Method electronic circuit for automatically measuring the horizontal scan frequency of a composite synchronism signal.

摘要

A method of automatically measuring the horizontal scan frequency of a composite synchronism signal (2), comprising horizontal synchronization impulses at line frequency (fh), consists of first performing a count of a number (m) of impulses having a repeat frequency (fc) higher than said line frequency (fh), as intervening between two successive impulses (3) at line frequency. The count value, corresponding to said number (m) of impulses, is stored to obtain the line frequency of the signal, and thereafter, a series of down counts is effected, as initiated at predetermined times, until a change of frequency of the signal (2) is detected. <IMAGE>