Re:

[Gary E. Miller]

Yo Anton!

On Tue, 6 Sep 2022 09:05:10 +0200
Anton Strydom <agstrydom@gmail.com> wrote:

> I design and develop hardware and use Beagles and Pi's purely for
> their UARTS and USB ports for developing low cost accurate GPS and
> long distance communications transmitting video for the monitoring of
> structures.

Yup, many of us here doing similar.

> I used RTKLIB for the hardware development

Uh, RTKLIB is software?

> The luxury of 9 professionally surveyed and post processed markers at
> your disposal has made a huge difference to my development plus the
> markers are in a typical urban type environment where there is lots
> of multipath, restricted skyviews etc. that needed to be overcome to
> develop the device

Many of us here do our own PPP to a high accuracy.  But nice to have
professional confirmation.

> Below is a data set collected as follows, the unit was assembled and
> the antenna placed on a brick marked with a piece of chalk. The
> receiver was turned on and a position as indicated below was logged.
> Position 1 differs by 1.12 meters from the rest and was done on
> purpose, the balance differs 1 to 4 cm. The receiver was then powered
> down and disassembled. The process was repeated hourly with the
> receiver powered down and disassembled as well as removing the
> antenna and placing it as close as humanly possible to its previous
> position marked with chalk.

Hourly?  That will miss almmost all of the "interesting" data points.

> The positions (waypoints) were logged with Global Mapper and please
> disregard the height.

A fair tart on the data, but where is your data analysis?  CEP(50),
CEP(95), etc?

> The reason for all my questions is that it is easier for the survey
> community to work with ECEF than lat lon for a number of reasons.

Of course.  Which is why gpsd dowrks well with ECEF.

OTOH, no receiver tells us which ECEF they are using...

> The datum is changeable on all the receivers I use, if it cannot be
> displayed
> it is not the end of the world but would help a lot.

Once again, if you receiver sends it, then gpsd will pass it along.
But an accurate datum requires a very large data table.  No receiver I
know has a complate and accurate datum.  If you need accuracy, you need
to just take the ECEF and externally compute lat/lon/alt.

> GPSD is used in the navigation side of the new system where the track,
> latitude and longitude values are used with a precise PPS input to
> calculate course and distance and navigate the vehicle using skid
> steer.

Very common, especially on boats.  On a boat, skidding is your only
steering option.

> I am long past the proving accuracy phase

Not without a 24 hour gpsprof you aren't.

> and am looking at developing
> something meaningful to compliment the receiver and from all my
> research GPSD looks like it ticks a number of boxes for me

Good.  Let us know if there are easy improvements we can make.

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

            Veritas liberabit vos. -- Quid est veritas?
    "If you can't measure it, you can't improve it." - Lord Kelvin

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