[op25-dev] RE: Phase 2?
mmills at 2bn.net
Thu Feb 6 03:42:17 UTC 2014
Thanks for the update. I have a Phase 2 system that is supposed to go live
near me soon, I will attempt to capture and provide some samples with both
the control channel and voice channels.
On Tue, Feb 4, 2014 at 11:50 AM, <ikj1234i at yahoo.com> wrote:
> 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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