| 摘要 |
<p>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 10<SP>6</SP> possible settings of which only 4<SP>6</SP> 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.</p> |
