GB872384A - Improvements in or relating to colour television receivers - Google Patents

Abstract

872,384. Multiplex radio signalling. PHILIPS ELECTRICAL INDUSTRIES Ltd. April 21, 1960 [April 24, 1959], No. 14022/60. Class 40(5) [Also in Group XL(b) ] Relates to a colour television receiver for the reception of a signal transmitted by a system in which the transmitted signal, modulated on a carrier wave, comprises a component relating to brightness and at least one component constituted by an auxiliary carrier having modulated on it one or more signals relating to colour. In accordance with the invention, the receiver comprise a transformer 42 (in practice an I.F. transformer), a detector 15 coupled to the primary winding 41 for detection of the component constituted by a modulated auxiliary carrier, a further detector 5 coupled to the secondary winding 43 for detection of the component relating to brightness, and a delay line 52 connected in the output of detector 5 for the introduction of delay in the brightness component in order to compensate for delays introduced in the receiver into the signals relating to colour. The use of separate detectors for the brightness and colour components is stated to prevent distortion of the auxiliary carrier which arises with a single detector due to presence of the delay line in the detector output. An isolating video amplifier between the detector and delay line is not required and the line may be connected directly to the detector output without the interposition of a matching resistor. The detector input circuits are arranged to have band-pass characteristics covering the bands of the respective signals. The detector outputs include carrier (I.F.) filters. An intercarrier sound signal may be derived from the output of detector 15. A sound carrier suppression filter 46, 47 is included in the input circle of detector 5.