On Wed, 20 March 2002, "Mike" wrote:
>
> I would tend
> to think that even if the powerlines are reradiating
> energy from a single discharge point, the vector
> sum at your receiver should still looks like a single
> source
Yes, this is basically correct. The key point is that in order to null the
noise, there must be a stable RF phase relationship between the noise waveforms
received in the main receive antenna feedline and in the noise "sense" antenna
feedline. This should be true as long as there is only a single noise
generation source and the nulling only needs to be exact in a narrow bandwidth.
>
> Instead I would suspect that the noise
> cancellors are failing because the afflicted
> lines have multiple discharge sites that aren't
> time correlated.
Again, this is basically correct. Noise discharges originating from multiple
sources will generate multiple noise waveforms which are uncorrelated and
therefore whose phases will not be stable with respect to each other.
Therefore, the requirement of stable phases presented to the nuller fails and
the nuller can't null all the noise.
73, John W1FV
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