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Re: [TenTec] Orion II NR Performance Measurements

To: "'Discussion of Ten-Tec Equipment'" <tentec@contesting.com>
Subject: Re: [TenTec] Orion II NR Performance Measurements
From: "Grant Youngman" <nq5t@comcast.net>
Reply-to: Discussion of Ten-Tec Equipment <tentec@contesting.com>
Date: Mon, 27 Mar 2006 11:08:49 -0600
List-post: <mailto:tentec@contesting.com>
> > The way to test it would be to measure the difference between the 
> > noise levels with the tone turned off, as it would be 
> between dits and dahs.

What I hear, when I do this, is a nice quiet passband and then on a CW
element I hear the element PLUS noise.  So while the radio gets quiet in
between elements, each element still comes with the noise that would be
there if it were a steady carrier.  I initially interpreted this as
distortion, but now that I better understand how the apparent noise level
behaves when a signal is in the picture, it's just the effect of hearing a
"noisy" element against a quiet background.

The whole thing plays better with stronger signals, but that's because SNR
is already good, and the noise riding the signal element is small.

I don't think any of this actually changes the SNR picture.  Very weak
signals almost sound "hissy", because there's nearly as much noise on each
element as there is signal.  The background noise with no signal is
immaterial.  It's the noise present when the signal element is present that
matters.  

Of course, that's just one opinion :-)

Grant/NQ5T


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