[RFI] repetitive noise

Jim Jarvis jimjarvis at comcast.net
Sun Jan 23 12:34:32 EST 2005


All manner of sequential-starting things might be the
source.  Misbehaving thermostat...fishtank heater or home
type... Fluorescent light, with a bad bulb, which doesn't
ignite properly.  Could be a motor starting, but the rep rate
and pulse duration doesn't sound right.

Your WAV file sounds like a dirty oscillator, with a clipped,
triangular kind of waveform.  Might be a light dimmer. 

I think timing is the key to finding this, along with elimination
of sources by disabling the power.  

Start with your own house...run on battery, and kill your primary
power, to see if it's in your house.  Then, work methodically with
neighbors to do the same.  

If you can get a peak on the beam, that might help give you direction,
but being able to hear it in a portable radio is critical. 

Odds are, when you find this,you'll be doing someone else
a favor, by eliminating either noise in their home, or a 
fire hazard.  

I had one of these, in NJ, and eventually tracked it
down to a loose connection on a circuit breaker in a neighbor's
main distribution box.  The breaker was defective, and caused a hot
wire in the box, burning the insulation.  In that case, though, the 
noise was on or off...it didn't shift in pitch as yours does.   

Good luck!

jimjarvis at ieee.org 

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