[RFI] How very interesting...

[Jim Brown]

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