Like many other areas, the noise floor here has been creeping upwards over
the years. I am in a rural farm setting but heavy industry rolls closer
every year. While I have methods to address or at least mitigate other
noise sources, this one is causing me the most problems and I don't even
really know what it is. Here's a link to a short wav file I made after
sunrise this morning, around 1600 ut dec 3, just above the broadcast band.
The noise is quite broadband in nature, a series of short pulse like
ignition noise, and I routinely hear it up thru the 40m band. I have heard
it as high as 21 mhz.
http://www.savefile.com/files/1239501
This was on a 1000' beverage pointed NW, ICOM 7800 in AM mode. In the short
breaks the resting noise level was roughly s3, the pulses drove it to S9+10
or so.
I refer to it as "flare stack igniter noise" but I'm not certain that is
correct. The noise is loudest in the general direction of a large area of
heavy petrochemical industry (several large and many smaller flare stacks)
but driving in the area yields only weak signals. It has also been noted
louder under some 3 phase transmission lines, but they may be conducting it
from some distance. I don't know if the power utility here uses PLC (not
BPL) data schemes nor do I know what they would sound like if they did.
Another thought was automatic meter readers (using slow speed data over the
power lines) employed by the power utility, but I don't believe there are in
any use around here yet.
While this wave file is dominated by one strong pulser, other frequencies
and directional antennas show a myriad of different signals at times. So
does anyone have a similar noise or have ideas as to what it could be?
Thanks for your help.
73 Don
VE6JY
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