Phase and frequency control for carrier retrieval oscillator - is used in colour TV and uses amplitude of sync. demodulators output as control signal

摘要

The phase and frequency control circuit, for the carrier-retrieval oscillator in a colour television, synchronises the oscillator to the phase of the transmitted colour sync. signal using a small number of components and only a small amount of adjustment. The system may be used for PAL-FBAS signals. The colour sync. signal amplitude is measured at the output of the sync. demodulator (4) and stored (10) for the duration of one line. After filtering (13), this stored signal is used to control the oscillator (6). In its simplest form, the memory is a capacitor.