Re: DGPS / SBAS

[Gary E. Miller]

Yo Nick!

On Mon, 4 Dec 2023 10:48:04 +0000
Nick Taylor <nicktaylor@dataskill.uk> wrote:

> gps4.log probably the most interesting - this is after a few days of
> no SBAS but device still showing DGPS 


gps4.log is NMEA that shows DGPS:

$GNGGA,103832.000,5136.9347,N,00011.1125,W,2,12,0.79,100.2,M,47.0,M,,*6A
                                          ^^^

Field 6, GPS Quality indicator is a 2.

When I run gps4.log through gpsdecode, the resulting JSON shows DGPS.

{"class":"TPV","device":"stdin","status":2,"mode":3,"time":"2023-12-04T10[///]
                                ^^^^^^^^^^^

So your cgps should show DGPS, as the JSON is telling it.

> Seems the gps chip is likely to blame here but please let me know
> your thoughts

I wish, but no, the NMEA does say STATUS_RTK. (2), and gpsd is converting
it to JSON that says STATUS_RTK (2).  So cgps should show DGPS.

Does xgps show DGPS?

> cgps image attached > satellites gps3.log is after restart

My eyesight is bad, and limited resolution screen shots are hard for me
to read.  If you can send cut/paste, then I can use large fonts to
read it.

In any case, as you say, gps3.log is as you expect, I'd like to see
the cgps that you think is wrong.  Then I can match the timestamp of the
JSON with the timestamp of the cgps to be sure cgps is not showing what
the JSON says.

In the meantime I'll look at the cgps code for DGPS.

RGDS
GARY
---------------------------------------------------------------------------
Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
        gem@rellim.com  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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