Non-flickering illumination based communication

The present invention relates to the simultaneous dual use of radiation, e.g. visible light, for both a conventional application, e.g., illumination, combined with the additional application of transmitting information without wires. The present invention further relates to electronic ballast circuits for electric discharge lamps, e.g., fluorescent lamps. The present invention further relates to the application of a time-varying, modulated current through the lamp to produce electronically detectable variations in the lamp light that are invisible to the human eye. The present invention further relates to coding information in variations in the lamp light for purposes of transmitting all kinds of information, including, but not limited to, digital data, audio, textual, and graphical signals. The present invention further relates to efficient coding schemes to maximize the bandwidth or information transfer capability of the optical data channel. Wide bandwidth and efficiency are critical for intranets or other wide area networks that could be carried on the lighting in an office or factory. The present invention further relates to efficient power electronic circuits capable of producing modulated currents in a lamp with high power efficiency, maximum data rate, and the possibility of incorporating needed safety features such as galvanic isolation. The present invention further relates to the construction of receivers for detection of the modulated information in the lamp light. A system for and method of generating electromagnetic radiation in which the radiation has both a first and second utility. The electromagnetic radiation is modulated to produce electronically detectable variations to achieve the second utility, the variations not affecting the first utility. In one embodiment, the electromagnetic radiation is visible light. In this embodiment, the first utility is illumination and the second utility is the transmission of data. In another embodiment, the invention provides a lamp for generating visible light capable of providing illumination and transmitting data to a receiver. Any variations in the visible light resulting from the data transmission are imperceptible by a human eye regardless of the nature of the data being transmitted. In yet another embodiment, a power line carrier modem may be used with the present invention to transmit information to the source.