[TenTec] 2.033

[Lin Davis]

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
> 
> 
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