CW this time.
I spent a few hours this afternoon hunting on 20M for the weakest puniest CW
signals I could find. Admittedly, the band noise was low -- not even moving
the meter. Which doesn't mean you couldn't hear it, and doesn't mean
signals weren't very close to it. And yes, I agree the NR in the II does
not play quite like the NR in 1.371, and no, I wasn't trying to copy S-1
signals in the presence of 20-over thunderstorm noise or summer daytime
conditions on 160. But ...
In virtually every case, applying all the facilites available such as very
narrow bandwidths, NR increased the S/N ratio of the signal, did reduce the
residual background noise, and generally caused the signal to almost "pop"
in terms of overall clarity and copyability. What has been referred to as
distortion adds -- for me anyway,as I mentioned in my first O-II post very
early on --- some "edge" that really makes the signal stand out and
increases the clarity. Even with signals that were just at the hairy edge
of moving the meter, and in some cases that didn't move it all. They didn't
always end up "pure tones in a dome of silence", but in terms of apparent
S/N improvement, NR certainly appeared to be doing something very useful.
Using wider bandwidths and stronger signals, you could hear clearly the way
NR builds it's tight bandpass filter around the signal. As bandwidth was
narrowed or widened with NR on a high level, there was virtually no audible
bandwidth change -- because the narrow bandwidth established by the NR
algorithm was controlling the overall receiver response. That very
pronounced effect lessened the weaker the signal, and was weaker at lower NR
settings.
I still don't know which version is better. That would take two radios
copying the same signal on the same antenna in the same noise, which is a
luxury I don't have :-)
Grant/NQ5T
PS: I'm sure this will generate some disagreement :-)
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