[转帖]光纤通信的概述

wanglh1211

&nbsp;<p style="LINE-HEIGHT: 18pt;"><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;">&nbsp; </span><span style="FONT-SIZE: 10.5pt; mso-ascii-font-family: &quot;\000B&quot;; mso-hansi-font-family: &quot;\000B&quot;;">一、</span><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;">&nbsp;</span><span style="FONT-SIZE: 10.5pt; mso-ascii-font-family: &quot;\000B&quot;; mso-hansi-font-family: &quot;\000B&quot;;">概述</span><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;"><p></p></span></p><p style="LINE-HEIGHT: 18pt;"><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;">&nbsp;&nbsp;&nbsp; </span><span style="FONT-SIZE: 10.5pt; mso-ascii-font-family: &quot;\000B&quot;; mso-hansi-font-family: &quot;\000B&quot;;">当今世界，光纤通信已成为通信的主要手段。同时，光纤通讯技术也在飞速的发展，使得光纤传输系统以其众多的优点，赢得了大家的青睐。</span><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;"><p></p></span></p><p style="LINE-HEIGHT: 18pt;"><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;">&nbsp;&nbsp;&nbsp; </span><span style="FONT-SIZE: 10.5pt; mso-ascii-font-family: &quot;\000B&quot;; mso-hansi-font-family: &quot;\000B&quot;;">光纤传输系统具有以下显著优点：容量大、传输距离远。光纤理论带宽可达</span><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;">20000GHz</span><span style="FONT-SIZE: 10.5pt; mso-ascii-font-family: &quot;\000B&quot;; mso-hansi-font-family: &quot;\000B&quot;;">，无中继传输距离可达</span><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;">50-80</span><span style="FONT-SIZE: 10.5pt; mso-ascii-font-family: &quot;\000B&quot;; mso-hansi-font-family: &quot;\000B&quot;;">公里。由玻璃制成，抗电磁干扰、传输质量好，可用于电力网和变电所内等强电磁环境中。光纤重量轻，可以弯曲，易于铺设。可节约贵重金属，且抗腐蚀能力很强。制作光纤的原料丰富，随着工艺的进步、规模的扩大，其成本进一步下降，整个传输系统的成本也低。</span><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;"><p></p></span></p><p style="LINE-HEIGHT: 18pt;"><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;">&nbsp;&nbsp;&nbsp; </span><span style="FONT-SIZE: 10.5pt; mso-ascii-font-family: &quot;\000B&quot;; mso-hansi-font-family: &quot;\000B&quot;;">二、</span><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;">&nbsp;</span><span style="FONT-SIZE: 10.5pt; mso-ascii-font-family: &quot;\000B&quot;; mso-hansi-font-family: &quot;\000B&quot;;">光纤传输系统简介</span><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;"><p></p></span></p><p style="LINE-HEIGHT: 18pt;"><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;">&nbsp;&nbsp;&nbsp; </span><span style="FONT-SIZE: 10.5pt; mso-ascii-font-family: &quot;\000B&quot;; mso-hansi-font-family: &quot;\000B&quot;;">光纤传输即是以光波为载频，以光导纤维为传输介质的一种通信方式，因其拥有传输频带宽、信号损耗低、抗干扰能力强、重量轻等优点。光纤通信在近二十年来得到了飞速的发展。</span><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;"><p></p></span></p><p style="LINE-HEIGHT: 18pt;"><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;">&nbsp;&nbsp;&nbsp; 1</span><span style="FONT-SIZE: 10.5pt; mso-ascii-font-family: &quot;\000B&quot;; mso-hansi-font-family: &quot;\000B&quot;;">、光纤的结构</span><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;"><p></p></span></p><p style="LINE-HEIGHT: 18pt;"><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;">&nbsp;&nbsp;&nbsp; </span><span style="FONT-SIZE: 10.5pt; mso-ascii-font-family: &quot;\000B&quot;; mso-hansi-font-family: &quot;\000B&quot;;">光纤裸纤一般分为三层：中心高折射率玻璃芯</span><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;">(</span><span style="FONT-SIZE: 10.5pt; mso-ascii-font-family: &quot;\000B&quot;; mso-hansi-font-family: &quot;\000B&quot;;">芯径一般为</span><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;">50</span><span