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[aprssig] A-Star gateway repeaters?

Robert Bruninga bruninga at usna.edu
Mon Dec 13 16:33:14 UTC 2010


As you know, since 2001 or so, we have been striving for
universal TEXT and VOICE ham radio connectivity using only
callsigns.  We have made much progress on both.  Here are the
partculars for the VOICE side:

* Echolink, IRLP and D-star nodes now show up on APRS
* These and repeaters show their FREQs and Tones
* The D710, FTM-350 and D72 can instantly QSY to them
* We have global APRS signalling
* Echolink, IRLP and D-star have global voice.

But for 9 years, we still have not gotten someone to write the
AVRS engine to simply do the signalling and set up the calls.
Though we have an excellent volunteer A0OO in Atlanta who has
just started work on the AVRS engine.

But, recognizing that D-star already has the end-to-end
callsign-to-callsign voice connectivity, maybe a short cut to
universal connectivity is to simply make A-star gateways between
the D-star network and the analog-end user.  

See www.aprs.org/avrs.html

The concept is simple.  On the D-star network, the A-star
repeater just appears as another identical D-star gateway.  It
signals using the same 4 callsign fields as do all D-star
radios.  But on the Analog side, it is aware of all calls on the
A-star repeater because it can see their APRS beacons.  So it
can receive any incoming D-star-to-callsign call and pass the
audio to the repeater.

For an APRS user on the analog side of the A-star repeater, he
simply initiates a message TO ASTAR and the message content is
simply "A*CALLSIGN" indicating that he wants to make a call to
CALLSIGN.  This gets converted by the A-star repeater over to
D-star signalling and the connection is made on D-star.

The beauty of this approach is that there is zero change to
D-star connectivity, gateways, or callsigns or signalling.
Everyone (including the APRS users) appears on the D-star
network simply by callsign and appears as another D-star user.
But that last mile to the APRS user is made by analog audio on
the analog repeater and by APRS signalling.

If we can not be distracted by politics, this could be a win-win
for everyone.  Of course the devil is in the details... But why
not?

The one big advantage of the A-star end is that the CALLEE does
not even need to be on the A-star repeater to receive the call.
He receives the CALL message with the QSY info so he can go to
the repeater to receive the call.  This is why we have pushed
the QSY and TUNE buttons into all new APRS radios.  All along,
this capabilty was eventually going to support automatic-instant
radio QSY to receive such calls.  But until we had the whole
system working, the automatic feature was premature.

Of course, please correct any errors in this vision.  I am sure
I screwed something up somewhere.

Bob, WB4APR




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