5.1伪距单点定位原理5.2载波相位单点定位原理5.3精密单点定位原理5.1单点定位定义单独利用一台接收机确定待定点在地固坐标系中绝对位置的方法定位结果采用广播星历时，为WGS-84下的绝对坐标采用IGS–InternationalGPSService精密星历时为ITRF–InternationalTerrestrialReferenceFrames下的绝对坐标特点优点：单台接收机定位，观测简单，可瞬时定位缺点：精度主要受系统性偏差的影响，定位精度低应用领域低精度导航、资源普查、军事、...1-Principleofabsolutepositioning2-Observationequation3-Mathematicsmodel(leastsquaresadjustment)4-Processingsteps5.1单点定位steps1-Principleofabsolutepositioning(1/4)OnlyoneGPSreceiverisusedRealtimepositioningUsescodemeasurementsfromGPSsignal1-Principleofabsolutepositioning(2/4)i=measured1-Principleofabsolutepositioning(3/4)P(X,Y,Z)SpatialTrilaterationUnknowns(parameters):X,Y,Z1-Principleofabsolutepositioning(4/4)Why4satellites?2-Observationequation(1/10)Observationequationofpseudorangep=ρ+cdt-cdT+dion+dtrop+dmtp+εpp:Pseudorangeobservation(codesP(Y)ouC/A).r:geometricdistancebetweenthesatellitepositionatthetransmissiontimeandthepositionofthereceiveratthereceptiontimec:speedoflightinvacuum.dt:errorofthesatelliteclock.dT:errorofthereceiverclock.dion:errorofthedistanceduetoionosphericdelay(refraction).dtrop:errorofthedistanceduetotroposphericdelay(refraction).dmtp:errorofdistanceduetomultipaths.ep:nomodelederrors2-Observationequation(2/10)Errorssources40km2-Observationequation(3/10)p=ρ+cdt-cdT+dion+dtrop+dmtp+εp(Xp,Yp,Zp)Xs,Ys,Zs2-Observationequation(4/10)p=ρ+cdt-cdT+dion+dtrop+dmtp+εp2-Observationequation(5/10)p=ρ+cdt-cdT+dion+dtrop+dmtp+εpdTisunknownandisthe4thparametertodetermineintheprocessingateveryepoch!!!2-Observationequation(6/10)p=ρ+cdt-cdT+dion+dtrop+dmtp+εp2-Observationequation(7/10)p=ρ+cdt-cdT+dion+dtrop+dmtp+εp2-Observationequation(8/10)p=ρ+cdt-cdT+dion+dtrop+dmtp+εp2-Observationequation(9/10)p=ρ+cdt-cdT+dion+dtrop+dmtp+εpE:elevationangleofthesatellite(°)P0:totalatmosphericpressureneartheantenna(mbar)T0:atmospherictemperature(dry)neartheantenna(K)e0:watervapourpressureneartheantenna(mbar)2-Observationequation(10/10)p=ρ+cdt-cdT+dion+dtrop+dm