AMBE

[George Lemaster]

AMBE is from Digital Voice Systems. 
http://www.dvsinc.com/
They have voice samples on their page. Unfortunately the high rate 
samples seem to have a broken link.

AMBE compression is used in Iridium, APCO 25 digital radios, 
and the ham project designed by G4GUO some years ago. G4GUO's design
used a Motorola telephone exchange codec which outputs 8 bit mu law 
and is then compressed by a DVS ASIC. I don't know how much the 
ICOM version differs from the original, if any, in the voice coding
section. Dave Borden and I started to build up two systems
before he moved away. The system was described in QEX.
 http://www.arrl.org/tis/info/HTML/digital_voice/index.html
AMBE is considered by some to be the best available at very
low data rates, 2 and 4 kbps. And, it's a codec available
in small quantities that (at least at on time) hams could get.
You might run AMBE at a faster data rate but at a few kbps it is
difficult to get natural sounding speech.
George. 




-----Original Message-----
From: tacos-bounces+lemaster=verizon.net at amrad.org
[mailto:tacos-bounces+lemaster=verizon.net at amrad.org] On Behalf Of A.
Maitland Bottoms
Sent: Sunday, November 27, 2005 6:06 PM
To: tacos
Subject: AMBE

Anyone have some .WAV files from an XM Radio?
I just saw a comment on AMBE (the codec used in the ICOM D-STAR):

"We are currently using AMBE (4Kbps) for our Traffic/Weather Channels.
If you have ever had a chance to hear the service, you will know that
AMBE does not do us well."

   - Terry Carr
     Manager, Broadcast Applications
     XM SATELLITE RADIO
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