APRStt-PL adds PL decoding!                          WB4APR 25 Mar 2002
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APRStt-PL listens for PL's on the repeater voice input and sends out a
very brief APRS STATUS packet (direct. No hops) whenever it hears a new
PL(has not been heard in the last N minutes).  The packets would look
like this:
 
W3VPR>APLxxx:>Heard 088
W3VPR>APLxxx:>Heard 105
 
Where W3VPR is the callsign of the repeater (APRS will already konw the
locatin of this repeater from its once every 30 minute BText).  "XXX"
is the PL tone heard (without the tenths digit).  And these 9 chars fit
beautifully on the D7 and D700 front panel when the packet comes in.
 
Thus, my APRS software could then maintain a list of every such PL heard
at that site in the last 30 minutes.  Thus you can see WHO is using that
repeater or use it for other inaudible signaling tasks.  Here is how I
might use this tremendous ID capability.
 
1) My kids could turn on PL XYZ when they call me.  My APRS in the office
BEEPS me that my kid is on the air (I cannot maintain a listening watch on
our VERY BUSY 2m repeater at work, its just TOO distracting).

2) My kids could turn on PL ABC when the soccer game is over and while I
am out running errands I will  see that PL and hear the BEEP on my D7 HT
or Mobile D700 front panel and know to go get them.
 
3) VIPS in ARES/RACES could have PL codes and if APRStt-PL was running on
all local repeaters, then the APRS map could show What repeater they are
on.
 
I can think of endless possiblities.  And it is so easy. My biggest
frustration with new neat applications is that nothing gets through modern
repeaters end-to-end except voice.  I cannot use CTCSS, DCS, TTones, or
Packet to get through a repeater.  The only easy signaling method is ARPS
but it requires a $400 HT (which I am not yet willing to give to my kid on
a routine basis and it is too big anyway for her b ackpack)..  But,
APRStt-PL allows ANY HT even the tiniest ones to be used as a singnaling
device.
 
This APRStt-PL is a method of signalling "around" any repeater in a method
that is machine (and human) readable to augment voice or other signallling
needs.  It also works well with PL heard on FRS... (no imediate idea comes
to mind, but for a $29 signalling device with built in PL encoder, its a
thought)..
 
There are only 38 PL tones, so in a HAM club like ours with over 250
members, we cannot just assign everyone a unique code for daily use.
So that is not what is envisioned here.  But in that same club there are
probably only a half-dozen people on any given day that really play with
neat new things or APRS and so there is ample room for uniqueness.  Also,
you have to more or less  eliminate the PL's used in the surrounding area,
because they will be  heard all day long as people come and go on the
repeater.  But in our  area, most PL's in Maryland are the same for user
convenience anyway, so  that leaves LOTS of PL's for unique signalling...
 
In APRSdos, I will just add these APRSPL packets to the existing
"vicinity" plotting which will randomly place them on the map in the
vicinity of the voice repeater using the normal Vicinity plotting ICON of
the biq Questionmark.  So at a glance, you can see them and where they are
being heard.
 
de WB4APR@amsat.org, Bob