style="FONT-SIZE: 10.5pt; mso-ascii-font-family: &quot;\000B&quot;; mso-hansi-font-family: &quot;\000B&quot;;">或</span><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;">62.5</span><span style="FONT-SIZE: 10.5pt; mso-ascii-font-family: &quot;\000B&quot;; mso-hansi-font-family: &quot;\000B&quot;;">μ</span><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;">m)</span><span style="FONT-SIZE: 10.5pt; mso-ascii-font-family: &quot;\000B&quot;; mso-hansi-font-family: &quot;\000B&quot;;">，中间为低折射率硅玻璃包层</span><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;">(</span><span style="FONT-SIZE: 10.5pt; mso-ascii-font-family: &quot;\000B&quot;; mso-hansi-font-family: &quot;\000B&quot;;">直径一般为</span><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;">125</span><span style="FONT-SIZE: 10.5pt; mso-ascii-font-family: &quot;\000B&quot;; mso-hansi-font-family: &quot;\000B&quot;;">μ</span><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;">m)</span><span style="FONT-SIZE: 10.5pt; mso-ascii-font-family: &quot;\000B&quot;; mso-hansi-font-family: &quot;\000B&quot;;">，最外是加强用的树脂涂层。</span><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;"><p></p></span></p><p style="LINE-HEIGHT: 18pt;"><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;">&nbsp;&nbsp;&nbsp; 2</span><span style="FONT-SIZE: 10.5pt; mso-ascii-font-family: &quot;\000B&quot;; mso-hansi-font-family: &quot;\000B&quot;;">、光纤的分类</span><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;"><p></p></span></p><p style="LINE-HEIGHT: 18pt;"><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;">&nbsp;&nbsp;&nbsp; 1</span><span style="FONT-SIZE: 10.5pt; mso-ascii-font-family: &quot;\000B&quot;; mso-hansi-font-family: &quot;\000B&quot;;">）</span><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;">&nbsp;</span><span style="FONT-SIZE: 10.5pt; mso-ascii-font-family: &quot;\000B&quot;; mso-hansi-font-family: &quot;\000B&quot;;">按传输模式来划分：</span><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;"><p></p></span></p><p style="LINE-HEIGHT: 18pt;"><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;">&nbsp;&nbsp;&nbsp; </span><span style="FONT-SIZE: 10.5pt; mso-ascii-font-family: &quot;\000B&quot;; mso-hansi-font-family: &quot;\000B&quot;;">单模光纤（</span><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;">Single-mode</span><span style="FONT-SIZE: 10.5pt; mso-ascii-font-family: &quot;\000B&quot;; mso-hansi-font-family: &quot;\000B&quot;;">）</span><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;"><p></p></span></p><p style="LINE-HEIGHT: 18pt;"><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;">&nbsp;&nbsp;&nbsp; </span><span style="FONT-SIZE: 10.5pt; mso-ascii-font-family: &quot;\000B&quot;; mso-hansi-font-family: &quot;\000B&quot;;">单模光纤只传输主模，由于完全避免了模式色散，使得单模光纤的传输频带很宽，因而适用于大容量、长距离的传输系统。</span><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;"><p></p></span></p><p style="LINE-HEIGHT: 18pt;"><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;">&nbsp;&nbsp;&nbsp; </span><span style="FONT-SIZE: 10.5pt; mso-ascii-font-family: &quot;\000B&quot;; mso-hansi-font-family: &quot;\000B&quot;;">多模光纤（</span><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;">Multi-mode</span><span style="FONT-SIZE: 10.5pt; mso-ascii-font-family: &quot;\000B&quot;; mso-hansi-font-family: &quot;\000B&quot;;">）</span><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;"><p></p></span></p><p style="LINE-HEIGHT: 18pt;"><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;">&nbsp;&nbsp;&nbsp;&nbsp; </span><span style="FONT-SIZE: 10.5pt; mso-ascii-font-family: &quot;\000B&quot;; mso-hansi-font-family: &quot;\000B&quot;;">多模光纤有多个模式在光纤中传输，由于色散和相差，其传输性能较差、频带较窄、容量小、距离也较短。