At 05:05 AM 9/2/2010, you wrote:
>John, > >Try plugging a better quality speaker into the radio. >I personally find this does wonders to increase fidelity. >Icom should be ashamed of the speakers in the D-Star HT's. A better quality speaker certainly works, as anyone who's listened to a DV Dongle on PC speakers can attest to. Actually, I find the quality of the audio of my 91AD is very good (for a HT), only complaint is there's not enough of it for some environments. As for the "robotic" sound, well, we're stuck with it. The whole point of speech codecs is to literally throw away anything that's not directly contributing to intelligibility, to reduce the bitrate. There is a tradeoff here between bitrate and fidelity. AMBE is designed to achieve very low bitrates, so it's not going to sound very "natural". My own view of D-STAR audio is that while it doesn't sound natural, I find it very intelligible, often more so than FM in the real world (where there's a lot of poorly adjusted radios and radios with wonky audio response). I'm also able to recognise who is speaking, so enough of the voice is preserved to allow that. The AMBE vocoder excels at what it sets out to do in my opinion - provide communications grade speech at very low bitrates. > >I'm not sure, but there also may be something else going on as well. >If I set up my 80 or 880 and connect to a reflector and do the same >with the ID-1 using the same speaker, the fidelity improves big time >with the 80 and 880 but the ID-1 still sounds much better (and the >RF signal is much weaker). Different radios will have different audio responses. RF signal strength is largely irrelevant in D-STAR, until the bit error rate starts to increase significantly to the point that the FEC has trouble correcting those errors. 73 de VK3JED / VK3IRL http://vkradio.com
