文档介绍：汽车音响指标测试方法()TestingmethodofcaracousticsindexOne,FMindextestmethod(%.DEV)130dBpracticalsensitivity(USABLE,SENSITIVITY,〃S/N:30dB〃)Themachineis90Mhz(98Mhz,106Mhz),(LEVEL)inthenormallevelofdBnumber(about40),receivefinevolumetoOdB,thenremovethesignal(,OFFandlayabutton)andthentwistmillivoltmeter(30dB,three,eachtwistislOdB)・Thelevelandthenadjustthesignalgenerator(LEVEL),thepointerandthepointerhasnosignalsignal(ifnotrepeatrepeatcarmotbemorethan1dBm),thelastlevel(LEVEL)dBshowsthatthismachine-%distortionsensitivity(.,SENSITITV,75khz,DEV,3%)Themachineis90Mhz(98Mhz,106Mhz),themodulationinthe75%play,willplayintheDIST,10%distortionmeter(~20dB)file,andthenadjustthevolumelevelpotentiometerandgenerator(LEVEL)dBnumber,thedistortionmeterpointerinthe3%place(notmorethan3%%),thenthegeneratorlevel(LEVEL)dBnumberisthismachine(forexample:3%distortionsensitivitylevel(LEVEL)thedBnumberis11,thenthe3%distortionsensitivityis11).Three,-3dBlimitsensitivity(~3dB,LIMITING,SENSITIVITY)Themachineis98Mhzlevel(LEVEL)inthe66dBnumber,volumesmallertoOdB,andthenreducethegeneratorlevel(LEVEL)dBnumber,toreduce3dBMVmeterpointerstop,thelevelofdB(LEVEL)isthenumberof-3dBlimitsensitivity・4signal-to-noiseratio(S/N,RATIO,***@lmv,INPUT)Themachineis98Mhzlevel(LEVEL)toplayinthe66dB,thevolumesmallertoOdB,thenremovethesignal(|,OFFabutton)callmillivoltmeter,eachtwistislOdB,butthevoltmeterpointercannotexceedOdB,howmuchisthelastpointerindexnumberplusatotalofamillivoltmeter(eachfileislOdB),(forexample:youplayedatotalofthreepointerindexis6,sothesignal-to-noiseratiois30+6=36dB)・Thisisthesignaltonoiseratioofthismachine・Five,600kHzREJECTION(IF)Themachineis90Mhz,thenumberofmeasureddBpracticalsensitivity,(FMfrequency),andthenadjustthelevelof(LEVEL)dBnumber,thepointernumberdBdBminusthenumberofpracticalsensitivityisdisplayedinthe2Vwhenthefrequencyvalueissuppressed・6iffrequency(INTERMEDIATEFREQUENCY)Tomeasureifrej