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Re: [TenTec] [Orion] Orion II Noise Blankers

To: "'Discussion of Ten-Tec Equipment'" <tentec@contesting.com>
Subject: Re: [TenTec] [Orion] Orion II Noise Blankers
From: "Grant Youngman" <nq5t@comcast.net>
Reply-to: Discussion of Ten-Tec Equipment <tentec@contesting.com>
Date: Sun, 26 Feb 2006 01:27:58 -0600
List-post: <mailto:tentec@contesting.com>
> is different NR code for the Orion I (pre-V2) and that is 

I agree with you there.  Something is different.  But it isn't clear what.
The "time constants" for adaption seemed to be different in the 2.x code.
Maybe other stuff.

> there just doesn't appear to be any lag at all when NR 1 (as 
> opposed to NR 2 or 5, etc) is turned on, regardless of 
> whether there is a weak or strong signal or no signal at all.

Lower values seem a little slower than higher values.  Big diff between 1
and 9.  But the lower values are much faster than in 1.371 and prior code.

> Another thing the manual description claims is that once the 
> NR has adapted, changing the NR value will have no effect. 
> Again, this is contrary to what I've observed. If the NR is 
> on 1, even for an extended time, then you increase the value, 
> a difference IS heard; it does have an effect.

If adaption time is made faster, you will hear something different on any
signal that isn't just a constant carrier. Higher values WILL sound
different since it as adapting and re-adapting to changing spectral
components in the passband at a faster rate.
> Besides, there is no way to filter out random, white noise 
> within a given passband, 

Random white noise is the easiest thing to get rid of in the presence of a
constant signal.  If you know the power spectra of the noise it can be done
almost almost perfectly.  The trick is to notch out the parts of the
spectrum which do not contain signal. Virtually all noise reduction
techniques involve the elimination of junk from the areas in the bandpass
that are not occupied by signal -- either a CW signal (many), or spectral
components of a voice signal, etc.  So you eliminate some spectral regions
-- effectively that is a filter around the regions you want to keep.

> if the passband is made smaller, a 
> user listening to a SSB signal would notice the bandwidth 
> reduction in an instant, 

Maybe I wasn't clear.  On CW, that's effectively what happens -- you get a
narrow filter around the signal (or signals, if you have more than one in
the passband)

In the case of SSB, it's going to effectively build bandpass filters around
the major spectral components of the SSB signal.  So you won't necessarily
perceive the bandwidth getting narrow on SSB, although there's certainly
some reduction in high frequency noise if you have the bandwidth set at a
high value (since there may not be spectral components of the signal up


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