公司简介测试标准讲解.ppt

* How should you test your installation? In the US and Canada, one traditional configuration to test installed cabling was the basic link. But the basic link is no more. So if you care to test to active standards, you cannot use the basic link anymore. But we will try to compare typical basic link results with those of the other tests configurations. We now have the permanent link to replace the basic link. But there was always and still is the end-to-end link, which is the channel configuration. The reason for no longer testing the basic link has to do that return loss measurements became required, and the return loss of adapters can create inconsistent results. * * The two types of optical transmission systems use specific cable designs. Each containing similar components, but variations in form. Core - Portion where light will travel Cladding - Portion that will contain light within the core Coating - Adds mechanical strength and protects fiber from moisture The multimode has a larger core or center where the light will travel. The singlemode fiber has a much smaller core. Both have a cladding thickness that is similar. The two numbers shown below each fiber type in this illustration define the size of core and the cladding. 62.5 micrometer core / 125 micrometer cladding or in the case of single mode 8.3 micrometer core / 125 micrometer cladding. * * 16 光纤与铜缆的对比 项目 光纤（FIBER） 铜缆（COPPER） 线缆价格 低 较高 抗电磁/射频（EMI/RFI）干扰能力 不会被干扰 NEXT、FEXT等 连接器抗电磁/射频（EMI/RFI）干扰能力 不存在 总要被考虑 接地回路 不存在 总要被考虑 损耗 低 相对高 带宽 高 正在提高 温度稳定性 可能是个问题 可能是个问题 重量 非常轻 可能是个问题 易于安装 熔接困难 比较容易 安装及维修工具的价格 高 低 网卡价格 光/电/光转换部件昂贵 路由器便宜 放大器价格 光/电/光转换部件昂贵 测试工具价格 昂贵的OTDR 认证测试要求 损耗、传输延迟和长度 单根或成对测试 测试项目较多，可同时双向多线对测试 光纤基础知识—电磁谱 Frequency (Hz) UV 可见光 (750 - 380 nm) X-Rays IR AM Radio Wavelength (m) 1012 108 1014 1010 1016 1018 1 UHF VHF 106 10-3 10-9 常用的光波长 (660, 850, 1300, 1310, 1550 nm) 光纤基础知识—波长的选择 First Window Second Window Third Window 波长 (nm) 800 1200 1600 0 8 Loss (dB/km) 4 多模(MD) 工作于 850 nm 和 1300 nm 单模(SM