New England Power Service Company

Reed H Johnston

Dennis C Jeffreys

Lawrence J Stratton

Albert W Welz, Jr

A method for improving signal quality while simultaneously enhancing the data rate in a communications system in which individual signaling events are, at least in principle, capable of representing a bit of digital intelligence. When the method is applied to power-line communication systems, the pattern of signaling events extends over some integer multiple of four cycles of the power-line wave. Signaling events of each particular type are found in exactly half of the cycles contained in any pattern. Patterns containing but one type of signaling event are arranged into orthogonal patterns--the term orthogonal implying that each pattern can be sensed only by a detection mode that maximizes the signal therefrom, and the application of any detection mode to a pattern for which it is not optimum will result in no net accumulation of signal. When two types of independent signaling events which yield signals of comparable magnitude are achieved they are arranged into pseudo-orthogonal patterns to further expand the data rate without impairing signal quality. Under these conditions quaternary coding proves to be the preferred technique. Examples are given wherein a multiplicity of simultaneous noninterfering messages are transmitted under circumstances where it is possible to transmit them in synchronism. Where multiple messages cannot be synchronized the method can be used to increase the data rate through the use of encoding schemes based on numerical bases greater than binary.

Method for communication utilizing multi-mode reception

A method and an apparatus for communicating over electric power lines in a direction from load to source is disclosed. The power line voltage wave is loaded in a predetermined pattern to produce a corresponding pattern of signaling currents at a receiving site. Detection of the signaling current is accomplished in the preferred embodiment by integrating the current in the phase or the neutral of the feeder that serves the signaling site during predetermined time windows which are synchronized with the power line voltage wave. The current integration is performed in accordance with a detection algorithm to accumulate principally the current differences that are attributable to the signaling currents while in the presence of steady and transient currents on the feeder.

Method and apparatus for communication over electric power lines

A method and apparatus for transmitting intelligence over a carrier wave are disclosed in which a signal waveform is added to a carrier wave to produce a composite wave having a recognizable pattern of variations in intervals that are defined by preselected locations in the composite wave. The pattern of variations in intervals resulting from the addition of the signal waveform to the carrier wave represents at least a portion of the intelligence to be transmitted over the carrier wave. The variations in intervals defined by the preselected locations in the carrier waves are detected and the detected interval variations are converted into a signal which has a characteristic that is a function of the recognizable pattern of interval variations. In the preferred embodiment the intelligence is transmitted over an electric power distribution network utilizing the alternating voltage therein as the carrier wave.

Method and apparatus for transmitting intelligence over a carrier wave

A cycloconverter apparatus and method is disclosed in which the cycloconverter works into an active load. The cycloconverter is connected between an external power source and a load so that the load current flows through the cycloconverter. In the preferred embodiment, the cycloconverter is used to impress a signaling voltage waveform upon the voltages of the three phases of an electric power distribution feeder. This voltage is impressed by injecting it between the common point of the wye-connected secondary of the substation transformer and the grounded neutral that serves all phases of the distribution feeder. The neutral current of the distribution feeder flows through the cycloconverter. Protective by-pass circuitry is provided to maintain the integrity of the neutral path in the event of a phase-to-neutral short circuit or a failure of the cycloconverter.

Cycloconverter apparatus and method for working into an active load

A method and apparatus for transmitting intelligence over a carrier wave are disclosed in which a signal wave is combined with a carrier wave to produce a composite wave having a recognizable pattern of variations in intervals that are defined by preselected locations in the composite wave. The pattern of variations in intervals resulting from the combination of the signal wave with the carrier wave represents at least a portion of the intelligence to be transmitted over the carrier wave. The intelligence is extracted from the composite wave for subsequent utilization. In the preferred embodiment the intelligence is transmitted over an electric power distribution network utilizing the alternating wave thereon as the carrier wave. The variations in intervals defined by the preselected locations in the composite wave are detected and the detected interval variations are converted into a signal which has a characteristic that is a function of the recognizable pattern of interval variations.

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Wellesley, MA, United States of America

Reed H Johnston