Re: [gpsd-dev] [RFC] $GPVTG & magnetic course

[Gary E. Miller]

Yo teyrana!

On Thu, 31 May 2018 18:46:33 -0400
teyrana <address@hidden> wrote:

> > I've not look at that code, so take care that users of
> > compass_variation can tell good from bad data in that field.  
> 
> Are you referring to "users" internal to gpsd (like the struct -> json
> code)? or client applications? ...

Yes,

> > > grep -Rn -e compass_variation   *.c  
> 
> gps.h:1853:    double compass_variation;

Hehehe.  I guess it then needs to be added in libgps_json.c and gpsd_json.c
before anything use can be had of it.

But since we are starting pretty much from scratch, how about just adding
a new variable in gps_data_t for magnetic track, righ next to the
current true north track.

Be sure it gets initialized to NaN.  Then modify libgps_json.c and gpsd_json.c
to use it.


> ... (plus my addition).  Does this match your experience?

Sorry, I have no experience with that variable.

> Do you have any external projects in mind, that we should check with?

None come to mind.



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

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