Bob ZL2CA wrote:
Also note that it is ineffective to use a separate noise receiver to
derive noise blanking drive, as it does not "reverse" the situation that
once a noise spike has become a noise blob (due to band limiting) then
the process can not be reversed, and the noise blob passes through the
receiver to the demodulator.
I guess the "noise blob" you mentioned is the exponentially decaying
ringing which occurs when a high Q antenna, such as a tuned loop, is
excited by a short noise spike.
As far as I understand, the traditional way is to put a switch somewhere in
the signal path that opens up during the blanking pulse. This pulse has to
be quite long if a high Q antenna is used (long blob).
I think it is possible to kill that blob right at the antenna by using a
separate
wideband noise receiver and feed the blanking pulse to a switch (analog
switch, fet or something) connected ACROSS the loop. This will "eat" the
pulse energy almost instantly and the blanking pulse width can be made
much shorter than in the "traditional" case.
Has anyone tried this idea?
73 de Johan Bodin, SM6LKM
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