On Sat, 2007-01-27 at 18:51 -0500, Carl Moreschi wrote:
> The problem with any noise blanker comes down to how they work. When a high
> noise spike is detected, the audio is blanked for a very short time (like 10
> milliseconds). If a strong station comes on that is in the noise blanker
> passband but not in the receiver passband and is stronger than the noise,
> then the noise is not heard by the noise blanker, so the blanker does not
> blank the audio while this signal is on. What you end up with is the noise
> appears to be modulated by the strong signal. That is you only hear the
> noise while the strong signal is on. This is not intermod, but just the
> noise blanker not hearing the noise while the strong signal is on. This is
> hard to explain but once you think about, you should get the idea.
>
> Carl Moreschi N4PY
> 121 Little Bell Drive
> Bell Mountain
> Hays, NC 28635
Maybe but the way I understand it is that the blanker still sees the
noise but while it blanks the receiver IF, it also chops holes (more
like microsecond length than millisecond length) in the strong signal
giving it a wide spectrum. Most often the noise spikes though short are
stronger than the strongest signals.
At least this is what I have observed with analog noise blankers for the
past quarter or third century.
73, Jerry, K0CQ
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