Full-field teletext system with dynamic addressability
First Claim
1. In a teletext system having a head-end station, a group of subscriber stations, a data base comprising a multiplicity of data pages transmitted from the head-end station to the subscriber stations on a video channel, each data page comprising a group of data, said data base arranged into program service levels each comprising a respective set of pages in the data base, the data base and service levels being individually accessible to particular subscribers on a selective basis in response to subscriber requests for access to the teletext system, the improvement for controlling and adjusting subscriber access to particular service levels comprising:
- means at the head-end station for transmitting to each of the subscriber stations a service level description page comprising data defining each of said service levels and a subscriber service level authorization code page comprising a group of subscriber service level authorization codes for plural subscribers, each of said authorization codes specifying the service levels to which a corresponding subscriber is entitled to have access; and
a respective logic circuit located at each subscriber station responsive to said description page and said authorization page for controlling access at its subscriber station to service levels on the basis of the authorization code corresponding to such subscriber station and the service level corresponding to the request by the subscriber.
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Accused Products
Abstract
The present invention permits a teletext system operator to adjust subscriber access to service levels individually by adjusting a code at the head end station. A head-end station transmits a tier description page and a tier authorization page. The tier description page divides the data base into a group of tiers each comprising a defined range of pages. The authorization page lists authorization codes for all subscribers, one code per subscriber. Each subscriber station includes a permanent location code. When access is requested by the subscriber, the subscriber station uses the location code to acquire the authorization code transmitted by the head-end station. The authorization code indicates which tiers the subscriber station may decode. To change the service, the system operator may change the authorization codes at the head-end station or change the range definitions for the service level tiers.
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Citations
21 Claims
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1. In a teletext system having a head-end station, a group of subscriber stations, a data base comprising a multiplicity of data pages transmitted from the head-end station to the subscriber stations on a video channel, each data page comprising a group of data, said data base arranged into program service levels each comprising a respective set of pages in the data base, the data base and service levels being individually accessible to particular subscribers on a selective basis in response to subscriber requests for access to the teletext system, the improvement for controlling and adjusting subscriber access to particular service levels comprising:
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means at the head-end station for transmitting to each of the subscriber stations a service level description page comprising data defining each of said service levels and a subscriber service level authorization code page comprising a group of subscriber service level authorization codes for plural subscribers, each of said authorization codes specifying the service levels to which a corresponding subscriber is entitled to have access; and a respective logic circuit located at each subscriber station responsive to said description page and said authorization page for controlling access at its subscriber station to service levels on the basis of the authorization code corresponding to such subscriber station and the service level corresponding to the request by the subscriber. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. In a teletext system having a head-end station, a plurality of subscriber receiving stations, a data base comprising a multiplicity of pages cyclically transmitted from the head-end station to said subscriber stations on a video channel, said data base being arranged into a group of service levels each comprising a set of pages in said data base, a method for controlling access to said service levels upon request from a particular subscriber station including:
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transmitting to each subscriber station data comprising a description page defining a range of pages in said data base for each of said service levels; transmitting to each subscriber station data comprising a subscriber service level authorization code page containing service level authorization codes for each of plural subscribers, each of said authorization codes being representative of said service levels to which the corresponding subscriber stations is authorized to have access; determining at said subscriber station the identity of the service level to which said subscriber station requests access by examining said service level description page; and determining whether said subscriber station is to have access to said determined service level by examining said subscriber'"'"'s service level authorization code. - View Dependent Claims (11, 12, 13, 14, 15)
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16. In a teletext system having a cyclically transmitted, service level-subdivided data base, the method comprising:
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transmitting to plural subscriber stations service level descriptions which define the portion of said data base allotted to each of said service level subdivisions; transmitting to said subscriber stations a group of authorization codes each containing data representing a corresponding subscriber'"'"'s access to each of said service level subdivisions; and dynamically controlling the access of all subscriber stations to the data base by adjusting the defined range of said service level subdivisions. - View Dependent Claims (17)
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18. In a teletext system, a method for altering the access to particular portions of a data base for system subscribers comprising:
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transmitting via a communication link a data base divided into service levels from a head-end station to various subscribers; transmitting via said link service level descriptions which define the portion of said data base allotted to each of said service level subdivisions from said head-end station to the subscribers; transmitting via said link to the subscribers a group of subscriber service level authorization codes which contain data representative of each subscriber'"'"'s access to said service level subdivisions, said service level descriptions and authorization codes being used at each subscriber station to determine access thereat to service levels of said date base; and changing a service level description at said head-end station and transmitting it to said subscribers to alter access to said data base by said subscribers.
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19. A decoder for a teletext system having a head-end station, a data base arranged in a multiplicity of data pages, each data page comprising a group of data, said pages being grouped into program service levels each comprising a respective set of data pages, the head-end station communicating the data base to said decoder via a video channel, wherein said decoder includes:
a data processor communicating with (1) a data acquisition circuit, (2) a data input device, and memory means for storing an authorization code and (3) a service level description page, said data processor being responsive to a request entered by said data input device for access to a particular page within said data base, said data processor being arranged for acquiring via said video channel and storing within said memory means a subscriber service level authorization code transmitted to said decoder by said head-end station within a transmitted service level authorization code page, said data processor being operable further for acquiring and storing in said memory means a service level description page transmitted from said head-end station to said decoder via said video channel, said data processor being operable for determining the service level corresponding to the requested page of said data base by consulting said memory means, for determining whether said service level is authorized by comparison with said authorization code stored in said memory means, and for determining whether said decoder is authorized to decode said page.
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20. A method of controlling access to a data base in a teletext system having a head-end station communicating with a group of subscriber stations via a video channel, the data base being arranged in a plurality of data pages each comprising a group of data, the data base being arranged into plural service levels each comprising a respective set of pages in the data base, comprising the steps of:
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transmitting from said head-end station via said video channel to each of said subscriber stations a service level description page comprising data defining each of said service levels; storing said service level description page at each of said subscriber stations; transmitting from said head-end station via said channel to each of said subscriber stations an authorization code page comprising respective data for each of corresponding plural subscribers specifying the service levels to which said corresponding subscribers are entitled to have access; storing a respective authorization code at each subscriber station requesting access to the data base; determining at a subscriber station the page to which the corresponding subscriber requests access in said data base; determining the service level of the requested page from the data base by consulting said stored service level description page; and determining at the subscriber station whether said determined service level is authorized on the basis of said authorization code. - View Dependent Claims (21)
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Specification