Re: [gpsd-dev] PQXFI NMEA, what is it?

[Eric S. Raymond]

Gary E. Miller <address@hidden>:
> > First there is time, lat, lon and MSL altitude, then the 3 unknowns.
> > First 2 unknowns vary from about 250 down to about 2, 3rd one varies
> > between about 5 and 0.03. All are bigger when sky is blocked, smaller
> > when view is good. First ones could be uncertainties, in meters, but
> > the 0.03 ? 
> 
> Yeah, either DOPs or Error Estimates.  Have you connected that to gpsd?
> 
> gpsd will compute the DOPs and Error Estimates, then you can see
> which match.

They may not match exactly.  SiRF does some undocumented jiggery-pokery
to deweight satellites that it thinks are likely to add more noise than
signal. Other vendor firmware might pull similar tricks. 
-- 
                <a href="http://www.catb.org/~esr/";>Eric S. Raymond</a>

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