GB959274A - Cueing system for television - Google Patents

Abstract

959,274. Television; signal distribution systems. PYE Ltd. Jan. 5, 1961 [Jan. 6, 1960], No. 483/60. Headings H4F and H4R. In a cueing system for television there are added to the television waveform during at least one line of the frame suppression period, plural different cue signals occurring one after another throughout the line period. Each signal consists of a burst of a sine wave of a predetermined frequency, a different frequency being employed for each different cue signal. The arrangement at the transmitting terminal is shown in Fig. 2, where a generator 10 controlled by vertical and horizontal synchronizing pulses produces first and second half-line duration pulses coinciding with the respective halves of a predetermined line of the frame suppression interval, the pulses being applied each through a selected one of a group of switches 13 to key a burst generator 11. In this way a time division conbination of two signals, each having a different frequency, is generated and added to the transmitted video signal in a mixer 14. At the receiving terminal, Fig. 1, a gate 2 controlled appropriately by vertical and horizontal synchronizing pulses derived by a separater stage 1 separates out the line during the frame suppression interval which contains the cueing signal and applies the signal through a switch operating a halfline interval to two groups of tuned circuits 4, each arranged to trigger an associated relay or other control device 5. In accordance with the pattern of operated devices 5, a desired control operation is performed. The invention is stated to be of use for automatic switching in line and V.H.F. networks, and the control of domestic apparatus, e.g. in connection with prepayment television.