On Mon, 17 Aug 2009 19:22:09 -0700, David Nebenzahl
wrote:

On 8/17/2009 6:44 PM Jeff Liebermann spake thus:

Got $10.70? Build your own:
http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=561-1014-ND

Interesting.

But once you've picked up WWV, what do you do with that signal to derive
a time base from it? (I guess you gots to know something about the
signal, which I don't.) Pretty simple?

Well, that's the basic receiver without that CPU. If you want to
build a complete receiver, methinks this one:
http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=561-1016-ND
is more appropriate. However it costs $71. The full development
system, with software costs about $250. I was thinking that it might
be best to have the PC do the processing, and use the cheaper
receiver.

I don't know that much about the code used by WWVB. (I are not a
programmist). I've gone as far as to disembowl an "atomic" clock
(cheap LCD display), and sniff the time signals with a scope. It
doesn't look too horrible. Some app notes on the CME8000 chip:
http://www.c-max-time.com/downloads/search.php?search=CME8000
Software flow chart:
http://www.c-max-time.com/downloads/getFile.php?id=525
Also, the demo board app note was misnamed. Download the file and
rename it with a .PDF extension. Then, it will be readable.

Start he
http://tf.nist.gov/stations/wwvb.htm
http://tf.nist.gov/timefreq/stations/radioclocks.htm
http://en.wikipedia.org/wiki/WWVB#Modulation_Format
http://en.wikipedia.org/wiki/Radio_clock
Basically, you're building a clock, but instead of driving a display,
you're converting the UTC to something the PC will digest. There are
plenty of project on the internet, but none that I could find that
included PC interface software.

PIC Based WWVB Decoder
http://www.geocities.com/hagtronics/wwvb.html

Parallax Basic Stamp II Atomic Time Clock Receiver
http://marwww.in2p3.fr/~levansuu/projets_es2i/Parallax/parallax%20website/stamps/atomictimeclock.htm

Build a WWVB Radio Controlled Nixie Clock
http://www.amug.org/~jthomas/wwvb.html

Decoding WWVB from a Sony atomic time radio controlled clock
http://leapsecond.com/pages/sony-wwvb/

etc...


One more... WWVH on a ISA or PCI card:
http://www.beaglesoft.com/clcahome.htm

Research: Chip-scale atomic clock:
http://tf.nist.gov/timefreq/ofm/smallclock/CSAC.html