I have had a receiver capable of tuning down to 30 KHZ
here in North-Central Oklahoma for a little over a year. My HF
antenna is the guy wires on a 50-foot tower so it is not really
well suited for reception at 60 KHZ, but even so, WWVB is
normally very audible at any time during the day with a little
better reception at night.

	The modulation is an inverted modulation in that full
carrier means no pulses. Pulses are -10 DB drops in the carrier.
Listening with the BFO on as for Morse Code, one hears a strong tone which
almost, but not quite, disappears during the pulses which
are varying lengths depending upon whether they
denote a 0 bit, a 1 bit or a sync.

	Other than being able to say that it is there, listening
to it isn't terribly productive.

	What I have noticed is that there isn't nearly as much
man-made interference on 60 KHZ as I expected there to be but I
am sure that is highly local.

	There is a lot of natural static from
lightning over hundreds of miles so that is a problem especially
this time of year.

	There have also been times in which the signal is
unusually weak for periods of time. I am not sure why this is
but it would probably make a marginal system stop receiving
altogether.

	The fades are probably due to electromagnetic activity
although we have had extremely calm and boring ionospheric
conditions for a couple of years now.

	Do the WWVB modules just give you  a logic level output
that you feed in to a CPU like those little IR modules that can
be used to receive IR remote controls? I have thought about
trying to build some self-setting accurate clocks for
automatically setting our VCR as the auto clock setting function
never worked properly for some reason.

Martin McCormick WB5AGZ  Stillwater, OK 
Systems Engineer
OSU Information Technology Department Telecommunications Services Group
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