顾及TGD与DCB改正的单点定位研究

TGD是调制导航电文中的一个时延差参数，它反映了L1P（Y）信号与L2P（Y）信号内部时延间的差异，对于单频导航用户，必须进行TGD改正。DCB是一表征不同测距码间差异的参数，利用DCB参数可以将L1C／A码测距精度提升到L。P（Y）码水平。本文评估了TGD与DCB参数的量级，利用IGS站数据，分析了二者对GPS单点定位的影响，结果表明：进行TGD改正后，三维定位精度有平均约1．5m的提高，平均改善率为27．3％；在TGD改正的基础上进行DCB改正后，三维定位精度有平均约0．1m的提高，平均改善率为2．59／6．

The Research Considering TGD and DCB Corrections for Single Point Positioning

Time group delay （TGD） is a time delay differential parameter which is coded in the navigation message, and it can reflect the difference of internal time delay between lAP（Y） and L2P（Y）. For the single-frequency navigation user, the TGD correction must be applied. The differential code biases （DCB） can reflect the difference between different kinds of ranging codes, and it can be used to enhance the ranging accuracy of L1C/A to the level of 1.1P（Y）. The magnitudes of TGD and DCB corrections are estimated and their influences on single point positioning （SPP） are analyzed in this paper. The analysis results based on IGS observation data indicate that the average improvement of 3-D positioning accuracy is about 1.5 m and the average improvement rate reaches 27.3%after the TGD correction is conduc- ted. Based on the TGD correction, after the DCB correction is applied, the further average improvement of 3-D positioning accuracy is about 0. 1 m and the further average improvement rate reaches 2.5%.