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ID:11606247
大小:983.00 KB
页数:53页
时间:2018-07-12
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1、单工无线呼叫系统(D题)摘要:单工无线呼叫系统分发射和接收两大部分。发射部分采用锁相环式频率合成器技术,MC145152和MC12022芯片组成锁相环,将载波频率精确锁定在35MHz,输出载波的稳定度达到4×10-5,准确度达到3×10-5,由变容二极管V149和集成压控振荡器芯片MC1648实现对载波的调频调制;末级功放选用三极管2SC1970,使其工作在丙类放大状态,提高了放大器的效率,输出功率达到设计要求。接收部分以超大规模AM/FM立体声收音集成芯片CXA1238S为主体,灵敏度、镜像抑制、信噪比等各项性能指标均
2、达到设计要求;音频功率放大器采用集成芯片LM386,电压放大倍数最大为200。采用PT2262/2272编码/解码电路实现了数据传输业务以及对台号的选择等功能;音频输入和数据输入可自动转换;AT89S52作为整个系统的控制部分,程序设计采用C语言在KEIL51的编译器上编程实现;显示采用128×64点阵型液晶显示。经测试,整机功能齐全,各项性能指标符合系统要求,接收波形稳定,无明显失真。关键词:锁相环、压控振荡器、灵敏度、编码/解码simplexwireless-callingsystemAbstract:Thesimp
3、lexwireless-callingsystemconsistsoftwoparts:transmitpartandreceivepart.Thetransmitpartadoptsthephase-lockedlooppatternoffrequencysynthesizingtechnologyandusestheMC145152andMC12022chipstocomposethephase-lockedloop.Itlocksthefrequencyofthecarrier-waveat35MHz.Thesta
4、bilizationofthecarrier-wavecanbe4×10-5,theaccuracycanbe3×10-5.Thefrequencymodulationandtheconfectionofthecarrier-wavearerealizedbythecapacity-changingdiodeV149andtheintegrationvoltage-controloscillatorMC1648chip.Theendpoweramplifierusestheaudion2SC1970tomakeitwor
5、kinthethirdmagnifyingstate,itimprovestheefficiencyofthemagnifierandthepoweroftheoutputreachesthedesigndemand.ThereceivepartusesthesupercosmicallyAM/FMdimensionalsoundstereoradioreceptionintegrationchipCXA1238Sasthemainpart.Thesensitivity、themirror-controlrestrain
6、、theSNRandeverycapabilityindexallreachthedesigndemand.TheaudiofrequencypoweramplifieradoptstheintegrationchipLM386.Themaximumvoltageamplifyingmultipleis200.ItusesPT2262/2272coding/decodingcircuittorealizethedatatransmissionoperationaswellastheplatform-choosingfun
7、ction.Theinputoftheaudiofrequencyandthedatacanbeautomaticallytransformed.AT89S52isusedasthecontrollingpartofthewholesystem.ThedesignoftheprogramadoptstheClanguagetomakeitbeprogramminglyrealizedinthetranslator.Thedisplayadopts128×64latticeLCDtoshow.Aftertested,the
8、wholemachine’sfunctionisverycomplete,everydemandcanberealized,thereceivingwaveisstable,withoutevidentdistortion.Keyword:PLL、VCO、Sensitivity、Ding/decoding52目录1、
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