SECAM L and SECAM BG transmission norm recognition method

摘要

The method involves multiplying a colour synchronisation signal of a colour-under colour signal with itself. One of the colour synchronisation signals is phase shifted by 90 degrees if it has a frequency above the frequency of a red colour synchronisation signal of a SECAM BG signal in colour-under frequency position. A phase shift of minus 90 degrees is carried out if the frequency is below the frequency of a blue colour synchronisation signal of a SECAM BG signal in colour-under frequency position. The product is low pass filtered, rectified, inverted alternating in display lines and integrated. The integrated signal is coupled to a first capacitance whose charge state indexes a colour signal of the SECAM BG transmission norm. The low pass filtered signal is integrated and the integrated signal is coupled to a second capacitance whose charge state indexes a colour signal of the SECAM L transmission norm.