> + <table> + <tr> + <td>Command</td> + <td> </td> + <td>Reply</td> + </tr> + <tr> + <td><tt><ENQ>1J<ETX></tt></td> + <td> </td> + <td><tt><STX>JYYMMDD HHMMSSS<ETX></tt></td> + </tr> + </table> + <br> + <dt>NTP configuration ( ntp.conf ) + <dd> + <p>server 127.127.40.X mode 2</p> + </dl> + </ul> + <p>JJY is the radio station which transmites the JST (Japan Standard Time) in long wave radio. The station JJY is operated by the Communication Research Laboratory. An operating announcement and some information are avaiable from <a href="http://www.crl.go.jp/">http://www.crl.go.jp/</a> (English and Japanese) and <a href="http://jjy.crl.go.jp/">http://jjy.crl.go.jp/</a> (Written in Japanese only)</p> + <p>The user is expected to provide a symbolic link to an available serial port device. This is typically performed by a command such as:</p> + <p><tt>ln -s /dev/ttyS0 /dev/jjy0</tt></p> + <p>Windows NT does not support symbolic links to device files. COM<i>X</i>: is the unit used by the driver, based on the refclock unit number, where unit 1 corresponds to COM1: and unit 3 corresponds to COM3:</p> + <h4>Monitor Data</h4> + <p>The driver writes each timecode as received to the <tt>clockstats</tt> file.</p> + <h4>Fudge Factors</h4> + <dl> + <dt><tt>time1 <i>time</i></tt> + <dd>Specifies the time offset calibration factor, in seconds and fraction, with default 0.0. + <dt><tt>time2 <i>time</i></tt> + <dd>Not used by this driver. + <dt><tt>stratum <i>number</i></tt> + <dd>Specifies the driver stratum, in decimal from 0 to 15, with default 0. + <dt><tt>refid <i>string</i></tt> + <dd>Specifies the driver reference identifier, an ASCII string from one to four characters, with default <tt>WWVB</tt>. + <dt><tt>flag1 0 | 1</tt> + <dd>Not used by this driver. + <dt><tt>flag2 0 | 1</tt> + <dd>Not used by this driver. + <dt><tt>flag3 0 | 1</tt> + <dd>Not used by this driver. + <dt><tt>flag4 0 | 1</tt> + <dd>Enable verbose <tt>clockstats</tt> recording if set. + </dl> + <hr> + <script type="text/javascript" language="javascript" src="../scripts/footer.txt"></script> + </body> + +</html>
\ No newline at end of file diff --git a/html/drivers/driver42.html b/html/drivers/driver42.html new file mode 100644 index 0000000..c509db0 --- /dev/null +++ b/html/drivers/driver42.html @@ -0,0 +1,29 @@ +<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> + +<html> + + <head> + <title>Zyfer GPStarplus Receiver</title> + <link href="../scripts/style.css" type="text/css" rel="stylesheet"> + </head> + + <body> + <h3>Zyfer GPStarplus Receiver</h3> + <hr> + <h4>Synopsis</h4> + Address: 127.127.42.<i>u</i><br> + Reference ID: <tt>GPS</tt><br> + Driver ID: <tt>Zyfer GPStarplus</tt><br> + Serial Port: <tt>/dev/zyfer<i>u</i></tt>; 9600 baud, 8-bits, no parity<br> + Features: <tt>(none)</tt> + <h4>Description</h4> + <p>This driver supports the <a href="http://www.zyfer.com/">Zyfer GPStarplus</a> receiver.</p> + <p>The receiver has a DB15 port on the back which has input TxD and RxD lines for configuration and control, and a separate TxD line for the once-per-second timestamp.</p> + <p>Additionally, there are BNC connectors on the back for things like PPS and IRIG output.</p> + <h4>Additional Information</h4> + <p><a href="../refclock.html">Reference Clock Drivers</a></p> + <hr> + <script type="text/javascript" language="javascript" src="../scripts/footer.txt"></script> + </body> + +</html>
\ No newline at end of file diff --git a/html/drivers/driver43.html b/html/drivers/driver43.html new file mode 100644 index 0000000..914693a --- /dev/null +++ b/html/drivers/driver43.html @@ -0,0 +1,64 @@ +<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> + +<html> + + <head> + <title>RIPE NCC interface for Trimble Palisade</title> + <link href="../scripts/style.css" type="text/css" rel="stylesheet"> + </head> + + <body> + <h3>RIPE NCC interface for Trimble Palisade</h3> + <hr> + <img src="../pic/driver43_2.jpg" alt="Trimble Acutime 2000" align="right"> + <h4>Synopsis</h4> + Address: 127.127.43.<i>u</i><br> + Reference ID: <tt>RIPENCC</tt><br> + Driver ID: <tt>RIPENCC</tt> + <h4>Description</h4> + <p>This is a special driver developed to be used in conjuction with the RIPE NCC clock card in the RIPE NCC Test Traffic Measurements project.</p> + <h4>Why this driver?</h4> + <p>The reason why we created a seperated driver for an antenna for which already a (vendor supplied) driver exist is a design decision. To be more specific, the standard Trimble interface uses a 12 pin connector. The cable sold by Trimble to connect to this wire is a very thick cable. Certainly not something you wish to run for several 100 meters through your building. And if you wanted to run it for 100 meters, you always would have to really run the cable, and didn't have the option to use existing wiring.<br> + </p> + <p>This is where we wanted more flexibility. We wanted to be able to use existing wiring in buildings. That leaded us to CAT-5(UTP) which only gives us 8 wires. Therefor we decided to redesing the use of the Trimble antenna. The Trimble supports two modes: EVENT driver and PPS mode. The default is to use the EVENT mode which needs all 12 wires. We only use the PPS timestamps for which we have enough with 8 wires. For our purposes this is more than fine.</p> + More information about the project can be found on the <a href="http://www.ripe.net/test-traffic" target="_new">Test Traffic Measurements</a> website. <img src="../pic/driver43_1.gif" alt="RIPE NCC clock card" align="right"> + <h4>RIPE NCC clock card</h4> + <p>The card is very a simple PCI card. The only feature on the bus it uses is the power supply. It uses this power supply to power the Trimble GPS antenna.</p> + <p>The card basicly just is a RS422 to RS232 converter. It gets the Trimble's RS422 signal on a RJ45 connector and transforms that to RS232 on a DIN9 connector. This connector should be loopbacked on the back of the machine to the serial port. As said, the card doesn't do any PCI data transfers.</p> + <p>The schematics of the interface card is available here: <a href="http://www.ripe.net/ripencc/mem-services/ttm/Documents/gps_interface_schematic.pdf">gps_interface_schematic.pdf</a>. You are free to create this card yourself as long as you give some credit or reference to us. Note that we don't sell these cards on a commercial basis, but for interested parties we do have some spares to share.</p> + <p></p> + <h4>Monitor Data</h4> + <p>In the <tt>filegen clockstats</tt> file the following (example) data is collected:</p> + <pre> +52445 41931.275 127.127.40.0 U1 20.6.2002 11:38:51 13 11 +52445 41931.395 127.127.40.0 C1 20062002 113851 6 364785 110.2 450 6.7 13 5222.374737 N 0453.268013 E 48 7 11 0 1 -14 20 0 -25 +52445 41931.465 127.127.40.0 S1 07 1 1 02 59.3 291.5 39.3 +52445 41931.485 127.127.40.0 S1 11 2 1 02 59.9 138.0 60.2 +52445 41931.525 127.127.40.0 S1 01 4 1 02 48.4 185.7 28.3 +52445 41931.555 127.127.40.0 S1 14 5 2 02 32.7 41.0 15.4 +52445 41931.585 127.127.40.0 S1 20 6 1 02 59.9 256.6 78.0 +52445 41931.615 127.127.40.0 S1 25 8 2 00 0.0 86.6 20.1 +</pre> + <p>This is in the form of:</p> + <pre> +All output lines consist of a prefix and a message, the prefix is: +[days since epoch] [sec.ms since start of day] [peer address] + +And all individual messages: + +*Primary UTC time packet: +U1 [date] [time] [trackstat] [utcflags] + +*Comprehensive time packet: +C1 [date] [time] [mode] [bias] [biasunc] [rate] [rateunc] [utcoff] [latitude] [longtitude] [alt] [vis sat](x8) + +*Tracking status packet: +S1 [prn] [channel] [aqflag] [ephstat] [snr] [azinuth] [elevation] +</pre> + <h4>Additional Information</h4> + <p><a href="../refclock.html">Reference Clock Drivers</a></p> + <hr> + <script type="text/javascript" language="javascript" src="../scripts/footer.txt"></script> + </body> + +</html>
\ No newline at end of file diff --git a/html/drivers/driver44.html b/html/drivers/driver44.html new file mode 100755 index 0000000..e5cbf68 --- /dev/null +++ b/html/drivers/driver44.html @@ -0,0 +1,92 @@ +<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
+ +<html>
+ + <head> + <title>NeoClock4X</title> + <link href="../scripts/style.css" type="text/css" rel="stylesheet"> + <meta http-equiv="content-type" content="text/html; charset=ISO-8859-15"> + </head> + + <body> + <h1>NeoClock4X - DCF77 / TDF serial line receiver<br> + </h1> + <hr size="2" width="100%"> + <h2>Synopsis</h2> + <table width="100%" border="0" cellspacing="0" cellpadding="0"> + <tbody> + <tr> + <td valign="top"> + <table width="100%" border="0" cellspacing="0" cellpadding="2"> + <tbody> + <tr> + <td valign="top">Adress<br> + </td> + <td valign="top">127.127.44.u<br> + </td> + </tr> + <tr> + <td valign="top">Reference ID<br> + </td> + <td valign="top">neol<br> + </td> + </tr> + <tr> + <td valign="top">Driver ID<br> + </td> + <td valign="top">NEOCLK4X<br> + </td> + </tr> + <tr> + <td valign="top">Serial Port<br> + </td> + <td valign="top">/dev/neoclock4x-u<br> + </td> + </tr> + </tbody> + </table> + <br> + </td> + <td align="right" valign="top"><a href="http://www.linum.com"><img src="../pic/neoclock4x.gif" alt="NeoClock4X - DCF77 receiver" height="195" width="150"> </a><br> + </td> + </tr> + </tbody> + </table> + <hr size="2" width="100%"> + <h2>Description</h2> + The refclock_neoclock4x driver supports the NeoClock4X receiver available from <a href="http://www.linum.com">Linum Software GmbH</a>. The receiver is available as a <a href="http://www.dcf77.de">DCF77</a> or TDF receiver. Both receivers have the same output string. For more information about the NeoClock4X receiver please visit <a href="http://www.linux-funkuhr.de">http://www.linux-funkuhr.de</a>. + <hr size="2" width="100%"> + <h2>Fudge Factors</h2> + <dl> + <dt><b><a href="../clockopt.html">time1 time</a></b> + <dd>Specifies the time offset calibration factor with the default value off 0.16958333 seconds. This offset is used to correct serial line and operating system delays incurred in capturing time stamps. If you want to fudge the time1 offset <b>ALWAYS</b> add a value off 0.16958333. This is neccessary to compensate to delay that is caused by transmit the timestamp at 2400 Baud. If you want to compensate the delay that the DCF77 or TDF radio signal takes to travel to your site simply add the needed millisecond delay to the given value. Note that the time here is given in seconds. + <dd>Default setting is 0.16958333 seconds.