Importance

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Abstract

A power-line communication system (10) for use with a conventional AC source (12) having a hot wire (14) and a neutral wire (16). The communication system (10) includes a pulse transmitter (16) and at least one receiver (18) connected downstream from the pulse transmitter (16). The pulse transmitter (16) is coupled between the hot wire (14) of the AC source (12) and either the neutral wire (16) of the AC source (12) or earth ground. Each receiver (14) is coupled to the AC source (12). The pulse transmitter (16) includes a control circuit (30) for controlling the conduction of a shunt circuit (32) and sends messages to the receivers (20) by inducing momentary pulses in the AC voltage supplied by the AC source (12). The shunt circuit (32) includes a power switch (52) and an energy clamp circuit for limiting the amplitude and the duration of the current through the power switch (52) and the pulse induced in the AC line voltage. Each receiver (18) detects the momentary pulses and translates a given sequence of pulses into its corresponding message. In a preferred embodiment, the pulse transmitter (16) is used to send control commands to one or more controllable electronic ballasts (22) for powering fluorescent lamps (24).

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First Claim