| 摘要 |
PURPOSE:To change the control signal of a voltage control oscillator according to the change of the oscillating frequency of a low frequency oscillator and to improve a communicating quality by providing the low frequency oscillator and a control circuit to superpose the output of the low frequency oscillator on the output of a phase comparator in response to an alarm generated by means of an alarming circuit. CONSTITUTION:A low frequency oscillator 21 oscillates a low frequency signal. A control circuit 22 is composed of a variable attenuator 23 and an integrating circuit 24. The integrating circuit 24 integrates the alarm output of an alarming circuit 18. In the case where the alarm is eliminated while a certain voltage is generated at the low frequency oscillator 21, when the output of the low frequency oscillator 21 is abruptly interrupted, the frequency is abruptly changed by the degree of the voltage, and a step-out may be generated again. Consequently, an attenuation is needed to be gentle enough for a lead-in to follow, and for such a reason, the alarm output is integrated and inputted to the variable attenuator. The output of the integrating circuit 24 is given to the variable attenuator 23. |