<br> + + </dl> + <dl> + <dt><b><a href="../clockopt.html">time2 time</a></b> + <dd>Not used by this driver. + </dl> + <dl> + <dt><a href="../clockopt.html"><b>flag1 0 | 1</b></a> + <dd>When set to 1 the driver will feed ntp with timestampe even if the radio signal is lost. In this case an internal backup clock generates the timestamps. This is ok as long as the receiver is synced once since the receiver is able to keep time for a long period. + <dd>Default setting is 0 = don't synchronize to CMOS clock. + <dd> + <dt><a href="../clockopt.html"><b>flag2 0 | 1</b></a> + <dd>You can allow the NeoClock4X driver to use the quartz clock even if it is never synchronized to a radio clock. This is usally not a good idea if you want preceise timestamps since the CMOS clock is maybe not adjusted to a dst status change. So <b>PLEASE</b> switch this only on if you now what you're doing. + <dd>Default setting is 0 = don't synchronize to unsynchronized CMOS clock. + <dt> + <dt><a href="../clockopt.html"><b>flag3 0 | 1</b></a> + <dd>Not used by this driver.<tt><tt><tt><tt><tt><tt> </tt></tt></tt></tt></tt></tt> + <dd> + <dt><a href="../clockopt.html"><b>flag4 0 | 1</b></a> + <dd>It is recommended to allow extensive logging while you setup the NeoClock4X receiver. If you activate flag4 every received data is logged. You should turn off flag4 as soon as the clock works as expected to reduce logfile cluttering. + <dd>Default setting is 0 = don't log received data and converted utc time. + </dl> + <hr size="2" width="100%"> + Please send any comments or question to <a href="mailto:neoclock4@linum.com">neoclock4x@linum.com</a>. + <hr> + <script type="text/javascript" language="javascript" src="../scripts/footer.txt"></script> + </body> + +</html>
\ No newline at end of file diff --git a/html/drivers/driver5.html b/html/drivers/driver5.html new file mode 100644 index 0000000..405c3ab --- /dev/null +++ b/html/drivers/driver5.html @@ -0,0 +1,72 @@ +<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> + +<html> + + <head> + <meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1"> + <title>TrueTime GPS/GOES/OMEGA Receivers</title> + <link href="../scripts/style.css" type="text/css" rel="stylesheet"> + </head> + + <body> + <h3>TrueTime GPS/GOES/OMEGA Receivers</h3> + <hr> + <h4>Synopsis</h4> + Address: 127.127.5.<i>u</i><br> + Reference ID: <tt>GPS, OMEGA, GOES</tt><br> + Driver ID: <tt>TRUETIME</tt><br> + Serial Port: <tt>/dev/true<i>u</i></tt>; 9600 baud, 8-bits, no parity<br> + Features: <tt>tty_clk</tt> + <h4>Description</h4> + <p>This driver supports several models models of Kinemetrics/TrueTime timing receivers, including 468-DC MK III GOES Synchronized Clock, GPS- DC MK III and GPS/TM-TMD GPS Synchronized Clock, XL-DC (a 151-602-210, reported by the driver as a GPS/TM-TMD), GPS-800 TCU (an 805-957 with the RS232 Talker/Listener module), OM-DC OMEGA Synchronized Clock, and very likely others in the same model family that use the same timecode formats.</p> + <p>Most of this code is originally from refclock_wwvb.c with thanks. It has been so mangled that wwvb is not a recognizable ancestor.</p> + <p>Timcode format: <tt>ADDD:HH:MM:SSQCL</tt> A - control A (this is stripped before we see it) Q - Quality indication (see below) C - Carriage return L - Line feed Quality codes indicate possible error of</p> + <dl> + <dt>468-DC GOES Receiver<br> + GPS-TM/TMD Receiver + <dd>? +/- 500 milliseconds # +/- 50 milliseconds<br> + * +/- 5 milliseconds . +/- 1 millisecond<br> + space less than 1 millisecond + <dt>OM-DC OMEGA Receiver: + <dd>> +/- 5 seconds<br> + ? +/- 500 milliseconds # +/- 50 milliseconds<br> + * +/- 5 milliseconds . +/- 1 millisecond<br> + A-H less than 1 millisecond. Character indicates which station is being received as follows<br> + A = Norway, B = Liberia, C = Hawaii, D = North Dakota, E = La Reunion, F = Argentina, G = Australia, H = Japan<br> + The carriage return start bit begins on 0 seconds and extends to 1 bit time. + </dl> + <h4>Notes on 468-DC and OMEGA receiver:</h4> + <p>Send the clock a <tt>R</tt> or <tt>C</tt> and once per second a timestamp will appear. Send a <tt>R</tt> to get the satellite position once (GOES only).</p> + <h4>Notes on the 468-DC receiver:</h4> + <p>Since the old east/west satellite locations are only historical, you can't set your clock propagation delay settings correctly and still use automatic mode. The manual says to use a compromise when setting the switches. This results in significant errors. The solution; use fudge time1 and time2 to incorporate corrections. If your clock is set for 50 and it should be 58 for using the west and 46 for using the east, use the line</p> + <p><tt>fudge 127.127.5.0 time1 +0.008 time2 -0.004</tt></p> + <p>This corrects the 4 milliseconds advance and 8 milliseconds retard needed. The software will ask the clock which satellite it sees.</p> + <p>The PCL720 from PC Labs has an Intel 8253 look-alike, as well as a bunch of TTL input and output pins, all brought out to the back panel. If you wire a PPS signal (such as the TTL PPS coming out of a GOES or other Kinemetrics/Truetime clock) to the 8253's GATE0, and then also wire the 8253's OUT0 to the PCL720's INPUT3.BIT0, then we can read CTR0 to get the number of microseconds since the last PPS upward edge, mediated by reading OUT0 to find out if the counter has wrapped around (this happens if more than 65535us (65ms) elapses between the PPS event and our being called.)</p> + <h4>Monitor Data</h4> + <p>When enabled by the <tt>flag4</tt> fudge flag, every received timecode is written as-is to the <tt>clockstats</tt> file.</p> + <h4>Fudge Factors</h4> + <dl> + <dt><tt>time1 <i>time</i></tt> + <dd>Specifies the time offset calibration factor, in seconds and fraction, to be used for the West satellite, with default 0.0. + <dt><tt>time2 <i>time</i></tt> + <dd>. Specifies the time offset calibration factor, in seconds and fraction, to be used for the East satellite, with default 0.0. + <dt><tt>stratum <i>number</i></tt> + <dd>Specifies the driver stratum, in decimal from 0 to 15, with default 0. + <dt><tt>refid <i>string</i></tt> + <dd>Specifies the driver reference identifier, an ASCII string from one to four characters, with default <tt>TRUE</tt>. + <dt><tt>flag1 0 | 1</tt> + <dd>Silence the clock side of ntpd, just reading the clock without trying to write to it. + <dt><tt>flag2 0 | 1</tt> + <dd>Generate a debug file /tmp/true%d. + <dt><tt>flag3 0 | 1</tt> + <dd>Not used by this driver. + <dt><tt>flag4 0 | 1</tt> + <dd>Not used by this driver. + </dl> + <h4>Additional Information</h4> + <p><a href="../refclock.html">Reference Clock Drivers</a> <a href="../index.html"></a></p> + <hr> + <script type="text/javascript" language="javascript" src="../scripts/footer.txt"></script> + </body> + +</html>
\ No newline at end of file diff --git a/html/drivers/driver6.html b/html/drivers/driver6.html new file mode 100644 index 0000000..8e7cc1e --- /dev/null +++ b/html/drivers/driver6.html @@ -0,0 +1,89 @@ +<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> + +<html> + + <head> + <meta name="generator" content="HTML Tidy, see www.w3.org"> + <title>IRIG Audio Decoder</title> + <link href="../scripts/style.css" type="text/css" rel="stylesheet"> + </head> + + <body> + <h3>IRIG Audio Decoder</h3> + <h4>Related Links</h4> + <script type="text/javascript" language="javascript" src="../scripts/links8.txt"></script> + <hr> + <h4>Synopsis</h4> + Address: 127.127.6.<i>u</i><br> + Reference ID: <tt>IRIG</tt><br> + Driver ID: <tt>IRIG_AUDIO</tt><br> + Audio Device: <tt>/dev/audio</tt> and <tt>/dev/audioctl</tt> + <p>Note: This driver supersedes an older one of the same name, address and ID which required replacing the original kernel audio driver with another which worked only on older Sun SPARC architectures and SunOS operating systems. The new driver requires no modification of the operating system and works on FreeBSD, SunOS and Solaris. While it is generic and likely portable to other systems, it is somewhat slower than the original, since the extensive signal conditioning, filtering and decoding is done in user space, not kernel space.</p> + <h4>Description</h4> + <p>This driver supports the Inter-Range Instrumentation Group (IRIG) standard time distribution signal using the audio codec native to some workstations. This signal is generated by several radio clocks, including those made by Arbiter, Austron, Bancomm, Odetics, Spectracom and TrueTime, among others, although it is often an add-on option. The signal is connected via an optional attenuator box and cable to either the microphone or line-in port. The driver receives, demodulates and decodes the IRIG-B and IRIG-E signal formats using internal filters designed to reduce the effects of noise and interference.</p> + <p>This driver incorporates several features in common with other audio drivers such as described in the <a href="driver7.html">Radio CHU Audio Demodulator/Decoder</a> and the <a href="driver36.html">Radio WWV/H Audio Demodulator/Decoder</a> pages. They include automatic gain control (AGC), selectable audio codec port and signal monitoring capabilities. For a discussion of these common features, as well as a guide to hookup, debugging and monitoring, see the <a href="../audio.html">Reference Clock Audio Drivers</a> page.</p> + <p>The IRIG signal format uses an amplitude-modulated carrier with pulse-width modulated data bits. For IRIG-B, the carrier frequency is 1000 Hz and bit rate 100 b/s; for IRIG-E, the carrier frequenchy is 100 Hz and bit rate 10 b/s. While IRIG-B provides the best accuracy, generally within a few tens of microseconds relative to IRIG time, it can also generate a significant load on the processor with older workstations. Generally, the accuracy with IRIG-E is about ten times worse than IRIG-B, but the processor load is ten times less.