The key to understanding what kind of noise a Noise Blanker works with
is in the word "Blanker". Noise Blankers are triggered by noise pulses
and blank all signal for some duration after the triggering pulse. Then
you are left to hear only the signal between the blanked periods. This
works real good on noise which only occurs for short percentages ot the
time because the human brain fills in the gaps in signal, barely or not
at all noticing the gaps. I don't know for certain, but I suspect that a
traditional noise blanker in front of DSP noise reduction may give the
DSP system a harder time than it gives the human signal processor.
Trying to use both a noise blanker and DSP may be difficult. Perhaps
somebody who writes code for DSP could offer some more insight.
Another side effect of Noise Blankers is caused by the fact that they
typically pick up signal before the really narrow filters and use that
signal to trigger the blanking. This is so that the noise pulses are not
stretched out in the time domain by the narrow filters and then only the
minimum necessary length of time is the signal blanked. This is why
strong signals only a few kHz away also trigger the blanker, or affect
the blanker in detrimental ways, sometimes making the noise that blanker
works on reappear.
DE N6KB
> the problem a large number of hams have with noise blankers
>is that they do not understand what type of noise they blank.
>
>The NB works on short width, high amplitude noise spikes in the IF, such as
>those caused by a car spark plug. They do not function on every atmospheric
>noise that you hear on the bands. It does not cut alternator whine, or act
>like a DSP.
>
>
>
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