Re: [gpsd-users] Polling for GPS data using python3 API

[Gary E. Miller]

Yo pisymbol!

On Tue, 13 Aug 2019 15:03:42 -0400
"pisymbol ." <address@hidden> wrote:

> > The samples are buffering because you are not reading them.  You
> > need to keep up with the incoming messages.
> >  
> 
> Yes, I see that and now that is what I'm doing. I wrote a poller
> process that is just reading samples continuously (no sleep)
> and emits a sample into shared memory for other threads to pick up.
> The change is being tested as I write this to see if the "lag" issue
> disappears that I saw on 3.9.

You shoud neither sleep, nor poll continuously.  Use the gpsd API to
wait on data available.

> > A good mix, depending on your application, may be something like:
> >
> >  GPGLL   - Geographic Position - Latitude longitude
> >  GPRMC   - Recommended Minimum Specific GNSS Sentence
> >  GPVTG   - Course Over Ground and Ground Speed
> >  GPGGA   - GPS Fix Data
> >  GPGSA   - GNSS DOPS and Active Satellites
> >  GPGSV   - GNSS Satellites in View
> >  GPZDA   - Time & Date
> >
> > Without knowing your Trimble model, and application, it is hard to
> > say what your optimal may be.
> Are you saying I have to enable more strings for gpsd to give me a
> fix?

No.  Your question was how to know you had an RTK fix.  But you should
want more.

> Basically, what I am asking is how can I get access to the GGA quality
> indicator number from the python client API?
> https://www.trimble.com/OEM_ReceiverHelp/V4.44/en/NMEA-0183messages_GGA.html
> 
> Field 6.

That is remporting in the TPV JSON.  RTFM: "man gpsd_json".

But GPGGA can only report up to 12 sats in use.  You don't want to be
using an old GNSS receiver that uses so few sats...

RGDS
GARY
---------------------------------------------------------------------------
Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
        address@hidden  Tel:+1 541 382 8588

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    "If you can't measure it, you can't improve it." - Lord Kelvin

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