</p> + <p>The program processes 8000-Hz <font face="symbol">m</font>-law companded samples using separate signal filters for IRIG-B and IRIG-E, a comb filter, envelope detector and automatic threshold corrector. Cycle crossings relative to the corrected slice level determine the width of each pulse and its value - zero, one or position identifier. The data encode 20 BCD digits which determine the second, minute, hour and day of the year and sometimes the year and synchronization condition. The comb filter exponentially averages the corresponding samples of successive baud intervals in order to reliably identify the reference carrier cycle. A type-II phase-lock loop (PLL) performs additional integration and interpolation to accurately determine the zero crossing of that cycle, which determines the reference timestamp. A pulse-width discriminator demodulates the data pulses, which are then encoded as the BCD digits of the timecode. The timecode and reference timestamp are updated once each second with IRIG-B (ten seconds with IRIG-E) and local clock offset samples saved for later processing. At poll intervals of 64 s, the saved samples are processed by a trimmed-mean filter and used to update the system clock.</p> + <p>Infinite impulse response (IIR) filters are used with both IRIG-B and IRIG-E formats. An 800-Hz highpass filter is used for IRIG-B and a 130-Hz lowpass filter for IRIG-E. These are intended for use with noisy signals, such as might be received over a telephone line or radio circuit, or when interfering signals may be present in the audio passband. The driver determines which IRIG format is in use by sampling the amplitude of each filter output and selecting the one with maximum signal. An automatic gain control feature provides protection against overdriven or underdriven input signal amplitudes. It is designed to maintain adequate demodulator signal amplitude while avoiding occasional noise spikes. In order to assure reliable capture, the decompanded input signal amplitude must be greater than 100 units and the codec sample frequency error less than 250 PPM (.025 percent).</p> + <p>The program performs a number of error checks to protect against overdriven or underdriven input signal levels, incorrect signal format or improper hardware configuration. The specific checks are detailed later in this page. Note that additional checks are done elsewhere in the reference clock interface routines.</p> + <p>Unlike other drivers, which can have multiple instantiations, this one supports only one. It does not seem likely that more than one audio codec would be useful in a single machine. More than one would probably chew up too much CPU time anyway.</p> + <h4>IRIG-B Timecode Format</h4> + <p>The 100 elements of the IRIG timecode are numbered from 0 through 99. Position identifiers occur at elements 0, 9, 19 and every ten thereafter to 99. The control function (CF) elements begin at element 50 (CF 1) and extend to element 78 (CF 27). The straight-binary-seconds (SBS) field, which encodes the seconds of the UTC day, begins at element 80 (CF 28) and extends to element 97 (CF 44). The encoding of elements 50 (CF 1) through 78 (CF 27) is device dependent. This driver presently decodes the CF elements, but does nothing with them.</p> + <p>Where feasible, the IRIG signal source should be operated with signature control so that, if the signal is lost or mutilated, the source produces an unmodulated signal, rather than possibly random digits. The driver will automatically reject the data and declare itself unsynchronized in this case. Some devices, in particular Spectracom radio/satellite clocks, provide additional year and status indication in the format:</p> + <pre> + Element CF Function + ------------------------------------- + 55 6 time sync status + 60-63 10-13 BCD year units + 65-68 15-18 BCD year tens +</pre> + Other devices set these elements to zero. + <h4>Performance and Horror Stories</h4> + <p>The <font face="symbol">m</font>-law companded data format allows considerable latitude in signal levels; however, an automatic gain control (AGC) function is implemented to further compensate for varying input signal levels and to avoid signal distortion. For proper operation, the IRIG signal source should be configured for analog signal levels, NOT digital TTL levels.</p> + <p>The accuracy of the system clock synchronized to the IRIG-B source with this driver and the <tt>ntpd</tt> daemon is 10-20 <font face="symbol">m</font>s with a Sun UltraSPARC II running Solaris 2.6 and maybe twice that with a Sun SPARC IPC running SunOS 4.1.3. Be however acutely aware that the accuracy with Solaris 2.8 and presumably beyond has seriously degraded to the order of several milliseconds. The Sun kernel driver has a sawtooth modulation with amplitude over 5 ms peak-peak and period 5.5 s. The crafty IRIG driver uses a transverse filter to remove the modulation and something called a botttom-fisher to remove incidental positive spikes especially prevalent with Sun Blade 1000 and possibly other systems. The result is nominal accuracy and jitter something less than 0.5 ms, but the this is still far inferior to the performance with older systems.</p> + <p>The processor resources consumed by the daemon can be significant, ranging from about 1.2 percent on the faster UltraSPARC II to 38 percent on the slower SPARC IPC. However, the overall timing accuracy is limited by the resolution and stability of the CPU clock oscillator and the interval between clock corrections, which is 64 s with this driver. This performance, while probably the best that can be achieved by the daemon itself, can be improved with assist from the PPS discipline as described elsewhere in this documentation.</p> + <h4>Monitor Data</h4> + The timecode format used for debugging and data recording includes data helpful in diagnosing problems with the IRIG signal and codec connections. With debugging enabled (-d on the ntpd command line), the driver produces one line for each timecode in the following format: + <p><tt>00 1 98 23 19:26:52 721 143 0.694 47 20 0.083 66.5 3094572411.00027</tt></p> + <p>The first field containes the error flags in hex, where the hex bits are interpreted as below. This is followed by the IRIG status indicator, year of century, day of year and time of day. The status indicator and year are not produced by some IRIG devices. Following these fields are the carrier amplitude (0-8100), codec gain (0-255), field phase (0-79), time constant (2-20), modulation index (0-1), carrier phase error (0±0.5) and carrier frequency error (PPM). The last field is the on-time timestamp in NTP format. The fraction part is a good indicator of how well the driver is doing. With an UltrSPARC 30, this is normally within a few tens of microseconds relative to the IRIG-B signal and within a few hundred microseconds with IRIG-E.</p> + <p>The error flags are defined as follows in hex:</p> + <dl> + <dt><tt>x01</tt> + <dd>Low signal. The carrier amplitude is less than 100 units. This is usually the result of no signal or wrong input port. + <dt><tt>x02</tt> + <dd>Frequency error. The codec frequency error is greater than 250 PPM. This may be due to wrong signal format or (rarely) defective codec. + <dt><tt>x04</tt> + <dd>Modulation error. The IRIG modulation index is less than 0.5. This is usually the result of an overdriven codec, wrong signal format or wrong input port. + <dt><tt>x08</tt> + <dd>Frame synch error. The decoder frame does not match the IRIG frame. This is usually the result of an overdriven codec, wrong signal format or noisy IRIG signal. It may also be the result of an IRIG signature check which indicates a failure of the IRIG signal synchronization source. + <dt><tt>x10</tt> + <dd>Data bit error. The data bit length is out of tolerance. This is usually the result of an overdriven codec, wrong signal format or noisy IRIG signal. + <dt><tt>x20</tt> + <dd>Seconds numbering discrepancy. The decoder second does not match the IRIG second. This is usually the result of an overdriven codec, wrong signal format or noisy IRIG signal. + <dt><tt>x40</tt> + <dd>Codec error (overrun). The machine is not fast enough to keep up with the codec. + </dl> + <h4>Fudge Factors</h4> + <dl> + <dt><tt>time1 <i>time</i></tt> + <dd>Specifies the time offset calibration factor, in seconds and fraction, with default 0.0. + <dt><tt>time2 <i>time</i></tt> + <dd>Not used by this driver. + <dt><tt>stratum <i>number</i></tt> + <dd>Specifies the driver stratum, in decimal from 0 to 15, with default 0. + <dt><tt>refid <i>string</i></tt> + <dd>Specifies the driver reference identifier, an ASCII string from one to four characters, with default <tt>IRIG</tt>. + <dt><tt>flag1 0 | 1</tt> + <dd>Not used by this driver. + <dt><tt>flag2 0 | 1</tt> + <dd>Specifies the microphone port if set to zero or the line-in port if set to one. It does not seem useful to specify the compact disc player port. + <dt><tt>flag3 0 | 1</tt> + <dd>Enables audio monitoring of the input signal. For this purpose, the speaker volume must be set before the driver is started. + <dt><tt>flag4 0 | 1</tt> + <dd>Enable verbose <tt>clockstats</tt> recording if set. + </dl> + <hr> + <script type="text/javascript" language="javascript" src="../scripts/footer.txt"></script> + </body> + +</html>
