[Xastir] Help with TH-D72

[Alex Carver]

--- On Mon, 1/17/11, Curt, WE7U wrote:


> > I don't think the D72 is going to take a Control-E
> much like the D7 doesn't either.  The processor in the
> original D7 was configured to tee one single NMEA string
> from the GPS out onto the serial port every time it saw one
> come in on the GPS port.  That's the nature of the
> GPSHEAD command in the TNC.  You fill the GPSHEAD with
> a NMEA prefix (like "$GPGGA") and then every time the
> processor sees the prefix it pauses the output of the TNC,
> spits out the NMEA sentence, and then resumes the TNC data.
> 
> Ah.  In some Paccomm and Kantronics TNC's you set
> something like GPSHEAD and it captures the NMEA string into
> a variable each time it comes by.  Then a Control-E
> causes the TNC to dump that string out.  I thought the
> Kenwoods did the same, but not owning one, will defer to
> those that do.  Thanks for clearing that up!

Yeah, Kenwood decided to echo as soon as the sentence shows up so there's no Control-E operation at all.  It just pops out of the serial port.  I got my poor D700 confused one day with that little "$" experiment.  It just couldn't keep up with my Garmin 12XL which is transmitting five sentences per second.  The main problem was the system was trying to keep up with two data streams at once (the APRS data coming in plus the GPS data) and the bandwidth was just too low for that.

Now if everything could have run at 115200 baud with a huge GPS buffer and some more processor power it probably wouldn't have been much of a problem.  Save a second worth of GPS data and then blast it out at high speed.

> 
> It sounds like we need to modify the THD7 startup script,
> or create a new one for the D72.  Hopefully someone
> that has the APRS + GPS strings working on one or the other
> will let us know the details.  I'll be happy to made
> the mods or add a new file to CVS.