</span><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;"><p></p></span></p><p style="LINE-HEIGHT: 18pt;"><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;">&nbsp;&nbsp;&nbsp; 2) </span><span style="FONT-SIZE: 10.5pt; mso-ascii-font-family: &quot;\000B&quot;; mso-hansi-font-family: &quot;\000B&quot;;">按折射率分布来划分：</span><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;"><p></p></span></p><p style="LINE-HEIGHT: 18pt;"><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;">&nbsp;&nbsp; </span><span style="FONT-SIZE: 10.5pt; mso-ascii-font-family: &quot;\000B&quot;; mso-hansi-font-family: &quot;\000B&quot;;">多模光纤可分为：阶跃型（突变型）和梯度型（渐变型、自聚焦型）。</span><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;"><br/>&nbsp;&nbsp; </span><span style="FONT-SIZE: 10.5pt; mso-ascii-font-family: &quot;\000B&quot;; mso-hansi-font-family: &quot;\000B&quot;;">单模光纤则为阶跃型。</span><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;"><p></p></span></p><p style="LINE-HEIGHT: 18pt;"><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;">&nbsp;&nbsp;&nbsp; 3</span><span style="FONT-SIZE: 10.5pt; mso-ascii-font-family: &quot;\000B&quot;; mso-hansi-font-family: &quot;\000B&quot;;">、常用光纤规格</span><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;"><p></p></span></p><p style="LINE-HEIGHT: 18pt;"><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;">&nbsp;&nbsp;&nbsp; </span><span style="FONT-SIZE: 10.5pt; mso-ascii-font-family: &quot;\000B&quot;; mso-hansi-font-family: &quot;\000B&quot;;">单模：</span><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;">8/125</span><span style="FONT-SIZE: 10.5pt; mso-ascii-font-family: &quot;\000B&quot;; mso-hansi-font-family: &quot;\000B&quot;;">μ</span><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;">m</span><span style="FONT-SIZE: 10.5pt; mso-ascii-font-family: &quot;\000B&quot;; mso-hansi-font-family: &quot;\000B&quot;;">，</span><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;">9/125</span><span style="FONT-SIZE: 10.5pt; mso-ascii-font-family: &quot;\000B&quot;; mso-hansi-font-family: &quot;\000B&quot;;">μ</span><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;">m</span><span style="FONT-SIZE: 10.5pt; mso-ascii-font-family: &quot;\000B&quot;; mso-hansi-font-family: &quot;\000B&quot;;">，</span><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;">10/125</span><span style="FONT-SIZE: 10.5pt; mso-ascii-font-family: &quot;\000B&quot;; mso-hansi-font-family: &quot;\000B&quot;;">μ</span><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;">m<br/>&nbsp;&nbsp;&nbsp; </span><span style="FONT-SIZE: 10.5pt; mso-ascii-font-family: &quot;\000B&quot;; mso-hansi-font-family: &quot;\000B&quot;;">多模：</span><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;">50/125</span><span style="FONT-SIZE: 10.5pt; mso-ascii-font-family: &quot;\000B&quot;; mso-hansi-font-family: &quot;\000B&quot;;">μ</span><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;">m </span><span style="FONT-SIZE: 10.5pt; mso-ascii-font-family: &quot;\000B&quot;; mso-hansi-font-family: &quot;\000B&quot;;">欧洲标准；</span><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;">62.5/125</span><span style="FONT-SIZE: 10.5pt; mso-ascii-font-family: &quot;\000B&quot;; mso-hansi-font-family: &quot;\000B&quot;;">μ</span><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;">m </span><span style="FONT-SIZE: 10.5pt; mso-ascii-font-family: &quot;\000B&quot;; mso-hansi-font-family: &quot;\000B&quot;;">美国标准</span><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;"><br/>&nbsp;&nbsp;&nbsp; </span><span style="FONT-SIZE: 10.5pt; mso-ascii-font-family: &quot;\000B&quot;; mso-hansi-font-family: &quot;\000B&quot;;">工业，医疗和低速网络：</span><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;">100/140</span><span style="FONT-SIZE: 10.5pt; mso-ascii-font-family: &quot;\000B&quot;; mso-hansi-font-family: &quot;\000B&quot;;">μ</span><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;">m</span><span style="FONT-SIZE: 10.5pt; mso-ascii-font-family: &quot;\000B&quot;; mso-hansi-font-family: &quot;\000B&quot;;">，</span><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;">200/230</span><span style="FONT-SIZE: 10.5pt; mso-ascii-font-family: &quot;\000B&quot;; mso-hansi-font-family: &quot;\000B&quot;;">μ</span><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;">m<br/>&nbsp;&nbsp;&nbsp; </span><span style="FONT-SIZE: 10.5pt; mso-ascii-font-family: &quot;\000B&quot;; mso-hansi-font-family: &quot;\000B&quot;;">塑料：</span><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;">98/1000</span><span style="FONT-SIZE: 10.5pt; mso-ascii-font-family: &quot;\000B&quot;; mso-hansi-font-family: &quot;\000B&quot;;">μ</span><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;">m </span><span style="FONT-SIZE: 10.5pt; mso-ascii-font-family: &quot;\000B&quot;; mso-hansi-font-family: &quot;\000B&quot;;">用于汽车控制。</span><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;"><p></p></span></p><p style="LINE-HEIGHT: 18pt;"><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;">&nbsp;&nbsp;&nbsp; 4</span><span style="FONT-SIZE: 10.5pt; mso-ascii-font-family: &quot;\000B&quot;; mso-hansi-font-family: &quot;\000B&quot;;">、光纤的衰减</span><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;"><p></p></span></p><p style="LINE-HEIGHT: 18pt;"><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;">&nbsp;&nbsp;&nbsp; </span><span style="FONT-SIZE: 10.5pt; mso-ascii-font-family: &quot;\000B&quot;; mso-hansi-font-family: &quot;\000B&quot;;">造成光纤衰减的主要因素有：本征，弯曲，挤压，杂质，不均匀和对接等。</span><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;"><br/>&nbsp;&nbsp;&nbsp; </span><span style="FONT-SIZE: 10.5pt; mso-ascii-font-family: &quot;\000B&quot;; mso-hansi-font-family: &quot;\000B&quot;;">本征：是光纤的固有损耗，包括：瑞利散射，固有吸收等。</span><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;"><br/>&nbsp;&nbsp;&nbsp; </span><span style="FONT-SIZE: 10.5pt; mso-ascii-font-family: &quot;\000B&quot;; mso-hansi-font-family: &quot;\000B&quot;;">弯曲：光纤弯曲时部分光纤内的光会因散射而损失掉，造成的损耗。</span><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;"><br/>&nbsp;&nbsp;&nbsp; </span><span style="FONT-SIZE: 10.5pt; mso-ascii-font-family: &quot;\000B&quot;; mso-hansi-font-family: &quot;\000B&quot;;">挤压：光纤受到挤压时产生微小的弯曲而造成的损耗。</span><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;"><br/>&nbsp;&nbsp;&nbsp; </span><span style="FONT-SIZE: 10.5pt; mso-ascii-font-family: &quot;\000B&quot;; mso-hansi-font-family: &quot;\000B&quot;;">杂质：光纤内杂质吸收和散射在光纤中传播的光，造成的损失。</span><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;"><br/>&nbsp;&nbsp;&nbsp; </span><span style="FONT-SIZE: 10.5pt; mso-ascii-font-family: &quot;\000B&quot;; mso-hansi-font-family: &quot;\000B&quot;;">不均匀：光纤材料的折射率不均匀造成的损耗。