The method of the current invention provides a fault tolerant access to a network resource. A replicated network directory database operates in conjunction with server resident processes to remap a network resource in the event of a server failure. The records/objects in the replicated database contain for each network resource, a primary and a secondary server affiliation. Initially, all users access a network resource through the server identified in the replicated database as being the primary server for the network resource. When server resident processes detect a failure of the primary server, the replicated database is updated to reflect the failure of the primary server, and to change the affiliation of the network resource from its primary to its backup server. This remapping occurs transparently to whichever user/client is accessing the network resource. As a result of the remapping, all users access the network resource through the server identified in the replicated database as the backup server for the resource. When the server resident processes detect a return to service of the primary server, the replicated database is again updated to reflect the resumed operation of the primary server. This remapping of network resource affiliations also occurs transparently to whichever user/client is accessing the network resource, and returns the resource to its original fault tolerant state.

Method for providing a fault tolerant network using distributed server processes to remap clustered network resources to other servers during server failure

An object identification system includes a monitor and a plurality of transceivers that communicate over a common medium. The monitor includes a first transmitter, a first receiver, and a processor. Each transceiver includes a resonant circuit, a transmitter, a receiver, and an antenna coupled to the resonant circuit. The processor performs a method for performing transceiver communication that includes the steps of: (a) transmitting from the first transmitter a first frequency for a first duration; (b) after lapse of the first duration, receiving via the first receiver a response signal from at least one of the resonant circuits; (c) determining a second frequency from the received response signal; and (d) performing transceiver communication using the second frequency. Transceivers of the type having a resonant circuit coupled to an antenna, when operating in close proximity to each other, may interfere with the response from a single transceiver by absorbing the energy intended to be received by the transceiver, absorbing the energy transmitted by the transceiver, or altering the resonant frequency of the resonant circuit. By determining the second frequency for transceiver communication, the monitor may establish communication with the single transceiver at a frequency better suited for transferring operative power to the transceiver, conducting an interrogation protocol for identifying the transceiver, or for data transfer.

Object identification system with adaptive transceivers and methods of operation

Replica correlation processing, and associated representative signal-data reduction and reconstruction techniques, are used to detect signals of interest and obtain robust measures of received-signal parameters, such as time differences of signal arrival and directional angles of arrival, that can be used to estimate the location of a cellularized-communications signal source. The new use in the present invention of signal-correlation processing for locating communications transmitters. This enables accurate and efficient extraction of parameters for a particular signal even in a frequency band that contains multiple received transmissions, such as occurs with code-division-multiple-access (CDMA) communications. Correlation processing as disclosed herein further enables extended processing integration times to facilitate the effective detection of desired communications-signal effects and replication measurement of their location-related parameters, even for the communications signals modulated to convey voice conversations or those weakened through propagation effects. Using prior, constructed, signal replicas in the correlation processing enables elimination of the inter-site communications of the signal representations that support the correlation analyses. Reduced-data representations of the modulated signals for voiced conversation, or for the variable components of data communications, are used to significantly reduce the inter-site communications that support the correlation analyses.

Robust, efficient, localization system

A system for fault tolerant execution of an application program in a server network, which includes: a first server for executing the application program; a cluster network database, coupled to the first server; an object, stored in the cluster network database, which represents the program and contains information pertaining to the program; a failure detection module which detects a failure of the first server; a second server, coupled to the cluster network database; and a failover module which loads the application program in the second server upon detection of the failure of the first server. The information contained within the object includes: a host server attribute which identifies which server is currently executing the program; a primary server attribute which identifies which server is primarily responsible for executing the program; and a backup server attribute which identifies which server is a backup server for executing the program if the primary server experiences a failure.

System for clustering software applications

A method for fault tolerant execution of an application program, in a server network having a first and second server, wherein the method includes: executing the application program in the first server; storing an object which represents the program in a cluster network database, wherein the object contains information pertaining to the program; detecting a failure of the first server; and executing the application program in the second server upon detection of the failure of the first server, in accordance with the information in the object. The information may include: a host server attribute which identifies which server is currently executing the program; a primary server attribute which identifies which server is primarily responsible for executing the program; and a backup server attribute which identifies which server is a backup server for executing the program if the primary server experiences a failure.

Method for clustering software applications

The invention is embodied in a digital direction finding receiver having N frequency channels (50a, 50e) spanning a frequency band of the receiver and capable of receiving signals simultaneously from a plurality of antennas (30a, 30e) spaced from one another, one of the antennas including a reference location antenna. The receiver of the invention includes a plurality of analog-to-digital converters (32a, 32e) having their analog inputs connected to respective ones of the antennas, a reference source (58) capable of outputting a reference digital signal containing at least a local frequency component within a selected one of the N frequency channels, a plurality of digital down converter modules (50a, 50e), each one of the digital down converter modules having a reference input connected to the reference source and a signal input connected to the digital output of a respective one of the analog-to-digital converters, each the digital down converter modules including a multiplier (56a, 56e) for producing at an output of the digital down converter a product of the reference signal and the signal from the respective one of the antennas, and a digital phase detector (35) having plural phase detector signals inputs connected to the outputs of remaining ones of the digital down converters, the phase detector detecting phase angles of the signals on each of the phase detector signal inputs relative to a corresponding signal received at the reference antenna.

James C. Kolanek

Papers

Digital direction finding receiver