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1、电子产品调试与测试总复习电视技术小知识Picturetubeisakindofspecialelectricvacuumdevice.Theelectronicgunismainlycomposedoffilament,cathode,gate,acceleratingpole,focusingpoleandhighvoltageanode.TheinterlacedbroadcasttelevisionsystemusedinChina,thefrequencyis15625Hz,frequencyis50Hz,theframerateof25Hz.Thethreeelementsofcol
2、orarebrightness,hue,andcolorsaturationThethreeprimarycolorsusedinthetelevisionsystemarered(R),green(G)andblue(B)]Thewholecolortelevisionsignalconsistsofluminance,chrominance,colorsynchronization,compositesyncandcompositeblankingIntheTVsystemusedinourcountry,themodulationmodesofimageandsoundareamplit
3、udemodulationandfrequencymodulationThebasiccomponentsincludetunerinputcircuit,ahighfrequencyamplifier,frequencyconversioncircuitetc.Themaincomponentsoftheintermediatereleasechannelincludepre-andmiddischargecircuit,sawfilter,intermediatefrequencyamplifier,videodetector,intermediatefrequencyAGC,ANCand
4、soon.Thecomponentsofluminancechannelincludecolorsubcarriertrap,brightnessdelaycircuit,DCclampcircuit,contourcompensationcircuit,laststagevisualdischargecircuit,etc..Thecompositionoftheaudiochannelincludestheaudiosystemconversioncircuit,thesoundincircuit,theaudiofrequencydiscriminationcircuit,thelowd
5、ischargecircuitandthepoweramplifiercircuitThescanningsystemconsistsofsynchronousseparationcircuit,linescanningcircuitandfieldscanningcircuitThecompositionoflinescanningcircuitincludeslineAFCcircuit,oscillatingcircuit,linedrivingcircuit,lineoutputcircuit,etc.Thefieldscanningcircuitconsistsofafieldosc
6、illatingcircuit,asawtoothwaveformingcircuit,afielddrivingcircuit,andafieldoutputcircuitAtpresent,thethreepopularcolorsystemsarePALsystem,NTSCsystemandSECAMsystemThemaincomponentsofNTSCencoderincludecodingmatrix,low-passfilter,subcarrieroscillator,delaycircuit,balancedamplitudemodulatorandadderThemai
7、ncomponentsofNTSCdecoderincludebandpassfilter,subcarrierrecoverycircuit,synchronousdetector,delaycircuit,matrixcircuitandsubcarriertrapComparedwithNTSCencoder,PALencoderhasincreasedtheinverter,PALswit