Re: ppp averaging and circular error of probability

[Gary E. Miller]

Yo gpsd!

On Sat, 10 Sep 2022 22:07:35 +0200
gpsd--- via <gpsd-users@nongnu.org> wrote:

> >> If someone is interested I can also support the 10mb plot file.  
> > I would prefer the raw data, then I can make my own plot file and
> > see for myself.  Maybe even fix it.  
> 
> Sorry for my stupid question: which raw data ?

The stuff that came from you GNSA receiver, that you fed to youg gpsd,
PPP and RTK as inputs.

Easy to grab:  gpspipe -R > raw.log


>        FILENAME=scatter72h_f9p_mnt
>        dc <<< '10k 86400 3 * p'
>        gpsprof -n 259200   -T pngcairo localhost:gpsd:/dev/serial0 > 
> $FILENAME.plot

Better to capture the raw data with gpsd and gpspipe, then you can re-use
the raw data and make many derivatives of the data.

>        gnuplot < $FILENAME.plot > $FILENAME.png
>        display scatter72h_f9p_mnt.png
> 
> I have a plot file and a png file.

But no raw file, that is the most important one to have.

> But should I do it in a different way, so I can do it.

Check the gpsprof man page for examples.

> >> I also calculated the distance between the different results. They
> >> are all below 4 cm. So I am not sure if this CEP gives a useful
> >> information at all.  
> > My mind reading is not good at this distance.  Can you show your
> > work?  
> 
> I calculated the distance for the result for 3 days to the result for
> 2 days. And then the 3 days result to a 24h result. And the 2 days
> result to 24h , and so on

Which does  not tell you as much as gpsprof tells you.

> # haversine_dist_ksh 48.149295051 16.283842249 48.149294787
> 16.283842015 DIST = 0.034 m
> BEARING = 210.599 deg
> # haversine_dist_ksh 48.149295051 16.283842249 48.149294919
> 16.283841993 DIST = 0.024 m
> BEARING = 232.302 deg
> # haversine_dist_ksh 48.149294787 16.283842015 48.149294919
> 16.283841993 DIST = 0.015 m
> BEARING = 353.655 deg

That just tells you the long term averages are close, not that your
location is stable at any one time.

> Have done this with all combinations. I wrote my own script 
> "haversine_dist_ksh" as I didn't find an online tool which works on
> cm base. Maybe there is one anywhere.

Why bother?


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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