1/2/2011

With the help of a very smart person in Germany we now have a solution. His post to the DSTAR_DIGITAL Yahoo group is below.

Attached is a functional program (linux) that can decode the 9 hex byte sequences to find the DTMF code (not the two tone codes), both
source and compiled. I also attached a copy of voice data I captured from packets coming into eth1 on my gateway. Run the program
and then when it asks for Input, copy one of the 9 byte groups from the worksheet and paste it to the input. When you press enter, it
should give you the right DTMF character.

Much of the source is from a the in Germany who clearly already had code to decode the DV data but had not determined before how to
find the DTMF digit. The more non-professional parts are mine. I spend most of my days programing in PHP, so my C is getting rusty.

I posted these results back to the DSTAR_DIGITAL group along with some questions on how to proceed now. I'd hate to see 35 different
implementations of DTMF control start showing up but it would be nice to accommodate everyone's desires in any implementation.

I believe there's also a D-Star development discussion group, but I'm not currently on that. Do either of you have a suggestion as to where
any development on this should be centralized?

Chuck, N8DNX



-Quoted text -
Happy new year!

I had time in the last few days to take a closer look at the 72 bits
in the AMBE voice frame. I found the DTMF in-band channel with all
4 bits of DTMF information. If you want to know more, please look
at the source code of  ircDDB-mheard.c  line 383.

https://github.com/dl1bff/ircDDB-mheard

This program is part of the ircDDB software which runs on several repeaters.

http://ircDDB.net


73s from Berlin
 de Michael, DL1BFF
