Analysis of the Multipath Impact on Dual-Frequency Positioning Error Under GEO and IGSO Constellation

Abstract

The positioning error of the user in satellite navigation systems is affected by various factors, such as tropospheric delay error, ionospheric delay error, clock error, orbital error and multipath effects error, which are the primary factor of restricting the accuracy of the navigation receivers. In dual -frequency positioning mode, the multipath effects error is always amplified because of the combination of measuring error. As a result, certain kind of user terminal has lower accuracy under dual-frequency mode than under single-frequency mode under GEO and IGSO satellite geometry. By establishing a simulated model, this paper analyses the multipath impact on dual-frequency positioning error, and proposes an improved experiment scheme for the user terminal. The dual-frequency positioning accuracy of user terminal using anti-multipath pseudorange imported to the terminal is compared with dual-frequency positioning accuracy using pseudorange contaminated by multipath. The experiment result testifies that when the multipath effects error reaches a certain level, the amplify effect of dual-frequency measuring errors will exceed the effect of eliminating ionospheric path delay error. Thus the user terminal has lower accuracy under dual-frequency mode than under single-frequency mode. This paper also analyses the multipath effects change tendency under various constellation and distinct satellite impact on dual-frequency positioning error, and provides beneficial reference to the satellite selection strategy for the user terminal.