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[aprssig] APRS DF reporting

Jason Winningham jdw at eng.uah.edu
Tue Nov 21 20:16:08 UTC 2006


On Nov 21, 2006, at 11:27 AM, R. Simmons wrote:

> I would also have to create an IBM
> program to set the semi-static variables

As one of the non-wintel users, I'd rather see the config program run  
on the microcontroller, which is configured via a standard RS232  
terminal application.  That's a relatively minor nit to pick, though.

I've done a bit of looking at this problem myself, mostly because I'd  
like to have semi-automatic APRS df reports generated.  Issues for a  
mobile array include resolving relative bearing reported by the DF  
unit with the vehicle's true (or magnetic) bearing.  I've managed  
this by using a GPS with a relatively sane bearing algorithm (until  
you put the vehicle in reverse), but a GPS with a compass or a  
straight electronic compass would be better.

Also, There are small issues like how many objects to use - if you're  
one of a team of hunters, maybe the last report only is good enough,  
but if you're alone you want several reports to assist with  
triangulation.

I suspect custom OT firmware would be useful, but you'd probably need  
to merge DF and GPS/compass rs232 streams to talk to the OT's single  
serial port.  The T2 might be a better choice, if a little more  
expensive, because it has more code space and an extra serial port.

Come to think of it, Scott, you could write this in to accept any  
Agrelo (sp?) interface DF device; use a digital input to trigger the  
TX of a DF object, with other DF parameters configured as usual.

-Jason
kg4wsv







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