"David" wrote in message
...
On Fri, 21 Apr 2006 17:46:36 -0500, clifto wrote:

David wrote:
wrote:
Are you sure about the patent cost? I thought sync detection was mostly
implemented through a PLL type circuit.

A PLL and a Product Detector

You can do without the PLL, too. You just create the signal with a
separate stage that overamplifies the signal into clipping, then
you have basically a sorta-square wave to feed into the product
detector.

Does that work when the station carrier fades?

Not as well in deep fades as a 'truly' synchronous detector. That's often
called a 'quasi-synchronous' detector since there is not a synchronised
oscillator, just the amplified carrier, mixed with the signal in the product
detector.

Tom