Hi Vojtech, Thanks for the tip. I totally forgot about the possible effect of deemphasis and what effect the center audio frequency might have.
Our goal with NBEMS has always been able to reach at least 100 miles reliably, in order to span the largest expected disaster area to reach Internet or phone connectivity. We were recently surprised to find over a 117 mile path on 2 meters, that, on the average, FM with DominoEx actually worked better than SSB with DominoEx, even with the poorer S/N of FM compared to SSB. The surprise was an unexpected, consistent, fast flutter which did not seem to affect FM nearly as badly as SSB. Thanks to Tony's wondering, we will continue to evaluate different modes (and different audio center frequencies!) and post the results here. 73, Skip KH6TY > Skip, it would be interesting, if you could investigate, which > modulation bandwidths and at which center audio frequency the common > FM transceivers work best with common HF weak signal digital modes. > Keep the good work. > Someone able to do the math? > 73, Vojtech OK1IAK > White noise tests show DominioEX-4 to be a bit more sensitive than MFSK16, > but it doesn't seem to handle HF distortion nearly as well. > > I was surprised that it did better than MFSK16 with multipath and was > wondering if you thought the better throughput was due to MFSK16 tuning > issues rather than actual robustness? > > Tony - KHMU >
