At 01:43 AM 6/8/2010, you wrote: >OK, but there's nothing wrong with extending the current protocol >and calling it D*Star+ or just "D*Star Compatible" or whatever.
2 words: "backwards compatibility". There would have to be a LOT of money spent to make this work. >Heck, there are already some freely available CODECs out there >anyway that seem to perform pretty well (although weren't >specifically designed for wireless usage): Speex and the Skype-CODEC >come to mind. (I'm not up on the specific licenses, however -- >they're "free as in beer" at least, though.) Speex is free (as in freedom), same as codec2. However, it operates at a higher bit rate, which was one reason codec2 was developed. Skype is only "free as in beer", and I'm not sure what codec(s) they actually use. >One thing to keep in mind is that, since most hams operate D*Star >through repeaters anyway, one approach here would be to have the >*repeater* have both AMBE and CODEC2 (or whatever) capabilities, and >just translate between them on-the-fly. (This approach is used with public 2 problems: 1. The repeaters currently have no audio hardware on board. They are simple bit regenerators, so we're talking about adding up to at least 3 voice transcoding modules (one for each band) per stack, to make this possible. 2. What about the case where radios on air are running incompatible codecs. Current Icom (AMBE only) and home brew PC based SDR (Codec2 only). I see a lot of potential for this sort of breakage. The only way around this would be to enforce AMBE in any situation where older radios could intercept the signal. This means adding codec2 would be totally pointless, since AMBE would still be required anyway. >service radio systems, since there lots of different companies >decided to build their own proprietary protocols and used different >CODECs as well.) I would wager that repeater usage probably >accounts for more than 90% of D*Star voice traffic, and getting >repeater builders to incorporate a backwards compatible radio into >their system (that has the same interface as the current Icom boxes) >is nowhere near as daunting as getting everyone with an HT or mobile >D*Star rig to buy something new. I can think of a lot of corner cases that wouldn't work, unless you mandate the repeater transmits in AMBE (which renders Codec2 pointless in D-STAR). :) 73 de VK3JED / VK3IRL http://vkradio.com
