Scientific-atlanta, Inc.

Other

Cisco Technology, Inc.

Joseph Graham Mobley

Lamar E West, Jr

John Alexander Ritchie, Jr

Jiening Ao

Steven E Blashewski

Florin Farcas

John W Brickell

Richard J Futch

Donald C Sorenson

James O Farmer

Robert O Banker

Leo Montreuil

Forrest M Farhan

Lamar West

John E Tumblin

Gregory C Cole

Blair J Schodowski

Anatoly Kozushin

Leo J Thompson

Herman A Kruse

Frank R Little

William P Lafay

Robert J Wilson

David P Womble

Steve Addison

Christopher P Lewis

Howard Paulk

Saeed Baher

John A Ritchie

Lamar E West

An architecture for providing high-speed access over frequency-division multiplexed (FDM) channels allows transmission of Ethernet frames and/or other data across a cable transmission network or other form of FDM transport. The architecture involves downstream and upstream FDM multiplexing techniques to allow contemporaneous, parallel communications across a plurality of frequency channels. Furthermore, the architecture allows a central concentrator to support a plurality of remote devices that each has guaranteed bandwidth through connection-oriented allocations of bi-directional data flows. The upstream and downstream bandwidth allocation can support symmetrical bandwidth as well as asymmetrical bandwidth in either direction. As a local network, the architecture supports guaranteed bandwidth for delivery of data flows to a plurality of host devices.

Clock synchronization in a bidirectional network

An architecture for providing high-speed access over frequency-division multiplexed (FDM) channels allows transmission of ethernet frames and/or other data across a cable transmission network or other form of FDM transport. The architecture involves downstream and upstream FDM multiplexing techniques to allow contemporaneous, parallel communications across a plurality of frequency channels. Furthermore, the architecture allows a central concentrator to support a plurality of remote devices that each have guaranteed bandwidth through connection-oriented allocations of bi-directional data flows. The upstream and downstream bandwidth allocation can support symmetrical bandwidth as well as asymmetrical bandwidth in either direction. The architecture generally can be used to support connection-oriented physical layer connectivity between a remote device and the central concentrator. Furthermore, the architecture may be integrated into other higher level devices such as, but not limited to, bridges, switches, routers, and/or gateways. The architecture generally may peacefully coexist with other services commonly-found in cable distribution networks.

Multi-carrier frequency-division multiplexing (FDM) architecture for high speed digital service

Disclosed herein are methods of providing a client with local area network connectivity and access to other services in a cable network. One such method includes: allocating bandwidth in the network to support bi-directional data communication between the host and a central concentrator. Bandwidth is allocated for a downstream flow on at least one downstream frequency channel based on a mapping between the downstream flow and a particular octet in a downstream packet. Bandwidth is allocated for an upstream flow on at least one non-shared upstream tone. The method also includes conveying a bi-directional data flow between the host and the concentrator over the allocated bandwidth, including conveying the upstream flow using the allocated bandwidth and conveying the downstream flow using the allocated bandwidth. The method also includes utilizing bandwidth in the network not allocated to data communications to provide the host with at least one audio/visual service.

Multi-carrier frequency-division multiplexing (FDM) architecture for high speed digital service in local networks

An architecture for providing high-speed access over frequency-division multiplexed (FDM) channels allows transmission of ethernet frames and/or other data across a cable transmission network or other form of FDM transport. The architecture involves downstream and upstream FDM multiplexing techniques to allow contemporaneous, parallel communications across a plurality of frequency channels. Moreover, an automatic frequency control resolves some issues of a free-running clock in an upstream tuner of the central concentrator by performing adjustments based on the average frequency error of a number of active upstream tones. In the preferred embodiments of the present invention, the automatic frequency control (AFC) utilizes a feedback loop for at least each active upstream tone. Also, the average of the active upstream tones is determined and is utilized in providing feedback to adjust the automatic frequency control (AFC).

Automatic frequency control of multiple channels

A cable television system ( ) includes a transmitter ( ) for generating a digital optical signal ( ) and a receiver ( ) for receiving said digital optical signal and converting it to an analog signal. The transmitter ( ) includes a processor ( ) for processing inputs and generating a gain/loss parameter which is applied via a gain/loss amplifier ( ) to an incoming analog signal ( ). The modified digital signal received by the digital optical receiver ( ) decodes the applied gain/loss parameter at a converter ( ) and applies the information to the output analog signal via a gain/loss amplifier ( ).

Digital optical transmitter with improved noise power ratio

A cable television system ( ) includes forward and reverse paths. In the reverse path, an optical transmitter ( ), which could be located in an optical node ( ), receives an analog information signal from subscriber equipment ( ) and transmits in accordance therewith a digital optical signal. The optical transmitter ( ) digitizes its incoming signal, compresses the signal, and generates therefrom the digital optical signal. The cable television system ( ) also includes an optical receiver ( ) for receiving the digital optical signal, decompressing information included in digital optical signal, and recovering therefrom an analog signal representative of the analog information signal. The optical receiver ( ) could be included in a hub or headend equipment ( ) of the cable television system ( ).

