Monday, July 29, 2013

AMBE Proxy

From my interest in D-Star that has since waned, I was most interested in a SIP to AMBE trans-coding bridge.  Allowing digital radio to inter-operate with ordinary VOIP.

About the time of all the Codec 2 buzz (2008-09), I was relaxing my interest in D-Star and kind of waiting to see if it would take off.  Sadly some 6 years later and there are no radio's or adapters supporting it.  Oddly enough Yaesu's System Fusion that was unveiled in 2011, could have but didn'tAnd I guess it still could as the user radios are firmware upgradable (but don't hold your breath)

Now that DMR seems to be taking off, once again we have that proprietary AMBE codec.

It was also disappointing that the user end radios and repeaters didn't have a way to address the
AMBE chips inside them in a digital manner.  I.e: Stream Ulaw in, and get AMBE out for example.

Originally the only feasible way to build this bridge was to buy a DV dongle (circa 2007).  Since then, it's clear that is not the best bang for the buck, as it can really only process the AMBE stream used in D-Star.  It cannot do DMR's AMBE+2.

Now there is the DVSI Products USB-3000,  NW Radio Thumb DV (DV3000U ), Matrix Circuits/MoenComm - Star*DV, and the DVMEGA AMBE3000 shield.  The best bang for the buck seems to be the Thumb DV.

Sadly they all use a chip solution (minus the DVSI USB-3000 maybe), and can only process one AMBE stream at a time.  If someone would have entered a agreement with DVSI maybe they could have cooked their own device that could process more than one stream at a time.

So why do I care about more than one stream at a time?  Well for one; DMR has two time slots.  For two, I'd really like to see:

Software written to let users capture the raw AMBE audio from D-Star, DMR and Yaesu and save it to a file, and/or re-direct it. (Think remote AMBE dongle) Ideally something that lets them do this off a discrimination tap. 

Then websites equipped with the hardware AMBE processor could be set up where;
-You could upload the raw captured AMBE file, and get a MP3 file back.
-You redirect the AMBE output of this previously mentioned software to (much like how an Echolink Proxy works), and get a normal m3u stream back or whatever.

Hams have had their underwear all up tight about AMBE since D-Star was unveiled, and maybe if they had some tools that let them at the very least self police themselves that didn't involve buying a proprietary vocoder of their own, they'd calm down a bit?

These community vocoders would allow hams to create custom repeater voice ID's, club announcement reminders, etc.   The real-time community vocoders could be used for when the need arises to patch traffic from one system to another.

A free software application called Digital Speech Decoder was unveiled in 2010 that lets them do this, but remember despite hams supposed to advancing the radio art, many are prudes, and don't want to even speak of the software.  The mbelib component may contain code the infringes on (soon to be expired) patents in the USA.

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