High security subscription television system employing real time control of subscriber's program reception

Claim 1

A subscription television system having means for collecting, processing and disseminating a plurality of television programs, at least some of which are in scrambled form, from a central transmitting station via cable distribution means to a plurality of individual subscribers, said system comprising; (a) at least one video reproduction and modulation scrambling subsystem means for serving as a source of standard television program signals having sync and video components for amplitude modulating of a carrier signal, and for producing scrambled television signals characterized by the substantially complete polarity inversion of the amplitude modulation of the sync and video components of said standard television program signals, and for applying said standard television program signals or said scrambled television signals to a cable for distribution; (b) central controlling subsystem means for: (i) receiving program orders for individual subscribers, and for processing and storing said program orders; (ii) generating coded control signals for controlling the scrambling sequence of said video reproduction and modulation scrambling subsystem means and for use throughout said subscription television system; (iii) generating subscriber control signals having an address portion and a frequency determining portion for each subscriber being served to be used throughout said subscription television system; (c) a control signal transmitting subsystem means for directing said coded control signals and said subscriber control signals to said plurality of subscribers by impressing onto said cable a signal containing said coded control and subscriber control signals modulated onto a second carrier simultaneous with and separate from said sync and video carrying amplitude modulated carrier signal; and (d) a plurality of subscriber control units each in receiving communication with said video subsystem means and said control signal transmitting subsystem means via said cable, and each adapted to provide standard television output signals, said subscriber control units comprising: (i) converter means having a voltage controlled oscillator therein and connected to said cable for receiving and converting any one of a plurality of cable connected CATV channels to at least one predetermined frequency band in response to said frequency determining portion establishing a substantial part the frequency of said voltage controlled oscillator; (ii) descrambler means connected to said receiving and converting means for descrambling said single predetermined frequency band in response to said coded control signals so as to render the resultant signal directly usable by a conventional TV receiver; and (iii) processor means connected to said cable for receiving and processing said coded control signals and said subscriber control signals and for applying said processed signals to, and partially controlling said descrambler means and converter means.