To shorten the time required for start and to improve stability by fixing an output frequency (at the time of frequency unlock) from the time of the start until frequency lock.
At the time of a frequency unlock state, the control voltage of a voltage controlled oscillator 101 is swept. At the time, the output data of a frequency setting data generation part 104 are continuously changed so as to fix the output frequency even when the input frequency of a frequency control circuit 103 is changed corresponding to swept control voltage change. Thus, only input to an atomic resonance part 102 is turned to the state of frequency sweep and a fixed frequency is taken out from the frequency control circuit 103 as the output frequency of a device. That is, the frequency setting data generation circuit 104 changes frequency setting data corresponding to the control voltage of the voltage controlled oscillator 101 swept at the time of starting the device and the output frequency of the frequency control circuit 103 is turned to a fixed value even for the change of the output frequency of the voltage controlled oscillator 101.
MATSUURA HIDEYUKI
NAKAJIMA YOSHIBUMI
FURUYAMA YOSHITO
NAKAMUTA HIROSHI
