Scrambling method

• US 5,442,700 A
• Filed: 09/22/1994
• Issued: 08/15/1995
• Est. Priority Date: 09/28/1990
• Status: Expired due to Term

• Current Assignee: ActiveVideo Networks, Inc. (CommScope Holding Company, Inc.)
• Original Assignee: ICTV, Inc.
• Inventors: Fisher, Delmer D., Snell, Stephen C.
• Primary Examiner(s): Swann, Tod R.
• Application Number:
  US08/310,719
• Time in Patent Office: 327 Days
• Field of Search: 380/15, 380/17, 380/20, 348/10, 348/5.5, 455/26.1
• US Class Current: 380/222
• CPC Class Codes: G06F 2203/04802 3D-info-object: information is displayed on the internal or external surface of a three dimensional manipulable object, e.g. on the faces of a cube that can be rotated by the user
• CPC Class Codes: G06F 3/04815 Interaction with a metaphor-based environment or interaction object displayed as three-dimensional, e.g. changing the user viewpoint with respect to the environment or object
• CPC Class Codes: H04N 19/48 using compressed domain processing techniques other than decoding, e.g. modification of transform coefficients, variable length coding [VLC] data or run-length data motion estimation in a transform domain H04N19/547; processing of decoded motion vectors H04N19/513
• CPC Class Codes: H04N 19/61 in combination with predictive coding
• CPC Class Codes: H04N 19/90 using coding techniques not provided for in groups H04N19/10-H04N19/85, e.g. fractals
• CPC Class Codes: H04N 2007/17372 the upstream transmission being initiated or timed by a signal from upstream of the user terminal
• CPC Class Codes: H04N 2007/1739 the upstream communication being transmitted via a separate link, e.g. telephone line
• CPC Class Codes: H04N 21/2221 being a cable television head-end CATV in broadcast systems H04H20/78
• CPC Class Codes: H04N 21/2347 involving video stream encryption
• CPC Class Codes: H04N 21/2351 involving encryption of additional data arrangements using cryptography for the use of broadcast information or broadcast-related information H04H60/23
• CPC Class Codes: H04N 21/2383 Channel coding or modulation of digital bit-stream, e.g. QPSK modulation arrangements for detecting or preventing errors in the information received by adapting the channel coding H04L1/0009; analogue front ends or means for connecting modulators, demodulators or transceivers to a transmission line H04L27/0002
• CPC Class Codes: H04N 21/2385 Channel allocation H04N21/266 takes precedence; Bandwidth allocation H04N21/24 takes precedence ; allocation of channels according to the instantaneous demands of the users in time-division multiplex systems H04J3/1682; admission control, resource allocation in open networks H04L12/5692; arrangements for maintenance or administration in data switching networks involving bandwidth and capacity management H04L41/0896; negotiating bandwidth in wireless networks H04W28/16
• CPC Class Codes: H04N 21/25866 Management of end-user data customer care in data networks H04L41/5077
• CPC Class Codes: H04N 21/2665 Gathering content from different sources, e.g. Internet and satellite
• CPC Class Codes: H04N 21/2668 Creating a channel for a dedicated end-user group, e.g. insertion of targeted commercials based on end-user profiles information retrieval from the Internet by querying with filtering and personalisation G06F16/9535; arrangements for replacing or switching information during the broadcast H04H20/10; push services over packet-switching network H04L12/1859; adaptation of message content in packet-switching networks H04L51/063
• CPC Class Codes: H04N 21/426 Internal components of the client ; Characteristics thereof H04N5/44 takes precedence
• CPC Class Codes: H04N 21/4353 involving decryption of additional data arrangements using cryptography for the use of broadcast information or broadcast-related information H04H60/23
• CPC Class Codes: H04N 21/4382 Demodulation or channel decoding, e.g. QPSK demodulation analog front ends or means for connecting modulators, demodulators or transceivers to a transmission line H04L27/0002
• CPC Class Codes: H04N 21/4383 Accessing a communication channel
• CPC Class Codes: H04N 21/4405 involving video stream decryption
• CPC Class Codes: H04N 21/47 : End-user applications
• CPC Class Codes: H04N 21/482 : End-user interface for program selection broadcast systems using EPGs H04H60/72
• CPC Class Codes: H04N 21/4821 : using a grid, e.g. sorted out by channel and broadcast time
• CPC Class Codes: H04N 21/6118 : involving cable transmission, e.g. using a cable modem
• CPC Class Codes: H04N 21/6168 : involving cable transmission, e.g. using a cable modem
• CPC Class Codes: H04N 21/654 : Transmission by server directed to the client
• CPC Class Codes: H04N 21/658 : Transmission by the client directed to the server
• CPC Class Codes: H04N 5/265 : Mixing
• CPC Class Codes: H04N 5/45 : Picture in picture , e.g. displaying simultaneously another television channel in a region of the screen
• CPC Class Codes: H04N 7/10 : Adaptations for transmission by electrical cable H04N7/12 takes precedence
• CPC Class Codes: H04N 7/173 : with two-way working, e.g. subscriber sending a programme selection signal
• CPC Class Codes: H04N 7/17318 : Direct or substantially direct transmission and handling of requests
• CPC Class Codes: H04N 7/17336 : Handling of requests in head-ends
• CPC Class Codes: H04N 7/17345 : Control of the passage of the selected programme
• CPC Class Codes: H04N 7/22 : Adaptations for optical transmission

Abstract

A system for scrambling a television signal by designating a horizontal line number on a pseudorandom basis and then stripping the vertical and horizontal synch components from the signal at each location of a frame except at the designated line.

Claims

1. A system for scrambling a television signal, the signals having vertical and horizontal sync components, a color burst reference, a video luminance component, comprising:

(a) means for designating a horizontal line number on pseudorandom basis;

(b) means for stripping the vertical and horizontal sync components from the signal at each-location of a frame except at the line corresponding to the horizontal line number.

2. A system according to claim 1, further comprising:

(c) means for clamping the luminance component of the signal to a nearly white level during the intervals in which the removed sync signals were formerly present.

3. A system according to claim 1, further comprising:

means for designating a second horizontal line number on a pseudorandom basis;

means for inverting the luminance component during the active video portion of each second horizontal line number.

4. A system according to claim 1, further comprising:

means for permitting the occurance of the vertical and horizontal sync components of the stripped signal to be not suppressed in at least one line subsequent to the horizontal line number, the fact of non-suppression on a plurality of horizontal lines permitting the restoration of a descrambled television signal.