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diff --git a/html/driver30.htm b/html/driver30.htm new file mode 100644 index 0000000..d2ec9dd --- /dev/null +++ b/html/driver30.htm @@ -0,0 +1,190 @@ +<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 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> +</HEAD> +<BODY> + +<H3> +Motorola Oncore GPS receiver</H3> + +<HR> +<H4> +Synopsis</H4> + +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><i>u</i> or, +<TT>/etc/ntp.oncore.<TT><i>u</i>, or <TT>/etc/ntp.oncore<TT>. +<H4> +Description</H4> +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>The three most interesting versions of the Oncore are the VP, +the UT+, and the "Remote" which is a prepackaged UT+. +The VP is no longer available. +The Motorola evaluation kit +can also 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. +Two less expensive interface kits are available from +<A HREF="http://www.tapr.org">TAPR</A>. + +<BR> +<CENTER><TABLE NOSAVE > +<TR NOSAVE> +<TD NOSAVE><IMG SRC="pic/oncore_utplusbig.gif" HEIGHT=124 +WIDTH=210></TD> + +<TD><IMG SRC="pic/oncore_evalbig.gif" HEIGHT=124 WIDTH=182></TD> + +<TD><IMG SRC="pic/oncore_remoteant.jpg" 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. +If you do not have the PPS signal available, then you should probably be using +the NMEA driver rather than the Oncore driver. + +<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. +<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.htm> 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. +<H4> +Fudge Factors</H4> + +<DL> +<DT> +<TT>time1 <I>time</I></TT></DT> + +<DD> +Specifies the time offset calibration factor, in seconds and fraction, +with default 0.0.</DD> + +<DT> +<TT>time2 <I>time</I></TT></DT> + +<DD> +Not used by this driver.</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>GPS</TT>.</DD> + +<DT> +<TT>flag1 0 | 1</TT></DT> + +<DD> +Not used by this driver.</DD> + +<DT> +<TT>flag2 0 | 1</TT></DT> + +<DD> +Not used by this driver.</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> +<B>Additional Information</B> +<P>The driver was initially developed on FreeBSD, and has since been tested +on Linux, SunOS and Solaris. +<P><B>Configuration</B> +<P>There is a driver specific configuration file <TT>/etc/ntp.oncore</TT> +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>The <TT>/etc/ntp.conf</TT> file will need a line of the form<BR> + +<TT> pps /dev/oncore.pps.0 [ assert/clear ] hardpps</TT><BR> +if you want the oncore driver to control the kernel PLL. +For more information, see the <A HREF=clockopt.htm>Reference Clock +Options</A> page. + +<P><B>Performance</B> +<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>. +<HR> +<ADDRESS> +Poul-Henning Kamp (phk@FreeBSD.org), +Reg Clemens (reg@dwf.com) +</ADDRESS> +</BODY> +</HTML> |
