Page 147 - 卫星导航2021年第1-2合期

Liu et al. Satell Navig (2021) 2:6 Page 14 of 17

Fig. 17 Single-epoch ambiguity resolution success rates based on
dual-frequency observations

positioning. Additionally, compared with BDS-2 B1I
solutions, the success rates of BDS-3 B1C solutions were Fig. 18 The positioning errors with dual-frequency BDS-3/BDS-2
much lower with the elevation cut-of angle below 25° observations at the elevation cut-of angle of 10°
and much higher beyond the elevation cut-of angle of
30°. It is noteworthy that the success rates for the BDS-3
B1I solutions increased with an increase in the elevation tightly combined BDS-3/BDS-2 solution. Moreover, the
cut-of angle from 25° to 30°, which was due to the low RMS of BDS-3 B1C/B2a solution were slightly larger than
observational quality of BDS-3 C19 within a range of the those of the BDS-3 B1I/B3I solution, whereas they were
elevation angle from approximately 25° to 30°. obviously smaller than BDS-2 B1I/B3I solution.
Figure 17 shows the ambiguity resolution success rates
with dual-frequency observations under diferent eleva- Conclusions and discussions
tion cut-of angles. Similarly, the success rates of the In this study, we assessed the single-epoch RTK posi-
BDS-2 B1I/B3I solutions were lower than those of the tioning performance of tightly combined BDS-2 and
BDS-3 B1I/B3I solutions at all elevation cut-of angles. the newly completed BDS-3 full constellations. We frst
However, diferent from the static test, they were in gen- investigated the existence of DISBs between BDS-3/
eral comparable to the BDS-3 B1C/B2a solutions. With BDS-2 B1I/B3I signals. Ten we assessed the RTK posi-
increasing elevation cut-of angle from 10° to 40°, the tioning performance for short baselines with single- and
success rates decreased from approximately 99.1–90.6% dual-frequency observations from BDS-2/BDS-3 in
for the BDS-3 B1I/B3I solutions. Meanwhile, the success aspects of ADOP, ambiguity resolution success rate, as
rates of almost 100% were obtained for the tightly com- well as positioning accuracy. Both static and kinematic
bined BDS-3/BDS-2 solutions at the elevation cut-of datasets collected in Wuhan were processed and ana-
angle below 35°, and 97.5% and 97.8% under the eleva- lyzed. Te following conclusions were obtained:
tion cut-of angles of 35° and 40°, respectively. Te results
demonstrate that a promising RTK performance can be 1. Regarding the specifc receivers employed in this
achieved with the dual-frequency observations from the study, it was demonstrated that the BDS-3/BDS-2
current BDS-3 full constellation alone or the combina- B1I/B3I code and phase DISBs were approximately
tion of BDS-2 and BDS-3. zero for baselines with the same or diferent receiver
Figure 18 depicts the positioning errors in the E, N, and
U components for BDS-2, BDS-3, and tightly combined types at their endpoints, implying that when the
legacy B1I/B3I signals were used for precise relative
BDS-3/BDS-2 based on dual-frequency observations
under the elevation cut-of angle of 10°, and the position-
ing accuracy (only for ambiguity fxed solutions) is listed
in Table 7. For the B1I/B3I signals, the positioning accu- Table 7 RMS of the single-epoch BDS-2/BDS-3 RTK
racy of the BDS-3 solution (0.52 cm/0.39 cm/2.14 cm) positioning errors
was obviously better than that of the BDS-2 solution Observations E (cm) N (cm) U (cm) 3D (cm)
(0.85 cm/1.02 cm/3.01 cm), particularly in the North
and Up components. Te combined BDS-3/BDS-2 solu- BDS-2 B1I/B3I 0.85 1.02 3.01 3.29
tion improved the positioning accuracy with RMS values BDS-3 B1I/B3I 0.52 0.39 2.14 2.24
of 0.52 cm/0.22 cm/1.80 cm. Te 3D position RMS was BDS-3 B1C/B2a 0.71 0.66 2.36 2.55
3.29 cm for BDS-2, 2.24 cm for BDS-3, and 1.89 cm for BDS-2/BDS-3 B1I/B3I 0.52 0.22 1.80 1.89