[Xastir-dev] args to data_add()

[Owen DeLong]

I may be completely wrong here (haven't actually used GPSD yet), but
as I understand it, you don't "ask" GPSD for anything.  You subscribe
to it (essentially) and it acts as a multiplexer.  It connects to a GPS
via serial port and listens on a socket for subscription
requests.  Then, every string it gets from the GPS is duplicated into
each of the attached clients.

That way, multiple clients (applications) can get the data from the same
GPS.  The GPS NMEA strings should include altitude in the $GPGGA and/or
$GPRMC sentences (if memory serves).  To the best of my knowledge, the
GPS doesn't provide a callsign and GPSD doesn't know anything about
amateur radio.  The callsign would be "Mycall" with regards to a GPS,
anyway.

If you're creating a synthetic GPS, then, you could use a "proprietary
extension" sentence to include the callsign, and, I think it would be
pretty simple and harmless to have XASTIR process that appropriately.
Choose your sentence name carefully (try to avoid existing GPS vendors
sentence names).  I don't think XASTIR uses any of these yet, but, I
wouldn't want to rule it out.


Owen

--On Wednesday, April 14, 2004 17:53 -0400 Wendell Turner 
<wendell at adsi-m4.com> wrote:

>> > - a udp input routine in the main loop (optional, I'll look into
>> >   using gpsd instead, since that is the 'xastir way')
>> >
>> I think GPSD would be a better way to go.
>
> Is there a way for xastir to ask gpsd for the callsign and
> altitude?  I didn't see that in the gpsd documents.  Also, there
> is just one gpsd for everything, right?  Not a gpsd running
> for each peer entity, correct?
>
> Wendell
>