【正文】 ess munications, so the technology is receiving increasing recent years, with very large scale integrated circuit technology, the rapid development of microprocessor technology, as well as the application of some new ponents, spread spectrum munications is technically feasible to enter a new level, not only in an important military munications status, and are quickly perated into the personal munications and puter munications and other civilian areas, to bee the new century, the most potential of munication study is spread spectrum munication with farreaching significance, I through the thesis the design, conduct indepth study of the spread spectrum munication technology and its applications for simulation, knowledge will be summarized and summed in order to consolidate the basic knowledge of munications for the After the individual to lay a foundation to study and work. 2 The basic principles of spread spectrum munication The definition of spread spectrum munication The socalled spread spectrum munications, can be simply expressed as follows:Spread spectrum munication technology is a means of information transmission,Share some of its signal bandwidth is much larger than the minimum mass of information necessary bandwidth。 TECHNOLOGY 外文翻譯 題目： 擴(kuò)頻通信系統(tǒng)及 MATLAB 仿真 學(xué) 生 姓 名 學(xué) 號(hào) 班 級(jí) 通信 072201H 所屬院（系） 電子信息工程系 指 導(dǎo) 教 師 2021 年 6 月 1 Spread Spectrum Communication System and MATLAB Simulation ABSTRACT This thesis expounds the basic principles of spread spectrum munication , and then the article mainly acts according to the Shannon theorem and tan oak Czechoslovakia you Nepal may the husband latent antijamming theory,With the aid of MatLab toolbox and Monte Carlo simulation algorithm,it has established the direct sequence spread spectrum munications system simulation model which does not have when the disturbance through the analysis error rate simulation curve and theory predicted value,had proven constructs the simulation model the accuracy. Key words： Spread spectrum； munication； MATLAB 1 Introduction Spread Spectrum Communication System Spread spectrum munication, namely, spread spectrum munications (Spread Spectrum Communication), with fiberoptic munications, satellite munications, with access to the information age as the three major hightech munications spectrum munication is to send the information to be pseudorandom data is coded (spread spectrum sequence: Spread Sequence) modulation, spread spectrum and then the realization of transmission。 the receiving end is using the same modem code and related processing, the restoration of the original spectrum munication system has three main characteristics. Carrier is an unpredictable, or socalled pseudorandom broadband signal. Carrier data bandwidth than the modulation bandwidth is much wider. Receiving process is generated by local broadband carrier signal and receiving a copy of the signal to the broadband signal to achieve. The main way of spread spectrum are as follows:Direct Sequence Spread Spectrum (DSSS) using highspeed pseudorandom code on to the lowspeed data transmission spread spectrum modulation。The expansion of the band through a separate code sequence to plete, using the method of coding and modulation to achieve, with the mass of information has nothing to do。s , the processing gain G reflects the spread spectrum munication system to improve the level of signal to noise ratio. 2) interference tolerance Spread spectrum munication system refers to how much interference in the environment39。 C for more information. (7) means that in a given signal power S and noise power N of the conditions, using a coding system to a very small bit error rate of close to C transmission of information transfer rate. Baryshnikov in accordance with theory, we can see: )/( 0e NEFP? （ 8） Where: eP For the bit error rate。 1) information and data, Repeat for each information CL Times, CL Correspond to the information contained in each of the pseudocode chip number, a random number generator PN Sequence )(nc Multiplied,And then superimposed on the sequence of variance for 2/02 N?? Gaussian white noise and the form of nAni 0sin)( ?? Sinusoidal interference signal, which ?? ?? 00 and CLA? .In the demodulator, PN sequence with interrelated operations Information and will form the sum of d and will form the sum of CL output will be sent to decision, and on the signal and threshold 0 to determine the data transmission +1 or 1, Figure 2 in the counter39。 1 引言 擴(kuò)頻通系統(tǒng)概述 擴(kuò)頻通信，即擴(kuò)展頻譜通信 (Spread Spectrum Communication)，它與光纖通信、衛(wèi)星通信，一同被譽(yù)為進(jìn)入信息時(shí)代的三大高技術(shù)通信傳輸方式。幾種方式組合的混合系統(tǒng)也經(jīng)常得到應(yīng)用。擴(kuò)頻技術(shù)具有抗干擾能力強(qiáng)、保密性好、易于實(shí)現(xiàn)多址通信等優(yōu)點(diǎn)，因此該技術(shù)越來越受到人們的重視。這一定義包含了以下三方面的意思： 1）信號(hào)的頻譜被展寬了。在無線電通信中射頻信號(hào)的帶寬與所傳信息的帶寬是相比擬的。擴(kuò)展頻譜通信信號(hào)帶寬與信息帶寬之比則高達(dá) 100 1000，屬于寬帶通信 。信號(hào)的頻帶寬度與其持續(xù)時(shí)間近似成反比。這種很窄的脈沖碼序列，其碼速率是很高的，稱為擴(kuò)頻碼序列。 正如在一般的窄帶通信中，已調(diào)信號(hào)在接收端都要進(jìn)行解調(diào)來恢復(fù)所傳的信息。這種在發(fā)端把窄帶信息擴(kuò)展成寬帶信號(hào)，而在收端又將其解擴(kuò)成窄帶信息的處理過程，會(huì)帶來一系列好處。擴(kuò)頻通信的基本特點(diǎn)是傳輸信號(hào)所占用的頻帶寬度 (W)遠(yuǎn)大于原始信息本身實(shí)際所需的最小 (有效 )帶寬 (DF)，其比值稱為處理增益 Gp: FWGP ?? / (1) 眾所周知，任何信息的有效傳輸都需要一定的 頻率寬度，如話音為 ，電視圖像則寬到數(shù)兆赫。擴(kuò)頻通信的可行性，是從信息論和抗干擾理論的基本公式中引伸而來的。 擴(kuò)頻通信可行性的另一理論基礎(chǔ)，為柯捷爾尼可夫關(guān)于信息傳輸差錯(cuò)概率的公式： ）（ 0j /fow NEP ? （ 3） 式中： jPow 差錯(cuò)概率 E 信號(hào)能量 0N 噪聲功率譜密度 信號(hào)功率 TEP /? (T 為信息持續(xù)時(shí)間 ) 噪聲功率 0WNN? (W 為信號(hào)頻帶寬度 ) 15 信息帶寬 TDF /1? 則式 (3)可化為： )//(/ow FWNPfNPTWfP ????? ）（ （ 4） 式 (4)說明，對(duì)于一定帶寬 DF 的信息而言，用 PG 值較大的寬帶信號(hào)來傳輸，可以提高通信抗干擾能力，保證強(qiáng)干擾條件下，通信的安全可靠。 擴(kuò)頻通信的主要性能指標(biāo) 1）處理增益和抗干擾容限是擴(kuò)頻通信系統(tǒng)的兩個(gè)重要性能指標(biāo)。 16 圖 1 數(shù)字?jǐn)U頻通信系統(tǒng)基本框圖 圖 1 所示為一個(gè)數(shù)字?jǐn)U頻通信系統(tǒng)的基本框圖。 3 擴(kuò)頻通信系統(tǒng)的特點(diǎn) 擴(kuò)頻信號(hào)是不可預(yù)測(cè)的偽隨機(jī)的寬帶信號(hào) ,其帶寬遠(yuǎn)大于欲傳輸數(shù)據(jù) (信息 ) 帶寬 ,同時(shí) ,接收機(jī)中必須有與寬帶載波同步的副本。 低截獲性 擴(kuò)頻信號(hào)的功率相當(dāng)于均勻地被分布在很寬的頻帶上 ,以至于被傳輸信號(hào)的功