NTSC的双混频时差测量系统试运转结果分析-豆柴文库

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NTSC的双混频时差测量系统试运转结果分析
NTSC(NationalTelevisionSystemCommittee)isastandardforanalogtelevisionbroadcastingthatisprimarilyusedinNorthAmerica,CentralAmerica,andJapan.InordertoensureaccuratesynchronizationbetweentheaudioandvideosignalstransmittedbytheNTSCsystem,adual-heterodynetime-differencemeasurementsystemiscommonlyused.Thissystemisdesignedtomeasurethephasedifferencebetweentheaudioandvideosignalswithhighaccuracyandstability.Inthispaper,wewilldiscusstheresultsofatrialrunofanNTSCdual-heterodynetime-differencemeasurementsystemandtheanalysisofitsperformance.
Thedual-heterodynetime-differencemeasurementsystemconsistsoftwomajorcomponents:theaudio-visualseparatorandthephasedifferencedetector.Theaudio-visualseparatorisusedtoextracttheaudioandvideosignalsfromtheNTSCtransmission,whilethephasedifferencedetectorisusedtomeasurethephasedifferencebetweenthetwosignals.Thephasedifferencedetectorismadeupoftwoheterodynemixersandalow-passfilter.Itgeneratesanoutputvoltagethatisproportionaltothephasedifferencebetweentheaudioandvideosignals.
DuringthetrialrunoftheNTSCdual-heterodynetime-differencemeasurementsystem,severaltestswereconductedtoevaluateitsperformance.Thetestsincludedmeasuringthestabilityofthesystemovertime,itsaccuracy,anditssensitivitytochangesintheNTSCsignal.Theresultsofthetestsshowedthatthesystemwashighlystableandaccurate,withasensitivityoflessthan0.1°permicrosecond.
ThestabilityofthesystemwasevaluatedbymeasuringitsoutputoveraperiodoftimewhiletheNTSCsignalremainedconstant.Thesystemwasfoundtobehighlystable,withminimaldriftinitsoutputovertime.Thisindicatesthatthesystemishighlyreliableandcanbeusedforlongperiodsoftimewithouttheneedforcalibrationoradjustments.
Theaccuracyofthesystemwasevaluatedbycomparingitsoutputtoaknownreferencesignal.Theresultsshowedthatthesystemwashighlyaccurate,withadeviationoflessthan0.1°fromthereferencesignal.Thisindicatesthatthesystemcanbeusedtomeasurethephasedifferencebetweentheaudioandvideosignalswithhighprecision.
Finally,thesensitivityofthesystemtochang