[aprssig] APRS Voice links?
bruninga at usna.edu
Sun May 19 12:08:29 CDT 2013
At Dayton there was a lot of excitement about FREE Digital Voice (FreeDV)
Although it is currently being applied to robust HF communications at about
1200 baud in a 3 KHz channel, the basic Vocoder works at about 1000 baud
or as low as 800 bits if the data stream is error protected. (Ie inside an
AX.25 connected packet).
At the risk of exposing my ignorance, I wonder how close we could get to
relaying the raw Vocoder over an AX.25 link using our existing 9600 baud
modems built into the Kenwoods? Even with the slow TXD delays (500 ms!)
in Kenwood 9600 baud modems, a conversation could be continuous if the
radio was transmitting this information at 9600 baud in packets once a
This would give experimenters a chance to see what we can do with Digital
Voice using existing AX.25 links.
I have no idea what a network would look like, but if IGates could receive
these 9600 baud connections, then it would seem like we could cobble
together some kind of A-STAR system where we use the frton panel controls
and APRS to set up who we want to talk to and then the IGates link us
between any two hams anywhewre on the planet along with their APRS traffic.
Anyway, a whole new exciting area to think about. Remember, it has always
been my goal to have callsign-to-callsign voice contact (using APRS
connectivity to set up the call). At first I thought IRLP, then Echolink,
then ALL-STARR would be the answere. Then D-star actally is now doing it,
and we still have not gotten organized to simply take what we have and do
it too. See http://aprs.org/avrs.html
Maybe this new FreeDV can serve as a spark for some new thinking…
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