| 摘要 |
<p>1,162,377. Wired broadcasting systems. COMMUNICATIONS PATENTS Ltd. 11 Sept., 1967 [13 Sept., 1966], No. 40834/66. Heading H4R. [Also in Division H1] A wired broadcasting system comprising a distribution feeder having a plurality of pairs 5, 6 and 7 of conductors, on each pair of which a channel or programme is transmitted and a number of subscriber stations 10 each connected by a single individual pair of signal conductors 9 to an individual connection unit 8 adapted to connect the signal conductors to a selected pair of conductors of the feeder under the remote control of the subscriber station. The connection units may incorporate reed or ferreed switches or transistor or diode gates. The control signal from the subscriber station to the connection unit may be electrical, mechanical, pneumatic or hydraulic. In one form (Fig. 2, not shown), the two signal conductors are enclosed in an outer conductive screen constituting a third conductor. To select one of six programmes the subscriber sets a switch to apply a D.C. potential between a selected pair of these conductors. Depending on the polarity of this potential and the particular conductors involved a corresponding relay located at the connection unit and connected between those conductors, through an appropriately poled diode is energized. In another form (see Division H1) a disc carrying a magnet is rotated, by mechanical linkage such as a Bowden cable or an electric, pneumatic or hydraulic motor, to a position in which the magnet closes a selected pair of reed switches to connect in the required channel.</p> |
