Inter-System Differencing between GPS and BDS for Medium-Baseline RTK Positioning

Gao, Wang; Gao, Chengfa; Pan, Shuguo; Meng, Xiaolin; Xia, Yan

doi:10.3390/rs9090948

Cited by 38 publications

(40 citation statements)

References 27 publications

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“…A tightly combined GPS + BDS RTK model with real-time estimation of differential ISB was proposed in [50]. Nevertheless, as studies show, both tight and loose coupling may provide comparative performance, especially in the case of a high number of tracked satellites [26,50]. Thus, considering the above, in this study we apply an intra-system model for assessing the performance of the relative kinematic positioning with the use of Galileo E14 & E18 satellites.…”

Section: Loosely Combined Relative Positioning Model With Parameterismentioning

confidence: 99%

“…At this point we should also highlight the most recent contributions considering an inter-system model with no overlapping frequencies. A tightly combined GPS + BDS RTK model with real-time estimation of differential ISB was proposed in [50]. Nevertheless, as studies show, both tight and loose coupling may provide comparative performance, especially in the case of a high number of tracked satellites [26,50].…”

Section: Loosely Combined Relative Positioning Model With Parameterismentioning

confidence: 99%

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On the Applicability of Galileo FOC Satellites with Incorrect Highly Eccentric Orbits: An Evaluation of Instantaneous Medium-Range Positioning

2018

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This study addresses the potential contribution of the first pair of Galileo FOC satellites sent into incorrect highly eccentric orbits for geodetic and surveying applications. We began with an analysis of the carrier to noise density ratio and the stochastic properties of GNSS measurements. The investigations revealed that the signal power of E14 & E18 satellites is higher than for regular Galileo satellites, what is related to their lower altitude over the experiment area. With regard to the noise of the observables, there are no significant differences between all Galileo satellites. Furthermore, the study confirmed that the precision of Galileo data is higher than that of GPS, especially in the case of code measurements. Next analysis considered selected domains of precise instantaneous medium-range positioning: ambiguity resolution and coordinate accuracy as well as observable residuals. On the basis of test solutions, with and without E14 & E18 data, we found that these satellites did not noticeably influence the ambiguity resolution process. The discrepancy in ambiguity success rate between test solutions did not exceed 2%. The differences between standard deviations of the fixed coordinates did not exceed 1 mm for horizontal components. The standard deviation of the L1/E1 phase residuals, corresponding to regular GPS and Galileo, and E14 & E18 satellite signals, was at a comparable level, in the range of 6.5-8.7 mm. The study revealed that the Galileo satellites with incorrect orbits were fully usable in most geodetic, surveying and many other post-processed applications and may be beneficial especially for positioning during obstructed visibility of satellites. This claim holds true when providing precise ephemeris of satellites.

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Section: Loosely Combined Relative Positioning Model With Parameterismentioning

confidence: 99%

Section: Loosely Combined Relative Positioning Model With Parameterismentioning

confidence: 99%

On the Applicability of Galileo FOC Satellites with Incorrect Highly Eccentric Orbits: An Evaluation of Instantaneous Medium-Range Positioning

2018

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“…Besides GPS and GLONASS, Galileo and BeiDou have also been establishing their global services. Recently, there has been research on combining Galileo or BeiDou with GPS for medium to long baseline positioning [46][47][48][49]. In future research we will also study the ambiguity resolution performance of Galileo and BeiDou in long baseline positioning.…”

Section: Resultsmentioning

confidence: 99%

Improved Method for GLONASS Long Baseline Ambiguity Resolution without Inter-Frequency Code Bias Calibration

