[op25-dev] RE: Phase 2?

ikj1234i at yahoo.com ikj1234i at yahoo.com
Tue Feb 4 18:50:32 UTC 2014

Hi Matt

 Two things 


 1. We're currently working on it (as are other groups, AFAIK) - parts of the Phase II TX/RX code have already been checked into svn and git (look for the tdma/ directory).  At this time the code that is present there covers the decode and encode processes only partially, and it's more or less batch-mode only.  That is it will generate the set of AMBE voice code words given a pre-captured file of samples.  More work will be needed to reduce the voice codewords into the voice model parameters so that our existing IMBE vocoders can work with it.  It turns out that both AMBE and IMBE are distinct front end layers on a common backend which we already have - this is because both of these codecs are members of the common MBE family and both use the same speech model with only the parameter quantization front ends being different.

 2. One user has provided some sample captures which have been very useful - but more samples would help greatly.  In particular it would be good to get samples which contain both the trunk control channel and the dicrete P2 voice channel at the same time.   Further out it would also be good to obtain captures of the uplink transmissions, which use a different modulation format.  That work is still pretty far off, however...




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