SYNCHRONIZING CIRCUIT OF VARIABLE FREQUENCY OSCILLATOR

摘要

PURPOSE: To eliminate the need of any other adjuster or the like and to simplify the synchronizing circuit by providing the circuit with a frequency discriminator for controlling an oscillator and a blocking circuit for blocking the control of the frequency discriminator and matching the frequency of the oscillator with reference frequency. CONSTITUTION: The frequency discriminator 30 compares frequency fO generated from the oscillator 21 and divided by a frequency divider 27 with frequency (f) generated by dividing stable frequency fN by a frequency divider 31. A signal determined by the frequency difference and outputted from the output of the discriminator 30 is connected to the output of a phase discriminator 23. The frequency fN and the frequency dividing ratio of the frequency divider 31 are selected so that resultantly generated frequency is slightly different from the frequency fO outputted from the oscillator 21 at the time of synchronizing with a pilot signal included in an input signal. The signal control the input of the oscillator 21 through a low-pass filter 26 so as to reduce a difference between the frequency fO and the frequency (f). Consequently the synchronizing circuit having a small blocking range and almost removing phase disturbance can be obtained.