System and method for transmitting parallel signals via an optical transmission path

摘要

A parallel signal transmission system for transmitting parallel signals from a transmission unit to a reception unit via an optical fiber, at a low cost without spoiling their quality. The transmission unit converts received parallel signals into serial signals frame by frame, by means of a frame sync signal, and further converts the serial signals into direct current equilibrium signals which are either CMI codes or DMI codes. At the same time, the direct current equilibrium signals are multiplexed with the frame sync signal in accordance with the code ruling violation in order to drive a laser diode having a 0.78 mu m wavelength and output intensity-modulated optical signals to the optical transmission path. As the optical transmission path, a plastic clad fiber is used whose core diameter is 200 mu m or larger in order to agree with the laser diode having a 0.78 mu m wavelength. In the reception unit, the optical signals are photo/electric converted by means of a silicone photo diode, amplified into direct current equilibrium signals having a predetermined amplitude by means of an alternating current coupling type amplifier. The amplified direct current equilibrium signals are divided into serial signals and the frame sync signal by detecting a coding rule violation, and reproduced into original parallel signals by using the divided frame sync signal.