[LinuxPPS] gpio-pps synchronisation -> discarded by intersection algorithm

[Miroslav Lichvar]

On Mon, Jan 09, 2012 at 06:52:07PM +0100, Thomas Smits wrote:
> NTP starts selecting GPS NMEA driver and PPS for synchronisation, but
> I get "discarded by intersection algorithm" quite soon.
> Then both sources are discarded.
> 
>      remote       refid       st t when poll reach   delay   offset  jitter
> ==============================================================================
> xGPS_NMEA(0)     .GPS.         0 l   16   16  377    0.000   7.888  5.425
> xPPS(0)          .PPS.         0 l   15   16  377    0.000   347.025  1.741

> config:
> >>>>>>>>>>>>>>
> server 127.127.20.0 mode 17 minpoll 4 maxpoll 4 prefer
> server 127.127.22.0 mode 1 minpoll 4 prefer
> fudge 127.127.22.0 flag3 1 flag2 0 refid NMEA

What ntp version is that? I think only the NMEA source should have the
prefer keyword. You can also try to use just the NMEA source alone
with the flag1 set to 1 and /dev/gpspps0.

I'm curious if you can get better jitter than 1 us (the best result
I've seen with PPS on serial port).

-- 
Miroslav Lichvar