</span><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;"><br/>&nbsp;&nbsp;&nbsp; </span><span style="FONT-SIZE: 10.5pt; mso-ascii-font-family: &quot;\000B&quot;; mso-hansi-font-family: &quot;\000B&quot;;">对接：光纤对接时产生的损耗，如：不同轴</span><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;">(</span><span style="FONT-SIZE: 10.5pt; mso-ascii-font-family: &quot;\000B&quot;; mso-hansi-font-family: &quot;\000B&quot;;">单模光纤同轴度要求小于</span><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;">0.8</span><span style="FONT-SIZE: 10.5pt; mso-ascii-font-family: &quot;\000B&quot;; mso-hansi-font-family: &quot;\000B&quot;;">μ</span><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;">m)</span><span style="FONT-SIZE: 10.5pt; mso-ascii-font-family: &quot;\000B&quot;; mso-hansi-font-family: &quot;\000B&quot;;">，端面与轴心不垂直，端面不平，对接心径不匹配和熔接质量差等。</span><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;"><p></p></span></p><p style="LINE-HEIGHT: 18pt;"><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;">&nbsp;&nbsp;&nbsp; 5</span><span style="FONT-SIZE: 10.5pt; mso-ascii-font-family: &quot;\000B&quot;; mso-hansi-font-family: &quot;\000B&quot;;">、光纤传输系统原理</span><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;"><p></p></span></p><p style="LINE-HEIGHT: 18pt;"><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;">&nbsp;&nbsp;&nbsp; </span><span style="FONT-SIZE: 10.5pt; mso-ascii-font-family: &quot;\000B&quot;; mso-hansi-font-family: &quot;\000B&quot;;">光传输系统由三部分组成：光源（光发送机），传输介质、检测器（光接收机）。</span><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;"><br/>&nbsp;&nbsp;&nbsp; </span><span style="FONT-SIZE: 10.5pt; mso-ascii-font-family: &quot;\000B&quot;; mso-hansi-font-family: &quot;\000B&quot;;">按传输信号划分，可分为数字传输系统和模拟传输系统。</span><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;"><p></p></span></p><p style="LINE-HEIGHT: 18pt;"><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;">&nbsp;&nbsp;&nbsp; </span><span style="FONT-SIZE: 10.5pt; mso-ascii-font-family: &quot;\000B&quot;; mso-hansi-font-family: &quot;\000B&quot;;">在模拟传输系统中，是把输入信号变为传输信号的振幅（频率或相位）的连续变化。光纤的模拟传输系统是把光强进行模拟调制，其光源的调制功率随调制信号的幅度变化而变化。但由于光源的非线性较严重，因此其信噪比、传输距离和传输频率都十分有限。</span><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;"><p></p></span></p><p style="LINE-HEIGHT: 18pt;"><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;">&nbsp;&nbsp;&nbsp; </span><span style="FONT-SIZE: 10.5pt; mso-ascii-font-family: &quot;\000B&quot;; mso-hansi-font-family: &quot;\000B&quot;;">数字传输系统是把输入的信号变换成“</span><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;">1</span><span style="FONT-SIZE: 10.5pt; mso-ascii-font-family: &quot;\000B&quot;; mso-hansi-font-family: &quot;\000B&quot;;">”，“</span><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;">0</span><span style="FONT-SIZE: 10.5pt; mso-ascii-font-family: &quot;\000B&quot;; mso-hansi-font-family: &quot;\000B&quot;;">”表示的脉冲信号，并以它作为传输信号。在接受端再把它还原成原来的信息。这样光源的非线性对数字码流影响很小，再加上数字通信可以采用一些编码纠错的方法，且易于实现多路复用，因此数字传输系统占有很大的优势，并在很多地方得到了广泛的应用。</span><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;"><p></p></span></p><p style="LINE-HEIGHT: 18pt;"><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;">&nbsp;&nbsp;&nbsp; </span><span style="FONT-SIZE: 10.5pt; mso-ascii-font-family: &quot;\000B&quot;; mso-hansi-font-family: &quot;\000B&quot;;">三、数字视频光传输简介</span><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;"><p></p></span></p><p style="LINE-HEIGHT: 18pt;"><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;">&nbsp;&nbsp;&nbsp; </span><span style="FONT-SIZE: 10.5pt; mso-ascii-font-family: &quot;\000B&quot;; mso-hansi-font-family: &quot;\000B&quot;;">目前在高速公路、交通、电子警察、监控、安防、工业自动化、电力、海关、水利、银行等领域视频图像、音频、数据、以太网、电话等光端机开始普遍大量应用。