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Re: [gpsd-users] Garmin 18X-5Hz
From: |
Miroslav Lichvar |
Subject: |
Re: [gpsd-users] Garmin 18X-5Hz |
Date: |
Fri, 12 Aug 2016 11:52:34 +0200 |
User-agent: |
Mutt/1.6.2 (2016-07-01) |
On Fri, Aug 12, 2016 at 09:20:52AM +0000, Roger Oberholtzer wrote:
> > From: Miroslav Lichvar address@hidden
>
> > Another issue with ntpd is that it reads from SHM only once per second
> > (and this can't be easily fixed), so in order to take advantage of a
> > higher rate PPS it needs to use some mechanism based on sockets or
> > pipes (maybe the GPSD JSON driver?).
>
> In fact I don't really want the higher rate of pulses. What I want are the
> NMEA messages at the highest rate for this receiver (5Hz), and the PPS at one
> per second. The question is if this could be done with this receiver. We have
> one on order, so we will see.
If I'm reading the specification for 18x-5Hz correctly, the rate of
NMEA messages and PPS rate are both fixed to 5 Hz. The only thing that
seems configurable is the width of the pulse.
I think a fix in gpsd will be needed for reliable operation. As ntpd
reads SHM only once per second, the error in the offset might be
stable, but I guess it will depend on what time ntpd is started and
there is a 4 in 5 chance it will be off :).
--
Miroslav Lichvar
- [gpsd-users] Garmin 18X-5Hz, Roger Oberholtzer, 2016/08/10
- Re: [gpsd-users] Garmin 18X-5Hz, Gary E. Miller, 2016/08/10
- Re: [gpsd-users] Garmin 18X-5Hz, Miroslav Lichvar, 2016/08/11
- Re: [gpsd-users] Garmin 18X-5Hz, Gary E. Miller, 2016/08/11
- Re: [gpsd-users] Garmin 18X-5Hz, Miroslav Lichvar, 2016/08/12
- Re: [gpsd-users] Garmin 18X-5Hz, Roger Oberholtzer, 2016/08/12
- Re: [gpsd-users] Garmin 18X-5Hz,
Miroslav Lichvar <=
- Re: [gpsd-users] Garmin 18X-5Hz, Roger Oberholtzer, 2016/08/12
- Re: [gpsd-users] Garmin 18X-5Hz, Gary E. Miller, 2016/08/12
- Re: [gpsd-users] Garmin 18X-5Hz, Gary E. Miller, 2016/08/12
- Re: [gpsd-users] Garmin 18X-5Hz, Miroslav Lichvar, 2016/08/15
- Re: [gpsd-users] Garmin 18X-5Hz, Gary E. Miller, 2016/08/15
- Re: [gpsd-users] Garmin 18X-5Hz, Gary E. Miller, 2016/08/12
- Re: [gpsd-users] Garmin 18X-5Hz, Roger Oberholtzer, 2016/08/16
- Re: [gpsd-users] Garmin 18X-5Hz, Doug Robinson, 2016/08/16
- Re: [gpsd-users] Garmin 18X-5Hz, David J Taylor, 2016/08/16
- Re: [gpsd-users] Garmin 18X-5Hz, Gary E. Miller, 2016/08/16