Both the BDS-3 and Galileo can offer four frequencies or more satellite signals.To maximize the use of these signals and enhance positioning accuracy and reliability,a quad-frequency precise point positioning(PPP)model for BDS-3/Galileo is established and its performance is analyzed.Firstly,two quad-frequency ionospheric-free combination models(QF1 and QF2)and uncombined model(QF3)are derived on the basis of the traditional dual-frequency model,and the combination coefficients,ionospheric and noise amplification coefficients of each model are given.Secondly,the influence of each model parameters on the positioning performance is analyzed.Finally,the positioning performance of each model is evaluated through static and simulated dynamic PPP experiments.The experimental results show that the static PPP convergence time of the proposed four-frequency models QF1,QF2 and QF3 is shortened by about 50%,57%and 25%compared with the IF12 model,and the positioning accuracy after convergence is improved by about 44%,44%and 41%.In the kinematic PPP experiments,the convergence time of QF1,QF2 and QF3 models is shortened by about 26%,26%and 3%compared with the IF12 model,and the positioning accuracy after convergence is improved by about 23%,22%and 13%.The QF1 and QF2 models have comparable performance and are superior to the QF3 model.
BeiDou navigation satellite system-3Galileoquad-frequencyprecise point positioningpositioning performance