初期主要以模拟调频、调幅、调相的模拟光端机为主，但数字代替模拟是光纤通信技术的发展趋势。由于数字光端机具有传输信号质量高，没有模拟调频、调相、调幅光端机多路信号同传时的交调干扰严重、容易受环境影响、传输质量低劣、长期工作稳定性差的缺点，因此许多大型重点工程已普遍采用数字光端机。</span><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;"><p></p></span></p><p style="LINE-HEIGHT: 18pt;"><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;">&nbsp;&nbsp;&nbsp; </span><span style="FONT-SIZE: 10.5pt; mso-ascii-font-family: &quot;\000B&quot;; mso-hansi-font-family: &quot;\000B&quot;;">人们早就知道数字通信具有许多优点，它最适于长途通信。由于数字信号在传输过程中可以不断地通过整形和判决再生，因此它可以实现无噪声积累和无非线性失真的高质量长途传输。光纤所具有的极宽传输带宽和极小传输损耗，使数字通信的广泛应用成为可能。数字视频光传输与传统的模拟光传输相比，具有如下显著特性：</span><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;"><br/>&nbsp;&nbsp;&nbsp; 1</span><span style="FONT-SIZE: 10.5pt; mso-ascii-font-family: &quot;\000B&quot;; mso-hansi-font-family: &quot;\000B&quot;;">）</span><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;">&nbsp;</span><span style="FONT-SIZE: 10.5pt; mso-ascii-font-family: &quot;\000B&quot;; mso-hansi-font-family: &quot;\000B&quot;;">可级联，随距离的增加，</span><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;">SNR</span><span style="FONT-SIZE: 10.5pt; mso-ascii-font-family: &quot;\000B&quot;; mso-hansi-font-family: &quot;\000B&quot;;">信噪比不会下降。</span><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;"><br/>&nbsp;&nbsp;&nbsp; 2</span><span style="FONT-SIZE: 10.5pt; mso-ascii-font-family: &quot;\000B&quot;; mso-hansi-font-family: &quot;\000B&quot;;">）</span><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;">&nbsp;</span><span style="FONT-SIZE: 10.5pt; mso-ascii-font-family: &quot;\000B&quot;; mso-hansi-font-family: &quot;\000B&quot;;">由于是数字传输方式，采用数字编码纠错方式，具有高稳定性和高可靠性。</span><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;"><br/>&nbsp;&nbsp;&nbsp; 3</span><span style="FONT-SIZE: 10.5pt; mso-ascii-font-family: &quot;\000B&quot;; mso-hansi-font-family: &quot;\000B&quot;;">）</span><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;">&nbsp;</span><span style="FONT-SIZE: 10.5pt; mso-ascii-font-family: &quot;\000B&quot;; mso-hansi-font-family: &quot;\000B&quot;;">多路信号同传时，采用数字时分复用技术（</span><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;">TMD</span><span style="FONT-SIZE: 10.5pt; mso-ascii-font-family: &quot;\000B&quot;; mso-hansi-font-family: &quot;\000B&quot;;">），不会产生模拟传输时的交调失真。</span><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;"><br/>&nbsp;&nbsp;&nbsp; 4</span><span style="FONT-SIZE: 10.5pt; mso-ascii-font-family: &quot;\000B&quot;; mso-hansi-font-family: &quot;\000B&quot;;">）</span><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;">&nbsp;</span><span style="FONT-SIZE: 10.5pt; mso-ascii-font-family: &quot;\000B&quot;; mso-hansi-font-family: &quot;\000B&quot;;">稳定性好，环境适应性高，比模拟传输系统易于维护与调节。</span><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;"><br/>&nbsp;&nbsp;&nbsp; 5</span><span style="FONT-SIZE: 10.5pt; mso-ascii-font-family: &quot;\000B&quot;; mso-hansi-font-family: &quot;\000B&quot;;">）</span><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;">&nbsp;</span><span style="FONT-SIZE: 10.5pt; mso-ascii-font-family: &quot;\000B&quot;; mso-hansi-font-family: &quot;\000B&quot;;">易于实现大容量传输，且性价比高。