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[aprssig] 40 meters?

Robert Bruninga bruninga at usna.edu
Wed Nov 17 13:34:59 UTC 2004


>40M was actually the first and only HF frequency for 
>APRS operations many years ago. When W3ADO fixed 
>an antenna some of us tested out 30M and eventually 
>all changed. 

Just to clarify the record, APRS and it's CETS pre-cursor
has been on 10.149 MHz since abouit 1983 when we first
developed the dual port Vic-20 based packet BBS and
also developed the conversion for the VADIC Bell 103
modems to do HF packet with 200 HZ shift.

The 10.149 MHz channel was chosen because I had
a crystal that just happened to be there.  By 1984 it had 
become the Connectionless Emergency Traffic System 
(CETS) which ran on a C64 for doing all of the UI decaying
algorithm UI protocol for efficient all-to-all delivery of tactical
real time digital data that APRS now uses.  When GPS
became cheap enough, in 1992, I added position reporting.
and changed the name to APRS.  The only time we were off
10.149 was during a family move in 1990...

The problem is, that most followon programs simply
implemented the GPS position reporting and maps, and
often ignored the underlying decaying comms UI protocol
to properly share the channel and make sure that new info 
is more relliably handled than old.  THus today, the APRS
channel is quite useless with old, fixed, unchaniging data
taking up all the bandwidth and not destinguishing between
new immediate data and old retry data...

Well, enough of that.... back to the program in progress...

de WB4APR, Bob





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