【正文】 3 Abstract ............................................................................................................................ 4 第一章 數(shù)字微波通信概述 .............................................................................................. 5 緒論 .................................................................................................................. 5 數(shù)字微波通信發(fā)展概況 ...................................................................................... 5 數(shù)字微波通信的主要特點(diǎn) .................................................................................. 6 通信頻段的頻帶寬 ................................................................................... 6 受外界干擾的影響小 ................................................................................ 6 通信靈活 ................................................................................................. 6 天線增益高、方向性強(qiáng) ............................................................................ 6 投資少、建設(shè)快 ....................................................................................... 7 數(shù)字微波通信系統(tǒng)的組成 .................................................................................. 7 用戶終端 ................................................................................................. 9 交換機(jī) ..................................................................................................... 9 數(shù)字終端機(jī) .............................................................................................. 9 微波站 ..................................................................................................... 9 第二章 數(shù)字微波中繼通信中的中繼方式 ....................................................................... 10 再生轉(zhuǎn)接方式 ...................................................................................................11 中頻轉(zhuǎn)接方式 ...................................................................................................11 微波轉(zhuǎn)接方式 .................................................................................................. 12 直放轉(zhuǎn)接和無源轉(zhuǎn)接方式 ................................................................................ 12 中繼方式的選擇 .............................................................................................. 13 第三章 數(shù)字微波發(fā)信設(shè)備 ............................................................................................ 14 發(fā)信設(shè)備的組成 .............................................................................................. 14 微波調(diào)制發(fā)射機(jī) ..................................................................................... 14 中頻調(diào)制發(fā)射機(jī) ..................................................................................... 14 發(fā)信設(shè)備的主要性能指標(biāo) ................................................................................ 15 1 工作頻段 ............................................................................................... 15 輸出功率 ............................................................................................... 15 頻率穩(wěn)定度 ............................................................................................ 16 干擾與噪聲 ............................................................................................ 16 第四章 數(shù)字微波收信設(shè)備 ............................................................................................ 17 數(shù)字微波收信設(shè)備 ........................................................................................... 17 收信設(shè)備的主要性能指標(biāo) ................................................................................ 18 工作頻段 ............................................................................................... 18 噪聲系數(shù) ............................................................................................... 18 本振頻率穩(wěn)定度 ..................................................................................... 18 通頻帶 ................................................................................................... 18 選擇性 ................................................................................................... 18 最大增益與自動增益控制范圍 ................................................................ 19 第五章 數(shù)字微波天線設(shè)備 ............................................................................................ 20 微波通信對天線設(shè)備的要求 ............................................................................. 20 天線增益 ......................................................................................................... 20 天線方向圖 ..................................................................................................... 20 第六章 數(shù)字調(diào)制設(shè)備 ................................................................................................... 22 數(shù)字調(diào)制設(shè)備的組成 ....................................................................................... 22 擾碼電路 ............................................................................................... 22 串 — 并行變換 ........................................................................................ 22 差分編碼電路 ........................................................................................ 23 四電平形成電路 ..................................................................................... 23 頻譜成形濾波器 ..................................................................................... 23 載波產(chǎn)生電路 ........................................................................................ 23 調(diào)制器電路 ............................................................................................ 24 數(shù)字調(diào)制設(shè)備的主要性能指標(biāo) ......................................................................... 24 鍵控信號的調(diào)制誤差 .............................................................................. 24 鍵控信號發(fā)送譜特性 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