D-Star vocoder emulator

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Posts: 3
Joined: Tue Jan 21, 2020 11:24 pm

D-Star vocoder emulator

Post by kb9mwr » Sat Apr 04, 2020 5:16 pm

There is a need for a D-Star vocoder emulator by the ham community for those who host cloud based bridges for digital voice modes.

If your a ham with this talent or know of one, the community would appreciate your efforts.

It should likely work similarly to the md380-emu tool by Travis (KK4VCZ) that folks have been using for DMR and the other modes.

https://github.com/travisgoodspeed/md38 ... e-decoding

As of 2017 the AMBE used in D-Star is out of patent. But all we have to decode (contained in dsd/mbelib) its a crude proof of concept code set figured out by some great folks on radioreference from around 2013.

From user groovy Jun 26 2015:
"If anybody wants to continue the research / work, I suggest you look at the osmocom GMR code that Sylvain Munaut worked on. Those phones use a similar codec - I believe with longer frames for the satellite latency. Initially he used the mbelib code, enhanced it for things like tone support, but he later rewrote the synthesis code completely. See OsmocomGMR for his presentations and source code. "

This COVID-19 time at home would be a good opportunity for someone to work on this. I am not much of a programmer, nor do I have the math credentials for such as task. However, I will do my part to make sure anyone who step up to the task gets recognized for their contribution to advancing the hobby.

Please help spread the word if you can think of someone who might have the needed talent for this project.

https://forums.radioreference.com/threa ... ss.215282/
http://forums.radioreference.com/thread ... st-2412739
https://github.com/boatbod/op25/blob/ma ... coder_sb.h

Posts: 3
Joined: Tue Jan 21, 2020 11:24 pm

Re: D-Star vocoder emulator

Post by kb9mwr » Sun Aug 30, 2020 4:13 am

Here is to bumping this post and providing some links for potential developers:

https://github.com/f4exb/dsdcc - dsd rewrite - C++ library with a single decoder object
http://git.osmocom.org/op25/tree/op25/g ... peater/lib - Op25 has encode and decode support for AMBE (D-Star, DMR and YSF) and IMBE (P25)
https://github.com/balint256/op25/tree/ ... be_vocoder - Pavel's IMBE Encoder/Decoder Fixed-Point implementation
https://github.com/dl1bff/ircDDB-mheard ... B-mheard.c - Line 383 - handles the bit interleaving and FEC processing
https://github.com/travisgoodspeed/md380tools/ - The MD380 Emulator (capable of AMBE encoding and decoding)

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