[hawski]

Radio time signal stations broadcast time and I would hope it would be cheap enough as we have radio controlled clocks, that do not cost a fortune. Otherwise a small battery and a RTC would be enough and probably a better solution.

[sgtnoodle]

A GPS receiver can be had for like $15 these days. That will give you time and position, and require less maintenance than an RTC.

Of course, a $15 receiver might not have the best sensitivity, so reception might actually be a practical concern. On the other hand, you only need 4 satellites for a coarse fix, and you could seemingly tolerate a many minute cold fix time.