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[TenTec] Ten-tec noise and RX questions

To: <tentec@contesting.com>
Subject: [TenTec] Ten-tec noise and RX questions
From: dacalvin@us.ibm.com (dacalvin@us.ibm.com)
Date: Thu, 28 Oct 1999 09:20:22 -0500

The noise I was referring to in my original posting on this topic is the
"white" or "pink" noise that is the more general atmospheric noise level -
maybe a little manmade noise thrown in for good measure.  Because I have an
antenna-deprived setup on a small lot, I deal a lot in marginal signals
when chasing DX (better to grab them before they get on the
packetcluster!).  With this kind of noise, my experience has been that the
"wider" frequency range of the noise provides a more even playing field for
the ear/brain to integrate it out.  The more that energy is limited to the
frequencies adjacent to the desired signal, the more difficult it becomes
for the ear to distinguish it from the surrounding noise.  So, I don't
agree that selectivity necessarily helps - to my ear, it doesn't.  The one
exception is the TT 6.3 MHz 2nd IF filter which, somehow, manages to
attenuate noise more than signal (qualitatively speaking).

     73,  Duane    AC5AA

Duane A. Calvin
Server Systems Test Engineer
Dept. 76TS   RS/6000 - SP Nodes
IBM Austin, TX      >O<     Tie: 793-3368

"Tom Rauch" <w8ji@contesting.com> on 10/28/99 08:57:59 AM

Please respond to W8JI@contesting.com

To:   Duane Calvin/Austin/IBM@IBMUS, Clark Savage Turner
cc:   tenteC@contesting.com
Subject:  Re: [TenTec] Ten-tec noise and RX questions

> Good point.  I believe that the narrowband noise does make it
> harder under some circumstances to pick out a weak signal.

Depends on the noise. With white noise, selectivity helps. With
rough noises, it can hurt because the filter ringing will draw out the
pulses and increase noise pulse duration.

For example, on a quiet day on 160 meters with only a steady
background hiss I find even a 125 Hz filter helps me copy weak
signals, especially when set for a low pitch.

When there are static crashes, or worse yet an accumulation of
several storms causing static (or powerline buzz or other harsh
hash) running my receivers with SSB filters and no AGC is much

73, Tom W8JI

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