\ No newline at end of file diff --git a/html/drivers/driver7.html b/html/drivers/driver7.html new file mode 100644 index 0000000..7c47b11 --- /dev/null +++ b/html/drivers/driver7.html @@ -0,0 +1,235 @@ +<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> + +<html> + + <head> + <meta name="generator" content="HTML Tidy, see www.w3.org"> + <title>Radio CHU Audio Demodulator/Decoder</title> + <link href="../scripts/style.css" type="text/css" rel="stylesheet"> + </head> + + <body> + <h3>Radio CHU Audio Demodulator/Decoder</h3> + <h4>Related Links</h4> + <script type="text/javascript" language="javascript" src="../scripts/links8.txt"></script> + <hr> + <h4>Synopsis</h4> + Address: 127.127.7.<i>u</i><br> + Reference ID: <tt>CHU</tt><br> + Driver ID: <tt>CHU</tt><br> + Modem Port: <tt>/dev/chu<i>u</i></tt>; 300 baud, 8-bits, no parity<br> + Autotune Port: <tt>/dev/icom</tt>; 1200/9600 baud, 8-bits, no parity<br> + Audio Device: <tt>/dev/chu_audio</tt> and <tt>/dev/audioctl</tt> + <h4>Description</h4> + <p>This driver synchronizes the computer time using data encoded in radio transmissions from Canadian time/frequency station CHU in Ottawa, Ontario. It replaces an earlier one, built by Dennis Ferguson in 1988, which required a special line discipline to preprocessed the signal. The new driver includes more powerful algorithms implemented directly in the driver and requires no preprocessing.</p> + <p>CHU transmissions are made continuously on 3330 kHz, 7335 kHz and 14670 kHz in upper sideband, compatible AM mode. An ordinary shortwave receiver can be tuned manually to one of these frequencies or, in the case of ICOM receivers, the receiver can be tuned automatically as propagation conditions change throughout the day and night. The performance of this driver when tracking the station is ordinarily better than 1 ms in time with frequency drift less than 0.5 PPM when not tracking the station.</p> + <p>While there are currently no known commercial CHU receivers, a simple but effective receiver/demodulator can be constructed from an ordinary shortwave receiver and Bell 103 compatible, 300-b/s modem or modem chip, as described on the <a href="../pps.html">Pulse-per-second (PPS) Signal Interfacing</a> page. The driver can use the modem to receive the radio signal and demodulate the data or, if available, the driver can use the audio codec of the Sun workstation or another with compatible audio interface. In the latter case, the driver implements the modem using DSP routines, so the radio can be connected directly to either the microphone or line input port.</p> + <p>This driver incorporates several features in common with other audio drivers such as described in the <a href="driver36.html">Radio WWV/H Audio Demodulator/Decoder</a> and the <a href="driver6.html">IRIG Audio Decoder</a> pages. They include automatic gain control (AGC), selectable audio codec port and signal monitoring capabilities. For a discussion of these common features, as well as a guide to hookup, debugging and monitoring, see the <a href="../audio.html">Reference Clock Audio Drivers</a> page.</p> + <p>Ordinarily, the driver poll interval is set to 14 (about 4.5 h), although this can be changed with configuration commands. As long as the clock is set or verified at least once during this interval, the NTP algorithms will consider the source reachable and selectable to discipline the system clock. However, if this does not happen for eight poll intervals, the algorithms will consider the source unreachable and some other source will be chosen (if available) to discipline the system clock.</p> + <p>The decoding algorithms process the data using maximum-likelihood techniques which exploit the considerable degree of redundancy available in each broadcast message or burst. As described below, every character is sent twice and, in the case of format A bursts, the burst is sent eight times every minute. In the case of format B bursts, which are sent once each minute, the burst is considered correct only if every character matches its repetition in the burst. In the case of format A messages, a majority decoder requires at least six repetitions for each digit in the timecode and more than half of the repetitions decode to the same digit. Every character in every burst provides an independent timestamp upon arrival with a potential total of over 60 timestamps for each minute.</p> + <p>A timecode in the format described below is assembled when all bursts have been received in the minute. The timecode is considered valid and the clock set when at least one valid format B burst has been decoded and the above requirements are met. The <tt>yyyy</tt> year field in the timecode indicates whether a valid format B burst has been received. Upon startup, this field is initialized at zero; when a valid format B burst is received, it is set to the current Gregorian year. The <tt>q</tt> quality character field in the timecode indicates whether a valid timecode has been determined. If any of the high order three bits of this character are set, the timecode is invalid.</p> + <p>Once the clock has been set for the first time, it will appear reachable and selectable to discipline the system clock, even if the broadcast signal is lost. Since the signals are almost always available during some period of the day and the NTP clock discipline algorithms are designed to work well even in this case, it is unlikely that the system clock could drift more than a few tens of milliseconds during periods of signal loss. To protect against this most unlikely situation, if after four days with no signals, the clock is considered unset and resumes the synchronization procedure from the beginning.</p> + <p>The last three fields in the timecode are useful in assessing the quality of the radio channel during the most recent minute bursts were received. The <tt>bcnt</tt> field shows the number of format A bursts in the range 1-8. The <tt>dist</tt> field shows the majority decoder distance, or the minimum number of sample repetitions for each digit of the timecode in the range 0-16. The <tt>tsmp</tt> field shows the number of timestamps determined in the range 0-60. For a valid timecode, <tt>bcnt</tt> must be at least 3, <tt>dist</tt> must be greater than <tt>bcnt</tt> and <tt>tsmp</tt> must be at least 20.</p> + <h4>Program Operation</h4> + <p>The program consists of four major parts: the DSP modem, maximum likelihood UART, burst assembler and majority decoder. The DSP modem demodulates Bell 103 modem answer-frequency signals; that is, frequency-shift keyed (FSK) tones of 2225 Hz (mark) and 2025 Hz (space). This is done using a 4th-order IIR filter and limiter/discriminator with 500-Hz bandpass centered on 2125 Hz and followed by a FIR raised-cosine lowpass filter optimized for the 300-b/s data rate. Alternately, the driver can be compiled to delete the modem and input 300 b/s data directly from an external modem via a serial port.</p> + <p>The maximum likelihood UART is implemented using a set of eight 11-stage shift registers, one for each of eight phases of the 300-b/s bit clock. At each phase a new baseband signal value from the DSP modem is shifted into the corresponding register and the maximum and minimum over all 11 samples computed. This establishes a slice level midway between the maximum and minimum over all stages. For each stage, a signal level above this level is a mark (1) and below is a space (0). A quality metric is calculated for each register with respect to the slice level and the a-priori signal consisting of a mark bit (previous stop bit), space (start) bit, eight arbitrary information bits and the first of the two mark (stop) bits.</p> + <p>The shift registers are processed in round-robin order as each modem value arrives until one of them shows a valid framing pattern consisting of a mark bit, space bit, eight arbitrary data bits and a mark bit. When found, the data bits from the register with the best metric is chosen as the maximum likelihood character and the UART begins to process the next character.</p> + <p>The burst assembler processes characters either from the maximum likelihood UART or directly from the serial port as configured. A burst begins when a character is received and is processed after a timeout interval when no characters are received. If the interval between characters is greater than two characters, but less than the timeout interval, the burst is rejected as a runt and a new burst begun. As each character is received, a timestamp is captured and saved for later processing.</p> + <p>A valid burst consists of ten characters in two replicated five-character blocks. A format B block contains the year and other information in ten hexadecimal digits. A format A block contains the timecode in ten decimal digits, the first of which is a framing code (6). The burst assembler must deal with cases where the first character of a format A burst is lost or is noise. This is done using the framing code to correct the phase, either one character early or one character late.</p> + <p>The burst distance is incremented by one for each bit in the first block that matches the corresponding bit in the second block and decremented by one otherwise. In a format B burst the second block is bit-inverted relative to the first, so a perfect burst of five 8-bit characters has distance -40. In a format A block the two blocks are identical, so a perfect burst has distance +40. Format B bursts must be perfect to be acceptable; however, format A bursts, which are further processed by the majority decoder, are acceptable if the distance is at least 28.</p> + <p>Each minute of transmission includes eight format A bursts containing two timecodes for each second from 31 through 39. The majority decoder uses a decoding matrix of ten rows, one for each digit position in the timecode, and 16 columns, one for each 4-bit code combination that might be decoded at that position. In order to use the character timestamps, it is necessary to reliably determine the second number of each burst. In a valid burst, the last digit of the two timecodes in the block must match and the value must be in the range 2-9 and greater than in the previous burst.</p> + <p>As each hex digit of a valid burst is processed, the value at the row corresponding to the digit position in the timecode and column corresponding to the code found at that position is incremented. At the end of each minute of transmission, each row of the decoding matrix encodes the number of occurrences of each code found at the corresponding position of the timecode. However, the first digit (framing code) is always 6, the ninth (second tens) is always 3 and the last (second units) changes for each burst, so are not used.</p> + <p>The maximum over all occurrences at each timecode digit position is the distance for that position and the corresponding code is the maximum likelihood candidate. If the distance is zero, the decoder assumes a miss; if the distance is not more than half the total number of occurrences, the decoder assumes a soft error; if two different codes with the same distance are found, the decoder assumes a hard error. In all these cases the decoder encodes a non-decimal character which will later cause a format error when the timecode is reformatted. The decoding distance is defined as the minimum distance over the first nine digits; the tenth digit varies over the seconds and is uncounted.