Processing method and circuit for PAL colour television signals

Abstract

Abstract A signal processing circuit (10) for colour television signals, e.g. PAL signals, i as first and second one-line delays (14, 16) connected in series to the input (12), an averager (18) connected across the two delays and a subtractor (20) connected to subtract the averager output from the output of the first delay (14). In this way the circuit provides (i) a first signal at the output of the first delay (14) which is the input signal delayed by one line period and (ii) a second signal at the output of the subtractor (20) which is the resultant of the average of the undelayed input signal and the input signal delayed by two line periods subtracted from the input signal. A band-pass filter (22) covering the chrominance band is connected to the output of the subtractor (20). A second subtractor (24) subtracts the filtered signal from the one-line delayed signal. Separated luminance and chrominance are obtained at the outputs of the second subtractor (24) and the filter (22) respectively, which are especially suitable for line-locked sampling frequencies. Either output may be used on its own. For N.T.S.C. signals, a divide-by-two circuit is included in series with the band-pass filter (22).

Inventors

• 👤 Christopher Keith Perry Clarke

Bibliographic Details