GB888380A - Improvements in or relating to the processing of television signals - Google Patents

Abstract

888,380. Television. BRITISH BROADCASTING CORPORATION. July 6, 1960 [July 9, 1959], No. 23669/59. Class 40(3). Phase variations of the line synchronising pulses in television signals derived from a magnetic recording (e.g. due to slight mechanical imperfections) are removed by supplying the derived signals to a delay line A and the various tappings A1 - - - An on which feed gating circuits B1 - - - Bn which are "opened" to pass the input signals to an output conductor C when coincidence occurs between the line synchronising pulses in the input -signals and the pulses of a reference synchronising source also supplied (if necessary in a delay device D) to the gating circuits. The reference synchronising pulses may be derived from the source controlling the operation of the recording/playback mechanism or by employing a "flywheel" arrangement, from the line synchronising pulses in the television signal input to the delay line. The gating circuits B 1 - - - B n , details of which are given with reference to Fig. 2 (not shown), operate to pass the input video signals to the output conductor C for the duration of one line following the coincidence of the two input line synchronising signals to any one of the gating circuits. The input video signals are thus subjected to different, discrete delays and the total delay of line A is made sufficient to embrace the maximum errors. The change in delay between adjacent taps on line A must be sufficiently small to reduce the phase variations of the line synchronising signals to a small value. Specification 806, 646 is referred to.