Jim Nye wrote:
Unfortunately, the technically unsophisticated do not recognize the
difference between coherent and non-coherent noise, and this makes it
easy for the ARRL to spread its FUD. But the fact is that, if BPL
signals are heard at all, they are coherent (have a predictable phase
and amplitude) and therefore can be completely removed at the
receiver. This can be done in many ways, most of which amount to
nulling the BPL signals by introducing an identical signal which is
180 degrees out of phase with the original. As a matter of fact, most
current HF transceivers have what they call a "noise reduction" option
already built into them which uses the nulling method to accomplish
its goal.

?? I'm not aware of ANY HF transceivers that contain nulling-type noise
reduction circuitry. (and as an active contester with 30 years in ham
radio, I'm aware of pretty much every transceiver available)

Many transceivers do include a "noise blanker". This works by detecting
unusual peaks in signal strength and temporarily muting the receiver.
They can be very effective against some types of noise, such as gasoline
engine ignitions and electric fences. I have no idea how they do
against BPL.

There are external nulling units available - MFJ makes one. Such
devices may be impractical for many types of amateur operation - they
require readjustment when making substantial changes in frequency.

The coherency (assuming it exists) of BPL signals doesn't affect the
effectiveness of either type of noise reduction. (I suppose a third
type of noise reduction would be possible that would take the coherency
into account.)
--
Doug Smith W9WI
Pleasant View (Nashville), TN EM66
http://www.w9wi.com