Characteristics of the BDS Carrier Phase Multipath and Its Mitigation Methods in Relative Positioning

Dai, Wujiao; Shi, Qiang; Cai, Changqun

doi:10.3390/s17040796

Cited by 24 publications

(16 citation statements)

References 28 publications

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“…The unique constellation design of BeiDou (GEO + IGSO + MEO) makes it more difficult to mitigate multipath effects compared to GPS (MEO only). The multipath issue of BeiDou signals has been intensively investigated recently [63][64][65][66][67][68]. It is expected that the algorithms for modeling multipath effects on BeiDou observations will be improved in the near future.…”

Section: Appl Sci 2019 9 X For Peer Reviewmentioning

confidence: 99%

Detection and Monitoring of Tunneling-Induced Riverbed Deformation Using GPS and BeiDou: A Case Study

et al. 2019

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Shield tunneling under rivers often requires monitoring riverbed deformations in near real-time. However, it is challenging to measure riverbed deformation with conventional survey techniques. This study introduces a comprehensive method that uses the Global Positioning System (GPS) of the USA and the BeiDou navigation satellite system (BeiDou) of China to monitor riverbed deformation during the construction of twin tunnels beneath the Hutuo River in Shijiazhuang, China. A semi-permanent GPS network with one base station outside the river and six rover stations within the river was established for conducting near real-time and long-term monitoring. The distances between the base and the rover antennas are within two kilometers. The network was continuously operating for eight months from April to December 2018. The method is comprised of three components: (1) Monitoring the stability of the base station using precise point positioning (PPP) method, a stable regional reference frame, and a seasonal ground deformation model; (2) monitoring the relative positions of rover stations using the carrier-phase double-difference (DD) positioning method in near real-time; and (3) detecting abrupt and gradual displacements at both base and rover stations using an automated change point detection algorithm. The method is able to detect abrupt positional-changes as minor as five millimeters in near real-time and gradual positional-changes at a couple of millimeters per day within a week. The method has the flexibility of concurrent processing different GPS and BeiDou data sessions (e.g., every 15 minutes, 30 minutes, one hour, one day) for diffident monitoring purposes. This study indicates that BeiDou observations can also achieve few-millimeter-accuracy for measuring displacements. Parallel processing GPS and BeiDou observations can improve the reliability of near real-time structural deformation monitoring and minimize false alerts. The method introduced in this article can be applied to other urban areas for near real-time and long-term structural health monitoring.

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Section: Appl Sci 2019 9 X For Peer Reviewmentioning

confidence: 99%

Detection and Monitoring of Tunneling-Induced Riverbed Deformation Using GPS and BeiDou: A Case Study

et al. 2019

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“…The received signals are the superposition of the direct and the reflected signals. The magnitude of the multipath errors is related to the distance between the antenna and the object, the angle of the reflected signal, and the characteristics of the reflector [7]. The principle of SICB is similar, but the reflection occurs at the satellite ends.…”

Section: Introductionmentioning

confidence: 99%

An Improved BDS Satellite-Induced Code Bias Correction Model Considering the Consistency of Multipath Combinations

