Just came from a meeting with a rep from a wireless clock supplier. Interesting tidbits:
Atomic clocks are pretty much limited to the residential market, or buildings of wood frame construction. The signal has trouble penetrating concrete or masonry.
The wireless system gets its signal from a satellite, which gets its signal from Colorado. A receiver/transmitter is placed outside, where it will not be buried by a foot of snow. (It will work if covered by a few inches of snow.) It just has to face the sky; no worries about direction or trees, etc. blocking the signal like satellite TV systems must be concerned about.
Primex is the rep's company, based near Milwaukee.
