Good point. Ed, what does a plasma TV look like compared to BPL. Is the
multidomain signature quite different?

I have not looked at a plasma TV, Chip, but I would make that diagnosis
primarily on on the basis of the sphere of influence. In the BPL test areas,
the interference was heard over the entire area that had the BPL couplers in
place.

There are other indicators, too. Knowing the involved BPL manufacturer would
let one pretty easily compare what was heard on the air to the known
characteristics of the BPL system involved. Interference from plasma TVs is not
going to be "modulated" with digital signals, as would a BPL signal. Those
OFDM carriers in the Ambient and Amperion BPL systems would be pretty hard to
confuse with anything else.

Another characteristic to look for is spectral occupancy. If the signal appears
suddenly in spectrum, is heard over several MHz, then suddenly tapers off, that
also matches the BPL characteristics, not that from other devices.

If the signal is noiselike, but clearly digital in sound, one can also look for
the bursts of the downloads, followed by the shorter, "keep alive" pulses that
some of the systems do.

If all of the above added up and started at the same time the BPL system was
brought on line, I would feel comfortable with my diagnosis.

73,
Ed Hare, W1RF