Digital optical transmitter with compression

This invention discloses a new and improved method of scrambling video signals by inversion of the video information by splitting the sync pulse into plural portions and transmitting each portion of the sync pulse at a predetermined level. This improves the quality of the recovered video compared with other video inversion systems by rendering the video less sensitive to variations in the modulation depth of the modulator carrying the inverted signal, the demodulation sensitivity of the demodulator and the stability of the recovery circuits. The invention further provides additional security against pirating by allowing the scrambling circuit to operate in diverse modes, each of which will cause a TV to react differently should a conventional pirating device be employed. The invention also renders the signal capable of being transmitted with unmodified modulators of the type normally employed in the CATV industry.

Method and apparatus for improving video scrambling and employing split

The present invention is directed to an inversion scrambler and unscrambler having pseudo-randomly controlled polarity-reversing switches to invert and re-invert, respectively, an audio signal so as to restrict the intelligent dissemination of the audio signal. To improve security of the scrambled signal, the audio signal is concealed prior to scrambling. Concealment includes clamping the original audio signal to a predetermined value and optionally offsetting this clamped signal prior to scrambling. The concealed signal is scrambled by inverting contiguous portions of the signal at pseudo-random intervals, accomplished by a polarity-reversing switching network controlled by a pseudo-random code generator. Upon unscrambling, artifacts will appear at the inversion points of the unscrambling signal, due to bandwidth limitations inherent in any transmission path. To mask the artifacts, track-and-hold circuitry is used to sample the unscrambled audio signal waveform level just prior to the artifact and hold this level throughout the short period when the artifact would occur.

Scrambling of signals by inversion

Scrambling and descrambling systems utilizing jamming signals provide improved pictures with minimal distortion due to ghosts and artifacts. The television signal is combined with a jamming signal or signals located preferably in the vestigial sideband (VSB) of the modulated picture carrier and at about a null in the spectrum of the modulation of the picture carrier by the horizontal sync. The jamming signal or signals also preferably are placed between the harmonic components of the horizontal sync which define the horizontal sync spectrum and at frequencies which comply with governmental regulations respecting frequency locations of strong signals of CATV purposes. The jamming signals are generated by phase locking to the horizontal sync signals of the television signals or to a submultiple of the horizontal sync frequency. Artifacts are further reduced by preemphasis of the transmitted television signal in the sideband opposite to that in which the jamming signal or signals are located and spaced by an equal frequency increment from the location of the jamming signal energy. In order to extract the jamming signal, so as to descramble the television signal for reproduction in the subscriber's television receiver, a network including at least one surface acoustic wave (SAW) resonator device is embedded in an all-pass network which allows essentially lossless transmission of the television signal spectrum, except for the jamming signal energy and enables that energy to be located close to (e.g., approximately 228 KHz) from the picture carrier in the VSB for enhanced security.

Jamming signal scrambling and descrambling systems for CATV

A FM demodulator system which provides threshold extension by frequency selective phase modulation of the input FM signal in a band pass filter to reduce phase error between the input and output of the filter. The output of the filter is applied to an FM discriminator which provides a base band signal. This base band signal is applied to a frequency selective phase compensation network to derive a signal which phase modulates the band pass filter. The filter rejects uncorrelated thermal noise so as to effect threshold extension in the demodulator system.

FM demodulator system with threshold extension

In an FM television signal angle modulated with luminance and chrominance information, there exists a high degree of correlation between picture elements occurring one line period apart. In an effort to steer the pass band of a tunable bandpass filter to the instantaneous frequency of the incoming television signal, a steering signal is developed which utilizes this high degree of correlation. For NTSC systems, luminance information is delayed by one-line period (63.5 .mu.s in the U.S.A.) and combined with suitably delayed chrominance information to form the filter's steering signal. For MAC systems, one-line delayed luminance and two-line delayed chrominance information are alternately applied to the filter as its steering signal. By steering the pass band of the filter to the incoming signal, maximum signal will be captured with minimum noise, enhancing the signal-to-noise ratio of a color television system.

Signal to noise ratio enhancement using baseband signals in an FM

In an FM television signal angle modulated with luminance and chrominance information, there exists a high degree of correlation between picture elements occurring one line period apart. In an effort to steer the pass band of a tunable bandpass filter to the instantaneous frequency of the incoming television signal, a steering signal is developed which utilizes this high degree of correlation. For NTSC systems, luminance information is delayed by one-line period (63.5 us in the U.S.A.) and combined with suitable delayed chrominance information to form the filter's steering signal. For MAC systems, one-line delayed luminance and two-line delayed chrominance information are alternately applied to the filter as its steering signal. By steering the pass band of the filter to the incoming signal, maximum signal will be captured with minimum noise, enhancing the signal-to-noise ratio of a color television system.

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Dunwoody, GA, United States of America

Joseph Graham Mobley