Abstract: A power line communication system and signaling protocol is usable for quick dimming of an electronic ballast. An encoding circuit transmits message frames having encoded control signals across a AC power line. Each of a first set of frames includes a bit pattern corresponding to a lighting zone, and a second set of frames includes hamming-encoded bit patterns corresponding to respective hexadecimal digits of a dimming level for the lighting zone. A ballast in a first (quick-dim) configuration detects the second set of frames, decodes the hamming-encoded digits and immediately adjusts the ballast output to the desired power level. The ballast in a second (normal) configuration determines the desired power level based on a pattern density in the first set of frames, and adjusts the output current of the ballast accordingly. If the ballast of the first configuration fails to detect the second set of frames, it defaults to pattern density recognition.

Abstract: A system and method is provided for encoding and decoding control signals to an electronic ballast. An encoding circuit is effective to transmit encoded control signals across an AC power line comprising patterns of energy bursts at zero crossings of an AC signal. Eight zero crossings define a set, five specific patterns of energy bursts within a set define distinct symbols, each defined symbol selected such that a Hamming distance between each symbol is greater than three. Four symbols correspond to a first logic condition and one symbol corresponds to a second logic condition. Each received symbol is sequentially associated with a distinct control channel having one or more control parameters. A receiving circuit in the ballast is effective to decode symbols with single-bit error correction by comparing received symbols to defined symbols and determining which symbol is a smallest Hamming distance from a received symbol.