Topband: Topband Digest, Vol 136, Issue 1

[Dave Olean]

Hello Mike
I have found that JT65 provides a bit better than 10 dB more than a good cw 
weak signal (read that as a real weak cw ) contact. I can copy signals by 
ear that are listed as about -18 dB or more below the noise in JT-65, and 
the rock bottom detection level for JT65 is about -28 or maybe a little more 
with a few tricks.  On HF, with all sorts of pops and squawks and 
keyclicks/splatter, that 10 dB may not be a correct number. It could be 
greater..I'm not sure.  There is no way I could copy extremely weak CW  with 
QRM competing with the signal. The 10 dB number is only for listening to a 
signal buried in galactic noise.  In my opinion, copying CW in noise is much 
more fun than reading callsigns on a monitor screen. There is no doubt 
though that JT65 is a huge improvement for detecting weak signals.  10 dB is 
a lot! JT65 cannot make up for a lack of propagation though!! (but what do I 
know?)  Does that help any?

Dave K1WHS

  That's interesting, and brings to mind a question I've been wondering 
about
for low-data-rate weak signal modes such as JT65, JT9 (which take 60
seconds to send a CQ), and QRSS (24 hours?!).

In the real world on 160, what would any of these modes really gain for an
operator already skilled in CW?

>From reading posts about JT9 and JT65 on 160, the distance gain over
ordinary CW is really nothing to write home about. Does anyone have any
real-word experiences that say otherwise?

73, Mike
www.w0btu.com