| 摘要 |
PURPOSE:To attain quick recovery of synchronization by applying an output signal of a sweep oscillator to a differentiating circuit. CONSTITUTION:When the phase locked loop is in the lock state, since an impedance at a point 6 is zero, a sweep oscillator 5 is not oscillated and when out of synchronism takes place, since the impedance at a point 6 is changed, the sweep oscillator 5 starts oscillation and the oscillated output is fed to a differentiating circuit 7, from which a differentiated waveform output is obtained. The output waveform is fed to a voltage controlled oscillator 2 to sweep the oscillating frequency of the oscillator 2 over a wide frequency range and the synchronization recovery is applied to an input signal whose frequency is within the sweep frequency. The frequency change in the oscillating frequency of the oscillator 2 is slow in the vicinity of a reference frequency and the convergence to the reference frequency is facilitated and quick synchronization recovery is realized. |
