[time-nuts] WWVB BPSK Receiver Project?

Jim Lux jimlux at earthlink.net
Thu Mar 15 03:32:13 UTC 2012


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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