自1978年春,为了在实际工作条件下估价光纤传输技术,在东京首都地区进行了一个大规模的光纤传输系统现场试验。在这现场试验中,光纤沿着东京商业区的五个电话局之间的线路。全部光缆长度共计21km,缆中含有48根光纤,其中包括多模阶跃率和梯度率两种类型。在现场试验中,使用和试验了三个不同的传输系统,它们是32Mb/s和 Since the spring of 1978, a field trial of a large-scale optical fiber transmission system has been conducted in Tokyo’s capital city in order to evaluate optical fiber transmission technology under actual working conditions. In this field trial, fiber optic lines along the lines between the five telephone offices in Tokyo’s business district. The total length of all optical cables is 21km, and the cable contains 48 optical fibers, including two types of multi-mode step rate and gradient rate. In the field test, three different transmission systems were used and tested, which are 32 Mb / s and