Subject: [NEXTEL-1] Looking for clarification on "openness" of P-25 standard

From: John M <[email-masked]>
Date: Mon, 23 Dec 2002 12:09:00 -0800 (PST)

Apoligies for the crosspost.

I'm trying to formulate a response to a post on
another group saying that an individual was going to
have a shareware software program for decoding APCO
voice "soon".

In addition to the complexity of the different
components, I seem to recall someone mentioning in a
discussion a while back that there was a license fee
of several hundred thousand dollars that had to be
paid in order to use an element, perhaps the IMBE
vocoder?

Can anybody give me a basic summary of why it would be
very difficult to create a "shareware APCO P25" DAC?

Many thanks and happy holidays.

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From: Rick Parrish <[email-masked]>
Date: Mon, 23 Dec 2002 14:38:14 -0600

DVSI created IMBE - the speech compression used in P25. They licensed it 
to APCO under "RAND" conditions (Reasonable And Non-Discriminatory). You 
could either license it through APCO or directly from DVSI.

A genuine reverse-engineering effort for IMBE is a serious undertaking 
whereas writing the software from APCO P25 specs is no big deal.

I defer to the "IAL"-s on the list as to the reasons why releasing a 
share-ware (or other commerical) implementation of IMBE would be a good 
or bad idea.

IMBE technology itself is a bit dated compared to newer, better, faster, 
cleaner speech codecs that do not need to be licensed under RAND or any 
other terms. It is conceivable that APCO could adopt an additional 
vocoder (something other than IMBE) that would result in lower systems 
costs due to the elimination of IMBE licensing fees. Frankly, I'm 
suprised Motorola & friends did not push for this sooner.

Regards.
Rick