GB1521295A - Circuit arrangement for demodulating chrominance television signals - Google Patents

Abstract

1521295 Television receivers INDESIT INDUSTRIA ELETTRODOMESTICI ITALIANA SpA 16 July 1975 [17 July 1974] 29764/75 Heading H4F A receiver for a television signal comprising colour signals modulated on quadrature carriers, one of which inverts in phase at line frequency, e.g. a PAL signal, includes a single synchronous demodulator fed with a constant phase reference subcarrier and the chrominance signal. The demodulator output is processed to provide at respective output terminals the one component and the other component of the colour vector along the reference subcarrier axis. As disclosed, Fig. 1, a burst gate 2 passes the colour bursts in a chrominance signal C to a gate 3 enabled at half line frequency so as to pass alternate bursts to a subcarrier generator 5. The generator feeds to the demodulator I a subcarrier which is in phase with the selected bursts. The output of the demodulator during each line therefore consists of portions of both the B-Y and R-Y signals. The output signals pass direct and via one-line delay 7 to a switch 6 which provides one component of the colour vector continuously at a terminal 8 and, simultaneously, the other component of the colour vector continuously at a terminal 9. The signals at 8, 9 are passed to a matrix circuit, Fig. 3 (not shown), which derives the R, G, B, signals.