List of the clock of the corrector non-limitative embodiments of the time base

摘要

A write clock generator of a digital time base corrector for removing time base errors from color video signals includes a voltage controlled oscillator (VCO) in a phase lock loop by which the oscillator output or write clock pulses, after being suitably divided, are compared, as to phase, with the horizontal synchronizing signals and the burst signals separated from the video signals for controlling the VCO on the basis of both comparisons. In order to avoid a lock-out condition of the phase lock loop as a result of variation in the time relationship of the horizontal synchronizing signals and the onset of the respective burst signals, the oscillator output which has been divided to generally correspond to the frequency of the burst signals is employed to produce first and second trains of pulses having the same frequency as such divided output but being out of phase with respect to each other, and one or the other of the trains of pulses is selected, in response to the timing of the burst signals, for phase comparison with the burst signals of the train of pulses which is substantially out of phase in respect to the latter.