Abstract: The stability of the passive atomic frequency standard can be influenced by the phase delay and system relaxation time. In the servo loop of the synchronization phase discrimination, we can realize the system locked based on the synchronous pulse signal of low frequency. In this paper, the phases of two square waves are adjusted by FSK mode of DDS, in order to satisfy the requirements of synchronous phase discrimination, and the improved experimental results are list out.

Key words: digital phase shift, atomic frequency standard, serial control