"Mark Lloyd" wrote

I see ads for clocks that claim to set themselves. They don't really, but
will adapt to DST (change hour twice a year). Of course, they won't do
anything about clock drift, so you still need to check occaisionally.

Sure they set themselves. They listen to WWVB, the longwave radio station
of the NIST. They usually listen between 3 and 5am when interference on the
LW band is low. Here's more info on WWVB and those self-setting clocks:

WWVB Info: http://www.nist.gov/pml/div688/grp40/wwvb.cfm