[RFI] RFI from street lights - finding source?

[Barry N1EU]

For over a year, I've been plagued by cyclical noise bursts on 160/80M
of about 30sec duration repeating every 2 minutes or so.  Here are
some examples (stereo recordings):

http://n1eu.com/29Jan07a.wav   - AM L channel, CW R channel
http://n1eu.com/09Oct07a.wav   - CW

I've been pondering how to go about locating the source.  Does it seem
reasonable that the source is likely to be between a quarter and half
mile distant?  Does the noise correlate with the lamps visibly
restarting/flickering?  I was thinking of putting a telephone next to
the rig's speaker and monitoring the audio with a cell phone while
driving around and observing the street lights.

Any comments/suggestions appreciated.

Thanks/73,
Barry N1EU