| 摘要 |
PURPOSE:To prevent various types of disturbing to a video signal and to avoid the deterioration of picture quality by retaining only a function of a converter in a subscriber house, incorporating functions for executing controls of looking and listening of subscribers in a distribution system unit and installing said unit outdoor. CONSTITUTION:A television signal from a branching line 1 is inputted to a branching filter 4 through a branching device 3. The television signal from the branching filter 4 is transmitted to a transmission module 16 through a variable resistance attenuator 6 with the aid of each terminal correspondence, simultaneously inputted to an FSK demodulator 8, and its data signal components are inputted to a control logic circuit 9. A periodical control signal with respect to a jamming signal generator 10 is transmitted from the logic circuit 9, while from the jamming generator 10 a jamming signal subjected to the time division with the aid of each channel correspondence is produced. With respect to this jamming signal, a prescribed modulation signal is frequency-modulated and overlapped with the jamming signal, whereby a control system of looking and listening in correspondence to plural terminals can be accomplished at a low cost. |
