It is instructive to calculate the Shannon maximum theoretical data rate (power limited case) (refer to wikipedia page for Shannon-Hartley theorem).
If S/N ratio (BW=2,500 Hz) = -24 dB, then S/N ratio (BW=1Hz) = -24 + 10 log 2,500 = -24 +34 = +10 dB. 10 dB converted to a dimensionless ratio is 10. Now, channel capacity = C <= 1.44 X 10 = 14.4 bits/second. This rate is a little more than twice the FT-8 rate. Now a days, achieving 1/2 of the Shannon limit is possible for AWGN. If your noise isn't AWGN, well then that is another source of error. Thus the claim of -24 dB sensitivity seems plausible, where the S/N is the true signal vs AWGN, as opposed to whatever random number FT-8 reports. So I think the beef with FT-8 is in the way it calculates the displayed S/N. We used to call those "marketing specs". It is also notable that FT-8 uses at least twice the average power compared to CW. If you compared them on an average power basis (vs PEP) the FT-8 advantage, if any, would drop 3 dB. On CW, you could send your call many times in 15 seconds for "error correction" and take advantage of QSB peaks. That tends to level the playing field. More playing field leveling is using Super Check Partial analogous to what FT-8 does. Rick N6RK _________________ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector