i know there are some power line communications systems in use out there.
remote reading power meters, home computer networks over existing power
wires, even x10 stuff puts signals over the power line. i have been hearing
a noise that i just can't identify, i have narrowed the source down to an
area of 3 or 4 houses about 1/2 mile away from my station, but need to build
a directional antenna to get it down closer. the real question is what
might i be looking for????

recording at: http://www.k1ttt.net/audio/rfi4125AM.wav
this recording was made at about the loudest peak i found at 4125khz, AM
mode, 6khz wide filter. as you can hear it is a pulsing about 2 or 3 beats
per second. this noise repeats at irregular intervals from at least 3410 to
4365 roughly every 30-60khz, in between the peaks there is virtually no
trace of it. the pulsing is not in sync on all the peaks. to me this
sounds like a multiple carrier fdm power line modem, but what kind of device
would be available that operates in this frequency range?? does anyone know
of a source of a noise like this??