</p> + <p>The result of the majority decoder is a nine-digit timecode representing the maximum likelihood candidate for the transmitted timecode in that minute. Note that the second and fraction within the minute are always zero and that the actual reference point to calculate timestamp offsets is backdated to the first second of the minute. At this point the timecode block is reformatted and the year, days, hours and minutes extracted along with other information from the format B burst, including DST state, DUT1 correction and leap warning. The reformatting operation checks the timecode for invalid code combinations that might have been left by the majority decoder and rejects the entire timecode if found.</p> + <p>If the timecode is valid, it is passed to the reference clock interface along with the backdated timestamp offsets accumulated over the minute. A perfect set of nine bursts could generate as many as 90 timestamps, but the maximum the interface can handle is 60. These are processed by the interface using a median filter and trimmed-mean average, so the resulting system clock correction is usually much better than would otherwise be the case with radio noise, UART jitter and occasional burst errors.</p> + <h4>Autotune</h4> + <p>The driver includes provisions to automatically tune the radio in response to changing radio propagation conditions throughout the day and night. The radio interface is compatible with the ICOM CI-V standard, which is a bidirectional serial bus operating at TTL levels. The bus can be connected to a standard serial port using a level converter such as the CT-17.</p> + <p>Each ICOM radio is assigned a unique 8-bit ID select code, usually expressed in hex format. To activate the CI-V interface, the <tt>mode</tt> keyword of the <tt>server</tt> configuration command specifies a nonzero select code in decimal format. A table of ID select codes for the known ICOM radios is given below. Since all ICOM select codes are less than 128, the high order bit of the code is used by the driver to specify the baud rate. If this bit is not set, the rate is 9600 bps for the newer radios; if set, the rate is 1200 bps for the older radios. A missing <tt>mode</tt> keyword or a zero argument leaves the interface disabled.</p> + <p>If specified, the driver will attempt to open the device <tt>/dev/icom</tt> and, if successful will tune the radio to 3.330 MHz. If after five minutes at this frequency not more than two format A bursts have been received for any minute, the driver will tune to 7.335 MHz, then to 14.670 MHz, then return to 3.330 MHz and continue in this cycle. However, the driver is liberal in what it assumes of the configuration. If the <tt>/dev/icom</tt> link is not present or the open fails or the CI-V bus or radio is inoperative, the driver quietly gives up with no harm done.</p> + <h4>Radio Broadcast Format</h4> + <p>The CHU time broadcast includes an audio signal compatible with the Bell 103 modem standard (mark = 2225 Hz, space = 2025 Hz). It consist of nine, ten-character bursts transmitted at 300 b/s and beginning each second from second 31 to second 39 of the minute. Each character consists of eight data bits plus one start bit and two stop bits to encode two hex digits. The burst data consist of five characters (ten hex digits) followed by a repeat of these characters. In format A, the characters are repeated in the same polarity; in format B, the characters are repeated in the opposite polarity.</p> + <p>Format A bursts are sent at seconds 32 through 39 of the minute in hex digits</p> + <p><tt>6dddhhmmss6dddhhmmss</tt></p> + <p>The first ten digits encode a frame marker (<tt>6</tt>) followed by the day (<tt>ddd</tt>), hour (<tt>hh</tt>), minute (<tt>mm</tt>) and second (<tt>ss</tt>). Since format A bursts are sent during the third decade of seconds the tens digit of <tt>ss</tt> is always 3. The driver uses this to determine correct burst synchronization. These digits are then repeated with the same polarity.</p> + <p>Format B bursts are sent at second 31 of the minute in hex digits</p> + <p><tt>xdyyyyttaaxdyyyyttaa</tt></p> + <p>The first ten digits encode a code (<tt>x</tt> described below) followed by the DUT1 (<tt>d</tt> in deciseconds), Gregorian year (<tt>yyyy</tt>), difference TAI - UTC (<tt>tt</tt>) and daylight time indicator (<tt>aa</tt>) peculiar to Canada. These digits are then repeated with inverted polarity.</p> + <p>The <tt>x</tt> is coded</p> + <dl> + <dt><tt>1</tt> + <dd>Sign of DUT (0 = +)/dd> + <dt><tt>2</tt> + <dd>Leap second warning. One second will be added. + <dt><tt>4</tt> + <dd>Leap second warning. One second will be subtracted. This is not likely to happen in our universe. + <dt><tt>8</tt> + <dd>Even parity bit for this nibble. + </dl> + <p>By design, the last stop bit of the last character in the burst coincides with 0.5 second. Since characters have 11 bits and are transmitted at 300 b/s, the last stop bit of the first character coincides with 0.5 - 10 * 11/300 = 0.133 second. Depending on the UART, character interrupts can vary somewhere between the beginning of bit 9 and end of bit 11. These eccentricities can be corrected along with the radio propagation delay using the <tt>fudge time1</tt> variable.</p> + <h4>Debugging Aids</h4> + <p>The most convenient way to track the program status is using the <tt>ntpq</tt> program and the <tt>clockvar</tt> command. This displays the last determined timecode and related status and error counters, even when the program is not discipline the system clock. If the debugging trace feature (<tt>-d</tt> on the <tt>ntpd</tt> command line)is enabled, the program produces detailed status messages as it operates. If the <tt>fudge flag 4</tt> is set, these messages are written to the <tt>clockstats</tt> file. All messages produced by this driver have the prefix <tt>chu</tt> for convenient filtering with the Unix <tt>grep</tt> command.</p> + <p>With debugging enabled the driver produces messages in the following formats:</p> + <p>A format <tt>chuA</tt> message is produced for each format A burst received in seconds 32 through 39 of the minute:</p> + <p><tt>chuA n b s code</tt></p> + <p>where <tt>n</tt> is the number of characters in the burst (0-11), <tt>b</tt> the burst distance (0-40), <tt>s</tt> the synchronization distance (0-40) and <tt>code</tt> the burst characters as received. Note that the hex digits in each character are reversed and the last ten digits inverted, so the burst</p> + <p><tt>11 40 1091891300ef6e76ecff</tt></p> + <p>is interpreted as containing 11 characters with burst distance 40. The nibble-swapped timecode shows DUT1 +0.1 second, year 1998 and TAI -UTC 31 seconds.</p> + <p>A format <tt>chuB</tt> message is produced for each format B burst received in second 31 of the minute:</p> + <p><tt>chuB n b f s m code</tt></p> + <p>where <tt>n</tt> is the number of characters in the burst (0-11), <tt>b</tt> the burst distance (0-40), <tt>f</tt> the field alignment (-1, 0, 1), <tt>s</tt>the synchronization distance (0-16), <tt>m</tt>the burst number (2-9) and <tt>code</tt> the burst characters as received. Note that the hex digits in each character are reversed, so the burst</p> + <p><tt>10 38 0 16 9 06851292930685129293</tt></p> + <p>is interpreted as containing 11 characters with burst distance 38, field alignment 0, synchronization distance 16 and burst number 9. The nibble-swapped timecode shows day 58, hour 21, minute 29 and second 39.</p> + <p>If the CI-V interface for ICOM radios is active, a debug level greater than 1 will produce a trace of the CI-V command and response messages. Interpretation of these messages requires knowledge of the CI-V protocol, which is beyond the scope of this document.</p> + <h4>Monitor Data</h4> + When enabled by the <tt>filegen</tt> facility, every received timecode is written to the <tt>clockstats</tt> file in the following format: + <pre> + sq yy ddd hh:mm:ss.fff ld dut lset agc rfrq bcnt dist tsmp + + s sync indicator + q quality character + yyyy Gregorian year + ddd day of year + hh hour of day + mm minute of hour + ss second of minute + fff millisecond of second + l leap second warning + d DST state + dut DUT sign and magnitude in deciseconds + lset minutes since last set + agc audio gain (0-255) + rfrq radio frequency + bcnt burst count + dist decoding distance + tsmp timestamps captured +</pre> + The fields beginning with <tt>year</tt> and extending through <tt>dut</tt> are decoded from the received data and are in fixed-length format. The <tt>agc</tt> and <tt>lset</tt> fields, as well as the following driver-dependent fields, are in variable-length format. + <dl> + <dt><tt>s</tt> + <dd>The sync indicator is initially <tt>?</tt> before the clock is set, but turns to space when the clock is correctly set. + <dt><tt>q</tt> + <dd>The quality character is a four-bit hexadecimal code showing which alarms have been raised during the most recent minute. Each bit is associated with a specific alarm condition according to the following: + <dl> + <dt><tt>8</tt> + <dd>Decoder alarm. A majority of repetitions for at least one digit of the timecode fails to agree. + <dt><tt>4</tt> + <dd>Timestamp alarm. Fewer than 20 timestamps have been determined. + <dt><tt>2</tt> + <dd>Format alarm. The majority timecode contains invalid bit combinations. + <dt><tt>1</tt> + <dd>Frame alarm. A framing or format error occurred on at least one burst during the minute. + </dl> + <p>It is important to note that one or more of the above alarms does not necessarily indicate a clock error, but only that the decoder has detected a condition that may in future result in an error.