Abstract: Transceiver system including a transmitter and receiver. The transmitter transmits radiation having a varying operating frequency. It is preferred that the radiation be visible light. The operating frequency is varied in a way that eliminates visible flicker. A receiver receives the encoded radiation, decodes the coded data, and delivers the decoded data signal to an output stage. The output may be audio information textural information or graphical information. A two level coding scheme is preferred.

Abstract: An apparatus for 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.