VTR mode discrimination method and discriminator therefor

摘要

A signal, which is delayed from a color under signal by two horizontal periods (1), and the color under signal are phase-shifted by +45 degrees (3) and -45 degrees (2) respectively and added or subtracted (4) so that whether the color under signal is of the PAL system or of the SECAM system is judged by utilizing the change in the arithmetic output of every horizontal period. Moreover, a color under signal fed from an input terminal is delayed by two horizontal periods by a delay circuit (1), and the input color under signal and the delayed color under signal are phase-shifted by +45 degrees and by -45 degrees, respectively, by phase circuits (2,3). These two signals are added or subtracted by an arithmetic circuit (4) so that whether the mode is of the PAL system or the SECAM system is judged by detecting the change in the arithmetic circuit for every horizontal period by a signal detector (5-9).