On 3/14/12 8:07 PM, J. Forster wrote:
John
Like your thought. I seem to remember costas loops work like that to
recover the carrier.
Paul,
It recovers a bipolar signal to steer the local VCO as well as the data..
It also needs a quadratue hybrid at the VCO frequency (although it might
be fairly easy to make a quadrature oscillator vat 60 kHz.)
One easy scheme is to make your VCO run at a multiple and divide down to
generate the two quadrature square waves.
Had seen it in amsat many years ago. So perhaps an approach is to limit
if possible the incoming signal.
I'm not sure if it works properly with clipped (digital) dignals, off hand.
Yes it will.
Though further simple dumb thought. A NE602 or SA602 or also teh 612
series. All the same mixer circuit (Or multiplier)will double the incoming
frequency if you delay the incoming by 90 degrees I think.
Sine and Cosine are orthogonal. You need to do (Sine)*(Sine)
sin^2 (wt) = 1/2(1 - cos (2wt)
This is like the classic squaring technique to receive PN coded signals
without knowing the code. (it's used in some "codeless" GPS receivers..
you can retrieve frequency and phase)
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