Scientific-atlanta, Inc.

Other

Cisco Technology, Inc.

John W Brickell

Steven E Blashewski

Jiening Ao

Lamar E West, Jr

Joseph Graham Mobley

John Alexander Ritchie, Jr

Richard J Futch

Donald C Sorenson

Florin Farcas

Stephan W Vogt

Pieter G Ibelings

Wayne H Nash

Alfredo Acosta

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

A communication system ( ) processes forward signals generated by headend equipment ( ) and reverse signals generated by subscriber equipment ( ). A communication medium ( ), such as fiber optic cable or coaxial cable, connects the headend equipment ( ) and the subscriber equipment ( ), and amplifiers ( ) are positioned at various locations along the medium ( ) to amplify the forward and reverse signals. The amplifiers ( ) include a dual forward/reverse test circuit (FIG. 6) having a forward test point ( ) coupled to the forward signal, a reverse test point ( ) coupled to the reverse signal, and a single directional coupler ( ) connected to the forward test point ( ), for providing the forward signal thereto, and to the reverse test point ( ), for providing the reverse signal thereto.

Termination circuitry for dual forward and reverse test points for amplifiers

An apparatus for indicating the configuration of a cable television line amplifier. The line amplifier contains a controller that senses a preset voltage on a status indication line. When the amplifier is reconfigured, such as by adding new circuits containing new functions or features, these new circuits contain resisters that are shunted to modify the preset voltage level on the appropriate status indication line. The controller senses the modified voltages and provides an indication of the new function of the new circuit to a headend through a cable television distribution system.

Apparatus for automatic sensing of line amplifier configuration for status monitoring

Voltage-induced hum modulation in an amplifier can be caused when shunt capacitors begin to saturate and enter their non-linear region of operation. Bypass coils within the amplifier are magnetically coupled to the shunt capacitors and exacerbate hum modulation by coupling additional energy to the shunt capacitors. By introducing a resistance (R) in series with the shunt capacitors (C), energy that would normally be stored in the shunt capacitors (C) is dissipated. As a result, the shunt capacitors (C) remain in their linear region of operation more often and present a more stable impedance. The resistor (R) is especially beneficial at reducing hum modulation at the resonant frequency of the shunt capacitors (C), when the transfer of energy from the bypass coils (L) is at a maximum.

Systems, methods, and circuits for reducing HUM modulation in amplifiers

A communication system (,) processes forward signals generated by headend equipment (,) and reverse signals generated by subscriber equipment (,). A communication medium (,), such as fiber optic cable or coaxial cable, couples the headend equipment (,) and the subscriber equipment (,), and amplifiers (,) are positioned at various locations along the medium (,) to amplify the forward and reverse signals. The amplifiers (,) include a dual forward/reverse test circuit (FIG.,) having a forward test point (,) coupled to the forward signal, a reverse test point (,) coupled to the reverse signal, and a single directional coupler (,) connected to the forward test point (,), for providing the forward signal thereto, and to the reverse test point (,), for providing the reverse signal thereto.

Dual forward and reverse test points for amplifiers

A multi-output distribution amplifier includes a forward amplifier and a reverse amplifier and multiple outputs. The forward and reverse paths are separated utilizing low and high pass filters. The geometric mean frequency between the respective pass bands of the high and low pass filters is known as the crossover frequency. A circuit for providing a 180 degree phase reversal such as a balun transformer is connected in series with one (in a dual output arrangement) or half the reverse paths of an arrangement involving three or more forward or reverse paths to improve crossover isolation. For example, in a typical dual output distribution arrangement where the amplifiers are not padded, close to 20 dB of crossover isolation improvement is accomplished by simply connecting a balun transformer in series with one or the other of the low pass filters connected to one or the other forward direction output. At a minimum, a 6 dB improvement can be achieved.

Phase cancellation in a multi-output distribution amplifier at crossover

The present invention solves the gain, noise figure, and distortion problems of prior art thermal compensation circuits by incorporating a temperature-compensating circuit in the feedback loop of a transistor amplifier arrangement. Using this method, the insertion loss is reduced as the gain of the amplifier varies proportionately to the temperature. This method has a negligible effect on the noise figure and distortion, and the incremental cost is much lower than the conventional circuits. Furthermore, the present invention can be used in both single-ended or push-pull dual amplifier configurations.

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Lawrenceville, GA, United States of America

John W Brickell