Re: How fast are decodes

"John D. Hays" <john@...>


Richard is correct, the AMBE3000F chip in the ThumbDV is a single stream vocoder.  It only vocodes the audio stream, not the P25 (or other transport) protocol.

Since it is a USB device, you can plug in several which will each appear on their own "COM" or "tty" device to the OS.   Plug in as many as your computer / OS / USB busses can handle for parallelism. Each appears as a 230.4 kbps serial device.

Your software will need to remove the AMBE stream from the P25 protocol (for each channel), buffer it into packets and send it to the ThumbDV, for each packet of AMBE it will return a packet of PCM encoded audio back (and visa-versa).

It will not decode IMBE (P25 Phase 1), only P25 Phase 2.

On Thu, Feb 5, 2015 at 11:52 AM, myyahoo@... [UniversalDigitalRadio] <UniversalDigitalRadio@...> wrote:

You would need a dongle per stream, the dongle can only decode one stream at a time.

Given the price of dongles, you might want to try a hybrid approach, and offload a stream or two and do the others in software?

- Richard, VE7CVS


John D. Hays

PO Box 1223, Edmonds, WA 98020-1223 

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