Distributed scrambling method and system

• US 6,055,315 A
• Filed: 12/07/1998
• Issued: 04/25/2000
• Est. Priority Date: 12/09/1997
• Status: Expired due to Term

• Current Assignee: ActiveVideo Networks, Inc. (CommScope Holding Company, Inc.)
• Original Assignee: ICTV, Inc.
• Inventors: Dunn, Timothy, Doyle, John F., Snell, Stephen C.
• Primary Examiner(s): Hayes, Gail O.
• Assistant Examiner(s): CODDINGTON, TREVOR Q
• Application Number:
  US09/206,529
• Time in Patent Office: 505 Days
• Field of Search: 380/10, 380/15, 380/9, 380/200, 380/210, 380/211, 380/216, 380/221, 380/222, 380/223, 380/226, 380/239, 380/240, 380/241, 380/242, 348/12, 348/13, 348/17, 345/327
• US Class Current: 380/242
• CPC Class Codes: G06F 3/1206 resulting in increased flexibility in input data format or job format or job type
• CPC Class Codes: G06F 3/126 Job scheduling, e.g. queuing, determine appropriate device
• CPC Class Codes: G06F 3/1284 Local printer device
• CPC Class Codes: H04N 21/2221 being a cable television head-end CATV in broadcast systems H04H20/78
• CPC Class Codes: H04N 21/234336 by media transcoding, e.g. video is transformed into a slideshow of still pictures or audio is converted into text
• CPC Class Codes: H04N 21/472 End-user interface for requesting content, additional data or services; End-user interface for interacting with content, e.g. for content reservation or setting reminders, for requesting event notification, for manipulating displayed content end-user interfaces for retrieving video data from a database G06F16/739; network services for supporting unicast streaming H04L65/612
• CPC Class Codes: H04N 21/4786 e-mailing message switching systems, e.g. electronic mail systems H04L51/00
• CPC Class Codes: H04N 21/4788 communicating with other users, e.g. chatting arrangements for providing for computer conferences, e.g. chat rooms, to substation in data switching networks H04L12/1813; distributed application using peer-to-peer [P2P] networks H04L67/104
• CPC Class Codes: H04N 21/6581 Reference data, e.g. a movie identifier for ordering a movie or a product identifier in a home shopping application
• CPC Class Codes: H04N 7/088 the inserted signal being digital
• CPC Class Codes: H04N 7/165 Centralised control of user terminal subsequent to an upstream request signal H04N7/17345; Registering at central by two-way working H04N7/17309
• CPC Class Codes: H04N 7/1675 Providing digital key or authorisation information for generation or regeneration of the scrambling sequence pseudo-random number generators in general G06F7/58
• CPC Class Codes: H04N 7/17309 Transmission or handling of upstream communications

Abstract

A scrambling system for a cable television system in which a group of channel frequencies are reused over a plurality of service areas includes an access controller, an encoder and a plurality of simplified scrambling units. Each service area receives different television signals on the group of channel frequencies. The access controller provides signal authorization information for a given channel frequency to a plurality of receiver/decoders located in the different services areas. The access controller also provides descrambling information corresponding to the signal authorization information to the encoder for the given channel frequency. The encoder produces a conditional access code by placing the descrambling information into a scrambled reference signal. An extracting unit removes the conditional access code from the scrambled reference signal and distributes the conditional access code to each of the simplified scrambling units operating at the given channel frequency. Each simplified scrambling unit scrambles the television signal that is to be delivered to its respective service area and inserts the conditional access code into the scrambled television signal.

Claims

1. A distributed scrambling method for a system in which a group of channel frequencies are reused over a plurality of service areas, each service area receiving different television signals over the group of channel frequencies, the method comprising the steps of:

providing signal authorization information for a channel frequency to a plurality of receiver/decoders located in different service areas, all assigned to the channel frequency;

providing descrambling information to an encoder, the encoder placing the descrambling information into a scrambled reference signal for a channel frequency to create a conditional access code;

extracting the conditional access code from the scrambled reference signal;

scrambling a television signal at each of a plurality of scrambling units, each scrambling unit producing a scrambled television signal for the channel frequency for delivery to a different one of the service areas;

distributing the conditional access code to each of the plurality of scrambling units; and

inserting the conditional access code into the television signal at each scrambling unit, the conditional access code enabling a receiver/decoder having the signal authorization information to descramble the television signal.

2. The method of claim 1 wherein the extracting step removes the conditional access code from a vertical blanking interval of the scrambled reference signal.

3. The method of claim 1 wherein the extracting step removes the conditional access code from an audio subcarrier of the scrambled reference signal.

4. The method of claim 1 wherein the step of scrambling comprises suppressing a synchronization signal.

5. The method of claim 1 further comprising encrypting the descrambling information and wherein the signal authorization information includes a key for decrypting the conditional access code created by the encrypted descrambling information.

6. A scrambling system for a cable television system in which a group of channel frequencies are reused over a plurality of service areas, each service area receiving different television signals on the group of channel frequencies, the scrambling system comprising:

an access controller for providing signal authorization information for a channel frequency to a plurality of receiver/decoders located in different service areas, all assigned to the channel frequency;

an encoder, in signal communication with the access controller, for receiving descrambling information from the access controller corresponding to the signal authorization information for the channel frequency and for producing a conditional access code by placing the descrambling information into a scrambled reference signal for the channel frequency;

a plurality of scrambling units, each scrambling a television signal for the channel frequency for delivery to a different one of the service areas;

an extracting unit, in signal communication with the encoder, and the plurality of scrambling units, for removing the conditional access code from the scrambled reference signal and for distributing the conditional access code to each of the scrambling units; and

means, associated with each scrambling unit, for inserting the conditional access code into the scrambled television signal.

7. The scrambling system according to claim 6 wherein the extracting unit removes the conditional access code from a vertical blanking interval of the scrambled reference signal.

8. The scrambling system according to claim 7 wherein the means for inserting comprises a vertical blanking interval inserter.

9. The scrambling system according to claim 6 wherein the extracting unit removes the conditional access code from an audio subcarrier of the scrambled reference signal.

10. The scrambling system of claim 9 wherein the means for inserting comprises an audio AM modulator.