Abstract: A multichannel television access control system is disclosed wherein processing of the broadband signal is performed by gated coherent RF injection on a plurality of channels, thereby effecting selective descrambling of an arbitrary subset of channels in a channel group. The system provides for a closed loop injection signal phasor control so as to maintain substantially constant relationship between the television signals and the injected signals. The combined signals are supplied to subscribers enabling the use of their cable ready equipment.

Abstract: A method is disclosed for modulating both quadrature components of each of a plurality of RF signals with waveforms comprising time varying vectors uniquely associated with each of the RF signals, the RF signals each occupying a bandwidth of a television channel and together comprising a multichannel signal spanning a frequency range that is substantially centered about a center frequency F. A CW signal is generated having a frequency equal to the center frequency F. Digital representations are produced of a first composite baseband signal and a second composite baseband signal. The digital representations of the first and second composite baseband signals are converted to a first analog and a second analog composite baseband signal respectively. The CW signal with the first analog and the second analog composite baseband signals are modulated in quadrature to generate the multichannel signal.

Abstract: A method for providing television services from a head-end to subscriber premises and includes receiving by a first subscriber terminal via a first transmission link coupled to the first subscriber terminal, a first television service transmitted from the head-end. System information data specifying attributes of at least one local television channel is transmitted to a second subscriber terminal coupled to the first subscriber terminal via a second transmission link. The at least one local television channel has a frequency that is unused on the first transmission link by the head-end. The first television service is transmitted by the first subscriber terminal, on one of the at least one local television channel via the second transmission link, to the second subscriber terminal located at the subscriber premises.

Abstract: A method and apparatus for modulating both quadrature components of each of a plurality of RF signals comprising a multichannel signal is disclosed. By employing certain digital signal processing techniques, a pair of composite baseband signals is produced in manner that is uniquely associated with the modulation content of the RF signals. According to one aspect of the invention, by using the composite baseband signals to modulate in quadrature a single quadrature modulator, the composite baseband signals are shown to have a baseband frequency span that is substantially half of the frequency range spanned by the multichannel signal. An application for the CATV field in which a 6 MHz channel spacing between the RE signals is also disclosed.

Abstract: A method and an apparatus are disclosed for digital synthesis of signals having a frequency which is a rational factor n/m times an existing reference or clock frequency, wherein n and m may be large relatively prime integers. The invention provides for the use of a periodic sequence generator having up to N taps which are connected to a cascade of digital commutating multiplexers. The periodic sequence generator and the commutating multiplexers have periodicities fi that are determined by programmable address counters and the choice of N. The resultant signal at the output of the last commutator stage has a spectral frequency component at a desired frequency which is an algebraic sum of the frequencies fi (each taken with either positive or negative signs). One aspect of the invention provides for the use of weighted linear combination of commutator output lines, thereby further aiding in improving its spectral purity performance.

Abstract: A method of and apparatus for digitally generating a broadband signal comprising a plurality of CW or quadrature modulated signals having incrementally related frequencies wherein said plurality of signals are centered about a center RF frequency is disclosed. The invention provides for generating a first and second composite baseband signal each comprising a linear combination of N sinusoids, or N modulated signals each modulated in quadrature so as to achieve a desired instantaneous phasor value for each of the RF signals. The invention further provides for modulating in quadrature the first and second composite baseband signals on a local oscillator signal having a frequency equal to the center RF frequency.

Abstract: A method for measuring composite distortion levels using a coherent multicarrier RF signal generator having incrementally related frequencies is disclosed. The invention provides for the use of a coherent multicarrier signal generator that permits arbitrary RF carrier phase control on an individual carrier basis in order to enable sequential distortion measurements under varying carrier phase conditions. In order to obtain measurement results that match those obtained by the use of prior art non-coherent signal sources, the present invention provides for averaging of distortion measurement results over a ‘phase configuration ensemble’ that is obtained by multiple sequential measurements, in which the individual carrier phases for each measurement are preselected at random.

Abstract: A multichannel television access control system is disclosed wherein processing of the broadband signal is performed by gated coherent RF injection on a plurality of channels, thereby effecting selective descrambling of an arbitrary subset of channels in a channel group. The system provides for a closed loop injection signal phasor control so as to maintain substantially constant relationship between the television signals and the injected signals. The combined signals are supplied to subscribers enabling the use of their cable ready equipment.

Abstract: An apparatus for centering the frequency of an injection locked oscillator (ILO) measures the difference of the phase (or a parameter related to the phase) between ILO output signals in response to alternate high level and low level RF drive signals, and can tune the center frequency of the ILO in accordance with the measurements to minimize the phase difference.

Abstract: A multichannel television access control system is disclosed wherein processing of the broadband signal is performed by gated coherent RF injection on a plurality of channels, thereby effecting selective descrambling of an arbitrary subset of channels in a channel group. The system provides for a closed loop injection signal phasor control so as to maintain substantially constant relationship between the television signals and the injected signals. The combined signals are supplied to subscribers enabling the use of their cable ready equipment.

