[AMRadio] Zero Hysteresis Clipper

[Donald Chester]

They probably mean a look-ahead circuit, in which the audio program material
is sent through a delay line (which could be analogue or digital) after the
peak limiter or clipper has been triggered.  The clipper or limiter stage
follows the delay line, so that it is already in limiting mode by the time
the rogue peak gets to it through the delay line.  This eliminates the
inevitable overshoot at the leading edge of peak, before a conventional
limiting circuit has been able to act on it.

"Bob Orban had essentially that in the AM Optimod 9000. It was accomplished
with an analog bucket brigade delay line for the main audio path. That delay
line chip is long ago unobtainium."

A problem with a lot of the current crop of  expensive hi-tech equipment,
including some of the highly-touted plastic radios you see advertised in
QST.  Within less than 5 years you may end up  with an expensive door stop
because some $5 chip has been "discontinued".


Don k4kyv




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