[aprssig] APRStt lives! (APRSspeak)

[Robert Bruninga]

> ... if someone forgets to turn off PL tones 
> that they may have left on in their radio.... 
> Somone could easily "hijack" my position..

Yes, a potential problem, but here are my thoughts.  

First, in the baltimore/washington metro area, there is a very
significant consistancy of PL tones.  In Maryland MOST repeaters
all use 107 or 156.  I think this was coordinated with
neighboring metro areas, such as New Jersey, has its own set of
common PL's?  I actually think this was planned by the frequency
coordination bodies?

It makes sense if we go back 20 years when individuals had to
add a hardware PL to a rig.  It made sense to add one for an
"area" and then the radio could be used on all the local
repeaters without changing the PL code.  Yet, it would keep out
ADJACENT area co-channel interference...

So, for APRStt at an event, the PLANNER prepares the list of
CALLSIGN-to-PL/DCS associations and blocks out all tones and
codes that are in common use in an area.  These are not
available for use.  All the rest are.  Once prepared, this list
would be useful for avoding conflicts during each such APRStt
supported event.

Bob