[time-nuts] DSP WWVB Receiver Idea

Brooke Clarke brooke at pacific.net
Tue Apr 21 21:06:48 UTC 2009


On the PICLIST there has been a discussion about the CMAX WWVB front ends and 
noise.  Olin mentioned that you could use a dsPIC to look at the I and Q 
signals resulting from mixing the WWVB signal with a carrier at 60 kHz.  His 
example case was to use a cheap crystal (+ or - 3 Hz) and so use a 10 Hz low 
pass filter on the I and Q signals prior to squaring and adding them.

But wouldn't it be better to use a LO with say 1,000 times better stability 
(still very reasonable priced) and some other DSP method of recovering the 
phase and amplitude of the WWVB signal.  (Olin was only looking at the AM signal).

I don't know DSP methods so am asking is there a way to demodulate the signal 
with a very narrow effective bandwidth so that the s/n is good 24/7 even on the 
left and right coasts?

Have Fun,

Brooke Clarke

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