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Re: [RFI] How very interesting...

To: rfi@contesting.com
Subject: Re: [RFI] How very interesting...
From: Jim Brown <jim@audiosystemsgroup.com>
Reply-to: jim@audiosystemsgroup.com
Date: Thu, 25 Aug 2016 09:43:30 -0700
List-post: <rfi@contesting.com">mailto:rfi@contesting.com>
On Thu,8/25/2016 8:18 AM, Frank N. Haas KB4T wrote:
Regrettably, the SDR system has proven nearly useless for my intended
purpose. Sometimes I can hear the arcing source but it never shows up on
the spectrum displays.

Several thoughts, Frank. First, and most important, spectrum displays are VERY VERY helpful in tracking noise that has any degree of coherence or is spectrally repetitive. These are characteristics of ELECTRONICALLY generated noise, but NOT of impulse noise.

Second, averaging is a very powerful tool for separating coherent noise from random noise. A spectrum display of noise is generally most useful with averaging set to a relatively number, and the amplitude and scale set so that random noise causes the display to go black and the signal (noise) fills the amplitude.

Third, SDR Play is not the only good choice -- there are many SDR receivers that can easily be connected to a computer and run from a vehicle, and some have greater dynamic range than others.

Fourth, overload can easily be eliminated by use of a simple resistive pad.

Fifth, as W0QE and W0IVJ showed in their plots, there are also noise sources in a vehicle. BTW -- they shared their work with me, and allowed me to include it in a tutorial wrote this spring. http://k9yc.com/KillingReceiveNoise.pdf

73, Jim K9YC

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