Method and device for automatically selecting the demodulation standard of a video signal, useful with an intermediate frequency demodulator

摘要

A method, and related device, for automatically selecting the demodulation standard of a video signal, useful with an intermediate frequency demodulator, which has an output for the demodulated signal and a so-called standard selecting input pin, consists of detecting the polarity of the demodulated signal at the output of the demodulator and comparing that polarity with the polarity of the input signal to the demodulator. The voltage value on the standard selecting pin is changed over on detecting a different modulation polarity between the input and output video signals to/from the demodulator to enable the latter to operate to the correct standard at all times.