I was not aware that the lowest S/N ratios allow for significant error rates. For example, the British study had what seemed perfect data throughput when they listed the S/N ratio below noise, although under AWGN and that is more similar to VHF and up compared to HF.
Based upon the multitone success of Pactor 3, it seems that having a moderate number of tones (18 perhaps?) might be better than having large numbers such as found with MT-63 (64 tones). What would happen with a DEX44 or DEX88, with or without FEC? 73, Rick, KV9U DuBose Walt Civ AETC CONS/LGCA wrote: >Rick, > >A couple of things to consider... > >Most of the published Lowest S/N (such as by Patrick, F6CTE, Pascal, F1ULT and >others is based on the signal level where you are getting about 2% errors. > >The lowest S/N for MT63 is - 8 dB for 5 bauds, - 5 dB for 10 bauds and -2 dB >for 20 bauds and is generally either error free or not decoding at all. > >DominoEX 16 is 15.625 baud ~100 WPM ~50 WPM w/FEC >DominoEX 22 is 21.533 baud ~140 WPM ~70 WPM w/FEC > >While no specific lowest S/N is given for DominoEX, I suspect that DominoEX 22 >is close to MT63-1K in throughput except that it more than likely DominoEx 22 >has a lower S/N than MT-63-1K. > >Therefore one would expect DominoEX-22 to work better than MT63-1K perhaps in >part due to the higher baud rate and less of a tendency to be affected by >Doppler. This might also be a reason that DominoEX 22 worked better than >DominoEX 16 w/FEC. > >As you say..."the ability to handle the vagaries of the ionosphere is often >more important than the raw ability to handle AWGN." > > >
