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.
