Transmitting Data Signals via Fiber-Optic Power Lines

Data signals can be transmitted via the same optical fibers that are used to transmit power from base stations to remote stations containing sensors and associated circuitry. [A prototype system based on fiber-optic transmission of data and power is described in "General-Purpose Optically Powered Sensor and Control System" (NPO-19604), which is the first of two articles preceding this one.] The implementation of the present data-transmission/power-transmission concept involves the choice of one of several possible modulation schemes (see figure); the choice of a scheme for a specific system depends, in part, on whether the power-supply optical signal is steady or is modulated as described in the immediately preceding article, "Transmitting Power to Sensor Circuitry via Modulated Light" (NPO-19603).