[aprssig] NMEA Sentence problems into SCS Tracker....from GarminEtrex

Jack Chomley radio at irock.com.au
Fri Nov 23 20:23:14 EST 2007


I think you may have given me the solution 8-)  I did a "read" of 
both Garmin units, with my old Psion Workabout 1 meg Terminal.

See later model specs   http://www.udsinc.com/psion_specs.htm

I used the terminal to send each file to the SCS DSP Tracker, it 
worked on BOTH files. =-O I logged those files direct from the GPS 
units, with their proprietary cables and the reads were OK.
I also logged both GPS units serial data to my Twinhead S14K laptop 
with no problems too.
Next, break out the scope and look at the levels, from each GPS.
I am not sure what sentence the SCS unit needs, but I think the 
Tigertronics TM1+ wants the $GPRMC sentence. I guess I could also use 
the terminal to try sending the known good log file at TTL to the 
tracker (my terminal has TTL port) That will test the tracker's 
ability to receive 5 volt levels.



At 10:34 AM 24/11/2007, you wrote:
>GPRMC is ok
>GPGGA is ok
>I would next be looking at grounds and also levels coming from the 
>two GPS devices.
>Be carefull - some GPS's use a 0 to 5 volts for "RS-232"
>You should be able to use hyperterminal to simulate a GPS stream.
>Take the data you have captured from the device that is not working, 
>and send it to you TNC etc using hyperterminal.
>This will prove it is something wrong on the electrical interface.
>The data looks ok to me.
>So disprove the data by sending it from a PC to the TNC.
>What GPS string is the device looking for ?
>Just pick on that one.
>No virus found in this incoming message.
>Checked by AVG Free Edition.
>Version: 7.5.503 / Virus Database: 269.16.5/1148 - Release Date: 
>23/11/2007 7:39 PM

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