GB1395643A - Colour distortion reduction circuit in a colour television receiver - Google Patents

Abstract

1395643 Colour television NIPPON VICTOR KK 4 May 1972 [6 May 1971 27 Aug 1971 (2)] 20798/72 Heading H4F Phase errors in a PAL colour television signal due to transmission errors are removed in the receiver by the use of notch filters 20, 21, Fig. 4, after the demodulators 16, 17. Filters 20, 21, each of which is formed of two impedance circuits Z1, Z2, Fig. 11, at least one which is a two-terminal reactance circuit, pass signals at frequencies which are integral multiples of the line frequency and remove signals at frequencies which are at odd integral multiples of half the line frequency, and thus the phase error components which have a repetition frequency of half the line-frequency. These frequencies may be removed only below a chosen frequency, all frequencies above this frequency being passed by filters 20, 21. Alternatively if an odd number (N) of vertical colour bars are to be displayed the frequencies removed may be those which are at an odd integral multiple of the number of colour bars times half the line frequency (N#H/2).