I had one here -- but it always kept losing signal. So, you
get a false sense of security *thinking* it is telling the correct
time -- only to discover it wasn't. I guess they are sensitive to
where they are located/oriented. Given how "unattractive" this
one was (think: functional not decorative), the choices for where
it could acceptably be sited were limited. So, it got relocated --
to the trash. :

Such clocks are best kept away from computers and other sources of EMI/RFI.
Once you find a clean spot, you should be okay.

Those with LCDs usually have an indicator that shows whether the clock has
been recently resynched.