Tamas Rudnai wrote:
> I am not sure about the rest of the world, but here in Europe there
> is the DCF77 so you can synchronise the watch to an atomic clock
> operated in Frankfurt, Germany. The radio signal circuit used to be
> quite difficult to build, however, nowadays you can buy these as a
> module and to interface it with PIC if fairly simple. Google is full
> of with example projects.

In North America we've got WWVB near Fort Collins Colorado.  Both its
carrier frequency and its time signal are derived from the NIST atomic clock
in Boulder.  The carrier is 60Khz (with a lot of zeros right of the decimal
point), so you can use ordinary opamps and "audio" range parts in the
receiver circuit.  Here in New England we are at the fringes of the signal's
range, so WWVB clocks tend to sync up only during the night.


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