| 摘要 |
A poach-resistant system enabling cable television subscribers to receive upon request certain programs otherwise unavailable (i.e., "secure") while precluding such reception by non-requesting subscribers as well as non-subscribers. Before transmission of such a secure program the roster of subscribers is scanned at a central control station having complied subscribers' requests for that program, and a resulting string of pulses corresponding in sequence to the respective subscribers is punctuated with program command pulses timed to designate those subscribers who have requested the program. Transmission of the resultant program command signal string over the cable to junctions with leads to the respective subscribers' television sets results in unblocking of such junction for each of the requesting subscribers only. Allocation of plural clocking pulses to each subscriber enables program availability to be tiered as desired. Appropriate circuitry in the junction of each subscriber's lead with the transmitting cable retains control there so that unauthorized program signals never enter a subscriber's premises, where security could be defeated.
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