</p> + <dt><tt>yyyy ddd hh:mm:ss.fff</tt> + <dd>The timecode format itself is self explanatory. Note that the Gregorian year is decoded directly from the transmitted timecode. + <dt><tt>l</tt> + <dd>The leap second warning is normally space, but changes to <tt>L</tt> if a leap second is to occur at the end of the month of June or December. + <dt><tt>d</tt> + <dd>The DST code for Canada encodes the state for all provinces. + <dt><tt>dut</tt> + <dd>The DUT sign and magnitude shows the current UT1 offset relative to the displayed UTC time, in deciseconds. + <dt><tt>lset</tt> + <dd>Before the clock is set, the interval since last set is the number of minutes since the program was started; after the clock is set, this is number of minutes since the time was last verified relative to the broadcast signal. + <dt><tt>agc</tt> + <dd>The audio gain shows the current codec gain setting in the range 0 to 255. Ordinarily, the receiver audio gain control or IRIG level control should be set for a value midway in this range. + <dt><tt>rfrq</tt> + <dd>The current radio frequency, if the CI-V interface is active, or 'X' if not. + <dt><tt>bcnt</tt> + <dd>The number of format A bursts received during the most recent minute bursts were received. + <dt><tt>dist</tt> + <dd>The minimum decoding distance determined during the most recent minute bursts were received. + <dt><tt>tsmp</tt> + <dd>The number of timestamps determined during the most recent minute bursts were received. + </dl> + <h4>Modes</h4> + <p>The <tt>mode</tt> keyword of the <tt>server</tt> configuration command specifies the ICOM ID select code. A missing or zero argument disables the CI-V interface. Following are the ID select codes for the known radios.</p> + <table width="100%" cols="6"> + <tr> + <td>Radio</td> + <td>Hex</td> + <td>Decimal</td> + <td>Radio</td> + <td>Hex</td> + <td>Decimal</td> + </tr> + <tr> + <td>IC725</td> + <td>0x28</td> + <td>40</td> + <td>IC781</td> + <td>0x26</td> + <td>38</td> + </tr> + <tr> + <td>IC726</td> + <td>0x30</td> + <td>48</td> + <td>R7000</td> + <td>0x08</td> + <td>8</td> + </tr> + <tr> + <td>IC735</td> + <td>0x04</td> + <td>4</td> + <td>R71</td> + <td>0x1A</td> + <td>26</td> + </tr> + <tr> + <td>IC751</td> + <td>0x1c</td> + <td>28</td> + <td>R7100</td> + <td>0x34</td> + <td>52</td> + </tr> + <tr> + <td>IC761</td> + <td>0x1e</td> + <td>30</td> + <td>R72</td> + <td>0x32</td> + <td>50</td> + </tr> + <tr> + <td>IC765</td> + <td>0x2c</td> + <td>44</td> + <td>R8500</td> + <td>0x4a</td> + <td>74</td> + </tr> + <tr> + <td>IC775</td> + <td>0x46</td> + <td>68</td> + <td>R9000</td> + <td>0x2a</td> + <td>42</td> + </tr> + </table> + <h4>Fudge Factors</h4> + <dl> + <dt><tt>time1 <i>time</i></tt> + <dd>Specifies the propagation delay for CHU (45:18N 75:45N), in seconds and fraction, with default 0.0. + <dt><tt>time2 <i>time</i></tt> + <dd>Not used by this driver. + <dt><tt>stratum <i>number</i></tt> + <dd>Specifies the driver stratum, in decimal from 0 to 15, with default 0. + <dt><tt>refid <i>string</i></tt> + <dd>Specifies the driver reference identifier, an ASCII string from one to four characters, with default <tt>CHU</tt>. + <dt><tt>flag1 0 | 1</tt> + <dd>Not used by this driver. + <dt><tt>flag2 0 | 1</tt> + <dd>When the audio driver is compiled, this flag selects the audio input port, where 0 is the mike port (default) and 1 is the line-in port. It does not seem useful to select the compact disc player port. + <dt><tt>flag3 0 | 1</tt> + <dd>When the audio driver is compiled, this flag enables audio monitoring of the input signal. For this purpose, the speaker volume must be set before the driver is started. + <dt><tt>flag4 0 | 1</tt> + <dd>Enable verbose <tt>clockstats</tt> recording if set. + </dl> + <hr> + <script type="text/javascript" language="javascript" src="../scripts/footer.txt"></script> + </body> + +</html>
\ No newline at end of file diff --git a/html/drivers/driver8.html b/html/drivers/driver8.html new file mode 100644 index 0000000..ebc5e25 --- /dev/null +++ b/html/drivers/driver8.html @@ -0,0 +1,136 @@ +<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> + +<html> + + <head> + <title>Generic Reference Driver</title> + <link href="../scripts/style.css" type="text/css" rel="stylesheet"> + </head> + + <body> + <h3>Generic Reference Driver</h3> + <hr> + <h4>Synopsis</h4> + Address: 127.127.8.<i>u</i><br> + Reference ID: <tt>PARSE</tt><br> + Driver ID: <tt>GENERIC</tt><br> + Serial Port: <tt>/dev/refclock-<i>u</i></tt>; TTY mode according to clock type + <h4>Description</h4> + <p>The timecode of these receivers is sampled via a STREAMS module in the kernel (The STREAMS module has been designed for use with SUN Systems under SunOS 4.1.x or Solaris 2.3 - 2.6. It can be linked directly into the kernel or loaded via the loadable driver mechanism). This STREAMS module can be adapted to be able to convert different time code formats. If the daemon is compiled without the STREAM definition synchronization will work without the Sun streams module, though accuracy is significantly degraded. This feature allows to use PARSE also on non Sun machines.</p> + <p>The actual receiver status is mapped into various synchronization states generally used by receivers. The STREAMS module is configured to interpret the time codes of DCF C51, PZF535, PZF509, GPS166, Trimble SV6 GPS, ELV DCF7000, Schmid, Wharton 400A and low cost receivers (see list below).</p> + <p>The reference clock support in ntp contains the necessary configuration tables for those receivers. In addition to supporting several different clock types and 4 devices, the generation a a PPS signal is also provided as an configuration option. The PPS configuration option uses the receiver generated time stamps for feeding the PPS loopfilter control for much finer clock synchronization.</p> + <p>CAUTION: The PPS configuration option is different from the hardware PPS signal, which is also supported (see below), as it controls the way ntpd is synchronized to the reference clock, while the hardware PPS signal controls the way time offsets are determined.</p> + <p>The use of the PPS option requires receivers with an accuracy of better than 1ms.</p> + <p>Fudge factors</p> + <p>Only two fudge factors are utilized. The time1 fudge factor defines the phase offset of the synchronization character to the actual time. On the availability of PPS information the time2 fudge factor defines the skew between the PPS time stamp and the receiver timestamp of the PPS signal. This parameter is usually zero, as usually the PPS signal is believed in time and OS delays should be corrected in the machine specific section of the kernel driver. time2 needs only be set when the actual PPS signal is delayed for some reason. The flag1 enables input filtering. This a median filter with continuous sampling. The flag2 selects averaging of the samples remaining after the filtering. Leap second-handling is controlled with the flag3. When set a leap second will be deleted on receipt of a leap second indication from the receiver. Otherwise the leap second will be added, (which is the default). flag3 should never be set. PPS handling is enabled by adding 128 to the mode parameter in the server/peer command.</p> + <p>ntpq (8)</p> + <p>timecode variable</p> + <p>The ntpq program can read clock variables command list several variables. These hold the following information: refclock_time is the local time with the offset to UTC (format HHMM). The currently active receiver flags are listed in refclock_status. Additional feature flags of the receiver are optionally listed in parentheses. The actual time code is listed in timecode. A qualification of the decoded time code format is following in refclock_format. The last piece of information is the overall running time and the accumulated times for the clock event states in refclock_states. When PPS information is present additional variable are available. refclock_ppstime lists then the PPS timestamp and refclock_ppsskew lists the difference between RS232 derived timestamp and the PPS timestamp.</p> + <p>Currently, eighteen clock types (devices /dev/refclock-0 - /dev/refclock-3) are supported by the PARSE driver.<br> + A note on the implementations:</p> + <ul> + <li>These implementations where mainly done <b><i>WITHOUT</i></b> actual access to the hardware. Thus not all implementations provide full support. The development was done with the help of many souls who had the hardware and where so kind to borrow me their time an patience during the development and debugging cycle. Thus for continued support and quality direct access to the receivers is a big help. Nevertheless i am not prepared to buy these reference clocks - donations to <a href="http://www4.informatik.uni-erlangen.de/%7ekardel">me</a> (<a href="mailto:%20kardel@acm.org">kardel@acm.org</a>) are welcome as long as they work within Europe 8-). + <p>Verified implementations are:</p> + <ul> + <li>RAWDCF variants + <p>These variants are tested for the decoding with my own homegrown receivers. Interfacing with specific commercial products may involve some fiddeling with cables. Especially commericial RAWDCF receivers have a seemingly unlimited number of ways to draw power from the RS232 port and to encode the DCF77 datastream. You are mainly on your own here unless i have a sample of the receiver.</p> + <li><a href="http://www.meinberg.de">Meinberg clocks</a> + <p>These implementations are verified by the Meinberg people themselves and i have access to one of these clocks.</p> + </ul> + </ul> + <p>The pictures below refer to the respective clock and where taken from the vendors web pages. They are linked to the respective vendors.