</span><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;"><br/>&nbsp;&nbsp;&nbsp; 6</span><span style="FONT-SIZE: 10.5pt; mso-ascii-font-family: &quot;\000B&quot;; mso-hansi-font-family: &quot;\000B&quot;;">）</span><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;">&nbsp;</span><span style="FONT-SIZE: 10.5pt; mso-ascii-font-family: &quot;\000B&quot;; mso-hansi-font-family: &quot;\000B&quot;;">采用无压缩编码，图像信号质量高，达广播级。</span><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;"><p></p></span></p><p style="LINE-HEIGHT: 18pt;"><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;">&nbsp;&nbsp;&nbsp; STF</span><span style="FONT-SIZE: 10.5pt; mso-ascii-font-family: &quot;\000B&quot;; mso-hansi-font-family: &quot;\000B&quot;;">系列数字视频光端机采用国际最先进的</span><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;">10</span><span style="FONT-SIZE: 10.5pt; mso-ascii-font-family: &quot;\000B&quot;; mso-hansi-font-family: &quot;\000B&quot;;">位数字视频编码技术，图像信号可达广播级质量。视频格式兼容</span><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;">AL</span><span style="FONT-SIZE: 10.5pt; mso-ascii-font-family: &quot;\000B&quot;; mso-hansi-font-family: &quot;\000B&quot;;">、</span><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;">NTSC</span><span style="FONT-SIZE: 10.5pt; mso-ascii-font-family: &quot;\000B&quot;; mso-hansi-font-family: &quot;\000B&quot;;">、</span><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;">SECAM</span><span style="FONT-SIZE: 10.5pt; mso-ascii-font-family: &quot;\000B&quot;; mso-hansi-font-family: &quot;\000B&quot;;">制式。可采用独立式，插卡式</span><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;">(</span><span style="FONT-SIZE: 10.5pt; mso-ascii-font-family: &quot;\000B&quot;; mso-hansi-font-family: &quot;\000B&quot;;">配插卡机箱</span><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;">)</span><span style="FONT-SIZE: 10.5pt; mso-ascii-font-family: &quot;\000B&quot;; mso-hansi-font-family: &quot;\000B&quot;;">安装方式。</span><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;">&nbsp;STF</span><span style="FONT-SIZE: 10.5pt; mso-ascii-font-family: &quot;\000B&quot;; mso-hansi-font-family: &quot;\000B&quot;;">系列数字视频光端机可使用一根光纤同时传输多达</span><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;">8</span><span style="FONT-SIZE: 10.5pt; mso-ascii-font-family: &quot;\000B&quot;; mso-hansi-font-family: &quot;\000B&quot;;">路视频（采用</span><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;">CWDM</span><span style="FONT-SIZE: 10.5pt; mso-ascii-font-family: &quot;\000B&quot;; mso-hansi-font-family: &quot;\000B&quot;;">可达</span><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;">64</span><span style="FONT-SIZE: 10.5pt; mso-ascii-font-family: &quot;\000B&quot;; mso-hansi-font-family: &quot;\000B&quot;;">路）以及多路双向音频和多路双向数据。数据格式有：</span><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;">RS-232</span><span style="FONT-SIZE: 10.5pt; mso-ascii-font-family: &quot;\000B&quot;; mso-hansi-font-family: &quot;\000B&quot;;">、</span><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;">RS-422</span><span style="FONT-SIZE: 10.5pt; mso-ascii-font-family: &quot;\000B&quot;; mso-hansi-font-family: &quot;\000B&quot;;">、</span><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;">RS-485</span><span style="FONT-SIZE: 10.5pt; mso-ascii-font-family: &quot;\000B&quot;; mso-hansi-font-family: &quot;\000B&quot;;">、</span><span lang="EN-US" style="FONT-FAMILY: &quot;\000B&quot;; FONT-SIZE: 10.5pt;">Manchester</span><span style="FONT-SIZE: 10.5pt; mso-ascii-font-family: &quot;\000B&quot;; mso-hansi-font-family: &quot;\000B&quot;;">码。其前面板上有电源指示及工作状态指示。该系列数字视频光端机性能优异，是一种可靠性高、性价比好的远距离光传输系统。</span></p>