Inter-System Differencing between GPS and BDS for Medium-Baseline RTK Positioning
Abstract
:1. Introduction
2. Combined GPS and BDS Observation Model
2.1. Intra-System and Inter-System Observation Model
2.2. Wide-Lane AR
2.3. Ambiguity Fixing Strategy for NL AR
3. Stability Analysis of GPS-BDS DISBs
3.1. Data Collection
3.2. Stability Analysis of DISBs
4. Experiments of Medium-Baseline RTK Positioning
4.1. Positioning Results of the 22.4-km Baseline
4.2. Positioning Results of the 75.9-km Baseline
5. Discussion
6. Conclusions
Acknowledgments
Author Contributions
Conflicts of Interest
References
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Options | Processing Strategy |
---|---|
Ephemeris | GPS and BDS broadcast ephemeris |
Signals | GPS L1/L2, BDS B1/B2 |
Elevation cutoff angle | 10° |
Troposphere modeling | Corrected using GPT2w model For the baseline longer than 30 km: RZTD estimated as a random walk process (Mapping function: GMF [31]; Initial value : 0; Initial variance: 0.1 m × 0.1 m; Spectral density: 10−9 m2/s) |
Observation weighting | Elevation-dependent weighting [32] Relative precision of code and phase observations: 100:1 |
Coordinates of rover station | Kinematic: estimated and modeled as a random walk process Spectral density of coordinates: 102 m2/s |
No. | Baseline | Receiver Type 1 | Receiver Type 2 | Baseline Length/m | Remark |
---|---|---|---|---|---|
1 | CUT0-CUTB | Trimble NETR9 | Trimble NETR9 | 4.3 | with the same receiver types |
2 | CUT1-CUAI | Septentrio POLARX4 | Septentrio POLARXS | 8.4 | |
3 | CUT3-CUBB | Javad TRE_G3TH | Javad TRE_G3TH | 4.3 | |
4 | CUT0-CUT1 | Trimble NETR9 | Septentrio POLARX4 | 0 | with different receiver types |
5 | CUT0-CUBB | Trimble NETR9 | Javad TRE_G3TH | 4.3 | |
6 | CUT1-CUBB | Septentrio POLARX4 | Javad TRE_G3TH | 4.3 | |
7 | SEU1-SEU2 | ComNav-K508 | Unicore-UB380 | 2.9 |
Epoch | GPS Reference Satellite | The Virtual SD Ambiguity | Single-Epoch Phase DISB and Its Transformed Form |
---|---|---|---|
Baseline | Length/km | Duration | Sampling Interval | Receivers (Modules) | Location |
---|---|---|---|---|---|
CUT0-PERT | 22.4 km | 6 days (DOY 001–006, 2017) | 30 s | Trimble NETR9 | Perth, Australia |
TG00-TGT0 | 75.9 km | 20 h (UTC 4:00–24:00, DOY 23, 2016) | 15 s | Trimble BD970 | Tianjin, China |
Number of Satellites | RMSs of Positioning Errors (cm) | Improvement (%) | |||||||
---|---|---|---|---|---|---|---|---|---|
Classical Differencing | Inter-System Differencing | ||||||||
N | E | U | N | E | U | N | E | U | |
7 | 1.07 | 1.18 | 6.96 | 0.81 | 0.95 | 4.59 | 23.9 | 19.6 | 34.1 |
8 | 0.91 | 0.89 | 4.73 | 0.77 | 0.82 | 4.15 | 15.9 | 8.1 | 12.3 |
9 | 0.83 | 0.77 | 3.80 | 0.73 | 0.74 | 3.64 | 11.0 | 4.0 | 4.1 |
10 | 0.79 | 0.69 | 3.38 | 0.71 | 0.68 | 3.28 | 9.7 | 2.8 | 2.9 |
11 | 0.75 | 0.64 | 2.95 | 0.68 | 0.62 | 2.87 | 9.5 | 2.3 | 2.6 |
12 | 0.72 | 0.61 | 2.41 | 0.64 | 0.60 | 2.33 | 11.7 | 0.8 | 3.6 |
All | 0.76 | 0.64 | 2.15 | 0.68 | 0.63 | 2.13 | 10.3 | 0.5 | 0.9 |
Number of Satellites | RMSs of Positioning Errors (cm) | Improvement (%) | |||||||
---|---|---|---|---|---|---|---|---|---|
Classical Differencing | Inter-System Differencing | ||||||||
N | E | U | N | E | U | N | E | U | |
7 | 1.93 | 1.33 | 11.25 | 1.25 | 0.96 | 9.90 | 35.2 | 27.6 | 11.9 |
8 | 1.49 | 1.03 | 8.08 | 1.05 | 0.82 | 6.97 | 29.7 | 20.7 | 13.7 |
9 | 1.04 | 0.78 | 5.02 | 0.95 | 0.74 | 4.88 | 8.5 | 4.7 | 2.7 |
10 | 0.91 | 0.69 | 2.77 | 0.85 | 0.68 | 2.71 | 6.1 | 2.4 | 2.2 |
11 | 0.77 | 0.65 | 2.63 | 0.72 | 0.64 | 2.60 | 6.2 | 0.6 | 1.1 |
12 | 0.73 | 0.56 | 2.44 | 0.68 | 0.56 | 2.44 | 6.7 | 1.5 | 0.3 |
All | 0.68 | 0.51 | 2.27 | 0.65 | 0.51 | 2.27 | 4.4 | 0.2 | 0.0 |
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Gao, W.; Gao, C.; Pan, S.; Meng, X.; Xia, Y. Inter-System Differencing between GPS and BDS for Medium-Baseline RTK Positioning. Remote Sens. 2017, 9, 948. https://doi.org/10.3390/rs9090948
Gao W, Gao C, Pan S, Meng X, Xia Y. Inter-System Differencing between GPS and BDS for Medium-Baseline RTK Positioning. Remote Sensing. 2017; 9(9):948. https://doi.org/10.3390/rs9090948
Chicago/Turabian StyleGao, Wang, Chengfa Gao, Shuguo Pan, Xiaolin Meng, and Yan Xia. 2017. "Inter-System Differencing between GPS and BDS for Medium-Baseline RTK Positioning" Remote Sensing 9, no. 9: 948. https://doi.org/10.3390/rs9090948