Evaluation of Multi-Constellation GNSS Positioning Using Double Differenced Observations

Abstract

Global navigation satellite system (GNSS) measurements contain several errors, including ionospheric delay, tropospheric delay, receiver clock bias, satellite clock bias, and multipath error. In the standalone positioning method, the ionosphere delay and tropospheric delay can be corrected using Klobuchar and Saastamoinen models, respectively. However, more accurate positioning is possible by the differencing method between the reference station and rover since it eliminates the delay factors. When multi -GNSS is utilized, the receiver clock bias for each GNSS is added to the state vector in addition to the three state variables for the position. Since multipath errors frequently occur in urban areas, if the receiver clock biases are removed through the difference between satellites, it has the advantage of accurate positioning. In addition, the fault detection and isolation (FDI) algorithm may not work properly if a jump in receiver clock bias occurs frequently. To evaluate the performance of the well-known double differencing method, vehicle driving test was conducted.