I have tracked noise and other RF sources for a long time and consider
myself competent in this regard. I definitely fall in the camp of
recording the noise is not that valuable for several reasons:
1.) Recording the noise at different receiver bandwidths, with radio
noise reduction on/off, etc. definitely changes the sound.
2.) Just because "your neighbors treadmill" has a certain sound does not
mean that all treadmills will sound the same. The RFI from the
treadmill is definitely a function of the rate(frequency) that the
treadmill motor(s) are modulated. Your neighbor's treadmill might be
modulated at 100Hz and my neighbor's one at 300Hz. These"small to the
manufacturer" differences change the demodulated sound that you hear as
RFI significantly.
3.) Ditto for the streetlights. In one person's area all the
streetlights may sound alike when failing but in another part of the
country which uses different streetlights there is no guarantee that the
sound is the same.
I feel that many folks are looking for a quick fix to identify a noise
source. Actually tracking it down is really not difficult. One thing
that is very valuable is the frequency spectrum of the noise (periodic
or broadband) and any periodicity to the noise such as on only at night,
on only in the early morning, 1sec on every 30 sec., 12 hours on/off etc.
I have helped many folks with noise issues but I generally do not get
involved with "listen to my recording" stuff as I would only be guessing
as to the source. This is my $.02.
73,
Larry, W0QE
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