Improvements in or relating to multiplex high frequency electrical pulse signalling systems

Abstract

Abstract 582,198. Pulse modulation; multiplex systems. STANDARD TELEPHONES & CABLES, Ltd., CHATTERJEA, P. K., and HOUGHTON, L. W. April 7, 1943, No. 18640/44. Divided out of 582,177. [Classes 39 (i) and 40 (v)] In a multi-channel pulse signalling system, interlaced time-modulated pulses are produced by means of cathode-ray tubes with shaped targets. For a four-channel system, the target may comprise four curved metal bars a.... d radiating from a central hub e. The ray is given a circular movement along the path f by pairs of plates or coils energized in quadrature. In addition, the ray is given a radial deflection by the four separate modulating signals applied between the central plate 1 and the four circumferential plates 2 ... 5,. so that each signal deflects the ray as it is passing the corresponding target. The four trains of timemodulated pulses are taken off across the resistance R. In a modified arrangement, a separate cathode-ray tube is used for each channel, the target in each being a metal bar set at an angle to the scanning co-ordinates which are provided respectively by the signal and by a saw-tooth or other wave of pulse repetition frequency as in Specification 523,575. The saw-tooth or other wave is suitably phased for each channel, and the pulses are combined into a single train before transmission. Slotted targets backed by collector plates may be used instead of the metal bars.

Inventors

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