单工无线呼叫系统资料

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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

2、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:Thesimplexwireless-callingsystemconsistsoftwoparts:transmitpartandrec

3、eivepart.Thetransmitpartadoptsthephase-lockedlooppatternoffrequencysynthesizingtechnologyandusestheMC145152andMC12022chipstocomposethephase-lockedloop.Itlocksthefrequencyofthecarrier-waveat35MHz.Thestabilizationofthecarrier-wavecanbe4×10-5,theaccuracycanbe3×10-5.Thefrequencymodulationandthecon

4、fectionofthecarrier-wavearerealizedbythecapacity-changingdiodeV149andtheintegrationvoltage-controloscillatorMC1648chip.Theendpoweramplifierusestheaudion2SC1970tomakeitworkinthethirdmagnifyingstate,itimprovestheefficiencyofthemagnifierandthepoweroftheoutputreachesthedesigndemand.Thereceivepartu

5、sesthesupercosmicallyAM/FMdimensionalsoundstereoradioreceptionintegrationchipCXA1238Sasthemainpart.Thesensitivity、themirror-controlrestrain、theSNRandeverycapabilityindexallreachthedesigndemand.TheaudiofrequencypoweramplifieradoptstheintegrationchipLM386.Themaximumvoltageamplifyingmultipleis200

6、.ItusesPT2262/2272coding/decodingcircuittorealizethedatatransmissionoperationaswellastheplatform-choosingfunction.Theinputoftheaudiofrequencyandthedatacanbeautomaticallytransformed.AT89S52isusedasthecontrollingpartofthewholesystem.ThedesignoftheprogramadoptstheClanguagetomakeitbeprogramminglyr

7、ealizedinthetranslator.Thedisplayadopts128×64latticeLCDtoshow.Aftertested,thewholemachine’sfunctionisverycomplete,everydemandcanberealized,thereceivingwaveisstable,withoutevidentdistortion.Keyword:PLL、VCO、Sensitivity、Ding/decoding目录1、系统