PURPOSE: To securely supply power even during data communication and improve data communication efficiency by equipping a signal processor with a pulse light transmitter which produces pulse light phase-modulated with codes having different high-level time interval.

CONSTITUTION: Pulse light, the phase of which is modulated according to bi- phase codes different high-level time intervals in a specified period S, is transmitted to a signal processor 10. Thereby constant power is securely supplied to a terminal device 20 without decreasing while data are transmitted from the signal processor 10 to the terminal device 20. Therefore, power is supplied and data are continuously transmitted to the terminal device 20 at the same time. Moreover, no optical fiber is required.