Sangamo Weston, Inc.

Intergraph Corporation

Lawrence B Horwitz

Donald W Rouse

John W Jerrim

E Thomas Wiggins

Eugene T Wiggins

A method of simulating the operation of a circuit utilizing voltage or current data obtained from measurements of actual samples of each of the circuit components. The actually measured voltage or current data is employed to mathematically analyze operation of the circuit. In this process, each circuit component is characterized as one or more of a voltage controlled voltage source, voltage controlled current source, current controlled voltage source and current controlled current source. After such characterization, a trial operating point is selected and values of current or voltage between actually measured data points are determined and linearized circuit equations are established with spline equations. The linearized equations are solved. The steps are repeated with a new trial operating point in accordance with a Newton-Rhapson iterative technique until the solution of the linearized equations is within a predetermined range.

Circuit simulation

A bidirectional data communications distribution network is established between the system operations center (SOC) and customer terminals of a load management and electrical energy distribution system. The distribution network comprises independent processor controlled, primary communications interface units (PCI) in communication with the SOC over telephone lines or other medium. Each PCI is in turn in communication with a plurality of independent processor controlled, secondary communications interface units (SCI) over electrical utility primary distribution power lines. Signals between PCIs and SCIs on the primary distribution power lines are code division multiplexed using direct sequence spread spectrum (DSSS) signal processing. Each SCI continuously polls a number of assigned customer load terminals on the low voltage side of the electrical energy distribution system, storing and calculating meter register readings and load status.

Distribution energy management system

A direct sequence spread spectrum transmitter and receiver can be synchronized when the timing reference frequency is less than or equal to the data sampling rate and the ratio of the data sampling rate to the timing reference is an integer by combining two, four or eight consecutive data samples to yield one data sample point. By combining these data samples, an optimum data sample point may be determined while receiving an alternating sign preamble by comparing the magnitudes of all possible summations and selecting the sample which gives a maximum output. If each sample is assigned to its own synchronization point, then synchronization may be accomplished by locking to the time that gives the maximum output.

Timing signal correction system for use in direct sequence spread signal

A plurality of transmitters synchronized to a common clock each transmit a data signal spread by a common bipolar pseudo-random code having a different assigned code sequence shift. A receiver, synchronized to the clock, discriminates the signal transmitted by a predetermined transmitter from signals transmitted by the others by generating a first pseudo-random code that is a replica of the common bipolar pseudo-random code and has a code sequence shift corresponding to that of the predetermined transmitter, and a second bipolar pseudo-random code that is a replica of the common bipolar pseudo-random code and has an unassigned code sequence shift. The difference between the first and second bipolar pseudo-random code sequences, which is a trinary code sequence, is cross-correlated with the incoming signal. The cross-correlation despreads only the signal having the predetermined code sequence shift. Each receiver includes a number of correlation detectors offset from each other by a fraction of a code chip, together with decision circuitry to identify cross-correlation peaks for optimum synchronization. The output of each sub-receiver is processed to extract data using weighting factors selected according to the particular distortion present, to improve signal-to-noise ratio.

System for improving signal-to-noise ratio in a direct sequence spread

A plurality of transmitters synchronized to a common clock each transmit a data signal spread by a common bipolar pseudo-random code having a different predetermined assigned code sequence shift. A receiver, synchronized to the clock, discriminates the signal transmitted by a predetermined transmitter from signals transmitted by the others by generating a first bipolar pseudo-random code that is a replica of the common bipolar pseudo-radom code and has a code sequence shift corresponding to that of the predetermined transmitter, and a second bipolar pseudo-random code and has an unassigned code sequence shift. The difference between the first and second bipolar pseudo-random code sequences, which is a trinary code sequence, is cross-correlated with the incoming signals. The cross-correlation despreads only the signal applied by the sequence having the predetermined code sequence shift. Each receiver includes a number of correlation detectors offset from each other by a fraction of a code chip together with decision circuitry to identify cross-correlation peaks for optimum synchronization.

Code division multiplexer using direct sequence spread spectrum signal

A plurality of transmitters synchronized to a common clock each transmit a data signal spread by a common bipolar pseudo-random code having a different assigned code sequence shift. A receiver, synchronized to the clock, discriminates the signal transmitted by a predetermined transmitter from signals transmitted by the others by generating a first bipolar pseudo-random code that is a replica of the common bipolar pseudo-random code and has a code sequence shift corresponding to that of the predetermined transmitter, and a second bipolar pseudo-random code that is a replica of the common bipolar pseudo-random code and has an unassigned code sequence shift. The difference between the first and second bipolar pseudo-random code sequences, which is a trinary code sequence, is cross-correlated with the incoming signals. The cross-correlation despreads only the signal spread by the sequence having the predetermined code sequence shift. Each receiver includes a number of correlation detectors offset from each other by a fraction of a code chip together with decision circuitry to identify cross-correlation peaks for optimum synchronization. Analog and digital implementations of the correlation detectors are disclosed.

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Alpharetta, GA, United States of America

Lawrence B Horwitz