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Diffstat (limited to 'contrib/ntp/html/driver30.htm')
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1 files changed, 54 insertions, 28 deletions
diff --git a/contrib/ntp/html/driver30.htm b/contrib/ntp/html/driver30.htm index 8d547b180c43..fab604b8a318 100644 --- a/contrib/ntp/html/driver30.htm +++ b/contrib/ntp/html/driver30.htm @@ -17,24 +17,32 @@ Motorola Oncore GPS receiver</H3> <H4> Synopsis</H4> -Address: 127.127.30.0 -<BR>Reference ID: <TT>GPS</TT> -<BR>Driver ID: ONCORE -<BR>Serial Port: <TT>/dev/cuaa0</TT>; 9600 baud, 8-bits, no parity -<BR>PPS Port: <TT>/dev/xpps0</TT>; <TT>PPS_CAPTUREASSERT</TT> -required, <TT>PPS_OFFSETASSERT</TT> supported. +Address: 127.127.30.0<BR> +Reference ID: <TT>GPS</TT><BR> +Driver ID: ONCORE<BR> +Serial Port: <TT>/dev/oncore.serial.0</TT>; 9600 baud, 8-bits, +no parity.<BR> +PPS Port: <TT>/dev/oncore.pps.0</TT>; <TT>PPS_CAPTUREASSERT</TT> +required, <TT>PPS_OFFSETASSERT</TT> supported. <H4> Description</H4> This driver supports various models of the <A HREF="http://www.mot.com/AECS/PNSB/products">Motorola Oncore GPS -receivers</A>. as long as they support the <I>Motorola Binary +receivers</A> as long as they support the <I>Motorola Binary Protocol</I>. -<P>The two most interesting version of the Oncore are the "UT+" -and the "Remote" which is a prepackaged "UT+". The evaluation kit +<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. + +<P>The evaluation kit can also be recommended, it interfaces to a PC straightaway, using the -parallel port for PPS input (supported under FreeBSD), and packs 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> @@ -61,18 +69,22 @@ WIDTH=210></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 +<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 UT models. <P>The driver will use the "position hold" mode if -available, with either the receivers built-in site-survey or a similar -algorithm implemented in this driver. +for the VP/UT models. + +<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. <H4> Monitor Data</H4> The driver is quite chatty on stdout if ntpd is run with debugging. A manual will be required though. +Additional information is written to the clockstats file, if configured. <H4> Fudge Factors</H4> @@ -114,7 +126,7 @@ Not used by this driver.</DD> <TT>flag2 0 | 1</TT></DT> <DD> -Assume GPS receiver is on a mobile platform if set.</DD> +Not used by this driver.</DD> <DT> <TT>flag3 0 | 1</TT></DT> @@ -128,26 +140,40 @@ Not used by this driver.</DD> <DD> Not used by this driver.</DD> </DL> -<B>Additional Information</B><B></B> -<P>The driver has been developed under FreeBSD, and may still be pretty -FreeBSD centric. Patches are most welcome. -<P><B>Performance</B><B></B> -<P>Really good. With the UT+, the generated PPS pulse is -referenced +<B>Additional Information</B> +<P>The driver has been tested on FreeBSD, Linux and SunOS. + +<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 +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)</ADDRESS> - +Poul-Henning Kamp (phk@FreeBSD.org), +Reg Clemens (reg@dwf.com) +</ADDRESS> </BODY> </HTML> |