GPS频间钟差特性分析及其对三频PPP的影响

Analysis of GPS inter-frequency clock bias characteristics and its effect on triple frequency PPP

针对全球定位系统(GPS)频间钟差(IFCB)显著影响多频精密单点定位(PPP)性能的问题,对全部GPS在轨的三频卫星的IFCB变化特性进行分析:可知BlockIIF卫星IFCB单日内变化从厘米到分米不等,存在明显的时变特性,而Block III卫星单日内变化量级较小,通常不超过1 cm,IFCB的时变特性相比于Block IIF卫星得到了明显的削弱;同时,BlockIIF卫星的IFCB存在12、6、8、4、4.8和3h的周期变化,并以此建立IFCB高阶谐波模型。实验结果表明,对于静态PPP,利用IFCB预报值改正后,定位精度在东(E)、北(N)、天(U)3个方向上分别提升29.4%、39.4%、35%;而对于动态PPP,利用IFCB预报值改正后,定位精度在E、N、U 3个方向上分别提升34.3%、20.0%、47.7%,同时可有效消除载波相位验后残差中的系统误差。

Aiming at the problem that the inter-frequency clock bias(IFCB)of global positioning system(GPS)significantly affects the positioning performance of multi-frequency precise point positioning(PPP),the paper analyzed the variation characteristics of IFCB for all GPS triple-frequency satellites:it was known that the IFCB of Block IIF satellite varied from centimeters to decimeters in a single day with obvious time-varying characteristics,while the variation of Block III satellite in a single day was smaller,usually not more than 1 cm,and the time-varying characteristics of IFCB were significantly weakened compared with Block IIF satellite;at the same time,the IFCB of the Block IIF satellite had periodic changes of 12,6,8,4,4.8 and 3 h,based on which the IFCB high-order harmonic model was established.Experimental result showed that for static PPP,the positioning accuracy could be improved by 29.4%,39.4%and 35%in the three directions of E,N and U,respectively,after applying the predicted IFCB correction;for kinematic PPP,after applying the predicted IFCB correction,the positioning accuracy could be improved by 34.3%,20.0%and 47.7%in the three directions of E,N and U,respectively,and the systematic error in the phase residuals could be effectively eliminated.