One of the design requirements/choices made by the JARL was to provide simultaneous voice/data transport on the DStar DV air interface. This contrained the final (4800 bps/6.25 kHz) air interface to a 2400 bps AMBE perceptual coder with 2/3 convolutional FEC. This left about ~1kilo bit a second of data on the air interface for usage as data (as any user saw fit!).
If the higher DV bit rate such as NEXEDGE/IDAS radios were chosen, then there would be no DPRS, DRATS, etc, or whatever is developed downstream. DStar is not about the voice, it's about the communications capability. I would not want to leverage a higher bit rate for the DV and eliminate the data transport and its utility. I would like to see a 2400 bps data only mode with 1/2 convolutional FEC with dispersed codewords for fast fade immunity (or something similar)on the narrow band GMSK radios. Better voice is available at the touch of a button, ancient Fat Mode or FM. Hit the button and move on because the perceptual coding for DStar users is not very likely to change due to the existing constraints in the radios/edge network. I appreciate the gentleman's opinion on the voice quality, but the MOS metric is a MEAN OPINION SCORE and is derived form a sample of users, not a single user. It is what it is, a damned fun and challenging mode that is very enjoyable in what I deem is the world's greatest hobby, Amateur Radio. Lots of degrees of freedom here to find something that suits you. Respectfully, Craig KV5E --- In dstar_digital@yahoogroups.com, Gerry Creager <gerry.crea...@...> wrote: If > I did, I might have a similar opinion, that we could crank up the > sampling and decoding rates and improve the audio. Since I do know > something about how things work (and since I've looked at the networking > side of D-Star), I respectfully disagree with John about how simple it'd > be to enhance the audio. Sorry, it's not how things work on the startship. > > 73 gerry n5jxs > > J. Moen wrote: > > > > > > There is a lot of room in our hobby for many niche interests and points > > of view. I became a Ham in the late 1950s and while I started out on > > AM, I switched to SSB fairly soon after. I have always liked > > communications quality audio for voice communications. When I > > discovered a whole subculture of Hams interested in Extended SSB, I had > > trouble understanding why. I listen to some people with carefully > > adjusted equalizers that sound like they are transmitting from their > > bathroom, what with echos etc. But then I realized that as long as they > > don't hog the bandwidth when a band is busy, there is nothing wrong with > > them wanting something more than communications quality. > > > > I just expect them to respect my preference for narrower audio response > > over RF. > > > > I am thinking D-Star will probably not work out for John, and he'll > > decide to move on to other parts of Ham radio. Or he'll get involved in > > experimentation with other types of digital radio that may involve other > > vocoders and different design parameters (I wonder what Codec2 sounds > > like?). And if we all live long enough, we will probably see other DV > > standards evolve. I like to think that if we left the planet and came > > back in 50 years, the vast majority of Ham transmissions will be some > > form of digital. It's inevitable. For John's sake, let's hope he has > > some audio quality choices. > > > > In the meantime, I like D-Star audio just fine, since I'm able to > > understand what everyone is saying. > > > > Jim - K6JM > > > > > > ----- Original Message ----- > > *From:* n2gyn <mailto:li...@...> > > *To:* dstar_digital@yahoogroups.com > > <mailto:dstar_digital@yahoogroups.com> > > *Sent:* Wednesday, September 01, 2010 3:19 PM > > *Subject:* [DSTAR_DIGITAL] Re: Bit Rate? > > > > > > It's NOT a microphone issue. It's the small bit processing. I have > > been in Pro sound for most of my life. Their is NO WAY to get any > > quality at 8bit. This is unexceptionable to me! I rather listen to > > all the QRM and QRN in the world with analog. > > I am very surprise that their are not more people that feel this way. > > The bit rate has to be at lest 28bit to starting sounding acceptable. > > John > > > > > > > -- > Gerry Creager -- gerry.crea...@... > Texas Mesonet -- AATLT, Texas A&M University > Cell: 979.229.5301 Office: 979.458.4020 FAX: 979.862.3983 > Office: 1700 Research Parkway Ste 160, TAMU, College Station, TX 77843 >
