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在现今新技术革命的高速推动下，在信息高速公路建设和全球网络化发展浪潮的推动下，通信技术得到迅猛发展，载波通信、卫星通信和移动通信技术正在向数字化、智能化、宽带化发展。信息的数字转换处理技术走向成熟，为大规模、多领域的信息产品制造和信息服务创造了条件。高新技术层出不穷。随着通信技术的发展，通信系统方面的设计也会越来越复杂，利用计算机软件的仿真，可以大大地降低通信过程中的实验成本。本文设计出一个QPSK仿真模型，以分析QPSK在高斯信道中的性能，通过此次实验，可以更好地了解QPSK系统的工作原理。正交相移键控，是一种数字调制方式。四相绝对移相键控(QPSK)技术具有抗干扰能力好、误码率低、频谱利用效率高等一系列优点。现正广泛地应用于数字微波通信系统、数字卫星通信系统、宽带接入、移动通信和有线电视系统之中。论文主要介绍了正交相移键控(QPSK)的概况，以及正交相移键控(QPSK)的调制解调概念和原理，传输比特错误率和符号错误率的计算，了解Simulink中涉及到QPSK的各种模块的功能，利用Matlab中的Simulink模块对QPSK的调制解调系统进行了仿真，对QPSK在高斯白噪声信道中的性能进行分析。其中解调器使用相关器接收机。通过多次运行仿真得到比特错误率与信噪比之间的关系。【关键词】MatlabQPSKSimulnk仿真ABSTRACTDrivenbythehigh-speedrevolutionofnewtechnology,theinformationhighwayconstructionandglobalnetworkdevelopment,communicationtechnologyhasrapidlydeveloped.Carriercommunication,satellitecommunicationsandmobilecommunicationtechnologyarealsodevelopedindigital,intelligent,broadbandway.Thetechnologyofinformationdigitalconversionbecamematurewhichcancreateabettercircumstanceforinformationproductsmanufacturinganinformationservice.Advancedtechnologyaretoemergeinanendlessstream.Asthedevelopmentofthecommunicationtechnology,communicationsystemdesignalsowillbemoreandmorecomplicated,theuseofcomputersoftwareofthesimulation,cangreatlyreducethecostintheprocessofcommunication.ThispaperdesignedaQPSKsimulationmodeltoanalyzetheperformanceoftheGaussianchannelQPSK.Throughthisexperiment,wecanbetterunderstandQPSKsystemprincipleofwork.QPSKisakindofdigitalmodulationmodewhichhasaseriesofadvantages,suchastheanti-interferenceability,lowBER(BitErrorRate),spectrumefficiency.QPSKiswidelyusedindigitalmicrowavecommunicationsystem,digitalsatellitecommunicationsystem,broadbandaccess,mobilecommunicationandcableTVsystemnow.ThispapermainlyintroducedisthesituationofQPSK,andtheconceptandprincipleofdemodulation.Toknowthetransmissionerrorrateandsymbolscalculation,thenunderstandthefunctionofthevariousmodulesinsimulinkusingQPSKmoduleofthesimulinkindemodulationsystem.ItcanalsoanalysistheQPSKGaussianwhitenoiseinthechannelperformance.Usingofmodemcorrelatorreceiverthroughtherunmultipletimesitcangetbiterrorratesimulationandtherelationshipbetweenthesignal-to-noiseratio.【Keywords】MatlabQPSKSimulinkSimulation目录前言...................................................................................................................................1第一章正交相移键控(QPSK)系统概述..........................................................................2第一节QPSK的系统简介.........................................................................................2第二节论文的仿真意义..............................................................................................3第三节论文的主要内容和任务..................................................................................3一、研究主要内容.................................................................................................3二、论文需要完成的任务.....................................................................................4第四节本章小结..........................................................................................................4第二章基带数字信号传输...............................................................................................6第一节二进制信号的传输........................................................................................6一、基带信号.........................................................................................................6二、加性高斯白噪声(AGWN)下的最佳接收机..................................................7三、双极性矩形波的最佳接收机.........................................................................7第二节多维信号的传输与最佳接受机......................................................................9一、多维正交信号.................................................................................................9二、AGWN下的多进制信号传输........................................................................9三、检测器...........................................................................................................10第三节本章小结........................................................................................................11第三章QPSK的调制与解调............................................................................................12第一节数字调相的介绍..........................................................................................12第二节QPSK的产生方法.......................................................................................12一、相乘法...........................................................................................................12二、选择法...........................................................................................................12第三节QPSK的调制与解调原理.............................................................................13第四节本章小结......................................................................................................15第四章基于Simulink的QPSK系统仿真分析..............................................................17第一节Simulink平台简介........................................................................................17一、MATLAB简介............................................................