Patent ID: 7006768

Claim:
A system providing bidirectional communication with remote devices comprising a plurality of lamp fixtures in fixed positions, each lamp fixture having identification information; power lines connected to each fixture for supplying AC electrical energy for each lamp fixture; and a base station coupled to the power lines; each fixture comprising: one or more lamps; a power supply comprising a rectifier, a filter, and a dual voltage power supply, the power lines electrically connected to the power supply to provide AC electrical energy; a power line carrier transceiver connected to the power lines adapted to receive a variable message including lamp fixture identification information transmitted by the base station over the power lines; a switching circuit, the power supply electrically connected to the switching circuit to supply high voltage electrical energy to the switching circuit, the switching circuit electrically connected to each lamp to provide electrical energy to each lamp to cause each lamp to produce light; the switching circuit capable of encoding a second variable message as an optical signal by generating a plurality of frequencies to modulate the high voltage electrical energy supplied to each lamp to frequency shift the light produced by each lamp to generate an optical signal; a microprocessor control circuit having memory circuitry and programmed with lamp fixture identification information, the microprocessor control circuit coupled to the power line carrier transceiver and the switching circuit, the microprocessor control circuit receiving the variable message from the power line carrier transceiver, the microprocessor capable of decoding the variable message, and, in response to identifying the lamp identification information and the decoded variable message, encoding a second variable message, including at least one remote device address and the identification information of the fixture, by controlling the switching rate of the switching circuit to generate a plurality of frequencies to modulate the high voltage electric energy supplied to each lamp to modulate the light produced by each lamp to encode and transmit the second variable message as an optical signal; and a radio transceiver that receives modulated radio signals from a remote device positioned to receive the modulate light from the lamps one or more of the fixtures, the remote device capable of decoding the second variable message encoded in the optical signal and responding to its address and the second variable message in the decoded optical signal by transmitting a radio signal to the radio transceiver, the radio signal including the identification information of the fixture from which the remote device received the optical signal.