Crazy George wrote:
Jason:

Very similar to what you are describing is popularly known as a "Noise
Blanker" Motorola introduced their design for mobile radios in 1959 as an
"Extender" In the same time frame, Collins offered a model for the S-Line
and KWM-2. I designed a tube model for GE's Progress Line radios, and I
forget who designed the solid state version. The concept has been described
in numerous places, so do a bibliographic search of Engineering Index, or
Scientific Abstracts, or whatever that school has access to. You also need
to familiarize yourself with the concepts involved in noise balanced
squelch, which was patented by Motorola back in the late 30s or early 40s.
It will tell you how to do the audio noise level measurement meaningfully
and apply it usefully.

--
Crazy George
Remove NO and SPAM from return address
"Jason Hsu" wrote in message
om...



..........snip..............

The Motorola "Extender" and subsequent NB developments are based on the
"Lamb Noise Silencer", patented (AFAIK) in 1937 and, ......with the
intervening war years, the patent expired shortly before the Motorola
product was introduced.

73,

Tom N4TAB