GB1280733A - Colour television circuit arrangement - Google Patents

Abstract

1280733 Colour television FERNSEH GmbH 12 Aug 1970 [16 Aug 1969] 38811/70 Heading H4F A PAL colour television signal having quarter line offset is separated into its luminance and chrominance components by transit time analysis in which the signal is delayed for one and two line durations and in which a delay line having a delay of “ of the colour carrier period is used. In Fig. 1 the phase diagrams of a “ line offset PAL signal in four successive lines are shown in column a, Y<SP>11</SP> indicating the high frequency portion of the luminance component and F and F the chrominance signal and complex conjugate chrominance signal respectively. By adding the (n+1) and (n-1) lines the chrominance-free luminance signal Y<SP>11</SP> is obtained as shown in column b, and by subtracting then (column c) the chrominance signal F (or F) is obtained and by subtracting the signals in columns a and b the chrominance signal F (or F) is obtained. The signal represented in column d is then delayed by “of the colour carrier period and the resulting signal (column e) is added and subtracted to the signal represented in column c to obtain the carrier frequency components U and ŒV (columns f and g). The high frequency component of the luminance signal Y<SP>11</SP> in column b is then supplemented by the low frequency component. In a first embodiment, Fig. 2, the PAL signal is separated into two frequency ranges by high and low pass filters 1 and 13, and the chrominance signal and high frequency luminance component are fed via two one line period delays 2 and 3 and then the above described operations are effected thereon. The low frequency luminance componence is delayed by one line period 14 and added 15 to the separated high frequency luminance component. In a second embodiment, Fig. 3, the PAL signal is not split into two frequency ranges, and to derive the separated luminance signal the output of one line delay 16 is further delayed 27 by “ of the colour carrier period and U is subtracted therefrom 29, 28 and ŒV added thereto 30. In a modification of this arrangement, (Fig. 4, not shown)reflection at the end of a single one line period delay line is used, the direct and reflected (two line period delayed) signals being combined with the input signal correctly dimensioned both directly and phase inverted to obtain the signals represented in columns b and c of Fig. 1.