| 摘要 |
PURPOSE:To supply an interference signal relative to a channel to be scrambled by providing a PLL circuit in a scramble unit between a terminal device and a transfer line. CONSTITUTION:A scramble unit between a distributor and a terminal device is constituted as shown in the figure. A PLL circuit 320 produces frequency in a scramble channel frequency band by data from a controller 318, and superposes it over a fall signal by a branching device 306 through an RF switch 317. By this structure, if a selective channel is a prohibition channel by the controller 318, the PLL circuit is actuated to superpose an interference signal on the fall signal and to fulfill a scramble function, thereby making of a prohibition channel impossible. |
