I don't see how the system you linked is more efficient than D-Star, in fact they use an AMBE vocoder (the heart of DStar digital audio) in their technical specifications.
It runs at the same effective baud rate, 4800, as current D-Star DV modes. The only difference I actually see is they were using FSK back then, and D-Star settled on GMSK as the base protocol to use for data transfer. They're both transferring the same amount of data over the same amount of spectrum at the same speed, thus they're equally efficient in terms of spectrum used to convey a given voice message. -Mike Trevor . wrote: > > > But commercial systems (NXDN) with mobiles, handhelds and repeaters that > use 6.25 kHz channel spacing have been available for years - both Icom > and Kenwood are active promoters of the system which uses a far more > efficeint modulation techique that D-Star, see > > 2005 - Icom and Kenwood demo 'Very Narrowband Digital Communications > Technology' > http://www.southgatearc.org/news/apr2005/icom_kenwood_demo.htm > <http://www.southgatearc.org/news/apr2005/icom_kenwood_demo.htm> > > 2008 - The Gadget Show tests digital and analog walkie talkies > http://www.southgatearc.org/news/november2008/gadget_show_radio_tests.htm > <http://www.southgatearc.org/news/november2008/gadget_show_radio_tests.htm> > > 73 Trevor M5AKA > -- Michael A. Waldron, AE0MW http://www.mikew.org PGP: http://www.mikew.org/mypgpkey.txt
