[aprssig] APRS-B?

Scott Miller scott at opentrac.org
Mon Jun 24 12:06:14 CDT 2013

> Obviously this would not be too difficult for a PC or microcontroller to
> do, but it does increase the hardware and software complexity external
> to the device sharply.
> I.e. are you going to use an entire second computer (Raspberry Pi,
> Arduino, Basic Stamp, etc) to glue a PC to a $20 gadget?

That part's already done:


I had these up and running a year ago, but have been too busy with other 
projects to do much with them.  These examples use the OpenTracker USB, 
but could just as easily have a Tracker3 processor.

When I went to test them last year, I had a software glitch that was 
causing the PA to not power up properly.  I didn't get much range out of 
them.  Next week, I'm headed back out to the Black Rock Desert again and 
I suppose I could dust them off and give it another try.  Nothing like 
60 miles of absolutely flat lake bed out in the middle of nowhere for 
testing RF stuff.

Some things need to be nailed down before we have an APRS-B standard. 
These units are presently set up to use KISS-style framing and 
Hamming(7,4) coding for error correction.  That was for simplicity, not 
because it's necessarily the best way to do it.

The rest of the code is pretty much unchanged.  KISS works as usual, 
along with digipeating and everything else.


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