| 摘要 |
This television information system transmits selected video picture information to one of a number of subscribers who have television sets connected to the system. First, the subscriber makes a selection by transmitting a request to the head end. A central computer interprets the request, searches the available data banks for the information, and records it. Next, the information along with an identifying number is returned to the system and sent to a control station. At the control station, the identifying number is used to route the information to a particular modulator associated with the subscriber who made the request. The information is stored and used to modulate a unique carrier frequency which has been dedicated to that subscriber. The control station sends the modulated carrier frequency (containing the selected information) to a feeder line to which may be connected a number of subscribers, including the one who made the request. If the requesting subscriber's television set is tuned to his carrier frequency, he can receive the requested information. Privacy is assured by dedicating to each subscriber a different carrier frequency and associated television channel, and by filtering out all other channels which might be transmitted on the feeder line. Standard, unmodified television sets may be used with this system; and rapid retrieval of information from large data banks is possible.
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