红外遥控基本知识

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NECCodeNECCodeFormat8bitcustomand8bitcommandlengthcustomandcommandaretransmittedtwicePulsedistancemodulationCarrierfrequencyof38kHzLSBistransmittedfirstlyNECCodeFormatLeadercode:AGCburst(9ms)+Space(4.5ms)Customcode:data(8bit)+inverteddata(8bit)Datacode:data(8bit)+inverteddata(8bit)Thelengthofoneframeis108msNECCodeFormatBitdataformatLogical“0”:ahighlevelofthedurationTfollowedbyalowlevelofduration1TLogical“1”:ahighlevelofthedurationTfollowedbyalowlevelofduration3TPs:T=0.56msNECCodeFormatCarrierformatfo=37.9kfz，占空比1/3可以减少干扰并提高发射效率NECCodeFormatForExample“Menu”keytransmitcode:00100000110111111100001000111101Customcode:000001000x04Datacode:010000110x43NECCodeFormatRepeatCodeOneframeis108msOneframeonlycontains9.56mscarrierwave,whichsavepowersupplybutbeinterruptedeasily.TheTransmitterConsumeaslittlepoweraspossibleThecurrentthroughtheLEDneedtobeashighaspossible,inordertogetanacceptablecontroldistance,needrefertoLEDparameters,batterylifetimeandmaximumcontroldistance.TheTransmitterTheReceiverThereceiverincludesphotodiodeandreceiverIC,forexampleFM-6038LM-5ANTheReceiverAGCcircuitgetaconstantpulselevelregardlessofthedistancetoremotecontrollerTheBandPassFilteristunedtothemodulationfrequencyWaveformdetectoristodetectthepresenceofthemodulationfrequency.Ifthismodulationfrequencyispresenttheoutputwillbelow.WaveformrectifierTheReceiverTburst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