Hi Steve and all,I've attached a plot comparing the sensitivities for decoding JT65A in WSJT 10.0 (r6088), WSJT-X v1.6-rc1, and WSJT-X v1.7 (r6131). The simulated channel is AWGN; the demodulators all use noncoherent measurement of symbol amplitudes. Correlation decoding and message averaging were not used.
Test measurements were made using 1000 simulated JT65A transmissions at each of the SNRs -20, -21, -22, ... -29 dB. I ran each program on the full set of files and counted the decodes for each generated SNR.
WSJT 10 uses the KV decoder and was tuned (a long time ago) for best performance with EME signals. WSJT-X v1.6 also uses KV, but in this case we tuned for decoding speed, good performance, and few false decodes on crowded HF bands. WSJT-X v1.7 uses the sfrsd decoder. For these tests I set "Random erasure patterns" to 8, which means ntrials=10^4.
As you can see in the plot, in these tests WSJT-X v1.7 is around 0.7 dB better than WSJT10 and 1.3 dB better than WSJT-X v1.6. I think this is truly superb performance.
For EME applications we'll want to implement message averaging and correlation decoding. This should buy us another 4 dB, more or less. These decoding approaches are already present in JT4 mode, and they work well.
I also need to make comparable tests and measurements for a simulated Rayleigh-fading channel, and for submodes JT65B and JT65C. I will turn some attention to these tasks, as time permits.
-- 73, Joe, K1JT
JT65A_decoding.pdf
Description: Adobe PDF document
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