jimmyterrence wrote:
Is there a maximum fudge value above which the NMEA refclock throws away input? Both my 18xLVC GPS receivers output serial data about 550 ms after the PPS signal. That works fine with gpsd, but I've been trying to set up the NMEA driver with pps compiled in the 2.6.34 kernel and it doesn't seem to work.I thought I read somewhere that it accepts a max of 400 ms but I can't seem to find that anywhere. Could anybody tell me what the value is, and maybe point me to the line in refclock_nmea.c (if that's where it is) that governs that?
I don't have a Linux system handy but I've used my Garmin no problem from both serial and with relatively poor performance from USB. This will have been on Ubuntu 9.04 and up. I just created symlinks /dev/gps0 => /dev/tty00 and /dev/pps0 => /dev/tty00. On NetBSD I've been trying parallel port device and hit a problem due to a bug in ntpd (corrected in later versions but these not available for NetBSD). For ntpd 4.2.4p6-o ntp.conf has tos mindist 0.8 and server 127.127.20.2 mode 1 minpoll 6 maxpoll 8 prefer fudge 127.127.20.2 time1 0.680 refid GPSb Note that in my docs it states that time2 is not used Without the fudge time1 the PPS doesn't kick in as time from GPS without serial DCD is too far out. PPSb is currently at offset 0.019 and has been getting more deviation from 0.000 during summer with growth of nearby trees. Even a mast of several metres is not likely to give any benefit for more than a couple of years at most. Most sats I've had in view when checked is three and I don't think that's enough. David _______________________________________________ questions mailing list questions@lists.ntp.org http://lists.ntp.org/listinfo/questions
