Dual standard PAL/SECAM receiver circuitry

In a color television receiver subject to reception of composite color television signals inclusive of a luminance component and of a chrominance component encoded in SECAM format, and to reception of composite color television signals inclusive of a luminance component and of a chrominance component encoded in PAL format;

• said receiver including:
• PAL decoder apparatus;
• a first bandpass filter having a passband encompassing the frequency band occupied by said chrominance component encoded in SECAM format;
• means responsive to received signals passed by said first bandpass filter for transcoding a chrominance component of SECAM format to a chrominance component of a quasi-PAL format;
• a path for received signals by-passing said transcoding means and including a second band-pass filter having a passband encompassing the frequency band occupied by said chrominance component encoded in PAL format;
• and a switching system which (a) couples the output of said transcoding means to the input of said PAL decoder apparatus and decouples the output of said bypassing path therefrom, when in a first switching state, and (b) couples the output of said bypassing path to the input of said PAL decoder apparatus and decouples the output of said transcoding means therefrom, when in a second switching state;
• apparatus comprising:
• a chrominance component trap circuit;
• a delay line;
• a first signal path for said received signals inclusive of said delay line;
• a second signal path for said received signals bypassing said delay line;
• means, responsive to the switching state of said switching system, for (a) enabling said delay line inclusive signal path while disabling said delay line bypassing signal path, when said switching system is in said first switching state, and (b) enabling said delay line bypassing signal path while disabling said delay line inclusive signal path, when said switching system is in said second switching state;
• and
• means, responsive to the products of chrominance component decoding by said PAL decoder apparatus and to the luminance component of received signals traversing both the enabled one of said signal paths and said chrominance component trap circuit, for forming a plurality of color signals;
• wherein said delay line imparts to signals passed thereby a delay substantially equal to the difference between (1) the delay incurred in processing of the chrominance component of said received signals when said switching system is in said first switching state, and (2) the delay incurred in processing of the chrominance component of said received signals when said switching system is in said second switching state;
• and
• wherein the delay imparted by said chrominance component trap circuit to signals passed thereby is of such a magnitude that the luminance component to which said color signal forming means responds when said switching system is in said second switching state suffers a delay which substantially matches the delay incurred in processing of the chrominance component of said received signals when said switching system is in said second switching state.