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

Robert Bruninga bruninga at usna.edu
Wed Jan 3 22:46:23 UTC 2007


> 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). 

Be sure you are expecting the right thing.  The Mic-E Format
consists of only a few bytes.  The entire APRS position report
in Mic-E format is only 9 bytes long and ususlly looks like
gyberish, just like any TH-D7 or D700 looks.

Could that be it?
Bob

> 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.
> 
> 73,
> 
> 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
> KPC-3.
> > 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
> 
> NEW!   TNC Test CD
>   http://wa8lmf.net/TNCtest
> 
> JavAPRS Filter Port 14580 Guide
>   http://wa8lmf.net/aprs/JAVaprsFilters.htm
> 
> "APRS 101"  Explanation of APRS Path Selection & Digipeating
>   http://wa8lmf.net/DigiPaths
> 
> Updated "Rev G" APRS            http://wa8lmf.net/aprs
> Symbols Set for UI-View,
> UIpoint and APRSplus:
> 
> 
> 
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> 
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