In article ,
Lars Janqqvist wrote:
I live about 2 miles from San Francisco International airport.
And I get a kind of annoying interference all up and down the SW
bands, although perhaps a little stronger on the higher frequency
end. Kind of a "schwufff... schwufff... schwufff..." that
repeats every second or so. It must be at a pretty low level
since it drops away when I catch a strong station.

Also, I haven't heard that at all on my scanner (FM, tho, I
know.)

First guess that now seems unlikely was the airport radar.
Thought of that because of the periodic nature of the noise. And
yes, I've shut down everything in the house by opening the main
breaker (had to do that for a repair anyway) and still got the
rfi.

Any guesses out there?

Yes. My best guess is ultrasonic pest repellers.

I started getting this about a month or two ago, which I blamed on
Over The Horizon surveillance radars. (I even dug up some web pages
at Raytheon on these systems, which they're hawking for the Homeland
Security business and for intercepting drug runners. Interesting stuff).

It shows up above 10 MHz, peaking around 12 and 18 MHz, but it also
shows up on the vacant areas of the FM audio broadcast band, and really
shows up on Channel 4 on the TV. (I'm one of a vanishingly small number
of people who use a rooftop TV antenna in my part of town). It shows
up on the TV screen (in the black areas of the picture) as about a 1
millisecond burst of 60-100 kHz digital pulses every second or so.

SO I took my portable (FR-200) receiver for a walk around the neighborhood
and found that it was heard only within about a half a block of my
neighbors that live above me on the hillside. Confirmed by a peak in
the interference when rotating the TV antenna.

I thought it might be some equipment like computer network gear, but
there was no sign of any intelligent modulation, or perhaps some sort
of smart battery charger.

Then I ran across this a junk mail catalog I had. Home Trends,
www.shophometrends.com (visit at your own risk ;-) ).

Sunbeam brand pest repellers "DRIVES PEST AWAY
This dual technology Pest Repeller uses both Ultrasonic and
Electromagnetic technology to help fight against pest. Use against mice,
rats, ants, and spiders. Built in AC Outlet, night-light and digital
clock are for added convenience. Plugs into any standard 110v outlet.
One unit recommended for large size room. UL listed. Cannot ship to
all states." $34.95, 2/$65

There are other (cheaper) ones that don't mention "Electromagnetic
technology", too.

I wonder if the FCC and FTC know about this CRAP.

Mark Zenier Washington State resident