Color television system employing index signal generating means

A main index signal is generated concurrently with the excitation of a plurality of triplet groups of color generating segments by a sweeping electron beam at a frequency which is a nonintegral number multiplied by the triplet frequency, a frequency at which the triplet groups are excited per a unit time. An auxiliary index signal is generated preceding the occurrence of the main index signal. A frequency counter is provided to convert the frequency of the main index signal to the triplet frequency. The auxiliary signal is delayed, differentiated and used to reset the counter to cancel the content therein to initiate counting of the significant bits of the main index signal at the start of each of the line scansions.