OPTICAL FIBER TRANSMISSION SYSTEM

摘要

PURPOSE:To improve the transmission efficiency and to reduce noise by applying envelope detection of a modulated carrier and adjusting the detected signal wave so as to be coincident with a threshold of an electrooptic conversion element. CONSTITUTION:A high frequency signal received from an input terminal T1 is subjected to envelope detection by a detector 2 and sent to an adder 4 from a low pass filter 3. The signal wave is superimposed on a high frequency signal outputted from an RF amplifier 1 and a lower limit of an amplitude of the superimposed signal wave is adjusted so as to be coincident with a threshold of an electrooptic conversion element 5 and the result is sent to an optical fiber from the element 5. Thus, a mean value of an optically converted current is decreased and in the case of multiplexing, the C/N is improved.