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光纤通信发展新技术 1.波分复用(WDM)技术 光纤通信的多路复用技术,开始采用原来铜缆沿用的PCM脉冲编码调制方式,把模拟信号变换为数字信号,再应用时分多路(TDM)技术组成一次群(即基群2Mb/s)、二次群(8Mb/s)、三次群(34Mb/s)、四次群(140Mb/s),这种系列又称为准同步数字系列(PDH)。PDH有三种系列,互不兼容;没有统一的标准接口规范,各个厂家生产的设备不能互通;上下电路困难故已改用新的同步数字系列(SDH),即
Optical fiber communication development of new technologies 1. Wavelength Division Multiplexing (WDM) Optical fiber multiplexing technology, began using the original copper PCM pulse coding modulation along the way, the analog signal into a digital signal, and then apply the time-division multiplexing (TDM) consists of primary (2Mb / s), secondary (8Mb / s), tertiary (34Mb / s), and quadruple (140Mb / s) Digital Series (PDH). There are three series of PDHs, which are not compatible with each other. There is no uniform standard interface specification and devices manufactured by different manufacturers can not communicate with each other. Up-and-down circuits have been switched to the new Synchronous Digital Hierarchy (SDH)