Pan

Guo

2018

Remote Sensing

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The satellite-induced systematic biases were identified to exist in the code observations from BeiDou navigation satellite system (BDS) satellites using multipath (MP) combinations. The current correction model for satellite-induced code bias (SICB) does not take into account the consistency of MP combinations, which limits the accuracy of the developed model. Both the cycle slips and different tracking of a satellite at different stations can affect the absolute values of MP combinations, although the variations remain unchanged. An improved SICB piecewise linear correction model as a function of elevations is proposed. We estimate the model parameters for each frequency and for each satellite. The single-difference of MP combinations in the domain of elevation angles is carried out to remove the unknown ambiguities and stable hardware delays so that the SICB modeling is free of the effects of MP combination inconsistency. In addition, a denser elevation node separation of 1°, rather than the 10° usually employed by the traditional model, is used to describe the more precise SICB variations. The SICB corrections show significant differences among orbit types and frequency bands. The SICB variations have much less effect on Inclined Geosynchronous Orbit (IGSO) satellites than on Medium Earth Orbit (MEO) satellites for the regional BDS (BDS-2). The B1 signal has the largest SICB corrections, which can be up to 0.9 m close to zenith for BDS-2 MEO satellites, and the B2 signal follows. After adding the SICB corrections to the code observations, the elevation-dependent code biases vanish, and we can obtain improved code observations. After applying the improved SICB correction model, the root mean square (RMS) values of MP combination time series are reduced by 7%, 6% and 2%, and 18%, 14% and 5% on the B1, B2 and B3 frequencies for the BDS-2 IGSO and MEO satellites, respectively. For comparison, we also establish the traditional SICB correction model. With the traditional SICB correction model, the corresponding RMS MP combinations are smaller than those of uncorrected MP series, but slightly larger than those of corrected MP series using the improved SICB correction model. To validate the effectiveness and correctness of our proposed model, single-frequency precise point positioning (PPP) processing with BDS-2 MEO and IGSO satellites is conducted. An accuracy improvement of 24%, 19% and 89%, and 7%, 7% and 6% for the single-frequency PPP applying the improved SICB corrections over the case without SICB corrections and the case using the traditional SICB corrections in east, north and vertical directions is achieved, respectively. Although only centimeter-level SICB variations could be observed for the two legacy signals B1 and B3 and the three new navigation signals B1C, B2a and B2b transmitted by the satellites of global BDS demonstration system (BDS-3S), we still establish an effective SICB correction model on the B1 and B3 frequencies for BDS-3S IGSO satellites, and the RMS MP combinations are reduced by 1–4% after applying the improved SICB corrections.

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“…ε is the noise, which may be ignored. After it is weighted by the elevation angle of satellites, the variance of observations σ 2 can be expressed as [19]:…”

Section: Dd Measurement Modelmentioning

confidence: 99%

“…The second group relies on date post-processing; employing methods such as a Kalman filter, an adaptive filter, Vondrak filter wavelet analysis, and a means of signal-to-noise ratio (SNR)-based weighting, all of which only effectively eliminate multipath issues by post-processing [12][13][14][15][16][17]. The last group involves mitigating multipath errors using short period repetition on the multipath, such as sidereal filter (SF) or the multipath hemispherical map (MHM) model [18][19][20][21][22][23]. Among these methods, a sidereal filter is dependent on the orbits of satellites, it is not commonly used for high-rate deformation monitoring [24].…”

Section: Introductionmentioning

confidence: 99%

SNR-Dependent Environmental Model: Application in Real-Time GNSS Landslide Monitoring

Han

Zhang

et al. 2019

Sensors

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The Global Navigation Satellite System (GNSS) is currently one of the important tools for landslide monitoring and early warning. However, the majority of GNSS devices are installed in mountainous areas and a variety of vegetation. These harsh environments lead to defective signals at high elevation angles, rendering real-time successive and reliable positioning results for monitoring difficult. In this study, an environmental model derived from signal-to-noise ratio (SNR) is proposed to enhance the precision and convergence time of positioning in harsh environments. A series of experiments are conducted on weighting and ambiguity-fixed models to evaluate performance. The results indicate that the proposed SNR-dependent environment model could lead to a significant improvement in precision and convergence time; with an obtained root mean squared result on the millimeter level, a convergence time of a few seconds, and utilization which could reach 100%, for continuous and reliable positioning results. These results indicate that the proposed SNR-dependent environment model enhances the performance of GNSS monitoring and early warning to provide continuous and reliable positioning results in real-time.

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Characteristics of the BDS Carrier Phase Multipath and Its Mitigation Methods in Relative Positioning

Cited by 24 publications

References 28 publications

Detection and Monitoring of Tunneling-Induced Riverbed Deformation Using GPS and BeiDou: A Case Study

Detection and Monitoring of Tunneling-Induced Riverbed Deformation Using GPS and BeiDou: A Case Study

An Improved BDS Satellite-Induced Code Bias Correction Model Considering the Consistency of Multipath Combinations

SNR-Dependent Environmental Model: Application in Real-Time GNSS Landslide Monitoring

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