--- In digitalradio@yahoogroups.com, "cesco12342000" <[EMAIL PROTECTED]> wrote: > > Question to the experts: > > What is the most robust digi-mode with a 400 to 600 bps raw capacity (or > 200 to 300 bps fec capacity) ? > > Is a boosted psk variant the best coice or is mfsk capable of such rates ? > > Other options ? > > Background: > Seems someone has developed a 200bps voice codec.
An MFSK mode may be possible in a 3kHz bandwidth, but I don't think there is one that is suitable for this application available in ham radio software now. The 8FSK raw speed of ALE-mode provides 375baud, but the coding/FEC is not optimised for voice throughput. One could design a 12FSK mode by building upon it, adding 2 tones frequencies above and below it, or 16FSK by adding 8 more tone frequencies, in between the present tone frequencies... that would meet your baud criteria, with 125symbol/second. PSK can be tested. Try the 8PSK mode in PCALE, under the configuration, FS1052 Appendix B options. It can be adjusted for 75 baud to 2400 baud, ARQ or non-ARQ. The increments are: 75, 150, 300, 600, 1200, 2400 baud. Also, look at the 6PSK in the RFSM2400 program. For this voice application, a robust flavor of OFDM would probably be the best. Bonnie KQ6XA
