Improvements in or relating to subscription television encoding apparatus

摘要

756,758. Television. ZENITH RADIO CORPORATION. Feb. 8, 1954 [Feb. 20, 1953; Feb. 1, 1954], No. 3601/54. Drawings to Specification. Class 40 (3). [Also in Group XXXVII] In a subscription television system the " coding " and " decoding " circuits include a switch assembly comprising a plurality of multi-position manually operated switches for effecting various combinations of circuit connections between a plurality of input and output channels. The invention is described as applied to a system of the kind set out in Specification 742,140 the switch assembly replacing the individual transposition switches and allowing over 106 possible settings of which only 46 produce effective interconnections between the six input channels and the four output channels. This arrangement improves the " secrecy " value especially in subscription systems in which the " decoding control signal is transmitted over a wireless channel instead of over a line. Specifications 647,892 and 647,893 also are referred to.