I read an article about WWVB reception for a frequency standard that made
use of a zero crossing detector to detect the 60 KHz signal.

His point was that many detection schemes can get a false count now and
then due to the 10 dB drop in signal strength that WWVB uses to encode the
time information.

Apparently, the zero crossings are quite stable regardless of the
amplitude change.

For a system to recover the time information, I'd be inclined to simply
amplify the incoming and then use a diode detector of some sort. Well, that
and a SLOW AGC system...

I do not think it would need anything as complex as a synchronous
detector since any changes in the propogation of 60 KHz is very slow.
Admitted, the occasional noise burst may result in a false pulse now and
then.

Since you are likely to feed the signal into a computer of some sort to
decode the pulses to a time signal, you can add some programming to handle
the occasional false pulse.



Jim Pennell
N6BIU