Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: A method and apparatus for use in identification of coins is disclosed in which a coin is passed through the electromagnetic field of an inductor in an oscillator circuit and the changes in both the frequency and amplitude of oscillation of said oscillator circuit are separately detected.