GB1287477A - Improvements in relating to oscillator circuit arrangements - Google Patents

Abstract

1287477 APC systems LICENTIA PATENT VERWALTUNGS GmbH 3 Dec 1969 [25 Feb 1969] 58980/69 Heading H3A In an APC system, a signal f T derived from the controlled oscillator is fed via two series connected gates Ga 1 , Ga 2 to a phase discriminator (not shown), the derived signal fT being further applied as a timing pulse to a first bi-stable unit BS which has one output terminal Q connected to an arrangement, e.g. multivibrators MF1, MF2, pulse shaper JF1 for producing a signal indicative of the control capture range and another terminal Q for delivering a timing pulse to a second bi-stable unit BS2, the arrangement being such that when the frequency error is within the capture range, BS2 delivers pulses at its Q, Q terminals such that gate Ga1 is held open and a multivibrator AS is switched off so that gate Ga2 is also held open to pass the derived frequency signal and when the error signal is outside the capture range, the pulses at Q, Q are such as to close gate Ga1 and to initiate operation of AS whose output is applied via gate Ga2 to the phase discriminator for sweeping the controlled oscillator until the frequency error fell within the normal capture range, BS1, BS2 may be JK bi-stable flip-flops. Fig. 4 (not shown) indicates the waveforms present at various points of the circuit.