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Re: [gpsd-users] Support for PPS on 10Hz Devices
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From: |
Gary E. Miller |
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Subject: |
Re: [gpsd-users] Support for PPS on 10Hz Devices |
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Date: |
Sun, 15 Sep 2013 21:17:38 -0700 |
Yo Andrew!
On Mon, 16 Sep 2013 08:53:26 +0800
Andrew Yong <address@hidden> wrote:
> Hi Anthony,
>
> > On 16 Sep, 2013, at 4:23 am, Anthony Stirk <address@hidden> wrote:
> >
> > I might be out of turn here but isn't the PPS output still 1Hz
> > regardless of the NMEA output frequency ?
>
> Yep, the PPS still comes in at 1Hz, but for some reason GPSD doesn't
> pick it up.
How do you know it is coming if you can't see it? What RS-232
pin is it coming in on? Have you tried high debugging levels in
gpsd to see hat gpsd is seeing?
> I recall seeing a patch to the code base to specifically support the
> Garmin 5Hz LVC.
Yes, applied a long time ago and it ws working last time someone checked.
> Perhaps GPSD is overwhelmed with the 10Hz output, or just is
> expecting 1Hz NMEA?
NMEA is all over the map. Even on a 5HZ GPS some sentences are only
output every 5 seconds, or less. None of it applies to PPS. All PPS
cares is that there is a good fix and the pulse is seen.
> > I did noticed when using the Adafruit module it seems to fire PPS
> > on both the rising and falling, i.e I was getting 2 pulse per
> > second. Switched it for a ublox which seems to work better (by
> > better I mean 1 pulse per second).
gpsd can handle a wide variety of 'PPS' inputs. There are no reports
of anything out there it does not handle.
> I can customize the PPS pulse duration; it's set to 100ms by default.
> Should I get that decreased or increased for better compatibility
> with GPSD's PPS detection?
gpsd can handle everything from a pulse so small the UART does not see
both edges to a 2HZ square wave where each edge is on the second. 100
milli Sec is good because there is no ambiguity on which edge, but 1
milli Sec to 200 milli Sec would be equally good. Just let it be.
RGDS
GARY
---------------------------------------------------------------------------
Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97701
address@hidden Tel:+1(541)382-8588