胡爱莲 刘栋 张立岩 曹蓓蓓

【摘要】    在实际光缆施工熔接中，通常采用OTDR测试光纤接头损耗，但OTDR单向损耗包含了被接续两根光纤的背向散射特性差异，并不代表光纤真实的熔接损耗，因此采用单向损耗作为熔接损耗的判断标准，通常会造成误解和不必要的返工。而光源功率计的测试原理相对简单，只需从一个方向进行测试。本文基于某移动干线在开盘检测过程中采用OTDR测试出现的熔接损耗“大正大负”现象，特设计实验，分别采用OTDR和光源光功率计测试了熔接点损耗和光缆链路损耗，验证OTDR双向平均值的结果和光源光功率计测试结果趋于一致，从而证明OTDR测试熔接损耗和链路损耗的正确方法是双向测试取平均值，单向熔接损耗不影响实际光纤的传输性能。

【关键词】    OTDR 光源功率计    熔接损耗 单向损耗    大正大负

Abstract：In the actual welding process of optical cable construction， OTDR is widely used to measure the fusion splice loss. But OTDR one-way measured loss is not the true splice loss because its affected by the difference of backscattering properties of the two connected fibres. If the unidirectional loss is used as the criterion of splice loss， it often causes misunderstanding or even unnecessary rework. Compared with OTDR， the testing principle of Light Source and Power Meter （LSPM） is simpler and just need to test from one direction. In this paper， based on the phenomenon of “apparent Gain and Loss” of fusion splice loss happened in the opening test of a China Mobile trunk project， an experiment was designed to test the splice loss and cable link loss by using OTDR and LSPM respectively. The result shows that OTDR bidirectional average value is consistent with the test result of LSPM， so its proved that the correct method to test fusion splice loss and cable link loss by OTDR is to take the average value of bidirectional traces， and the unidirectional test result has no effect on the actual link loss.

Key words：OTDR， LSPM， Fusion Splice Loss， unidirectional loss， Apparent gain or loss

引言

在光缆施工熔接过程中，通常采用OTDR（光时域反射仪）来測试光纤接头损耗，测试整段线路衰减时，则一般采用光源功率计进行测试，光源功率计测试损耗只需从一个方向进行测试，但单向测试方法对OTDR来说是不准确的，特别是用OTDR测试熔接损耗时，OTDR单向损耗与真实的熔接损耗没有必然的关系，如果采用单向损耗作为熔接损耗的判断标准，会造成对熔接损耗的误解和不必要的返工，甚至影响工程进度。本文基于某移动干线在开盘检测过程中出现的熔接损耗“大正大负”现象，特设计实验，分别采用OTDR和光源光功率计测试……