The ANC-4 is not a noise blanker, and it is also not a DSP noise
reduction device. As it's model number suggests it is a "noise canceller."
What it really does is use an additional antenna and some phase and
amplitude controls to make a phased array for receiving only. If the
offending noise arrives at the two antennas (the main antenna and the
"noise antenna") with a different phase and amplitude relation than the
signal you wish to hear, the adjustments can be made to cancel the noise
and still be able to hear the desired signal. If the noise source
arrives at the two antennas having the same phase and amplitude relation
as the desired signal, it will not be able to cancel the noise without
also cancelling the signal.
It does not "blank" or shut down the whole signal path during noise
pulses, and it does not do any frequency selective filtering or
reconstruction of the signal waveform as a DSP unit does.
All of these methods can be helpful.
DE N6KB
On 3/29/2014 1:37 PM, A R wrote:
But, given the very variable characteristics of my noise, requires fussing
with (adjusting) the phase and gain of the noise reference in the ANC-4. But
with a lot of patience in the adjustment, including an effective technique for
matching amplitude of the reference antenna noise with the main antenna noise,
it does a very good job. I can reduce 9+20db noise to an S3, without affecting
signal processing or audio within the radio. But, it does take a LOT of fussing
with adjustments.
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