Abstract: The method for generating the second signal is put forward based on the period rule of the phase difference for two frequency signals with the frequency difference. The two frequency signals with a certain frequency difference can be obtained from the same source. The phase coincidence detection circuit outputs an exclusive coincidence signal with the help of a time gate, and then the phases of the two frequency signals would be moved properly to make the coincidence signal synchronize to a normal second signal. Experiment shows that the method is same as the conventional one in generating a second signal, but facilitates the advantage of delivery and measurement of frequency signal when it is used in the time promulgation system. When used in the atomic clocks time comparison, the comparison can be fulfilled using the phase comparison of the frequency sources, so as to improve the accuracy as well as reduce the cost.

Key words: two frequency signals, phase coincidence, second signal