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题目：DQPSK调制解调技术的研究与实现学生姓名：学号：专业班级：指导教师：完成时间：I目录摘要...........................................................................................................................................IAbstract......................................................................................................................................II第一章绪论..............................................................................................................................11.1课题背景......................................................................................................................11.2DQPSK调制技术与数字通信.....................................................................................2第二章DQPSK调制与解调原理分析....................................................................................52.1DQPSK信号特点.........................................................................................................52.2差分编码与解码原理................................................................................................102.3FPGA实现方案..........................................................................................................12第三章DQPSK信号调制......................................................................................................143.1调制器总体设计方案................................................................................................143.2串并转换....................................................................................................................143.3差分编码....................................................................................................................153.4FIR滤波器设计..........................................................................................................173.5数字载波....................................................................................................................18第四章DQPSK信号解调......................................................................................................204.1解调器总体方案........................................................................................................204.2AD采样.......................................................................................................................204.3同步设计....................................................................................................................224.3.1COSTAS载波跟踪环.......................................................................................224.3.2位定时同步......................................................................................................264.4差分解码....................................................................................................................264.5并串转换....................................................................................................................29总结........................................................................................................................................30参考文献..................................................................................................................................31致谢........................................................................................................................................32I摘要QPSK（quadraturephaseshiftkeying）是四相移键控的简称，它兼有两方面的特性；从一方面看，它采用了4种相位；从另一方面看，它采用了正交的载波。DQPSK是差分四相移键控（differentialQPSK）的简称，是结合差分编码的QPSK。DQPSK调制解调方式以其抗干扰能力强、频带利用率高等优点，在现代数字通信系统如数字微波通信、等宽带无线通信等中得到广泛的应用。DQPSK是在QPSK(四相正交绝对调相)的基础上作的改进，它克服了QPSK信号载波的相位模糊问题，用相邻码元之间载波相位的相对变化来表示2位二进制数字信息。由于DQPSK传输信息的特有方式，使得解调时不存在相位模糊问题，这是因为不论提取的载波取什么起始相位，对相邻两个四进制码元来说都是相等的，那么相邻两个四进制码元的相位差肯定与起始相位无关，也就不存在由于相干解调载波起始相位不同而引起的相位模糊问题，所以，在使用中都采用相对的四相调制。本课题对DQPSK调制解调技术的FPGA实现进行了比较全面的研究,主要介绍了DQPSK调制解调技术,完成了FIR滤波器、载波跟踪环、位定时同步、并串转换等几个关键模块的设计。关键字：DQPSK；FPGA;FIR；载波同步IIAbstractQPSK(quadraturephaseshiftkeying)isafour-phaseshiftkeyingshort,itcombinescharacteristicsofboth;Fromoneangle,itusesfourkindsofphase;Ontheotherhand,itusestheorthogonalcarriers.DQPSKisdifferentialquadraturephaseshiftkeying(differentialQPSK)forshort,isacombinationofdifferentiallyencodedQPSK.DQPSKmodulationanddemodulationforitsanti-interferenceability,bandwidthefficiencyadvantages,hasbeenwidelyusedinmoderndigitalcommunicationsystemssuchasdigitalmicrowavecommunications,broadbandwirelesscommunications,etc..DQPSKismadeintheQPSK(QuadraturePhasequadratureabsolutephasemodulation)basedontheimprovementwhichovercomestheQPSKsignalcarrierphaseambiguities,therelativecarrierphasechangesbetweentheadjacentsymbolsisrepresentedby2-bitbinarydigitalinformation.DuetotheuniquewayDQPSKtransmissionofinformation,makingthephaseambiguityproblemdoesnotexistwhenthedemodulation,thisisbecausenomatterwhattheinitialextractionphaseofthecarriertakesontwoadjacentquaternarysymbolforbothequal,thenphaseotwophasequaternarysymbolscertainlynothingtodowiththestartingphase,thephasedoesnotexistbecausethestartingphasecoherentdemodulationcarrierblurcausedbydifferentproblems,therefore,areinusefour-phasemodulationusingrelatively.ThistopicDQPSKmodulationanddemodu