Re: Invalid position given by Telit HE910-EUG

[Gary E. Miller]

Yo Titouan!

On Fri, 3 Apr 2020 18:02:16 +0200
Titouan Christophe <address@hidden> wrote:

> Today I observed that one of my Telit HE910-EUG GPS module (NMEA0183 
> over USB serial) emitted an invalid position in a $GPRMC message. The 
> reported latitude is 153__N, which is clearly invalid.

Ouch.  And you are sure it is plain NMEA0183?

> See 2 sentences obtained from gpspipe below:
> 
> # Normal position (51__26.953'N)
> $GPRMC,120212.953,A,5126.1926,N,00758.5483,E,0.01,0.0,180800,,,A*5F
> # 1s after: invalid position (153__35.322'N)
> $GPRMC,120213.953,A,15335.322,N,00758.5483,E,0.01,269.58,180800,,,A*60

How did you ruin gpspipe?  With "-R", "-r", or "-w"?

> As you can see, this GPS has also rolled over in year 2000, but this
> is a different subject.

gpsd in git head can often handle GPS week roll over (WKRO) problems
now.

> However, we have applications that use gpsd to get the geolocation 
> information, and these applications received this wrong latitude.

Not good.

> Hence my question: shouldn't gpsd filter out these invalid
> coordinates ?

You might think so, but initially gpsd was designed to pass unfiltered.
Otherwise hard to debug receiver firmware.  And some people think the
out of band (OOB) values are signaling values.  Just last year someone
complained about gpsd filtering OOB values.

I tend to agree with you that gpsd needs to handle these odd values
because the average person writing gpsd clients does not understand
all the ways receivers send corrupted data.

Get back to us about your gpspipe settings then I can find the best
place to add checks for your problems.

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

            Veritas liberabit vos. -- Quid est veritas?
    "If you can't measure it, you can't improve it." - Lord Kelvin

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