305m长线缆的回波损耗和近端串扰的测试方法研究

数字平衡线缆广泛应用于综合布线系统以连通设备、互传信息,是工程建设中最常用的传输介质,其质量是保证信息顺利传递的关键,目前国际上通行的测试标准和方法均是基于90m长度的基线模型,而数字平衡线缆在工厂制造中通常是以1 000ft(305m)为基本单位进行绕匝装箱。因此为方便对生产线缆进行性能检测和质量控制,针对整箱线缆的测试方法研究尤为必要。文章提出针对305m长线缆的回波损耗和近端串扰的测试方法,利用网络分析仪和阻抗转换器实现对双绞线所有线对的近端性能测试,并与国际标准进行对比,验证了可以通过测试305m长线缆的回波损耗和近端串扰值来初步判断线缆的传输质量是否合格。

Research on Test Method of Return Loss and Near-end Crosstalk in 305m Long Cables

Digital balanced cable，which is widely utilized in Generic Cabling System (GCS)，is the primary transmission medium. However，the universal standards and test methods are based on 90 m baseline model，and in factory the digital balanced cable is generally produced in 1 000 ft (305 m) per case，for the convenience of performance monitor and quality control on cable products，test method on 305 m long cables is an urgent need. This paper has proposed a test method of return-loss and near-end cross-talk on 305 m long cables，it mainly utilizes vector network analyzer (VNA) and impedance converter to cover the measurements of all-pairs on near-end performance testing. We also make comparison and analysis according to 90 m Channel model in TIA IEC. It proves that we can preliminarily estimate the transmission quality of the communication cables through test results of return-loss and near-end cross-talk in 305 m long cables.