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[aprssig] Parallel UHF APRS level-4 node system.

Jason Winningham jdw at eng.uah.edu
Tue Dec 28 21:00:06 UTC 2004


On Dec 28, 2004, at 1:36 PM, John Denison wrote:

> from a newbie point of view, I wonder why 1200 baud is still being 
> used.

I think the biggest reason is that you can get a data signal into and 
out of a radio via the audio I/O. A big (the biggest?) component of ham 
radio is experimentation, and a digital mode that you can build digital 
hardware for without hacking or building a transceiver is very 
attractive.

The various microcontrollers out there (PIC, Atmel, 68HCxx, TI, etc) 
that can generate (or decode, or both) the audio with few or no 
external components gives us a very powerful experimental platform if 
we can live within that 1200 baud AFSK limit.  APRS trackers and 
weather stations fit wonderfully into that particular niche.

A local ham has an Atmel based tracker that will also decode packets.  
the last I heard he has experimental support for wiggling bits via APRS 
messages, so his rig can not only send tracking and telemetry data from 
an amateur balloon experiment, it can provide signals for cutdown 
mechanisms or experiment control.  Not bad for one IC, eh?

-Jason
kg4wsv





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