[RFI] Question

[kate]

Can anyone suggest what might be the type of system that makes the following
noise?

The noise is centered on the 160M band and consists of series of tones,
spaced up and down the band. Each tone is only a hundred Hz or so from the
preceding one. Goups of tones peak up about every 8 kHz. Once in a while
(every 5 or 10 minutes) the tones seam to be shifted slightly or modulated
slightly with a little buzz (AC?), but only briefly, 10 seconds.

This interference is located 3 miles away.  I have tracked it to an
intersection in the nearest town.  At first I thought it was the traffic
light system, and although I have not rejected the idea, I have come to
realize that it could be coming from any of a myriad of businesses located
near that intersection.  Propagation via the power lines complicated my
original assumption.  Also I can see no change in the noise as the signal
lights change.

The noise is being carried by HV power lines for up to a mile in each
direction from the intersection, as tracked in my mobile.

The spectrum of the nosie goes to zero by 2 Mhz, so DFing at higher
frequency is impossible. I am wondering if anyone has seen this kind of
noise in their experience, and perhaps can give me a clue of what to look
for in my search.  It's really making 160 difficult.   Thanks for any
thoughts.  Bob  N7UA