Maker Communications, Inc.

Emc Corporation

Data General Corporation

Zeevee, Inc.

Scott J Bleiweiss

James W Espy

Peter Chantiles

Brian William Gallagher

Robert C Solomon

Peter B Everdell

Brian K Bailey

Thomas B Hawkins

Victor Odryna

Preston C Shimer

Jeffrey R Bacon

Stephen D Metzger

Jeremy L Mordkoff

Oscar Purwin

David J Feng

Jeffrey A Brown

A video controller selects a channel for premises broadcasting to a premises television based on a fast scan of signal strength in channels available over a premises media. The signal strength of certain filtered channel frequencies can be evaluated to determine if a channel is occupied. Unoccupied channels can be ranked in relation to nearby occupied or unoccupied channels. The nearby channels may be ranked in terms of the signal strength content in relation to the channel being evaluated. The video controller can select an unoccupied channel with an optimal ranking to permit premises broadcasting with reduced interference or conflict with other channels.

System and method for channel selection for local broadcasting

A service clock regenerator regenerates a local clock from time stamps of a remote clock transmitted over a network by determining the slope of (or difference between current and previous) time stamps of the remote clock and the slope of time stamps of the local clock. A phase difference is formed as the difference between the slope of the time stamps of the remote clock and the slope of the time stamps of the local clock and this phase difference is accumulated to generate a phase error signal. The phase error signal is filtered to generate a frequency adjustment signal having a magnitude that depends on the phase error signal. The frequency of the local clock is adjusted according to the magnitude of the frequency adjustment signal thereby reducing a phase difference between the remote time stamps and the local time stamps. The (local service) clock signal has a nominal frequency of Fc/(N+K/L) Hz over each successive interval of L periods, where N, K and L are integers, and L&gt;K (where K can be the above noted frequency adjustment signal). Each set of L periods includes a first set of K periods and a second set of L-K periods. These two sets of periods are organized by interleaving two or more non-null subsequences of periods of the first set with two or more non-null subsequences of periods of the second set. During each period of one of the subsequences of the first set, the clock is outputted with a frequency of Fc/N Hz. Likewise, during each period of one of the subsequences of the second set, the clock is outputted with a frequency of Fc/(N+1) Hz. A service clock regeneration system with multiple service clock regenerator modules is also provided. A combined service clock regenerator/synchronous residual time stamp generator is furthermore provided.

Programmable fractional frequency digital frequency synthesizer for

A recovery method for use in a data storage system in which a plurality of data storage devices are connected to each of two communication paths. A switch may route requests to either of the two communication paths. With one data storage controller in communication with the data storage devices over a first path and a second data storage controller in communication with the data storage devices over a second path, upon detection of a malfunction on the first path, a data storage controller may request access to the other path. Thereafter, the controller may be switched into connection with the remaining operable path so as to share that path with the other controller.

Fail-over switching system

Modular circuitry architecture for residual time stamp service clock

Combined synchronous residual time stamp generator and service clock

Synchronous residual time stamp service clock regenerator phase locked

A recovery method and fail-over switch for use in a data storage system in which a plurality of data storage devices are connected to each of two communication paths. The switch may route requests to either of the two communication paths. Switching may be accomplished by two fail-over switches connected to each other and each in connection with one of the two communication paths. With one data storage controller in communication with the data storage devices over a first path and a second data storage controller in communication with the data storage devices over a second path, the fail-over switches may be used upon detection of a malfunction on one path to switch a controller into connection with the remaining operable path so as to share that path with the other controller.

A high frequency signal and a low frequency signal are coupled onto a pair of conductors providing a communication link between two computer components. The high frequency signal may be a differentially coupled Fibre Channel 8B/10B encoded signal. A diplexer includes a low pass filter for attenuating the Fibre Channel signal and a high pass filter for separately attenuating the low frequency signal. A two-way communication link may be provided over twinax cable. An environmental monitor may be in connection with the low frequency communication path.

System for orthogonal signal multiplexing

A dynamically upgradeable disk array chassis, and a method for dynamically upgrading a data storage system. The dynamically upgradeable disk array chassis includes a serial bus having a first bus for passing data in one direction and a second bus for passing data in the opposite direction. A shunt connects the first and second buses in a normal state. The shunt has a switched state in which each of the first and second buses is coupled to a separate output from the chassis. The chassis includes an environmental monitor connected to a communication path. Upon connecting a new disk array chassis to an active disk array chassis, the environmental monitor communicates through the communication path before switching the shunt to connect the serial bus with the serial bus of the new disk array chassis. The disk array chassis may include a diplexer for connecting the communication path to the separate outputs of the shunt and for combining the communication path signals with the serial path signals in one direction and for separating these signals in the other direction. The environmental monitor path communications and the serial bus communications can take place over a single twinax cable.

Dynamically upgradeable disk array chassis and method for dynamically

A fibre channel disk drive operating system configures a plurality of disk drives into a fibre channel drive loop. The system also provides plurality of disk drive controllers, and a software controlled switching circuit electrically connecting the disk drive controllers to the disk drives which are arranged in the fibre channel drive loop in varying selected configurations. The switching circuit has a plurality of switch elements arranged for selectively electrically connecting each fibre channel drive loop to a selected controller. Each switch element in a first mode of operation passes electrical signals in a through direction and in a second mode of operation passes electrical signals in a second bypass direction. Thereby each fibre channel drive loop is electrically connected to a selected one of disk drive controllers prior to operation of the system.

Apparatus for effecting port switching of fibre channel loops

A fiber channel, interconnecting a plurality of disk drive loops and associated high speed bypass switches, has a selected group of high speed bypass switches to modularize the fiber channel and to reduce electrical signal jitter on the channel. More particularly, the fiber channel loop has a first group of bypass switches being connected to either connect an associated disk drive to the loop or to electrically isolate the loop from the associated disk drive, and a second group of the bypass switches is then connected, in a first operating state, to connect a group of disk drives and their respective associated bypass switches for electrical signal communications with disk drive controller, and in a second operating state, for electrically isolating the group of disk drives and their respective associated bypass switches from communications with the controller. The disk drives and their associated bypass switches can be modularly added to the fiber channel configuration by employing the second group of bypass switches as high speed controllable gateways.

Growing community of inventors

Upton, MA, United States of America

Scott J Bleiweiss