Abstract: A multichannel television access control system is disclosed wherein processing of the broadband signal is performed by gated coherent RF injection on a plurality of channels, thereby effecting selective descrambling of an arbitrary subset of channels in a channel group. The system provides for a closed loop injection signal phasor control so as to maintain substantially constant relationship between the television signals and the injected signals. The combined signals are supplied to subscribers enabling the use of their cable ready equipment.

Abstract: A method for centering the frequency of an injection locked oscillator or (ILO) includes producing measurements of the magnitude and sign of the phase difference between ILO output signals in response to alternate high level and low level RF drive signals, and tuning the center frequency of the ILO in accordance with the measurements to minimize the phase difference.

Abstract: A multichannel television access control system is disclosed wherein processing of the broadband signal is performed by gated coherent RF injection on a plurality of channels, thereby effecting selective descrambling of an arbitrary subset of channels in a channel group. The system provides for a closed loop injection signal phasor control so as to maintain substantially constant relationship between the television signals and the injected signals. The combined signals are supplied to subscribers enabling the use of their cable ready equipment.

Abstract: A multichannel television access control system is disclosed wherein processing of the broadband signal is performed by gated coherent RF injection on a plurality of channels, thereby effecting selective descrambling of an arbitrary subset of channels in a channel group. The system provides for a closed loop injection signal phasor control so as to maintain substantially constant relationship between the television signals and the injected signals. The combined signals are supplied to subscribers enabling the use of their cable ready equipment.

Abstract: A multichannel television access control system is disclosed wherein processing of the broadband signal is performed by gated coherent RF injection on a plurality of channels, thereby effecting selective descrambling of an arbitrary subset of channels in a channel group. The system provides for a closed loop injection signal phasor control so as to maintain substantially constant relationship between the television signals and the injected signals. The combined signals are supplied to subscribers enabling the use of their cable ready equipment.

Abstract: Compromise of a predetermined secure data processing routine by a procedure known as a "clock attack" is prevented by a method that inhibits synchronization with externally generated instructions by preventing determination of the time of execution predetermined data processing routine in relation to occurrence of an externally observable event that precedes the execution of the predetermined routine. The method includes the step of (a) randomly varying the duration between the occurrence of the externally observable event and the execution of the predetermined routine. Step (a) includes the steps of (b) executing one or more interim data processing routines between the occurrence of the externally observable event and the execution of the predetermined routine; and (c) randomly varying the duration of said interim routines.

Abstract: A system and method for minimizing peak amplitudes and distortion in a communication system generating a composite signal. The present invention provides and maintains optimum phase conditions and a near-optimal set of auxiliary carriers in a closed-loop feedback system. An application to community antenna television (CATV) is disclosed.

Abstract: A system is provided for selectively transmitting horizontal television lines including video and digital audio components or equivalent digital data lines containing a plurality of audio program signals. A conventional television signal transmission places a digital audio signal in the horizontal blanking interval, followed by analog video information. In accordance with the present invention, the "window" containing the analog video information is replaced with a plurality of digital audio signals that are time division multiplexed within the window. An additional audio channel is placed in the horizontal blanking interval, at the same location the audio is placed when video information is transmitted. Selector switches are provided in the encoder and decoder for processing a composite waveform as either a video signal with an associated audio channel, or as a multiple channel digital audio signal. Independent encryption and decryption of each of the multiple audio channels is provided.

Abstract: A wide-aspect-ratio television signal is encoded for transmission within a standard-television-signal-compatible format is encoded by dividing the television signal into center-panel segments from which the horizontally central portion of a television picture produced from said wide-aspect-ratio television signal is displayed in accordance with a standard-television-signal aspect ratio, and side panel segments from which the left and right side portions of the television picture produced from said wide-aspect-ratio television signal are displayed in accordance with the wide aspect ratio; arranging the center panel segments for transmission in the standard-television-signal-compatible format; reducing the spatial frequency extent of at least a portion of said side-panel segments by vertically expanding said portion; and inserting said vertically expanded portion of the side-panel segments for transmission during transmission of said center-panel segments in a manner that enables said inserted portion of the si

Abstract: A system for controlling and accounting for retrieval of data from a CD-ROM memory containing encrypted data files from which retrieval must be authorized. The system includes an authorization and key distribution terminal and a plurality of customer data retrieval terminals having such memories loaded therein. The authorization terminal authorizes retrieval of data by authorized customer terminals by providing to the authorized customer terminals an encryption key for enabling retrieval of the data and a authenticated credit signal for use in limiting the amount of data to be retrieved from the files. The encryption key is encrypted for communication to the customer terminals in unique unit keys that are stored in the respective customer terminals.