The cRb-Clock is the world’s first commercially available portable cold Rubidium microwave atomic clock. The clock is designed for high frequency stability in the short term of 8×10-13 /√τ and for excellent long term frequency stability of 3 x 10-15 at one day and less than 1 x 10-15 at 10 days.
With this level of performance the cRb-Clock can be used as a substitute for Hydrogen masers. The cRb-Clock, does not require calibration since there is no long term frequency drift and has an accuracy of a few parts in 10-15.