----- Start Original Message ----- Sent: Wed, 19 Mar 2008 07:02:08 -0600 From: Jeff Brower <[EMAIL PROTECTED]> To: Rick Parrish <[EMAIL PROTECTED]> 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 > (STANAG > 4591). Common applications are HF radio and L band satellite apps where > bandwidth is > very limited. > ----- End Original Message ----- Hello, 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 _______________________________________________ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
