Jason Rabel wrote: > David, > > I have a Jupiter 8 unit that I am using the Jupiter Refclock and it works > perfect. However I looked over the specs for the Jupiter 21 and it only > supports SiRF and NMEA. AFAIK there is no SiRF refclock. > > With the older Jupiter modules you have to use them in their Binary mode, > using them in NMEA can cause a 1-2 second offset because of the delay in > processing NMEA output from the module. I don't know if that is still true > for the newer modules, but I would assume it's entirely possible. Even if > the time info was wrong you can use just the PPS signal from the GPS via the > PPS/ATOM refclock, then use another NTP server for the general time info. > > The catch here is: exactly what OS are you running? You said "linux embedded > machine", which by default linux does not support a PPS signal. You have to > patch the kernel to get PPS support. On the other hand FreeBSD supports PPS > and also has nanosecond precision. > > Jason > > _______________________________________________ > questions mailing list > [email protected] > https://lists.ntp.isc.org/mailman/listinfo/questions > > Ops, i'm sorry...i use a machine with thinstation 2.2 system and a linux 2.6.16.5 (i have patched the kernel with de Giometti's patch..). Now i try to use NMEA with ntp 4.2.4 (Udo van den Heuvel's ntpd NMEA patch) <http://time.qnan.org/linux2.6-pps/ntpd-nmea.patch>. I find this procedure on http://time.qnan.org/.
I must debugging some code because i have big problem with time_pps_create function on time_pps.h (refclock_nmea.c) and i have created a "personal" patch (the old code try to use a inexistent filedes even if in the comment say "/* We simply ignore "filedes" */") Now i have a jitter that sometimes "go away" but i think it's possible that in some case i lost a satellites cover.. Thanks to all. -- David Anullo Itaco S.r.l. Via Zoe Fontana, 220 Ed. B1 00131 ROMA - ITALY Tel. +390641294922 - Fax +39064191740 www.itacosystems.com _______________________________________________ questions mailing list [email protected] https://lists.ntp.isc.org/mailman/listinfo/questions
