[aprssig] APRS Voice links?

Robert Bruninga bruninga at usna.edu
Mon May 20 09:16:05 EDT 2013


You might want to read the http://aprs.org/avrs.html page.  It really has
nothing to do with adding voice over APRS.  It has to do with organizing
amateur radio voice systems so that the interactive front panel of the APRS
radio which has global callsign-to-callsign connectivity may be used to
–setup- a callsign-to-callsign voice connection with the only knowledge
needed by the caller or callee is a callsign.  Hope that helps.  Bob, WB4APR

*From:* aprssig-bounces at tapr.org [mailto:aprssig-bounces at tapr.org] *On
Behalf Of *Mike Goldweber
*Sent:* Sunday, May 19, 2013 6:27 PM
*To:* TAPR APRS Mailing List
*Subject:* Re: [aprssig] APRS Voice links?

At the risk of being a debbie downer, I would ask what is gained by adding
voice to APRS?    On the internet side of the equation I do see the value
of some value to his, and there probably isn't any real down side; but as
Bob pointed out there is a number of ways to talk VoIP already.
Multitasking OS's give us the means to run several programs at once,
letting someone do APRS-IS as well as Echolink and DStar all at once.

On the radio side of APRS, I see the potential for problems. I believe
adding voice data could potentially add a lot of data being sent, which
could prevent the usual stream of data from moving properly. My interest in
APRS came about from my involvement with emergency communications.  Our
area has well defined voice channels set up, but we only use a single
channel for APRS.  The frequencies used for voice are organized in such a
way to prevent problems with too much chatter.  Currently, there isn't a
problem getting the APRS data, but adding voice to the mix could change
that if everyone were to begin talking over the APRS channel.

Frankly, given the amount of bandwidth devoted to voice over VHF, I don't
see the advantage of having a voice-over-APRS.

Best Regards,

Mike Goldweber


-------- Original Message --------
Subject: [aprssig] APRS Voice links?
From: Robert Bruninga <bruninga at usna.edu>
Date: Sun, May 19, 2013 1:08 pm
To: aprssig at tapr.org
Cc: aprs at yahoogroups.com

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
second maybe...

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* <http://aprs.org/avrs.html>

Maybe this new FreeDV can serve as a spark for some new thinking…

Bob, Wb4APR


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