GB1198392A - Television Systems - Google Patents

Abstract

1,198,392. Pulse modulation systems. V. M. TSIRLIN, J. N. SHESTAKOV, G. V. TARASENKOV, and V. M. PALITSKY. 23 May, 1968 [24 May, 1967], No. 24664/68. Heading H4L In a system for the transmission of audio signals in the interline blanking period of a television signal means are provided for increasing the bandwidth available to the audio channel. Video signals a, Fig. 2, are supplied to sync. separator 2, Fig. 1, which supplies an output b to a pulse width modulator 3 at twice the repetition frequency of the line sync. pulses. Audio signals are supplied to the modulator 3 and the resulting width modulated pulses c are supplied to a differential circuit 4 and via a delay of half a line scanning period at 6 (pulses f) to a differential circuit 5. The pulses from 2 and 6 are also supplied to pulse shapers 9 and 10, respectively, which produce pulses d, g of standard duration which are always of shorter duration than pulses c and f, respectively. Pulses d are supplied to the differential circuit 4 and the resultant signal e in which the leading edge is modulated is supplied to a combining circuit 7. Similarly, pulses g are supplied to the differential circuit 5 and the resultant h in which the trailing edge is modulated is combined at 7 with the pulses e. Circuit 7 is controlled by a bi-stable device 8 (pulses i) which is triggered by the pulses b. The output j of circuit 7 is combined at 1 with the video signal to produce the composite signal k.