I have used World Time for years. It goes way beyond just synching, as it provides displayable clocks from various time zones..(YOUR choices)...and a world map with distances..etc...(and a timer that shows time since OR to, an event..in years, weeks, months, seconds...it is now 2473.77 days since Y2K, Jan 1, 2000)

If all you want is the time signal, use one of the smaller ones, but if you might want the extras, check it out.