Re: [gpsd-users] Will proprietary NMEA extensions be included in gpsd?

[Gary E. Miller]

Yo Gary!

On Fri, 26 Jun 2015 16:30:53 -0700
"Gary E. Miller" <address@hidden> wrote:

> > http://web.pdx.edu/~jduh/courses/Archive/geog481w07/Students/Franczyk_RMSE_Accuracy.pdf
> > 
> > http://www.leb.esalq.usp.br/disciplinas/Molin/leb447/Arquivos/GNSS/ArtigoAcuraciaGPSsemAutor.pdf
> > 
> > talking about the correct thing? I guess you guys know more about
> > this, but I want to make sure I read myself up on the right thing.
> 
> Pretty sloppy, RMS error is a bunch of errors lumped together.

I wrote this after looking at just the first URL.  The second one is quite 
good.  Note he took mmeasurements for 20 days to come up with a CEP(50)
and CEP(95).  I would have said at least a day of readings on a fixed
GPS are needed to compute a good CEP.  I doubt any instantaeous RMS
Error measurement is useful.  

I looked for a simple way to derive the horrizontal RMS error from HDOP
but this is the best I could find:

http://crowtracker.com/hdop-gps-position-errors/

Since you have a GPS with that RMS and HDOP data, you should be able to
run a gpsplot and generate your own CEP plots.  Then use the raw gpsd
output to look at the PORZD data and see if it correlates at all to what
you see.

If you do find that the PORZD indeed correlates to your observed PORZD
then maybe it will be worth adding the decode to gpsd.

RGDS
GARY
---------------------------------------------------------------------------
Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
        address@hidden  Tel:+1(541)382-8588

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