System for transmitting optical binary data signals through an optical

Abstract

For effective use of the optical energy and yet proper operation of an automatic gain or threshold control circuit comprised by a receiver of an optical data transmission system, a transmitter of the system produces an optical binary signal with at least one optical pilot pulse inserted between two sequences of optical data pulses only when the two sequences are spaced wider from each other than a predetermined interval that would render the control circuit no more operative and would thereby adversely affect correct reproduction of the data from an electrical binary signal derived from the received optical binary signal through the control circuit. By making the pilot pulses appear more than a first prescribed duration after the last data pulse of the preceding sequence and a second prescribed duration before the first data pulse of the succeeding sequence, electrical pilot pulse or pulses present in the electrical binary signal are removed without deforming the reproduced data if each prescribed duration is longer than the pulse width of the electrical pilot pulse and furthermore a sum of the prescribed durations and the pulse width is not longer than the predetermined interval. The removal is possible by providing the electrical binary signal with successive delays decided in consideration of the prescribed durations and the pulse width and carrying out logic operation on the electrical binary signal and the successively delayed signals if each optical data pulse lasts longer than a sum of the delays.