Abstract
Due to satellite signal deformations, there are different constant biases in the same satellite signal that are measured by different technical types of receivers and different satellite signals that are measured by the same type of receiver, which are named pseudorange biases. These biases cannot be transmitted to users with existing navigation parameters, such as satellite time group delay (TGD) and receiver differential code biases (DCB). With the improvement of the signal-in-space accuracy of the Global Navigation Satellite System (GNSS), the pseudorange bias has become one of the primary error sources affecting the accuracy of GNSS services. To ensure the accuracy for users under the wide area differential services (WADS), we extracted the pseudorange biases of Beidou Satellite Navigation System (BDS) B1I, B3I and B1I/B3I signals and analyzed the impact of those biases on users under the WADS. Finally, we tried to eliminate this influence. The results show that the pseudorange biases of the B3I signal are smaller than those of the B1I signal at the centimeter level, but the pseudorange biases of the B1I/B3I signal can reach the meter level. Due to the large pseudorange bias of the B1I/B3I signal, the average user equivalent ranging error (UERE) under the WADS is 1.19 m, which is no better than the average UERE under open services (OS). Influenced by the pseudorange biases, the average positioning accuracies of the B1I/B3I signal are 4.17 m and 4.24 m under the WADS and the OS. When the pseudorange biases are deducted, these accuracies are 3.03 m and 3.50 m, respectively.
Highlights
To improve the accuracy and integrity of satellite navigation, many countries and regions have established satellite-based augmentation systems, such as the Wide Area Augmentation System (WAAS) in the United States, the European Geostationary NavigationOverlay Service (EGNOS) in Europe, the MTSAT Satellite-based Augmentation System (MSAS) in Japan and Global Positioning System (GPS)-aided geostationary Earth orbit (GEO) Augmented Navigation (GAGAN) in India [1,2,3,4]
The results show that the user differential range error (UDRE) using the equivalent clock parameter is within 1 m, which is reduced by 50% compared to the open services (OS) user equivalent ranging error (UERE), and that the positioning service is within 2.6 m in the wide area differential service (WADS) of Beidou Satellite Navigation System (BDS)-3
Where de ρi A is the pseudorange observation residual, c is the speed of light, dtA is the error of receiver A clock offset, dti is the error of satellite i clock offset, time group delay (TGD) is the timing group delay of the satellite, IFB is the differential code bias of the receiver, dion is the ionospheric delay correction residual from satellite to receiver, dT is the error of the tropospheric correction from satellite to receiver, drel is the residual error of the relativistic correction of satellite to receiver, dorbe is the projection error of the satellite’s orbit prediction error in the direction of the receiver, α is the pseudorange bias of the B1I signal and ε is the multipath error and measurement noise
Summary
To improve the accuracy and integrity of satellite navigation, many countries and regions have established satellite-based augmentation systems, such as the Wide Area Augmentation System (WAAS) in the United States, the European Geostationary Navigation. Satellite-based augmentation systems track navigation satellites in real time using monitoring receivers located in service areas, calculate corrections, including satellite orbit and clock offset corrections and the corresponding integrity information, and broadcast augmentation messages through. It was first time that the effect of pseudorange bias caused by abnormally deformed signal in GPS Block II was reported in Ref. Researchers found that the pseudorange bias of the hybrid receiver was caused by satellite signal deformations [19]. The in-depth study conducted by the satellite-based augmentation research team at Stanford University on the pseudorange bias caused by satellite signal deformations in hybrid receivers showed that the pseudorange biases caused by such deformations were related to the receiver correlator spacing [21]. We tried to improve the service effect of the WADS by deducting the pseudorange biases
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