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Re: [Discuss-gnuradio] DV Dongle - AMBE USB Device

From: Eric Cottrell
Subject: Re: [Discuss-gnuradio] DV Dongle - AMBE USB Device
Date: Wed, 19 Mar 2008 11:38:23 -0400 (EDT)

----- Start Original Message -----
Sent: Wed, 19 Mar 2008 07:02:08 -0600
From: Jeff Brower <address@hidden>
To: Rick Parrish <address@hidden>
Subject: Re: [Discuss-gnuradio] DV Dongle - AMBE USB Device

> Rick-
> > > I am also thinking of writing a APCO P25 Voice to AMBE2000 frame 
> > > converter and see
> > > if the device can decode P25 as well.  This may be a general IMBE and
> > > AMBE codec.
> > >
> > 
> > I hope so. I looked at this a while back. What concerned me most was the
> > AMBE2000/2020 documentation seemed to omit P25 style IMBE compatibility.
> > Compare the docs to another DVSI product - the VC55 - to see what I mean.
> If you're looking at low bitrate codecs for GNU radio, why use a hardware 
> (dongle)
> dependent solution?  You might look at MELPe, which provides 600, 1200, and 
> 2400 bps,
> and can be implemented as a software solution.  MELPe is a US/NATO standard 
> 4591).  Common applications are HF radio and L band satellite apps where 
> bandwidth is
> very limited.
----- End Original Message -----

That would be a good idea if I was doing digital voice from scratch but I am 
trying to decode IMBE and AMBE used in APCO P25 and a number of other systems 
like MA/COM ProVoice and some Inmarsat stuff.

MELPe may be a great solution to get Ham Digital Voice away from IMBE and AMBE. 
 It may be difficult to do in the case of VHF/UHF with older P25 radios being 
available surplus.

IP issues can be a minefield as the Rembrandt Technologies suit about their 
ATSC patents shows.  I heard that HDTV Grand Alliance made the mistake of not 
having a formal patent pool and there was an informal agreement.  Rembrandt got 
the technology patents from AT&T which was part of the HDTV Grand Alliance and 
decided to play hardball and recover the costs of buying the patents plus make 
a profit.

Having dealt with companies that only release information under NDA, I can 
appreciate that DVSI has their information available so a device like DV Dongle 
can be made.  It is not a good clean open source solution but is like the 
MadWifi driver.

I would like to play with ALE and STANAG protocols someday.  Thanks for the 
information and I will look up more information on it.

73 Eric

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