COLOR IDENTIFICATION CIRCUIT FOR COLOR TELEVISION PICTURE RECEIVER USING SECAMMPAL CONVERSION SYSTEM

摘要

PURPOSE:To secure the stability of the color identification by giving the system switching between the phase-shifted false burst signal and the PAL burst signal at the SECAM and PAL receiving time respectively and then giving the phase detection to one of the two signals to secure an accurate synchronization the PAL color identification circuit and the SECAM color signal. CONSTITUTION:Burst gate circuit 14 extracts the signal at the position corresponding to the burst signal of the color signal among the PAL color subcarrier signals shifted every 1H period with phase angles of 0 deg. and 90 deg., i.e., the false burst signal. Then phase-shift circuit 15 gives the phase shift to the false burst signal to the phase angle featuring the positive and negative components to the PAL color subcarrier signal supplied to phase detector 8. and system switching 16 is given between the phase-shifted false burst signal and the output signal of PAL burst circuit 7 at the SECAM and PAL receiving time respectively. And either one of the two signals is supplied to detector 8. Thus, PAL color identification circuit 10 is operated in an accurate synchronization with the SECAM color signal, ensuring the stabilization for the color identification.