I've got a WWVB nixie clock sitting on the shelf _mostly_ done. [most of
the hardware, not a lot of the software] that got shelved because I was
having real problems with receiving the VLF WWVB signal in Seattle. I'm
not really familiar with VLF, but from what I gather it propagates
exclusively via groundwave.. I assume that at night during the winter is
the best time to receive, but now that I look at my design again, I
didn't have a real earth ground. I'll pick it up again now that I
actually know something about radios. :) You're right, seems pretty
simple. Basically just an AM carrier that drops power to encode the
nibbles for varying durations to identify what kind of nibbles they are.
http://tf.nist.gov/timefreq/stations/wwvbtimecode.htm
-Adam W7ATJ
On 8/3/2011 8:58 AM, threeneurons wrote:
Its an AM modulated signal. The date and time is encoded in BCD
nibbles. The date is given in Julian format. That is Jan 1 = day 001,
and Dec 31 = day 365 (or 366, for leap year). There are three types of
data bits: 0,1,& R (reference). Each is represented as a pulse of
varying duty cycle: 20%, 50%,& 80%. I have to dig into my notes, to
find which DC corresponds to which bit value. Or you can just Wiki, or
Google it.
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