[Linux-ham] Fwd: [KD4RAA-K4JDR Rptrs] RARS Testing UHF D-STAR Repeater

[Kevin Otte]

On Wed, Oct 24, 2007 at 01:58:44PM -0400, Tanner Lovelace wrote:
> Anyone here know more about D-STAR?  Basically all I know
> about it is that it's digital and fairly expensive in that you need
> to get all new equipment to use it (and tied to Icom hardware,
> so how's that for a conspiracy theory. :-).

The D-Star protocol is published, but there is one small fly in the
ointment.

"Voice is encoded as a 3600 bit/s data stream using AMBE encoding, with 1200
bit/s FEC..." [1]

So just what is AMBE?

"Advanced Multi-Band Excitation (AMBE) is a very powerful proprietary speech
coding standard developed by Digital Voice Systems, Inc.." [2]

"AMBE is controversial in that the licensing terms are very restrictive.
While a licensing fee is due for most codecs, DVSI does not disclose
software licensing terms. Anecdotal evidence suggests a minimum fee from
$100,000 to $1 Million. PC implementations are not allowed. For the purposes
of comparison, MP3's licensing starts at $15,000. For small-scale use and
prototyping, the only option is to purchase a dedicated hardware IC from
DVSI." [2]

In other words, if you want to roll your own, you are SOL.

Perhaps somewhat opinionated, but I'm wondering how this device got FCC
approval. FCC 97.113 states that "(a) No amateur station shall transmit: ...
(3) ... messages encoded for the purpose of obscuring their meaning, except
as otherwise provided herein;..." [3] Without coughing up the money to DVSI,
those transmissions are awfully obscure to me.

I have heard of some hackers trying to replace the AMBE bits with Ogg Speex. 
This would allow you to use an existing D-Star infrastructure, but not an
Icom endpoint.

[1] http://en.wikipedia.org/wiki/D-STAR
[2] http://en.wikipedia.org/wiki/Advanced_Multi-Band_Excitation
[3] http://www.arrl.org/FandES/field/regulations/news/part97/

-- 
Kevin Otte, N8VNR
nivex at nivex.net
http://www.nivex.net/

-=-

"Those who cannot remember the past are condemned to repeat it." 
-- George Santayana

"It seems no one reads Santayana anymore."
-- Cdr. Susan Ivanova, Babylon 5