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Old April 26th 10, 12:11 AM posted to rec.radio.shortwave
Michael Black[_2_] Michael Black[_2_] is offline
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First recorded activity by RadioBanter: Mar 2008
Posts: 618
Default recognising interference sources and countermeasures

On Sun, 25 Apr 2010, Brian Gaff wrote:

Well, it used to be so quiet here at my little hilltop in Greater London,
but of late it seems every form of annoying noise has come to this little
place.

And yet, in December of 1921, when Paul Godley went over to England to
receive US stations during the Transatlantic Test (the one that showed
that shortwave was useable, amateurs having been "exiled" to "200 metres
and down" because nobody believe those frequencies were useful), he
originally set up in London, only to move to a more rural location because
reception in London was awful. Too much interference, both man made and
natural.

What's really happening now is that there is so much stuff. Even forty
years ago, the average household had a tv set or two, a radio or two, and
maybe a stereo of some sort. (And it drops off even more the further back
you go.) Now, every household is loaded with electronic equipment,
computers, VCRs, digital clocks, microwave ovens, and on and on. It's not
so much that any one item is "noisy", it's that there is a collective
noise created by all that mass of electronic equipment. It also creates
a density issue, the noise generated by such equipment is often quite low,
but if you've got a good receiver next to one, it will cause interference.
Move the offending item a bit away from the receiver, and the interference
drops off fast, indicating it isn't a strong "noise". But the more stuff
you have in a room, the harder it is to get away from any of the units.
If I move a couple of feet away from this computer and monitor, that moves
me within a couple of feet of my DVD recorder and VCR.

Yes, some of it is noisier than it should, and obviously all of it
is often too noisy for good reception. But likely for much of the
equipment, reasonable steps have been made to quiet things down, and
it would take a whole lot more effort and money to make it even quieter.

And then you'd be stuck with the reality that the neighbors have their
own collection of electronic equipment that generates noise too.

Michael