April 12, 2000

A-Compass

By Jeff King WB8WKA

This software is available only for non-commercial amateur radio or educational 
applications. All other uses are prohibited. This software may be modified only 
if the resulting code be made available publicly and the original author given 
credit. Contact the author for information on commercial licenses.
(c) Copyright 2000, Robert Jeffrey King. All rights reserved.

A-Compass is a Fluxgate compass adapter intended to work with APRS(tm of Bob 
Burninga) type applications in direction finding applications. It can work on 
the same serial port as a existing GPS. It does this by inserting standard NEMA 
compass bearing sentences into the "dead spots" between the standard GPS type 
sentences. In this way, you don't have to up a additional serial port.

A WORK IN PROGRESS

When I started this project, I had access to the vector differential compass, 
and is what many of you saw at Dayton 99. However, shortly after that, I had to 
return the vector compasses to there owners (it was for a unrelated project) and 
now I have no way to test it. So instead of just letting the work I did so far 
fade away, I am releasing it to ARPSdom. Now if someone were to loan me a Vector 
2X compass, I would finish it up. However, since I have no personal interest in 
APRS DF'ing, I can't justify spending the $49.  But the project is more then 75% 
complete. All the Vector 2x routines are full debugged and working, the software 
just needs to be streamlined down into the format you see expressed in the 
schematic. I even have a wirewrap circuit made up for the schematic. The 
schematic is in both .gif and ORCAD format. No PCB has been done yet.

All source code is done using CCS PCM C compiler. I made no attempt to clean 
anything up, like I said, this was unreleased code.

73

Jeff King wb8wka