Abstract: A system for transmitting communication signals, the system comprising an injector circuit connected to a powered circuit conductor and configured to modulate a power signal with a direct current voltage offset, the direct current voltage offset being within a range that causes approximately 1 percent or less total harmonic distortion of the power signal; and a decoder connected to the powered circuit conductor and a load, the decoder configured to demodulate the direct current voltage offset to control the load. A method for transmitting communication signals, the method comprising modulating a power signal on a powered circuit conductor with a direct current voltage offset, the direct current voltage offset being within a range that causes approximately 1 percent or less total harmonic distortion of the power signal; and demodulating the direct current voltage offset to control a load.

Abstract: A system for transmitting communication signals, the system comprising an injector circuit connected to a powered circuit conductor and configured to modulate a power signal with a direct current voltage offset, the direct current voltage offset being within a range that causes approximately 1 percent or less total harmonic distortion of the power signal; and a decoder connected to the powered circuit conductor and a load, the decoder configured to demodulate the direct current voltage offset to control the load. A method for transmitting communication signals, the method comprising modulating a power signal on a powered circuit conductor with a direct current voltage offset, the direct current voltage offset being within a range that causes approximately 1 percent or less total harmonic distortion of the power signal; and demodulating the direct current voltage offset to control a load.

Abstract: A system for transmitting communication signals, the system comprising an injector circuit connected to a powered circuit conductor and configured to modulate a power signal with a direct current voltage offset, the direct current voltage offset being within a range that causes approximately 1 percent or less total harmonic distortion of the power signal; and a decoder connected to the powered circuit conductor and a load, the decoder configured to demodulate the direct current voltage offset to control the load. A method for transmitting communication signals, the method comprising modulating a power signal on a powered circuit conductor with a direct current voltage offset, the direct current voltage offset being within a range that causes approximately 1 percent or less total harmonic distortion of the power signal; and demodulating the direct current voltage offset to control a load.

Abstract: A system for transmitting communication signals, the system comprising an injector circuit connected to a powered circuit conductor and configured to modulate a power signal with a direct current voltage offset, the direct current voltage offset being within a range that causes approximately 1 percent or less total harmonic distortion of the power signal; and a decoder connected to the powered circuit conductor and a load, the decoder configured to demodulate the direct current voltage offset to control the load. A method for transmitting communication signals, the method comprising modulating a power signal on a powered circuit conductor with a direct current voltage offset, the direct current voltage offset being within a range that causes approximately 1 percent or less total harmonic distortion of the power signal; and demodulating the direct current voltage offset to control a load.

Abstract: A simple method and apparatus are described for controlling two or more electrical devices. An encoder receives an alternating current (AC) voltage waveform and converts the AC voltage waveform to a modified voltage waveform selected according to a control input. A decoder located near the electrical devices receives the modified voltage waveform and either energies or deenergizes each of the electrical devices, depending upon the modified voltage waveform. Energized electrical devices receive energy from the modified voltage waveform. The modified voltage waveform both selects electrical devices to be energized and provides power to the energized electrical devices.

Abstract: Energy dissipating loads are controlled from a location remote from the load. Load control information is transmitted between the remote location and the load by way of electrical energy transmission lines including a neutral conductor, a ground conductor and a line conductor. Load control information representative of the electrical energy applied to the load is determined and the load control information and applied to the energy transmission lines at an impressing end for transmission to a receiving end wherein the load control information is impressed between the neutral conductor and the ground conductor to provide impressed load control information. The impressed load control information is received at the receiving end by obtaining the load control information from between the neutral conductor and the ground conductor to provide received load control information. The energy of the load is controlled in accordance with the received load control information.

Abstract: A small puff of air is periodically exhausted through a semi-permeable stainless mesh (23) filter upward through the plane of the roadway surface. The puff of air is created by a miniature air pump (14) and timer, typically On one half second and Off 30 seconds. The timing can be adjustable. The puff of air is delivered to the sensor (20) through hose (5). When ice on pavement has formed over the sensor (20), it blocks the release of the air puff. This causes pressure to build up, triggering the pressure switch (16) which then turns on output switch (17) which can then be used to turn on any number of warning devices.

Abstract: A system for suppressing positive feedback in acoustical-electrical devices having acoustic or electric feedback paths or a combination of both. Electrical signals from a microphone are transmitted through a sampling switch to a signal storage device. The transfer rate and duration are controlled by a pulse generator driven by an oscillator to time domain process the signals. The discrete signals output from the signal storage device are smoothed by a low pass filter and used to drive follow on circuitry, e.g., a speaker. A plurality of switches, signal storage devices, oscillators and pulse generators can be arranged in serial or parallel to provide various processing combinations. Several embodiments of the system are employed in a bidirectional telephone unit having separate incoming and outgoing signal channels to enable full duplex mode operation.