【正文】 d of design of frequency modulation launch circuit. It uses the wireless frequency transmission chip BH1415F, its emissive is controlled by AT89C52 SCM (Single Chip Microcosm), and the peripheral circuit integrates the crystal module1602 showing the launch frequency. The operation is more directly and convenient, and the frequency launched by the circuit is paratively stable and has strong antijamming ability. It is fit for changing all kinds of frequency signal into a fixed frequency modulation signal of frequency and launching wirelessly. Key words: Digital Transmitter BH1415 AT89C52 digitization control LCD1602 the frequency modulation launch 蘭州交通大學畢業(yè)設(shè)計（論文） III 目 錄 摘 要 ................................................................................................................................. I Abstract...............................................................................................................................II 1. 緒論 ........................................................................................................................... 1 課題背景 ........................................................................................................ 1 無線通信系統(tǒng)概述 ........................................................................................ 2 模擬通信系統(tǒng) .......................................................................................... 2 數(shù)字通信系統(tǒng) .......................................................................................... 2 通信系統(tǒng)的主要性能指 標 ...................................................................... 4 發(fā)射機概述 .................................................................................................... 6 發(fā)射機的技術(shù)指標 .................................................................................. 7 2. 調(diào)頻發(fā)射機概述 ....................................................................................................... 8 發(fā)射機的電路結(jié)構(gòu) .............................................................................................. 8 間接調(diào)制發(fā)射機體系結(jié)構(gòu) ...................................................................... 8 直接調(diào)制發(fā)射機體系結(jié)構(gòu) ...................................................................... 8 偏移壓控振蕩器的直接調(diào)制發(fā)射機體系結(jié)構(gòu) ...................................... 9 基于鎖相環(huán)的直接調(diào)制壓控振蕩器發(fā)射機體系結(jié)構(gòu) ......................... 10 基于鎖相環(huán)的輸入基準調(diào)制發(fā)射機體系結(jié)構(gòu) ..................................... 11 BH1415 芯片 ................................................................................................... 11 芯片簡介 ................................................................................................ 11 芯片特點 ................................................................................................ 12 芯片引腳以及參數(shù)說明 ........................................................................ 12 3. 調(diào)頻發(fā)射機硬件電路設(shè)計 ..................................................................................... 15 BH1415 芯片電路 ........................................................................................... 15 預(yù)加重電路 ............................................................................................ 15 限幅電路 ................................................................................................ 16 低通濾波電路 ........................................................................................ 17 立體聲調(diào)頻 ............................................................................................ 17 FM 發(fā)射電路 .......................................................................................... 18 鎖相環(huán)電路 ............................................................................................ 18 蘭州交通大學畢業(yè)設(shè)計（論文） IV 單片機控制電路 .......................................................................................... 19 單片機介紹 ............................................................................................ 19 控制 BH1415 頻率 的方法 .................................................................... 21 單片機與芯片的連接 ............................................................................ 21 4. 調(diào)頻發(fā)射機的軟件程序設(shè)計 ................................................................................. 23 BH1415 的控 制模塊 ....................................................................................... 23 利用鍵盤控制 BH1415 的發(fā)射頻率值 ....................................................... 23 5. 調(diào)頻發(fā)射機的調(diào)試 ................................................................................................. 26 硬件部分調(diào)試 .............................................................................................. 26 軟件部分的調(diào)試 .......................................................................................... 26 系統(tǒng)整體調(diào)試 .............................................................................................. 27 結(jié)論 .................................................................................................................................. 29 致謝 .................................................................................................................................. 30 參考文獻 .......................................................................................................................... 31 附件一 .............................................................................................................................. 32 附件二 .............................................................................................................................. 33 蘭州交通大學畢業(yè)設(shè)計（論文） 1 1. 緒論 課題背景 隨著科技的發(fā)展， 通信在我們的生活中已經(jīng)變得愈發(fā)愈重要，廣義的說，通信即為發(fā)信者和收信者之間傳遞消息的 各種 方式。 ⑥ 噪聲是在傳輸過程中必須出現(xiàn)的干擾，這種干擾來自系統(tǒng)內(nèi)部和外部。 受信者則需要把接受到的信號轉(zhuǎn)化為原來的信息。這種傳輸控制技術(shù)大幅度的提高了信息的傳輸質(zhì)量。 由于數(shù)字通信系統(tǒng)具備以上優(yōu)點，數(shù)字通信系統(tǒng)的發(fā)展已經(jīng)成為當今社會的主流。 蘭州交通大學畢業(yè)設(shè)計（論文） 6 ???? = 傳錯的比特數(shù)傳輸?shù)目偙忍財?shù) 式 () 發(fā)射機概述 發(fā)射機和接收機是無線電通信系統(tǒng)核心的兩個部件， 收發(fā)系統(tǒng)通常工作在時分雙工（ TDD）或者頻分雙工 (FDD)方式下。此外，在中頻和射頻之間，實現(xiàn)高階低通濾波器的困難， 導致寄生信號（中頻的幾倍）的不完全被抑制。 基于鎖相環(huán)的直接調(diào)制壓