【正文】 e simple, the debugging more convenient and the performance more stable and reliable. In addition, this sweep generator can make stepping measurementautomatically in the whole frequency range. We can preset measuring range and stepping frequency, so the detailed frequency characterist ic curves can be seen clearly. This function brings users much convenience. Key words: sweep generator DDS techonology gain control 目 錄 摘 要 .............................................................................................................................................. I ABSTRACT ....................................................................................................................................II 第一章 緒論 ................................................................................................................................... 1 掃頻儀簡介 ...................................................................................................................... 1 掃頻儀的分類及其簡介 ................................................................................................... 1 第二章 便攜式掃頻儀器方案的選擇 ......................................................................................... 7 掃頻儀基本知識 ................................................................................................................ 7 掃頻儀的功能與用途 .............................................................................................. 7 基本測量原理 .......................................................................................................... 7 系統(tǒng)的 主要性能指標 ...................................................................................................... 8 總體方案設(shè)計與論證 ....................................................................................................... 9 方案一介紹 ............................................................................................................. 9 方案二介紹 ............................................................................................................. 9 方案比較 .......................................................................................................................... 10 總體方案確立 ................................................................................................................. 11 第三章 單元電路設(shè)計與分析 ..................................................................................................... 12 單片機主控模塊的設(shè)計與分析 ...................................................................................... 12 單片機簡介 .............................................................................................. 12 單片機主控電路 .................................................................................................... 16 信號發(fā)生模塊電路設(shè)計與分析 ..................................................................................... 17 AD9851 芯片簡介 .............................................................................................. 17 信號發(fā)生模塊電路 ............................................................................................... 18 ALC 寬帶放大器的設(shè)計與分析 ................................................................................ 19 電源電路模塊的設(shè)計與分 ............................................................................................. 20 LCD 顯示模塊電路 ....................................................................................................... 21 LCD 芯片簡介 ....................................................................................................... 21 LCD192X64 顯示電路 ....................................................................................... 23 ，檢波電路 ....................................................................................................................... 24 檢波電路的基本介紹： ........................................................................................ 24 檢波電路原理 ....................................................................................................... 27 第四章 軟件部分簡介 ................................................................................................................. 28 主程序模塊 .................................................................................................................... 28 AD9851 電路驅(qū)動程序 ................................................................................................... 29 總 結(jié) ............................................................................................................................................. 30 參考文獻 ....................................................................................................................................... 31 致 謝 ......................................................................................................................................... 32 南昌工程學(xué)院本科畢業(yè)設(shè)計（論文） 1 第一章 緒論 掃頻儀 簡介 在電子測量中，經(jīng)常遇到對網(wǎng)絡(luò)的阻抗特性和傳輸特性進行測量的問題，其中傳輸特性包括增益和衰減特性、幅頻特性、相頻特性等。它為被測網(wǎng)絡(luò)的調(diào)整，校準及故障的排除提供了極大的方便。其基本工作過程是通過電源變壓器將 50Hz 市電降壓后送入掃描鋸齒波發(fā)生器，就形成了鋸齒波，這個鋸齒波一方面控制掃頻信號發(fā)生