</p> + <ul> + <li><b><tt>server 127.127.8.0-3 mode 0</tt></b> + <p><b><tt><a href="http://www.meinberg.de">Meinberg </a>PZF535/<a href="http://www.meinberg.de/english/products/pzf509.htm">PZF509 receiver</a> (FM demodulation/TCXO / 50us)</tt></b><br> + </p> + <li><b><tt>server 127.127.8.0-3 mode 1</tt></b> + <p><b><tt><a href="http://www.meinberg.de">Meinberg </a>PZF535/<a href="http://www.meinberg.de/english/products/pzf509.htm">PZF509 receiver</a> (FM demodulation/OCXO / 50us)</tt></b><br> + <a href="http://www.meinberg.de/english/products/pzf509.htm"><img src="../pic/pzf509.jpg" alt="BILD PZF509" height="300" width="260" align="TEXTTOP"></a><br> + </p> + <li><b><tt>server 127.127.8.0-3 mode 2</tt></b> + <p><b><tt><a href="http://www.meinberg.de">Meinberg </a>DCF U/A 31/<a href="http://www.meinberg.de/english/products/c51.htm">DCF C51 receiver</a> (AM demodulation / 4ms)</tt></b><br> + <a href="http://www.meinberg.de/english/products/c51.htm"><img src="../pic/c51.jpg" alt="BILD C51" height="180" width="330" align="TEXTTOP"></a><br> + </p> + <li><b><tt>server 127.127.8.0-3 mode 3</tt></b> + <p><b><tt><a href="http://www.elv.de">ELV</a> DCF7000 (sloppy AM demodulation / 50ms)</tt></b><br> + </p> + <li><b><tt>server 127.127.8.0-3 mode 4</tt></b> + <p><b><tt>Walter Schmid DCF receiver Kit (AM demodulation / 1ms)</tt></b><br> + </p> + <li><b><tt>server 127.127.8.0-3 mode 5</tt></b> + <p><b><tt>RAW DCF77 100/200ms pulses (Conrad DCF77 receiver module / 5ms)</tt></b><br> + </p> + <li><b><tt>server 127.127.8.0-3 mode 6</tt></b> + <p><b><tt>RAW DCF77 100/200ms pulses (TimeBrick DCF77 receiver module / 5ms)</tt></b><br> + </p> + <li><b><tt>server 127.127.8.0-3 mode 7</tt></b> + <p><b><tt><a href="http://www.meinberg.de">Meinberg </a><a href="http://www.meinberg.de/english/products/gps167.htm">GPS166/GPS167 receiver</a> (GPS / <<1us)</tt></b><br> + <a href="http://www.meinberg.de/english/products/gps167.htm"><img src="../pic/gps167.jpg" alt="BILD GPS167" height="300" width="280" align="TEXTTOP"></a><br> + </p> + <li><b><tt>server 127.127.8.0-3 mode 8</tt></b> + <p><b><tt><a href="http://www.igel.de">IGEL</a> <a href="http://www.igel.de/eigelmn.html">clock</a></tt></b><br> + <a href="http://www.igel.de/eigelmn.html"><img src="../pic/igclock.gif" height="174" width="200"></a><br> + </p> + <li><b><tt>server 127.127.8.0-3 mode 9</tt></b> + <p><b><tt><a href="http://www.trimble.com">Trimble</a> <a href="http://www.trimble.com/cgi/omprod.cgi/pd_om011.html">SVeeSix GPS receiver</a>TAIP protocol (GPS / <<1us)</tt></b><br> + </p> + <li><b><tt>server 127.127.8.0-3 mode 10</tt></b> + <p><b><tt><a href="http://www.trimble.com">Trimble</a> <a href="http://www.trimble.com/cgi/omprod.cgi/pd_om011.html">SVeeSix GPS receiver</a> TSIP protocol (GPS / <<1us) (no kernel support yet)</tt></b><br> + <a href="http://www.trimble.com/cgi/omprod.cgi/pd_om011.html"><img src="../pic/pd_om011.gif" alt="SVeeSix-CM3" height="100" width="420" align="TEXTTOP" border="0"></a><br> + <a href="http://www.trimble.com/cgi/omprod.cgi/pd_om006.html"><img src="../pic/pd_om006.gif" alt="Lassen-SK8" height="100" width="420" border="0"></a><br> + </p> + <li><b><tt>server 127.127.8.0-3 mode 11</tt></b> + <p><b><tt>Radiocode Clocks Ltd RCC 8000 Intelligent Off-Air Master Clock support </tt></b><br> + </p> + <li><b><tt>server 127.127.8.0-3 mode 12</tt></b> + <p><b><tt><a href="http://www.hopf-time.com">HOPF</a> <a href="http://www.hopf-time.com/kart6021.html">Funkuhr 6021</a></tt></b><br> + <a href="http://www.hopf-time.com/engl/kart6021.html"><img src="../pic/fg6021.gif" alt="DCF77-Interface Board" height="207" width="238" align="TEXTTOP"></a><br> + </p> + <li><b><tt>server 127.127.8.0-3 mode 13</tt></b> + <p><b><tt>Diem's Computime Radio Clock</tt></b><br> + </p> + <li><b><tt>server 127.127.8.0-3 mode 14</tt></b> + <p><b><tt>RAWDCF receiver (DTR=high/RTS=low)</tt></b></p> + <li><b><tt>server 127.127.8.0-3 mode 15</tt></b> + <p><b><tt>WHARTON 400A Series Clocks with a 404.2 Serial Interface</tt></b></p> + <li><b><tt>server 127.127.8.0-3 mode 16</tt></b> + <p><b><tt>RAWDCF receiver (DTR=low/RTS=high) </tt></b></p> + <li><b><tt>server 127.127.8.0-3 mode 17</tt></b> + <p><b><tt>VARITEXT Receiver (MSF) </tt></b></p> + </ul> + <p>Actual data formats and set-up requirements of the various clocks can be found in <a href="../parsedata.html">NTP PARSE clock data formats</a>.</p> + <p>The reference clock support carefully monitors the state transitions of the receiver. All state changes and exceptional events such as loss of time code transmission are logged via the syslog facility. Every hour a summary of the accumulated times for the clock states is listed via syslog.</p> + <p>PPS support is only available when the receiver is completely synchronized. The receiver is believed to deliver correct time for an additional period of time after losing synchronizations, unless a disruption in time code transmission is detected (possible power loss). The trust period is dependent on the receiver oscillator and thus a function of clock type. This is one of the parameters in the clockinfo field of the reference clock implementation. This parameter cannot be configured by ntpdc.</p> + <p>In addition to the PPS loopfilter control a true PPS hardware signal can be applied on Sun Sparc stations via the CPU serial ports on the CD pin. This signal is automatically detected and will be used for offset calculation. The input signal must be the time mark for the following time code. (The edge sensitivity can be selected - look into the appropriate kernel/parsestreams.c for details). Meinberg receivers can be connected by feeding the PPS pulse of the receiver via a 1488 level converter to Pin 8 (CD) of a Sun serial zs-port. To select PPS support the STREAMS driver for PARSE must be loaded and the mode parameter ist the mode value of above plus 128. If 128 is not added to the mode value PPS will be detected to be available but it will not be used. For PPS to be used you MUST add 128 to the mode parameter.</p> + <p>For the Meinberg GPS166/GPS167 receiver is also a special firmware release available (Uni-Erlangen). This release should be used for proper operation.</p> + <p>The raw DCF77 pulses can be fed via a level converter directly into Pin 3 (Rx) of the Sun. The telegrams will be decoded an used for synchronization. AM DCF77 receivers are running as low as $25. The accuracy is dependent on the receiver and is somewhere between 2ms (expensive) to 10ms (cheap). Upon bad signal reception of DCF77 synchronizations will cease as no backup oscillator is available as usually found in other reference clock receivers. So it is important to have a good place for the DCF77 antenna. For transmitter shutdowns you are out of luck unless you have other NTP servers with alternate time sources available.</p> + <h4>Monitor Data</h4> + <p>Clock states statistics are written hourly the the syslog service. Online information can be found by examining the clock variable via the ntpq cv command.</p> + <h4>Fudge Factors</h4> + <dl> + <dt><tt>time1 <i>time</i></tt> + <dd>Specifies the time offset calibration factor, in seconds and fraction, with default depending on clock type. + <dt><tt>time2 <i>time</i></tt> + <dd>Specifies the offset if the PPS signal to the actual time. (PPS fine tuning). + <dt><tt>stratum <i>number</i></tt> + <dd>Specifies the driver stratum, in decimal from 0 to 15, with default 0. + <dt><tt>refid <i>string</i></tt> + <dd>Specifies the driver reference identifier, an ASCII string from one to four characters, with default according to current clock type. + <dt><tt>flag1 0 | 1</tt> + <dd>Not used by this driver. + <dt><tt>flag2 0 | 1</tt> + <dd>Not used by this driver. + <dt><tt>flag3 0 | 1</tt> + <dd>delete next leap second instead of adding it. + <dt><tt>flag4 0 | 1</tt> + <dd>Delete next leap second instead of adding it - flag will be re- defined soon - so don't use it. Statistics are provided by more common means (syslog, clock variable via ntpq) + </dl> + <h4>Making your own PARSE clocks</h4> + <p>The parse clock mechanismis deviated from the way other ntp reference clocks work. For a short description how to build parse reference clocks see <a href="../parsenew.html">making PARSE clocks</a></p> + <p>Additional Information</p> + <p><a href="../refclock.html">Reference Clock Drivers</a></p> + <hr> + <script type="text/javascript" language="javascript" src="../scripts/footer.txt"></script> + </body> + +</html> diff --git a/html/drivers/driver9.html b/html/drivers/driver9.html new file mode 100644 index 0000000..8a551de --- /dev/null +++ b/html/drivers/driver9.html @@ -0,0 +1,58 @@ +<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> + +<html> + + <head> + <meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1"> + <meta name="GENERATOR" content="Mozilla/4.01 [en] (Win95; I) [Netscape]"> + <title>Magnavox MX4200 GPS Receiver</title> + <link href="../scripts/style.css" type="text/css" rel="stylesheet"> + </head> + + <body> + <h3>Magnavox MX4200 GPS Receiver</h3> + <hr> + <h4>Synopsis</h4> + Address: 127.127.9.<i>u</i><br> + Reference ID: <tt>GPS</tt><br> + Driver ID: <tt>GPS_MX4200</tt><br> + Serial Port: <tt>/dev/gps<i>u</i></tt>; 4800 baud, 8-bits, no parity<br> + Features: <tt>ppsclock</tt> (required) + <h4>Description</h4> + <p>This driver supports the Magnavox MX4200 Navigation Receiver adapted to precision timing applications. It requires the <tt>ppsclock</tt> line discipline or streams module described in the <a href="../ldisc.html">Line Disciplines and Streams Modules</a> page. It also requires a level converter such as described in the <a href="../pps.html">Pulse-per-second (PPS) Signal Interfacing</a> page.</p> + <p>This driver supports all compatible receivers such as the 6-channel MX4200, MX4200D, and the 12-channel MX9212, MX9012R, MX9112.</p> + <p><a href="http://www.leica-gps.com/"><img src="../pic/9400n.jpg" alt="Leica MX9400N Navigator" height="143" width="180" align="left"></a> <a href="http://www.leica-gps.com/">Leica Geosystems</a> acquired the Magnavox commercial GPS technology business in February of 1994. They now market and support former Magnavox GPS products such as the MX4200 and its successors.</p> + <br clear="LEFT"> + <p>Leica MX9400N Navigator.</p> + <h4>Operating Modes</h4> + <p>This driver supports two modes of operation, static and mobile, controlled by clock flag 2.</p> + <p>In static mode (the default) the driver assumes that the GPS antenna is in a fixed location. The receiver is initially placed in a "Static, 3D Nav" mode, where latitude, longitude, elevation and time are calculated for a fixed station. An average position is calculated from this data. After 24 hours, the receiver is placed into a "Known Position" mode, initialized with the calculated position, and then solves only for time.</p> + <p>In mobile mode, the driver assumes the GPS antenna is mounted on a moving platform such as a car, ship, or aircraft. The receiver is placed in "Dynamic, 3D Nav" mode and solves for position, altitude and time while moving. No position averaging is performed.</p> + <h4>Monitor Data</h4> + <p>The driver writes each timecode as received to the <tt>clockstats</tt> file. Documentation for the <cite>NMEA-0183</cite> proprietary sentences produced by the MX4200 can be found in <a href="../mx4200data.html">MX4200 Receiver Data Format</a>.</p> + <h4>Fudge Factors</h4> + <dl> + <dt><tt>time1 <i>time</i></tt> + <dd>Specifies the time offset calibration factor, in seconds and fraction, with default 0.0. + <dt><tt>time2 <i>time</i></tt> + <dd>Not used by this driver. + <dt><tt>stratum <i>number</i></tt> + <dd>Specifies the driver stratum, in decimal from 0 to 15, with default 0. + <dt><tt>refid <i>string</i></tt> + <dd>Specifies the driver reference identifier, an ASCII string from one to four characters, with default <tt>GPS</tt>. + <dt><tt>flag1 0 | 1</tt> + <dd>Not used by this driver. + <dt><tt>flag2 0 | 1</tt> + <dd>Assume GPS receiver is on a mobile platform if set. + <dt><tt>flag3 0 | 1</tt> + <dd>Not used by this driver. + <dt><tt>flag4 0 | 1</tt> + <dd>Not used by this driver. + </dl> + <h4>Additional Information</h4> + <p><a href="../refclock.html">Reference Clock Drivers</a> </p> + <hr> + <script type="text/javascript" language="javascript" src="../scripts/footer.txt"></script> + </body> + +</html>
