【正文】 頻的擴頻通信系統(tǒng)框圖。RandomInteger Generator（隨機整數(shù)發(fā)生器）產(chǎn)生的二進制隨機信號，采樣周期為 。信號饋入載頻為 3000Hz 的 MPSK Modulator Passband（通帶 MPSK 調(diào)制器）調(diào)制，調(diào)制后的單列雙極性的實信號被周期為 31 的 m 序列（通過 Relay2（繼電器）轉(zhuǎn)換為雙極性二進制序列）直接相乘進行擴頻。擴頻后的雙極性二進制的信號進入 AWGN（加性高斯白噪聲）Es/No（信噪比）為20dB 的傳輸環(huán)境以后進入接收部分。信號首先進行解擴，然后進入 MPSK Demodulator Passband（通帶 MPSK 解調(diào)器）進行解調(diào)，解調(diào)后的信號直接輸入誤碼表。擴頻、解擴的方式可以使用單極性二進制碼元用異或的方式，但是 0 的結(jié)果有時沈陽理工大學(xué)學(xué)士學(xué)位論文27處理起來有一定困難；當(dāng)信號疊加了噪聲信號后已經(jīng)不是二進制碼時，就不能用異或方式處理。使用雙極性二進制碼元用相乘的方式同樣可以完成擴頻與解擴的運算，還可以克服上述方法的不足。圖 擴頻通信系統(tǒng)框圖信源：隨機整數(shù)發(fā)生器(Randon Integer generator )作為仿真系統(tǒng)的信源，隨機整數(shù)發(fā)生器產(chǎn)生二進制隨機信號，采用時間、初始狀態(tài)可自由設(shè)置，從而滿足擴頻通信系統(tǒng)所需信源的要求。擴頻與解擴：PN 序列生成器模塊(PN Sequence Generator)作為偽隨機碼產(chǎn)生器，擴頻過程通過信息碼與 PN 碼進行雙極性變換后相乘加以實現(xiàn)。解擴過程與擴頻過程相同，即將接收的信號用 PN 碼進行第二次擴頻處理。調(diào)制與解調(diào)：使用二相相移鍵控 PSK 方式進行調(diào)制、解調(diào)。調(diào)制由正弦載波與雙極性擴頻碼直接相乘實現(xiàn)，采用相干解調(diào)法進行解調(diào)。信道：傳輸新到位加性高斯白噪聲信道。在加性高斯白噪聲信道模塊中，可進行信號功率和信噪比的設(shè)置。誤碼計算：誤碼計算由誤碼儀實現(xiàn)，誤碼儀在通信系統(tǒng)中的主要任務(wù)是評估傳輸系統(tǒng)的誤碼率，它具有兩個輸入端口：第一個端口(Tx)接收發(fā)送方的輸入信號，第二個端口(Rx )接收接收方的輸入信號。在系統(tǒng)框圖搭建完畢后，還需設(shè)置功能模塊參數(shù)，才可進行仿真操作。不同功能模塊的參數(shù)是不相同的，用鼠標(biāo)雙擊該功能模塊自動彈出相應(yīng)的參數(shù)設(shè)置對話框。沈陽理工大學(xué)學(xué)士學(xué)位論文28圖 PN Sequence Generator 模塊對話框如圖 所示為 PN Sequence Generator（偽隨機序列產(chǎn)生器）主要參數(shù)。沈陽理工大學(xué)學(xué)士學(xué)位論文29圖 RandomInteger Generator 模塊對話框如圖 所示為 RandomInteger Generator（隨機整數(shù)發(fā)生器）的主要參數(shù)。圖 MPSK Modulator Passband 模塊對話框如圖 所示為 MPSK Modulator Passband（通帶 MPSK 調(diào)制器）的主要參數(shù)。沈陽理工大學(xué)學(xué)士學(xué)位論文30圖 MPSK Demodulator Passband 模塊對話框如圖 所示為 MPSK Demodulator Passband（通帶 MPSK 解調(diào)器）的主要參數(shù)。圖 Relay 模塊對話框如圖 所示為 Relay（繼電器）的主要參數(shù)。沈陽理工大學(xué)學(xué)士學(xué)位論文31圖 Error Rate Calculation 模塊對話框如圖 所示為 Error Rate Calculation（誤碼率計算器）的主要參數(shù)。此系統(tǒng)在沒有差錯控制的情況下，通過 Es/No(信噪比)為20dB 的傳輸環(huán)境可以達到誤碼率為 %的通信質(zhì)量，結(jié)果如圖 所示。 圖 擴頻通信系統(tǒng)誤碼率圖沈陽理工大學(xué)學(xué)士學(xué)位論文32結(jié) 論通過四個月的學(xué)習(xí)和研究，本題目基于 MATLAB 的擴頻通信系統(tǒng)仿真研究已經(jīng)順利完成。經(jīng)過設(shè)計，分析的結(jié)果均能達到題目中的要求。學(xué)習(xí)了 MATLAB 中 Simulink 這一簡歷系統(tǒng)方框圖和基于方框圖級的仿真環(huán)境。首先，我分別用構(gòu)建反饋移位寄存器和應(yīng)用 PN Sequence Generator（偽隨機序列產(chǎn)生器）模塊兩種方法對 m 序列進行了仿真，并對 m 序列的相關(guān)性進行了討論。之后，對擴頻通信原理進行了仿真，了解了擴頻這一過程的原理。最后，利用 Simulink 搭建了擴頻通信系統(tǒng)原理框圖并進行了仿真，此系統(tǒng)在沒有差錯控制的情況下，通過 Es/No（信噪比）為20dB 的傳輸環(huán)境可以達到誤碼率為 %的通信質(zhì)量。但遺憾的是，沒有進一步對擴頻增益和信噪比的關(guān)系進行進一步分析。綜上所述，本人較圓滿地完成了畢業(yè)設(shè)計課題所要求的內(nèi)容，基本達到了預(yù)期的目的。沈陽理工大學(xué)學(xué)士學(xué)位論文33致 謝本設(shè)計的完成是在我們的導(dǎo)師孟憲江老師的細心指導(dǎo)下進行的。在每次設(shè)計遇到問題時老師不辭辛苦的講解才使得我的設(shè)計順利的進行。從設(shè)計的選題到資料的搜集直至最后設(shè)計的修改的整個過程中，花費了孟老師很多的寶貴時間和精力，在此向?qū)煴硎局孕牡馗兄x！導(dǎo)師嚴(yán)謹(jǐn)?shù)闹螌W(xué)態(tài)度，開拓進取的精神和高度的責(zé)任心都將使學(xué)生受益終生！ 還要感謝和我同一設(shè)計小組的幾位同學(xué)，是你們在我平時設(shè)計中和我一起探討問題，并指出我設(shè)計上的誤區(qū)，使我能及時的發(fā)現(xiàn)問題把設(shè)計順利的進行下去，沒有你們的幫助我不可能這樣順利地結(jié)稿，在此表示深深的謝意。沈陽理工大學(xué)學(xué)士學(xué)位論文34參考文獻[1] Roger ,2022:39[2] 樊昌信,曹麗娜 .,2022: 147151[3] MATLAB ,2022:4144[4] ,2022:308327[5] 王立寧． MATLAB 與通信仿真 [M].人民郵電出版社,2022:5055[6] 劉學(xué)勇. MATLAB 通信系統(tǒng)建模與仿真 .電子工業(yè)出版社 ,2022:293309[7] ,2022:2025[8] John G. Proakis 著．張力軍,張宗橙,鄭寶玉譯．?dāng)?shù)字通信．電子工業(yè)出版社,2022:5558[9] 王華，李有軍，劉建存．MATLAB 電子仿真．