[time] Garmin GPS 18 5Hz usability

Arthur Konovalov kasjas
Mon Nov 13 11:58:56 UTC 2006


Arthur Konovalov wrote:
> Well, due to different reasons I had to obtain GPS 18-5Hz and now ran 
> into problems...
>  From my point of view 5Hz has 2 differences compared to LVC:
> - PPS (GPGGA and GPRMC too) 5 times per second ( .0, .2,  .4, .6,  .8 of 
> each second) instead of 1
> - UTC timestamp hhmmss.s instead of hhmmss
>
> I tried on PPS-patched Linux kernel (2.6.19-rc2-g02be1c39) and 
> nmea-patched ntp-4.2.2p4.
>
>   
Hello!
I hope that problem solved now.
Part of ntp's refclock_nmea.c file:

#ifdef HAVE_PPSAPI
    /*
     * If the PPSAPI is working, rather use its timestamps.
     * assume that the PPS occurs on the second so blow any msec
     */
    if (nmea_pps(up, &rd_tmp) == 1) {
        pp->lastrec = up->tstamp = rd_tmp;
        pp->nsec = 0;
    }
#endif /* HAVE_PPSAPI */

In case of 5Hz PPS we need millisecons part, commented out row:
       pp->nsec = 0;




Regards,
Arthur



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