Write clock pulse signal generator for digital time base corrector

In a time base corrector for periodic information signals containing first and second reference signals having relatively low and high frequencies, respectively varying with time base errors in such periodic information signals, and in which the following periodic information signals are converted to digital form and written in a memory at a clocking rate determined by a write clock pulse signal modulated in accordance with time base errors in the incoming signals, whereupon the digitized signals temporarily stored in the memory are read out therefrom substantially at a standard clocking rate and the resulting digitized output from the memory is reconverted to analog form for eliminating the time base errors:

• a generator for said write clock pulse signal comprising an automatic frequency control circuit including a variable frequency oscillator having an output with a center frequency which is a multiple of said high frequency of the second reference signal, and phase locked loop means receiving said oscillator output and said first reference signal for varying the frequency of said oscillator output in accordance with variations in the frequency of said first reference signal;
• and
• an automatic phase control circuit including variable phase shifting means, means for applying said oscillator output to said variable phase shifting means so as to obtain said write clock pulse signal at the output of said variable phase shifting means, and control means for said variable phase shifting means operative to vary the phase of said write clock pulse signal in dependence on a phase comparison of said second reference signal and said oscillator output.