et al. 2018

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Use of a frequency-division multiple access strategy causes Globalnaya Navigatsionnaya Sputnikovaya Sistema (GLONASS) receiving equipment to experience both inter-frequency phase bias (IFPB) and inter-frequency code bias (IFCB). While IFPB can be calibrated using a linear model, there is no general model for IFCB calibration, which causes great difficulty in GLONASS ambiguity resolution over long baselines; most current GLONASS ambiguity resolution research is confined to short baselines. In this paper, based on a single-differencing between-receivers (SDBR) model, a wide-lane phase combination-based approach is proposed to fix the GLONASS ambiguities over long baselines. External precise ionospheric products are introduced to eliminate the ionospheric delay. To mitigate the effect of the residual ionospheric delays, we fix the relative wide-lane ambiguity using the Hatch-Melbourne-Wubbena (HMW) combination. The results show that 96% and 55% of the wide-lane round-off residuals are within 0.2 cycles for the Global Positioning System (GPS) and GLONASS, respectively, if the traditional HMW method is used. The method proposed here for GLONASS can improve these percentages significantly, reaching up to 95.5%. The root mean square (RMS) position errors are 1.43, 1.06 and 4.32 mm for GPS in the north, east and up directions, respectively. When GLONASS with ambiguity fixing is added, the corresponding RMS values are reduced significantly to 1.26, 1.02 and 3.87 mm, respectively.

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“…Currently, most studies only focus on tightly combined relative positioning using observations from the overlapping frequencies between GPS, Galileo, QZSS, and IRNSS (i.e., L1-E1 and L5-E5a). Regarding BDS, existing contributions either focus on the overlapping frequency of BDS-2 B2I and Galileo E5b signals [19,24] or the non-overlapping frequencies between BDS-2 and GPS (i.e., B1I-L1 and B2I-L2) [26][27][28][29][30]. None have focused on the model and performance evaluation of tightly combined precise relative positioning of BDS-3 (especially operational satellites) with other GNSS systems such as GPS, Galileo, etc.…”

Section: Band Frequency (Mhz)mentioning

confidence: 99%

Differential Inter-System Biases Estimation and Initial Assessment of Instantaneous Tightly Combined RTK with BDS-3, GPS, and Galileo

Liu

Wang

et al. 2019

Remote Sensing

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In this contribution, we assess, for the first time, the tightly combined real-time kinematic (RTK) with GPS, Galileo, and BDS-3 operational satellites using observations from their overlapping L1-E1-B1C/L5-E5a-B2a frequencies. First, the characteristics of B1C/B2a signals from BDS-3 operational satellites is evaluated compared to GPS/Galileo L1-E1/L5-E5a signals in terms of observed carrier-to-noise density ratio, pseudorange multipath and noise, as well as double-differenced carrier phase and code residuals using data collected with scientific geodetic iGMAS and commercial M300Pro receivers. It’s demonstrated that the observational quality of B1C/B2a signals from BDS-3 operational satellites is comparable to that of GPS/Galileo L1-E1/L5-E5a signals. Then, we investigate the size and stability of phase and code differential inter-system bias (ISB) between BDS-3/GPS/Galileo B1C-L1-E1/B2a-L5-E5a signals using short baseline data collected with both identical and different receiver types. It is verified that the BDS-3/GPS/Galileo ISBs are indeed close to zero when identical type of receivers are used at both ends of a baseline. Moreover, they are generally present and stable in the time domain for baselines with different receiver types, which can be easily calibrated and corrected in advance. Finally, we present initial assessment of single-epoch tightly combined BDS-3/GPS/Galileo RTK with single-frequency and dual-frequency observations using a formal and empirical analysis, consisting of ambiguity dilution of precision (ADOP), ratio values, the empirical ambiguity resolution success rate, and the positioning accuracy. Experimental results demonstrate that the tightly combined model can deliver much lower ADOP and higher ratio values with respect to the classical loosely combined model whether for GPS/BDS-3 or GPS/Galileo/BDS-3 solutions. The positioning accuracy and the empirical ambiguity resolution success rate are remarkably improved as well, which could reach up to approximately 10%∼60% under poor observational conditions.

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Inter-System Differencing between GPS and BDS for Medium-Baseline RTK Positioning

Cited by 38 publications

References 27 publications

On the Applicability of Galileo FOC Satellites with Incorrect Highly Eccentric Orbits: An Evaluation of Instantaneous Medium-Range Positioning

On the Applicability of Galileo FOC Satellites with Incorrect Highly Eccentric Orbits: An Evaluation of Instantaneous Medium-Range Positioning

Improved Method for GLONASS Long Baseline Ambiguity Resolution without Inter-Frequency Code Bias Calibration

Differential Inter-System Biases Estimation and Initial Assessment of Instantaneous Tightly Combined RTK with BDS-3, GPS, and Galileo

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