《红外遥控基本知识》PPT课件

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1、红外遥控基本知识ByRobertHan红外线介绍红外线的波长范围为760nm～1500nm，我们所使用的遥控器发射的红外波长是940nm红外线遥控装置特点体积小、功耗低、功能强、成本低等红外遥控系统红外遥控系统一般分发射和接收两个部分红外线发射规范目前红外线的规范有NECcode,RC5,RC6,Toshibacode,Sharpcode,Matsushitacode,RCAcode,RCMMcode,Sony20bitcode,JVCcode.andsoon。NECCode最常用，目前VIZIO使用是NECCodeNECCodeFormat8bit

2、customand8bitcommandlengthcustomandcommandaretransmittedtwicePulsedistancemodulationCarrierfrequencyof38kHzLSBistransmittedfirstlyNECCodeFormatLeadercode:AGCburst(9ms)+Space(4.5ms)Customcode:data(8bit)+inverteddata(8bit)Datacode:data(8bit)+inverteddata(8bit)Thelengthofoneframei

3、s108msNECCodeFormatBitdataformatLogical“0”:ahighlevelofthedurationTfollowedbyalowlevelofduration1TLogical“1”:ahighlevelofthedurationTfollowedbyalowlevelofduration3TPs:T=0.56msNECCodeFormatCarrierformatfo=37.9kfz，占空比1/3可以减少干扰并提高发射效率NECCodeFormatForExample“Menu”keytransmitcode:00

4、100000110111111100001000111101Customcode:000001000x04Datacode:010000110x43NECCodeFormatRepeatCodeOneframeis108msOneframeonlycontains9.56mscarrierwave,whichsavepowersupplybutbeinterruptedeasily.TheTransmitterConsumeaslittlepoweraspossibleThecurrentthroughtheLEDneedtobeashighaspo

5、ssible,inordertogetanacceptablecontroldistance,needrefertoLEDparameters,batterylifetimeandmaximumcontroldistance.TheTransmitterTheReceiverThereceiverincludesphotodiodeandreceiverIC,forexampleFM-6038LM-5ANTheReceiverAGCcircuitgetaconstantpulselevelregardlessofthedistancetoremote

6、controllerTheBandPassFilteristunedtothemodulationfrequencyWaveformdetectoristodetectthepresenceofthemodulationfrequency.Ifthismodulationfrequencyispresenttheoutputwillbelow.WaveformrectifierTheReceiverTburst时间愈长，其抗干扰能力愈好，NECCODE:Tburst=560us、Tgap=560us、Tpause=30.94~48.94msTV红外接

7、收距离角度ψ=30°时：10m角度ψ=45°时：7m角度ψ=60°时：3m角度ψ定义如图ψ