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我国在七十年代初,富有生命力的光纤和半导体激光器研制问世后,已在通信领域中被广泛采用,成为通信传输的主要媒质.目前新建的光缆通信工程几乎都是采用单模光纤,国内生产和国外引进的34kb/s和140kb/s光电设备在干线、农话、市话通信网中大量被采用,并向565(PDH)、622(SDH)系列发展.结合我国市、县、乡分布的实际情
Our country in the early seventies, after the development of the vitality of optical fiber and semiconductor lasers, has been widely used in the field of communications, as the main media of communications transmission.At present, almost all new optical fiber communications project is the use of single-mode optical fiber, domestic production And 34kb / s and 140kb / s optoelectronic devices imported from abroad have been widely adopted in trunk lines, agricultural lines and local telephone networks, and have been developed to 565 (PDH) and 622 (SDH) series. Combining with the distribution of cities, counties and townships in China Actual situation