There are several different squelch techniques.  One of the most
popular works on the fact that white noise of the "no signal"
variety contains a high amount of ultrasonic noise, whereas
a signal doesn't.

You can also look at the RF signal strength and gate on
the audio if it exceeds a certain amount.

-----Original Message-----
From:   Jacques Vrey [SMTP:jvrey@IT.NEW.ISCORLTD.CO.ZA]
Sent:   Friday, February 27, 1998 4:36 AM
To:     PICLIST@MITVMA.MIT.EDU
Subject:        [OT] Squelch

Hi to all

I was wondering, with all you rf fundi's out there, if anyone could
explain to me how the squelch on two-way radio's works. I would
suspect that it would be some type of adjustable low pass or bandpass
filter ??

A simple circuit will also be of great help.

Sorry to push up the noise ratio but, dare I say, I haven't found a
group of more knowledgable people around.

TIA

Regards


Jacques Vrey
Iscor Steel Profile Products
Internal Post Point 74
PO Box 2
Newcastle
2940
South Africa
Tel: +27 (0)3431 48759
Fax: +27 (0)3431 48001
jvrey@it.new.iscorltd.co.za
The views expressed above are not necessarily
those of Iscor Limited.

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