Re: Running multiple instances of gpsd

[Gary E. Miller]

Yo Laurent!

On Tue, 7 May 2024 12:10:32 +0200
Laurent Smadja <laurent.smadja@konboi.one> wrote:

> Hey Gary !
> Thx for this quick reply and all recommendations !
> 
> Still have some questions.
> 
> > Not required.  You can just do this:
> >        gpsd -n /dev/ttyACM0 /dev/ttyACM1  
> My point is to get 2 positions so that I can compute the heading

Yes, that was my understanding, and is what my example does.

> anytime, using the known antenna positions on my robot (with a large
> enough baseline)
> What does gpsd do when connected to 2 receivers ?
> Does it average the 2 positions ?

No.

> How could I retrieve 2 distinct positions ?

Same way you receive any data from gpsd, as JSON.

Each HSON message tells you which GNSS receiver that data came from.

RedL "man gpsd_json"


> > Please note that, for now at least, I don't want to run gpsd using
> > systemd.
> > Thank you!  
> Why don't you recommend using gpsd with systemd ?

'cause systemd(umber) overcomplicates things for no benefit, while
casuing many problems.

> 
> > 3 things:
> > !. Run gpsd as root, not under sudo  
> ok
> > 2. All options go at the front, devices at the end.  
> ok
> > 3. Do not use -p unless you really, really, know what you are
> > doing.  
> We manually configured our receiver to output a 5Hz position, among
> other things, and didn't want gpsd to overload these parameters.

gpsd does not reset your position update rate.  Beware, most recivers
don't really do 5Hz, they just interpolate the 1Hz.

In any case, usually cleaner to start gpsd, and THEN update the receiver
config.  But either works.

And get rid of you 3.22, way old.  We can't support old binaries from
other sources.

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

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    "If you can't measure it, you can't improve it." - Lord Kelvin

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