[Elecraft] New Digital Mode and K3S Frequency Accuracy

[Jim Brown]

On 7/16/2017 10:54 AM, Christopher Hoover wrote:
> JT65 can decode arbitrary messages down to -24 dB (and certain messages
> down to -32 dB).

When functioning as a multi-decoder, late versions of WSJT-X often give 
me good decodes in the range of -24 to -29dB re: the full bandwidth 
noise floor, and they also include second-pass decoding for signals 
missed during the first pass. It is, for example, common to decode 2-3 
responses to the same CQ, all within a few Hz of each other. Second pass 
decoding subtracts out the decoded signals and then decodes what's left.

Particularly impressive was what happened when a W7-area station was 
calling JA7QVI on 6M, but got out of sync so that he was calling on the 
same cycle as JA7QVI. Both stations were decoded on consecutive passes, 
even though the W7-area station was 10-12 dB louder and nearly zero beat!

JT65 often decodes signals that overlap each other. FT8 does not, but 
FT8 signals only occupy about one-quarter the bandwidth of a JT65 signal.

73, Jim K9YC