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[aprssig] Ultimate APRS digi

Robert Bruninga bruninga at usna.edu
Fri Nov 19 17:51:59 UTC 2010


> > The result is vastly improved local user reliability since
their
> > input packets on 144.99 do not have to compete with any of
the
> > 144.39 congestion.  Yet 144.39 still has ALL info for ALL
users.
> 
> Isn't that still just two inputs?  
> Or are you counting 1200 and 9600 as
> separate inputs?  That can be done 
> simultaneously on the same input with
> the right software.

Yes, they can be combined, but the main reason for doing any of
this is to separate the INPUTS of digipeaters as much as
possible.  This lowers the ALOHA congestion that each signal has
to deal with to get in.  So its better to distribute users to as
many different inputs as possible.  I come up with 3 as a
starting point...

144.39 input for legacy, for transition and for visitors
144.99 (144.39+600) for local users
UHF 9600 for 9600 baud.  It doesn't need to be UHF but
eliminates 50% of blocking

Come to think about it, few people are going to run cavities on
the 2m band, so maybe we whoudl be looking for a LOCAL frequency
in the 147.5 area for the alternate input for the locals.  The
advantage is 3 MHz of isolation.  The disadvantage is that local
mobiles will have to program a SPLIT channel to use it.

Bob, Wb4APR





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