Selective viewing control system for CATV
AssigneePioneer Electronic Corporation
InventorHiroki Uemura
Life of this patent
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Abstract
A selective viewing control system for controlling viewing access to designated channels in a CATV system. A CATV control center sends to viewing control units a digital signal indicating which channels are to be jammed. In response, the viewing control unit produces a jamming signal, added with the unjammed television signal, containing frequency bursts at timed intervals. Each frequency burst corresponds to a single channel to be jammed. A digitally controlled phase-locked loop circuit is employed to generate the jamming signal.
Claims7
A CATV system having a central control center and a plurality of terminal units located at tap-off points for individual subscribers and coupled to said central control center via a signal distribution network, each of said terminal units comprising a selective viewing control system comprising:
- controlled oscillator means operating in response to digital values transmitted from said central control center over said signal distribution network indicating channels to be jammed for producing a jamming signal containing only a repeating sequence of signal bursts at frequencies determined by said digital values and falling within respective channels to be jammed;
- and
- means for adding said jamming signal to a television signal received from said central control center via said signal distribution network, a resulting sum signal being provided as an input signal to a respective subscriber's television set.
Dependencies are inferred from the claim text.