If you take a closer look at the spectral bandwidths of the current crop of digital VHF/UHF voice systems and compare them to 10k1 NBFM I think you'll be surprised. Unless govt agencies start racking and stacking digtal LMR systems without guard bands then there is no clear advantage. The technical requirements of each receiver goes through the roof with 10k1 systems as it. However there is a strong desire from government agencies to move toward encrypted communications, which is very easy with digital LMR; basically you get it for free. This does not relate to the amateur service.
In terms of Digital voice replacing SSB that has a very long long way to go. In truth SSB is very difficult to beat in terms of spectral efficiency. SSB puts just enough power into the right spectrum for near loss less communication. When you try to stuff the equivalent power into a low bit rate digital signal, the energy per bit is quite high, meaning you've got to lower your bit rate substantially until the two powers (SSB and DV) are the same. At this low bit rate (<600bps) there is no avoiding the donald duck or robotic voices at this point. That pesky information theory gets in the way. Lots of great progress has been made in this regard (i.e. Codec2), however it will be a while before the necessary 200-600MHz hard float DSP will be required in a K3S. Besides I'm sure a suitable retrofit DSP module can be squeezed in there somewhere when the time comes. 73 Matthew VK5ZM On 18 September 2015 at 10:33, Robert Nobis <n7...@nobis.net> wrote: > Take a look at the digital voice modes that are being used on the VHF and > UHF bands: DMR, D-STAR and Fusion. > > > Bob Nobis - N7RJN > n7...@nobis.net > > > > On Sep 17, 2015, at 17:49, Richard Fjeld <rpfj...@outlook.com> wrote: > > > > I was in to freeDV a year or two ago, and it has a long way to go. > Still, it did work. > > > > I'm told the bandwidth has increased since then from 1200 hertz to 1600 > hertz at present, which will be an improvement. > > At 1200 hertz, voices sounded robotic in nature. it lost sync often > which may, or may not, have been due to the compression. > > > > I haven't heard of the FCC's having ruled on it's mode and/or where if > permitted. I haven't been keeping up with it either. > > > > Dick, n0ce > > > > > > On 9/17/2015 1:00 PM, ae...@carolinaheli.com wrote: > >> I'm wondering since Digital voice is replacing FM around the world how > hard > >> it would be to add another mode to the K3S? I'm not even sure what the > >> standards are but one country just set the date to get rid of FM > permanently > >> and switch to DV. > >> > >> Jerry Moore > >> AE4PB, K3S - S.N. 10324 > >> > >> > > > > ______________________________________________________________ > > Elecraft mailing list > > Home: http://mailman.qth.net/mailman/listinfo/elecraft > > Help: http://mailman.qth.net/mmfaq.htm > > Post: mailto:Elecraft@mailman.qth.net > > > > This list hosted by: http://www.qsl.net > > Please help support this email list: http://www.qsl.net/donate.html > > Message delivered to n7...@nobis.net > > > > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:Elecraft@mailman.qth.net > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to vk...@bistre.net > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
