Write clock pulse signal generator for digital time base corrector

Abstract

In a time base corrector which converts incoming video signals to digital form and writes the digitized signals in a memory at a clocking rate varying in accordance with time base errors in the incoming signals, whereupon the signals temporarily stored in the memory are read out or fetched therefrom at a standard clocking rate and reconverted to analog form for eliminating the time base errors; the clocking rate for storing the digitized signals is determined by a write clock pulse signal generator having an automatic frequency control circuit in which the output frequency of a variable frequency oscillator is varied in dependence on the horizontal synchronizing signals in the incoming video signals, and an automatic phase control circuit in which the output of the variable frequency oscillator is phase shifted in dependence on the burst signals separated from the incoming video signals.