diff options
Diffstat (limited to 'contrib/ntp/html/driver5.htm')
| -rw-r--r-- | contrib/ntp/html/driver5.htm | 159 |
1 files changed, 159 insertions, 0 deletions
diff --git a/contrib/ntp/html/driver5.htm b/contrib/ntp/html/driver5.htm new file mode 100644 index 0000000..edbd045 --- /dev/null +++ b/contrib/ntp/html/driver5.htm @@ -0,0 +1,159 @@ +<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>TrueTime GPS/GOES/OMEGA Receivers +</TITLE> +</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> +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>Most of this code is originally from refclock_wwvb.c with thanks. It +has been so mangled that wwvb is not a recognizable ancestor. +<PRE>Timcode format: ADDD:HH:MM:SSQCL + +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 + + 468-DC GOES Receiver: + GPS-TM/TMD Receiver: + ? +/- 500 milliseconds # +/- 50 milliseconds + * +/- 5 milliseconds . +/- 1 millisecond + space less than 1 millisecond + + OM-DC OMEGA Receiver: + + > +/- 5 seconds + + ? +/- 500 milliseconds # +/- 50 milliseconds + * +/- 5 milliseconds . +/- 1 millisecond + + A-H less than 1 millisecond. Character indicates which +station + is being received as follows: A = Norway, B = Liberia, + C = Hawaii, D = North Dakota, E = La Reunion, F = +Argentina, + G = Australia, H = Japan.</PRE> +The carriage return start bit begins on 0 seconds and extends to 1 bit +time. + +<P>Notes on 468-DC and OMEGA receiver: + +<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>Notes on the 468-DC receiver: + +<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><TT>fudge 127.127.5.0 time1 +0.008 time2 -0.004</TT> + +<P>This corrects the 4 milliseconds advance and 8 milliseconds retard needed. +The software will ask the clock which satellite it sees. + +<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.) +<H4> +Monitor Data</H4> +When enabled by the <TT>flag4</TT> fudge flag, every received timecode +is written as-is to the <TT>clockstats</TT> file. +<H4> +Fudge Factors</H4> + +<DL> +<DT> +<TT>time1 <I>time</I></TT></DT> + +<DD> +Specifies the time offset calibration factor, in seconds and fraction, +to be used for the West satellite, with default 0.0.</DD> + +<DT> +<TT>time2 <I>time</I></TT></DT> + +<DD> +. Specifies the time offset calibration factor, in seconds and fraction, +to be used for the East satellite, with default 0.0.</DD> + +<DT> +<TT>stratum <I>number</I></TT></DT> + +<DD> +Specifies the driver stratum, in decimal from 0 to 15, with default 0.</DD> + +<DT> +<TT>refid <I>string</I></TT></DT> + +<DD> +Specifies the driver reference identifier, an ASCII string from one to +four characters, with default <TT>TRUE</TT>.</DD> + +<DT> +<TT>flag1 0 | 1</TT></DT> + +<DD> +Silence the clock side of ntpd, just reading the clock without trying to +write to it.</DD> + +<DT> +<TT>flag2 0 | 1</TT></DT> + +<DD> +Generate a debug file /tmp/true%d.</DD> + +<DT> +<TT>flag3 0 | 1</TT></DT> + +<DD> +Not used by this driver.</DD> + +<DT> +<TT>flag4 0 | 1</TT></DT> + +<DD> +Not used by this driver.</DD> +</DL> +Additional Information + +<P><A HREF="refclock.htm">Reference Clock Drivers</A> +<HR> +<ADDRESS> +David L. Mills (mills@udel.edu)</ADDRESS> + +</BODY> +</HTML> |
