第四讲:基带传输 一、引言 二、数字信息表示法 三、基带传输过程 四、功率谱密度 五、奈奎斯特准则 六、最佳检测准则 七、比特差错率

1关键器件 以光网络构建高速、大容量的信息网络系统需要重点解决高速光传输、复用与解复用技术等问题。 (1)光纤传输 通常单模光纤(SMF)色散很大,对抑制四波混频(FWM)引起的干扰有一定作用,但需要很多的色散来补偿光纤(DCF)实践表明 SMF(G.652)和DSF(G.653)用于DWDM系统时,其自相位调制(SPM)、交叉相位调制(XPM)的危害较小,没有想象的那么严重。 过去DSF光纤的FWM干扰严重,不宜作WDM系统,然而采用拉曼放大后,其放大作用是沿光纤分布而不是集中的,因而发送的光功 率可减小,FWM干扰可降低。色散补偿是长距离大容量WDM系统必然遇到的一个问题,如果想得到一个又宽又平的波段,那么对色散 补偿器件的色散和色散斜率须有一定要求

Unit9 Part 1 Notes to Text Part 2 Word Study Part5 Notes to Passage Part3 Practice on Text Part6 Practice on Passage Part4 Extensive Reading

Unit7 Part 1 Notes to Text Part4 Extensive Reading Part 2 Word Study Part5 Notes to Passage Part3 Practice on Text Part6 Practice on Passage

Chapter Two Data Processing Unit 5 Part 1 Notes to Text Part 2 Word Study Part5 Notes to Passage Part3 Practice on Text Part6 Practice on Passage Part4 Extensive Reading

Chapter One Transition to Modern Information Science Unit3 Part 1 Notes to Text Part 2 Word Study Part5 Notes to Passage Part3 Practice on Text Part6 Practice on Passage Part4 Extensive Reading

Part 1 Notes to Text Part4 Extensive Reading Part 2 Word Study Part5 Notes to Passage Part3 Practice on Text Part6 Practice on Passage

Chapter Four Measures For Computer Security Firewall Antispyware Antivirus Antispam Unit 18 Part 1 Notes to Text

Chapter Four High-level Programming Languages e Part 1 Notes to Text m Part4 Extensive Reading o Part 2 Word Study Part5 Notes to Passage s Part3 Practice on Text Part6 Practice on Passage

Chapter Four Computer Software ordPercE x3 Unit14 Part 1 Notes to Text Part4 Extensive Reading