\ No newline at end of file diff --git a/html/drivers/icons/home.gif b/html/drivers/icons/home.gif Binary files differnew file mode 100644 index 0000000..e181298 --- /dev/null +++ b/html/drivers/icons/home.gif diff --git a/html/drivers/icons/mail2.gif b/html/drivers/icons/mail2.gif Binary files differnew file mode 100644 index 0000000..21bc1c4 --- /dev/null +++ b/html/drivers/icons/mail2.gif diff --git a/html/drivers/oncore-shmem.html b/html/drivers/oncore-shmem.html new file mode 100644 index 0000000..91402eb --- /dev/null +++ b/html/drivers/oncore-shmem.html @@ -0,0 +1,158 @@ +<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> + +<html> + + <head> + <title>ONCORE - SHMEM</title> + <link href="../scripts/style.css" type="text/css" rel="stylesheet"> + </head> + + <body> + <h3>Motorola ONCORE - The Shared Memory Interface</h3> + <hr> + <h4>Introduction</h4> + <p>In NMEA mode, the Oncore GPS receiver provides the user with the same information as other GPS receivers. In BINARY mode, it can provide a lot of additional information.</p> + <p>In particular, you can ask for satellite positions, satellite health, signal levels, the ephemeris and the almanac, and you can set many operational parameters. In the case of the VP, you can get the pseudorange corrections necessary to act as a DGPS base station, and you can see the raw satellite data messages themselves.</p> + <p>When using the Oncore GPS receiver with NTP, this additional information is usually not available since the receiver is only talking to the oncore driver in NTPD. To make this information available for use in other programs, (say graphic displays of satellites positions, plots of SA, etc.), a shared memory interface (SHMEM) has been added to the refclock_oncore driver on those operating systems that support shared memory.</p> + <p>To make use of this information you will need an Oncore Reference Manual for the Oncore GPS receiver that you have. The Manual for the VP only exists as a paper document, the UT+/GT+/M12 manuals are available as a pdf documents at <a href="http://www.synergy-gps.com/Mot_Manuals.html">Synergy</a> .</p> + <p>This interface was written by Poul-Henning Kamp (phk@FreeBSD.org), and modified by Reg Clemens (reg@dwf.com). The interface is known to work in FreeBSD, Linux, and Solaris.</p> + <h4>Activating the Interface</h4> + <p>Although the Shared Memory Interface will be compiled into the Oncore driver on those systems where Shared Memory is supported, to activate this interface you must include a <b>STATUS</b> or <b>SHMEM</b> line in the <tt>/etc/ntp.oncore</tt> data file that looks like</p> + <pre> + STATUS < file_name ><br> + or<br> + SHMEM < file_name > +</pre> + Thus a line like + <pre> + SHMEM /var/adm/ntpstats/ONCORE +</pre> + <p>would be acceptable. This file name will be used to access the Shared Memory.</p> + <p>In addition, one the two keywords <b>Posn2D</b> and <b>Posn3D</b> can be added to see @@Ea records containing the 2D or 3D position of the station (see below). Thus to activate the interface, and see 3D positions, something like</p> + <pre> + SHMEM /var/adm/ntpstats/ONCORE + Posn3D +</pre> + <p>would be required.</p> + <h4>Storage of Messages in Shared Memory</h4> + <p>With the shared memory interface, the oncore driver (refclock_oncore) allocates space for all of the messages that it is configured to receive, and then puts each message in the appropriate slot in shared memory as it arrives from the receiver. Since there is no easy way for a client program to know when the shared memory has been updated, a sequence number is associated with each message, and is incremented when a new message arrives. With the sequence number it is easy to check through the shared memory segment for messages that have changed.</p> + <p>The Oncore binary messages are kept in their full length, as described in the Reference manual, that is everything from the @@ prefix thru the <checksum><CR><LF>.</p> + <p>The data starts at location ONE of SHMEM (NOT location ZERO).</p> + <p>The messages are stacked in a series of variable length structures, that look like</p> + <pre> + struct message { + u_int length; + u_char sequence; + u_char message[length]; + } +</pre> + <p>if something like that were legal. That is, there are two bytes (caution, these may NOT be aligned with word boundaries, so the field needs to be treated as a pair of u_char), that contains the length of the next message. This is followed by a u_char sequence number, that is incremented whenever a new message of this type is received. This is followed by 'length' characters of the actual message.</p> + <p>The next structure starts immediately following the last char of the previous message (no alignment). Thus, each structure starts a distance of 'length+3' from the previous structure.</p> + <p>Following the last structure, is a u_int containing a zero length to indicate the end of the data.</p> + <p>The messages are recognized by reading the headers in the data itself, viz @@Ea or whatever.</p> + <p>There are two special cases.</p> + <p>(1) The almanac takes a total of 34 submessages all starting with @@Cb.<br> + 35 slots are allocated in shared memory. Each @@Cb message is initially placed in the first of these locations, and then later it is moved to the appropriate location for that submessage. The submessages can be distinguished by the first two characters following the @@Cb header, and new data is received only when the almanac changes.</p> + <p>(2) The @@Ea message contains the calculated location of the antenna, and is received once per second. However, when in timekeeping mode, the receiver is normally put in 0D mode, with the position fixed, to get better accuracy. In 0D mode no position is calculated.</p> + <p>When the SHMEM option is active, and if one of <b>Posn2D</b> or <b>Posn3D</b> is specified, one @@Ea record is hijacked each 15s, and the receiver is put back in 2D/3D mode so the the current location can be determined (for position determination, or for tracking SA). The timekeeping code is careful NOT to use the time associated with this (less accurate) 2D/3D tick in its timekeeping functions.</p> + <p>Following the initial @@Ea message are 3 additional slots for a total of four. As with the almanac, the first gets filled each time a new record becomes available, later in the code, the message is distributed to the appropriate slot. The additional slots are for messages containing 0D, 2D and 3D positions. These messages can be distinguished by different bit patterns in the last data byte of the record.</p> + <h4>Opening the Shared Memory File</h4> + <p>The shared memory segment is accessed through a file name given on a <b>SHMEM</b> card in the <tt>/etc/ntp.oncore</tt> input file. The following code could be used to open the Shared Memory Segment:</p> + <pre> + char *Buf, *file; + int size, fd; + struct stat statbuf; + + file = "/var/adm/ntpstats/ONCORE"; /* the file name on my ACCESS card */ + if ((fd=open(file, O_RDONLY)) < 0) { + fprintf(stderr, "Cant open %s\n", file); + exit(1); + } + + if (stat(file, &statbuf) < 0) { + fprintf(stderr, "Cant stat %s\n", file); + exit(1); + } + + size = statbuf.st_size; + if ((Buf=mmap(0, size, PROT_READ, MAP_SHARED, fd, (off_t) 0)) < 0) { + fprintf(stderr, "MMAP failed\n"); + exit(1); + } +</pre> + <h4>Accessing the data</h4> + <p>The following code shows how to get to the individual records.</p> + <pre> + void oncore_msg_Ea(), oncore_msg_As(), oncore_msg_Bb(); + + struct Msg { + char c[5]; + unsigned int seq; + void (*go_to)(uchar *); + }; + + struct Msg Hdr[] = { {"@@Bb", 0, &oncore_msg_Bb}, + {"@@Ea", 0, &oncore_msg_Ea}, + {"@@As", 0, &oncore_msg_As}}; + + void + read_data() + { + int i, j, k, n, iseq, jseq; + uchar *cp, *cp1; + + + for(cp=Buf+1; (n = 256*(*cp) + *(cp+1)) != 0; cp+=(n+3)) { + for (k=0; k < sizeof(Hdr)/sizeof(Hdr[0]); k++) { + if (!strncmp(cp+3, Hdr[k].c, 4)) { /* am I interested? */ + iseq = *(cp+2); + jseq = Hdr[k].seq; + Hdr[k].seq = iseq; + if (iseq > jseq) { /* has it changed? */ + /* verify checksum */ + j = 0; + cp1 = cp+3; /* points to start of oncore response */ + for (i=2; i < n-3; i++) + j ^= cp1[i]; + if (j == cp1[n-3]) { /* good checksum */ + Hdr[k].go_to(cp1); + } else { + fprintf(stderr, "Bad Checksum for %s\n", Hdr[k].c); + break; + } + } + } + } + if (!strncmp(cp+3, "@@Ea", 4)) + cp += 3*(n+3); + if (!strncmp(cp+3, "@@Cb", 4)) + cp += 34*(n+3); + } + } + + oncore_msg_Bb(uchar *buf) + { + /* process Bb messages */ + } + + oncore_msg_Ea(uchar *buf) + { + /* process Ea messages */ + } + + oncore_msg_As(uchar *buf) + { + /* process As messages */ + } +</pre> + <p>The structure Hdr contains the Identifying string for each of the messages that we want to examine, and the name of a program to call when a new message of that type is arrives. The loop can be run every few seconds to check for new data.</p> + <h4>Examples</h4> + <p>There are two complete examples available. The first plots satellite positions and the station position as affected by SA, and keeps track of the mean station position, so you can run it for periods of days to get a better station position. The second shows the effective horizon by watching satellite tracks. The examples will be found in the GNU-zipped tar file <a href="ftp://ftp.udel.edu/pub/ntp/software/OncorePlot.tar.gz">ftp://ftp.udel.edu/pub/ntp/software/OncorePlot.tar.gz</a>.</p> + <p>Try the new interface, enjoy.</p> + <hr> + <address>Reg.Clemens (reg@dwf.com), Poul-Henning Kamp (phk@FreeBSD.org)</address> + <hr> + <script type="text/javascript" language="javascript" src="../scripts/footer.txt"></script> + </body> + +</html> |
