[time-nuts] DSP WWVB Receiver Idea
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?
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