Hi Grant,
Thanks for the info. Interesting.
I respect what you say, and hope that if you find out it what they are truly
doing, you let us know. I'll do likewise.
I totally agree that with a constant signal, the SNNR is not improved, but when
the signal pauses, the noise level is reduced, and that is a benefit to me. For
CW work, I notice that the weak CW note sounds raspy, but is is more distinct
and stands out from the noise more than without NR on. Especially with a very
narrow BW setting, where all the noise is spectrally close to the CW note.
73,
Lin
WB1AIW
Grant Youngman wrote:
What you say about the "distortion" actually being the noise
that had been suppressed until the cw element or ssb signal
raised the gain is accurate.
It's easily visible in a waterfall display.
http://mysite.verizon.net/nq5t/Misc/CWgram.png
I've never really figured out if you're right in your conclusion that NR is
a downward expander, but the one thing I'm absolutely certain of is that it
adds nothing to (S+N)/N ratio, and at any BW below about 1000 Hz actually
degrades it. While it may reduce background noise during no-signal
conditions, the signal elements are buried in just as much noise with NR as
without.
I took the time to remeasure SNNR changes with NR=9 tonight, since the
subject reared its ugly and already too-beaten-to-death head again today.
These numbers are consistent (+/- a dB) with what I found the last time I
did it many weeks ago.
BW Delta SNNR (NR=9)
-----------------------------
3000 Hz + 1.0 dB
1000 Hz - 0.4 dB
500 Hz - 1.0 dB
100 Hz - 2.0 dB
Disclaimers: The usual stuff about not hating my Orion II, etc. :-)
Grant/NQ5T
_______________________________________________
TenTec mailing list
TenTec@contesting.com
http://lists.contesting.com/mailman/listinfo/tentec
|
