Geometry-based method applied to single-epoch carrier ambiguity resolution for BDS-3 triple/quad/penta-frequency observations

Abstract The BDS-3 global navigation satellite system now supports five frequencies signals, enabling the construction of optimal combined observations characterized by long wavelength, ionosphere-reduced, and low noise. These features are advantageous for achieving real-time ambiguity resolution. In this contribution, the characteristics of optimal linear combinations for BDS-3 under various assumed error scenarios is analyzed in detail. Additionally, the performance of BDS-3 single-epoch multi-frequency carrier ambiguity resolution (MCAR) employing the geometry-based (GB) method is comprehensively evaluated, which encompasses triple-frequency (TCAR), quad-frequency (QCAR), and penta-frequency (PeCAR) ambiguities resolution. Utilizing measured data from BDS-3, the findings indicate that the ambiguity resolution rate of the B1C basic signal exceeds 95%, outperforming the B2a signal. Furthermore, when employing the GB-QCAR and GB-PeCAR, the positioning accuracy of the B1C signal under fixed solutions is essentially consistent with that of the GB-TCAR. Even with a satellite cutoff elevation angle of 30°, the B1C signal ambiguity resolution rate remains above 91%. In summary, the GB-MCAR method proves effective in obstructed environments, and an increase in the number of frequencies enhances the reliability of ambiguity resolution.