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[aprssig] Help with Interfacing a GPSto Kantronics KPC-3

EXT-Maetta, John john.maetta at boeing.com
Wed Jan 3 22:02:38 UTC 2007

Hi Bob,

I have put together the TAPR PIC-E 'dumb tracker'. The PIC-E does not
transmit the GPS data correctly, even though the PIC-E Diags run
correctly.  It does appear to parse or recognize the $GPRMC string, but
sends erroneous GPS characters to the radio(off air testing). MYCALL and
the other PIC-E programmed text transmits correctly, it is just the
parsed GPS strings that are corrupt. After much trial and error, I have
re-discovered that my long lost KPC-3 TNC may support what I need to
complete my project.

Although, it seems I will have to go through more trials with this
hardware before getting the results I need.


John N6VMO

-----Original Message-----
From: Stephen H. Smith [mailto:wa8lmf2 at aol.com] 
Sent: Wednesday, January 03, 2007 1:17 PM
To: TAPR APRS Mailing List
Subject: Re: [aprssig] Help with Interfacing a GPSto Kantronics KPC-3

john.maetta at boeing.com wrote:
> Hi Bob,
> Thanks for the reply.  I have yet to hook a transmitter up to the
> So 'On the Air' testing has not been tried yet.
> I am trying to get the basics working first, then I'll interface the
> KPC-3 to my transceiver. What I wanted to see was the Xmit LED 
> illuminate every 10 and 20 seconds to demonstrate that my system is 
> working.
> 73
> John N6VMO

The transmitting of raw NMEA strings over the air in routine APRS
beacons is highly discouraged in California.  Raw NMEA strings occupy up
to TEN times more air  time than the most compact encoding format for
APRS (Mic-E);  a luxury we can ill-afford on the overloaded 144.39 
frequency in most of California.       Real-time off-the-air channel 
loading data for southern Cal is here:

    < http://webs.lanset.com/wa8lmf/uitraffic/trafficlive.htm >

If you want to run a transmit-only "dumb tracker" consider using a
TinyTrack  < http://byonics.com > or Opentracker < 
http://n1vg.net/opentracker > instead.   Both these approx $35 kits 
transmit far shorter strings than an ordinary TNC in tracker mode and 
are smaller, lighter and consume less power than a full TNC.     Not to 
mention saving an expensive $200+ TNC for more elaborate
transmit/receive applications at a home station.


Stephen H. Smith    wa8lmf (at) aol.com
EchoLink Node:      14400    [Think bottom of the 2M band]
Home Page:          http://wa8lmf.com  --OR--   http://wa8lmf.net

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