國防教育出版社 ,2022:418420沈陽理工大學(xué)學(xué)士學(xué)位論文35附 錄附錄 A 英文原文Spread Spectrum TechniquesAbstract:Spreadspectrum techniques are methods by which a signal (. an electrical, electromagic, or acoustic signal ) generated in a particular bandwidth is deliberately spread in the frequency domain, resulting in a signal with a wider bandwidth. These techniques are used for a variety of reasons, including the establishment of secure munications, increasing resistance to natural interference and jamming, to prevent detection, and to limit power flux density (. in satellite downlinks).History Frequency hopping:The concept of frequency hopping was first alluded to in the 1903 . Patent 723,188 and . Patent 725,605 filed by Nikola Tesla in July 1900. Tesla came up with the idea after demonstrating the world39。s first radiocontrolled submersible boat in 1898, when it became apparent the wireless signals controlling the boat needed to be secure from being disturbed, intercepted, or interfered with in any way. His patents covered two fundamentally different techniques for achieving immunity to interference, both of which functioned by altering the carrier frequency or other exclusive characteristic. The first had a transmitter that worked simultaneously at two or more separate frequencies and a receiver in which each of the individual transmitted frequencies had to be tuned in, in order for the control circuitry to respond. The second technique used a variablefrequency 沈陽理工大學(xué)學(xué)士學(xué)位論文36transmitter controlled by an encoding wheel that altered the transmitted frequency in a predetermined manner. These patents describe the basic principles of frequency hopping and frequencydivision multiplexing, and also the electronic ANDgate logic circuit.Frequency hopping is also mentioned in radio pioneer Johannes Zenneck39。s book Wireless Telegraphy (German, 1908, English translation McGraw Hill, 1915), although Zenneck himself states that Telefunken had already tried it several years earlier. Zenneck39。s book was a leading text of the time, and it is likely that many later engineers were aware of it. A Polish engineer, Leonard Danilewicz, came up with the idea in other patents were taken out in the 1930s, including one by Willem Broertjes (Germany 1929, . Patent 1,869,695, 1932). During World War II, the US Army Signal Corps was inventing a munication system called SIGSALY for munication between Roosevelt and Churchill, which incorporated spread spectrum, but due to its top secret nature, SIGSALY39。s existence did not bee known until the 1980s.The most celebrated invention of frequency hopping was that of actress Hedy Lamarr and poser Gee Antheil, who in 1942 received . Patent 2,292,387 for their Secret Communications System. Lamarr had learned about the problem at defense meetings she had attended with her former husband Friedrich Mandl, who was an Austrian arms manufacturer. The AntheilLamarr version of frequency hopping used a pianoroll to change among 88 frequencies, and was intended to make radioguided torpedoes harder for enemies to detect or to jam. The patent came to light during patent searches in the 1950s when ITT Corporation and other private firms began to develop Code Division