my total miserable failed experiment with PPP and rtklib

[Hans Mayer]

Dear All,

I was fascinated about this article https://gpsd.gitlab.io/gpsd/ppp-howto.html Therefore I tried it.
I own a ZED-F9P from U-blox with a fix mounted antenna on the roof of my house.

I run 6 times a 24 hour job with the config after reset of my u-blox ZED-F9P ( defined as config1 for my me and my tests )

I calculated the distance between any of these results and it was not bigger than 37.2 cm.
One can say that all results are within a circle of about 20 cm radius.

the next test was to use “dynModel 2”. ( 2 = stationary )  (  I called it config4 )

    I expected better results. But this wasn’t the case.

The maximum distance between these results was 22.2 cm. Between all 12 measurements it is 40 cm. But the distance for these averaged values for config1 and config4 is only 2.4 cm.

Therefore I expected the real position of the fixed mounted antenna on the roof of my house will be the average value within a circle of about 20 cm but maybe even less.

Later on I stumbled over rtklib. It offers a lot of tools and one of the programs is rtkrcv. It gives the possibility of a more precision position for a "rover" with the correction from the "base" station.

Currently I don't have two stations. Only one, the fix mounted as "rover". So I registered myself for these public available ntrip streams. As base station I selected one near my position.

And this was the surprising result: the distance to the average position, which I was calculating previously, was more than 1.1 meter.

It could be that this base station delivers wrong data. So I check with others and it's the same. Distance is about 1.1 meter with a bearing of about 200 degrees.

Probably I have done something wrong. Or is my assumption is wrong that 12 times 24 hours PPP measurement gives an accurate value ?

Is there anywhere a forum to discuss rtklib with others ?   Didn't find anything till now.

Kind regards

Hans