Scientific-atlanta, Inc.

William B Thatcher

Mark E Schutte

Anthony John Wasilewski

Lamar E West, Jr

An off-premises method and apparatus for the interdiction of unauthorized channels of a broadband cable television signal includes common circuitry for adjusting the amplitude and equalization levels of the broadband CATV signals and one or more subscriber modules for generating jamming signals of different frequencies which are used to interdict one or more unauthorized channels. Each subscriber module is associated with a subscriber and is programmable and addressable to adjust the jamming parameters of that subscriber independently of other subscribers. Each subscriber module circuit comprises a plurality of latches, each of which is associated with one of a plurality of digital to analog converters. Each of the digital to analog converters drives one or more frequency agile oscillators with its analog output to generate the jamming signals. The subscriber module is based on a sequential state machine which loads frequency control words corresponding to the jammed channels from a frequency control memory into each latch on a cyclic basis. The state machine is adapted to modify the sequence in which the frequency control words are read out of memory to vary the jamming pattern of the subscriber. According to one illustrated implementation, the addresses of the memory are read out in a pseudo random sequence to produce varying jamming patterns but without changing a selected jamming factor for a selected group of channels. The pseudo-random pattern is generated by logically combining a predetermined address sequence with a random number seed from a seed generator. The random number seed can be varied either programmably or addressably to generate other pseudo-random jamming patterns. In another implementation the seed generator will evenly distribute the jamming energy of unused time slots to all the other active time slots.

Interdiction method and apparatus with random mode jamming

An apparatus providing a dynamic virtual service capability in a multi-service communications system is claimed. A dynamic virtual service comprises an associated group of basic services wherein only one of the basic services in the group is active at any time. Basic services comprise a number of service components which are transmitted to the apparatus on one or more of a plurality of different frequency channels. The apparatus comprises a service selection switch for selecting either one of the basic services directly or one of the dynamic virtual services. A dynamic virtual service map is provided that defines for each dynamic virtual service, on a time-varying basis, the currently active one of the group of basic services that comprise that dynamic virtual service. Means responsive to the service selection switch and to the dynamic virtual service map are provided for automatically selecting the currently active basic service of a subscriber selected dynamic virtual service. Finally, the apparatus provides means for receiving and accessing the service components of a selected basic service from the frequency channel carrying those components. According to one embodiment, dynamic virtual service map definitions are periodically re-transmitted to the apparatus on each frequency channel carrying service components of one of the group of basic services that comprise that dynamic virtual channel. Additionally, a 'home' basic service may be defined for each virtual dynamic service. When a dynamic virtual service is initially selected by a subscriber, the apparatus initially 'tunes' to the frequency channel carrying the service components of that home basic service.

Apparatus providing dynamic virtual service selection in a multi-service

An off-premises method and apparatus for the interdiction of unauthorized channels of a broadband cable television signal includes common circuitry for adjusting the amplitude and equalization levels of the broadband CATV signals and one or more subscriber modules for generating jamming signals of different frequencies which are used to interdict one or more unauthorized channels. Each subscriber module is associated with a subscriber and is programmable and addressable to adjust the jamming parameters of that subscriber independently of other subscribers. Each subscriber module circuit comprises a plurality of latches, each of which is associated with one of a plurality of digital to analog converters. Each of the digital to analog converters drives one or more frequency agile oscillators with its analog output to generate the jamming signals. The subscriber module is based on a sequential state machine which loads frequency control words corresponding to the jammed channels from a frequency control memory into each latch on a cyclic basis. The state machine is adapted to vary the sequence in which the voltage control words are read out of memory to modify the jamming pattern of the subscriber. In addition, according to one illustrated implementation, the loading of frequency control words to the latches in the sequence can be inhibited without changing the words in the memory. The sequential state machine will then in effect skip the deauthorized frequency control words and produce jamming signals at the previous frequencies. This provides flexibility in the system for either jamming or unjamming a specific channel to a subscriber for short periods of time. This allows a simple authorization and deauthorization technique without having to reload the frequency control memory or recalibrate a frequency control word for the specific channel selected.

Interdiction method and apparatus with frequency change inhibit function

Methods and apparatus for encoding compressed data streams efficiently, and methods and apparatus for decoding the encrypted data streams efficiently and inexpensively, are disclosed. In an encoder 10', an incoming data stream is fed to a Huffman coding block 10 that performs data compression. The output codewords of the Huffman coding block are fed to a forward error correction block 30, the output of which is a series of data blocks and associated parity data. The data blocks are fed to an error insertion block 32, which inserts a one-bit error in each data block. The parity data is fed to a first encryption block 34 that produces encrypted parity data. The output of the error insertion block 32, the encrypted parity data, and a synchronization word output by a sync generator 50 are fed to a multiplexer 48. A seed generator block 36 generates random numbers for use by the first encryption block 34 as seeds for encrypting the parity data. A multisession key register 40 stores a multisession key employed as a seed in a second encryption block 38 to encrypt the random number seed. A secret serial number (SSN) read from a database 46 and stored in an SSN register 44 is employed by a third encryption block 42 as a seed for encrypting the multisession key. The multiplexer outputs a multiplex comprising the sync signal, SDP, ADP, and Reed-Solomon data blocks with their corresponding parity data. A decoder 14' receives the multiplex data and recovers the original data.

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Atlanta, GA, United States of America

William B Thatcher