OPTICAL COMMUNICATION SYSTEM REDUCING OPTICAL BEAT INTERFERENCE IN CENTRAL EQUIPMENT

摘要

PROBLEM TO BE SOLVED: To obtain the optical system in which optical beat interference is reduced by allowing a light source to emit a light only for a 1st consecutive time interval separated by a 2nd time interval. SOLUTION: A terminal equipment 3(4) includes a laser equipment 5(7) as a light source, and a modulator 6(8) controlling the laser equipment 5(7) with a modulation signal S1 (t)(S2 (t)). The laser equipment 5(7) and the modulator 6(8) forms an optical transmitter set in the remote terminal equipment 3(4). The modulator 6(8) controls the light source 5(7) so that the light source 5(7) emits a light only for a consecutive time interval T1 L (T2 L) separated by a time interval T1 D (T2 D). The time interval T1 L (T2 L) is shorter than the time interval T1 D (T2 D). A generic repetitive frequency relation of 1/TP1 ≠1/TP2 is in existence in the modulation signal S1 (t)(S2 (t)). When the modulation signal S1 (t)(S2 (t)) is selected, the S/N in a central equipment 1 is improved by about 6dB.