Re: RTK Base and its accuracy

[Gary E. Miller]

Yo Florian!

On Wed, 10 Aug 2022 10:49:24 +0200
Florian Kiera <florian.kiera@logicway.de> wrote:

> > Which are not precise enough for what you are doing.  Just look at
> > what cgps is telling you.  That is much more "precIse" than some
> > random wiebdite.  

> That pretty much seems to be the issue already... the internet 
> translators seem to have some issues with calculating the latitude 
> correctly. cgps worked fine and gave the expected position.

Then you missed my point.  They can all be correct, and different.

> >> Latitude: 53.59931 11.41833  
> > Determined how?  
> With the position of the rover.

I don't think you understood my question.  How do you know the "accurate"
position of the rover?


> Here is probably more info needed. 

Yup.

> Considering the base was not that wrong after all we can go back to
> the RTK base-rover scenario.

How wrong?  How do you know how wrong?

> I start the survey-in as described in
> the first mail and than start str2str from the RTKLib to push the
> RTCM3 messages to the running ntripcaster.

Which can work, but there are easier wasys to get the same retuls.

> The rover
> currently is inside the building

M8P do not work well inside buildings.

> but close to one of our gps
> repeaters which get their values from the roof as well.

When you get a GPS signal off a repeater, you are getting the position
of the receiver, not the position is the antenna inside the building.

>>The latitude
> on the rover was accurate but the longitude was a bit off (~20m).

Once again, you do not use "accurate" propertly.  I'm guessing your
repeater antenna is 20 m away?

> I
> used the latitude and longitude that gpsd gave out in google maps
> which gave me the visual offset on the map.

Not exactly a high precision method.

> The rover itself reports
> a 2D error of 1m with the RTCM3 messages.

Those "errors" are a joke.  Ignore them except as "googness" indicators.

> Is this to be expected?

That is way better than I expect.

> > Runa 24 hour scatterplort with gpsprof, that will tell you what to
> > expect in "accuracy"/  
> 
> I am not sure if gpsprof works as intented.

I am very sure that gpsprof works very well, and it the right tool
to check your "accuracy".

> I will add the output. 

Looking forward to it.  Be sure to run gpsprof for at least 12 hours.

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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