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Re: [gpsd-users] Copernicus II / TSIP


From: Eric S. Raymond
Subject: Re: [gpsd-users] Copernicus II / TSIP
Date: Sun, 15 Sep 2013 12:21:35 -0400
User-agent: Mutt/1.5.21 (2010-09-15)

Peter Satlberger <address@hidden>:
> Hi Eric,
> 
> thanks for the reply - now there emerged some new questions.
> 
> When I saw the  *DOP's and satellite-data are the same for
> all four receivers, I split the output and used the SKY/5C
> packets to decide when I can use satellite data. Now it seems
> to be okay (different results for all four receiver). Is only
> the last satellite-record buffered or is there a way so that
> I can access to the *DOP's and satellite data of all four
> receivers? BTW - the SKY/5C packets give the same wrong
> date/time as the TPV/ID8F23 packet.

Each receiver should ship its own JSON object.  What's buffered
in the client library is the state of the last JSON object you
received.

> I also get "strange" error-results (long., lat., alt.) and a
> very high speed-err - what I didnt understand is the big
> difference between the error values of the receivers. When I
> checked it (speed-err) against the results of the tool from
> Trimble it is much too high (I use the receiver only in
> stationery mode with SBAS enabled). Did I missunderstood this
> Value? I thought it should be the error of the Speed Value.

It should be a speed error estimate to 95% confidence, yes.

> The position error of the Trimble-Tool seems to be ok (estimated
> 40m west to the correct point and very constant - says google
> maps).
> 
> Do you have any hints, for me to fix this?

Look at the error-modeling code in libgps_core.c.  The speed error estimate
is computed there if your driver doesn't return it.  It is possible there's
something wrong witjh that computation, though if there were I'd think
someone would have noticed much sooner.  That code has been stable for years.
-- 
                <a href="http://www.catb.org/~esr/";>Eric S. Raymond</a>



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