A new ionosphere-free ambiguity resolution method for long-range baseline with GNSS triple-frequency signals

Xu, Ying; Ji, Shengyue; Chen, Wu; Weng, Duojie

doi:10.1016/j.asr.2015.07.013

Cited by 21 publications

(21 citation statements)

References 24 publications

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“…However, it should be mentioned that it is not completely fair to compare MPCs of BDS and GPS satellites as the constellations of two GNSS system are completely different. As the multipath and code noise level of BDS pseudo-range measurements was larger than that of GPS, the sigma of pseudo-range noise was set to 0.5 m for BDS, instead of 0.3 m for GPS [11]. Time required for AR or initialization is an important index to measure the performance of the RTK and the benefit of the NWP ZTD.…”

Section: Gps/bds Rtk Resultsmentioning

confidence: 99%

“…The four schemes were the standard GPS RTK, standard GPS/BDS RTK, GPS RTK constrained with NWP ZTD and GPS/BDS RTK constrained with NWP ZTD. In the data processing, we mitigated the ionospheric delay using the medium/long-range baselines ionospheric delay estimation method we developed [11]. The popular R-ratio [38] was used as the validation method and a threshold value was set to 2.5.…”

Section: Gps/bds Rtk Resultsmentioning

confidence: 99%

“…As a consequence, the main errors that affect the performance of GPS/BDS RTK are the tropospheric delay and ionospheric delay. In this study, we focus on the tropospheric delay, and use the ionospheric delay estimation method for medium/long-range baselines we developed to reduce the ionospheric delay [11]. After the ionospheric delay and other measurement errors are removed, the GPS/BDS RTK processing model can be expressed as follows:…”

Section: Gps/bds Medium/long-range Rtk Algorithm Constrained With Nwpmentioning

confidence: 99%

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GPS/BDS Medium/Long-Range RTK Constrained with Tropospheric Delay Parameters from NWP Model

Chen

et al. 2018

Remote Sensing

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Tropospheric delay is a major error source that affects the performance of the Global Navigation Satellite Systems (GNSS) Real Time Kinematic (RTK) positioning especially for the medium/long-range baseline. Although high precision tropospheric delay can be estimated by GNSS carrier phase measurement, together with position and ambiguity, a relatively long period of convergence time is necessary. In this study, we develop a new GPS/BDS RTK algorithm constrained with a tropospheric delay parameters from Numerical weather prediction (NWP) model for medium/long-range baselines. The accuracy of the tropospheric delays derived from NWP is assessed through comparisons with the results of GAMIT (GNSS at MIT). The positioning performance with standard GPS RTK, standard GPS/BDS RTK, the developed NWP-constrained GPS RTK and NWP-constrained GPS/BDS RTK over medium/long-range baselines are compared in terms of the initialization time and the positioning accuracy. Experiment results show that the mean differences between the NWP and GAMIT zenith tropospheric delay (ZTD) are between −5.50 mm and 5.60 mm, and the RMS values of the NWP ZTD residuals are from 24.02 mm to 32.62 mm. A reduction in the initialization time of over 41% and 58% for medium-and long-range baselines can be achieved with the NWP-constrained RTK (both GPS alone and GPS/BDS RTK solutions) compared to the standard RTK solution, respectively. An improvement of over 30% can be found with the GPS/BDS RTK compared with that of the GPS alone RTK for both standard and the NWP-constrained modes. The positioning precision of NWP-constrained GPS/BDS RTK is better than 3 cm in the horizontal direction and better than 5 cm in the vertical direction, which satisfies the requirement of the precise positioning service.

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Section: Gps/bds Rtk Resultsmentioning

confidence: 99%

Section: Gps/bds Rtk Resultsmentioning

confidence: 99%

Section: Gps/bds Medium/long-range Rtk Algorithm Constrained With Nwpmentioning

confidence: 99%

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GPS/BDS Medium/Long-Range RTK Constrained with Tropospheric Delay Parameters from NWP Model

Chen

et al. 2018

Remote Sensing

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“…This method ignores the effect of the ionospheric and tropospheric delay and is limited to the short-range baseline. In another paper, we developed a new method to fix the ambiguity of GPS/BDS for a long-range baseline [26].…”

Section: Ambiguity Resolution Of Gps/glonass Signalsmentioning

confidence: 99%

A New GNSS Single-Epoch Ambiguity Resolution Method Based on Triple-Frequency Signals

Wang

Deng

et al. 2017

IJGI

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Fast and reliable ambiguity resolution (AR) has been a continuing challenge for real-time precise positioning based on dual-frequency Global Navigation Satellite Systems (GNSS) carrier phase observation. New GNSS systems (i.e., GPS modernization, BDS (BeiDou Navigation Satellite System), GLONASS (Global Navigation Satellite System), and Galileo) will provide multiple-frequency signals. The GNSS multiple-constellation and multiple-frequency signals are expected to bring great benefits to AR. A new GNSS single-epoch AR method for a short-range baseline based on triple-frequency signals is developed in this study. Different from most GNSS multiple-constellation AR methods, this technique takes advantage of the triple-frequency signals and robust estimation as much as possible. In this technique, the double difference (DD) AR of the triple-frequency observations is achieved in the first step. Second, the triple-frequency carrier phase observations with fixed ambiguities are used with the dual-frequency carrier phase observations to estimate their ambiguity. Finally, to realize reliable GNSS single-epoch AR, robust estimation is involved. The performance of the new technique is examined using 24 hours of GPS/GLONASS/BDS observation collected from a short-range baseline. The results show that single-epoch AR of the GNSS signals can be realized using this new technique. Moreover, the AR of BDS Geostationary Earth Orbit (GEO) satellites' observations is easier than are those of the Medium Earth Orbit (MEO) and Inclined Geosynchronous Satellite Orbit (IGSO) satellites' observations.

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“…Compared with traditional GNSS systems with dual-frequency signals, triple-frequency measurements can significantly benefit precise satellite-based data processing, such as cycle slip detection [1][2][3], integer ambiguity resolution (AR) [4] for both baseline solutions [5][6][7][8], and precise point positioning (PPP) [9,10]. To alleviate the computational burden, we can select more special linear combinations.…”

Section: Introductionmentioning

confidence: 99%

Triple-Frequency Code-Phase Combination Determination: A Comparison with the Hatch-Melbourne-Wübbena Combination Using BDS Signals

et al. 2018

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Considering the influence of the ionosphere, troposphere, and other systematic errors on double-differenced ambiguity resolution (AR), we present an optimal triple-frequency code-phase combination determination method driven by both the model and the real data. The new method makes full use of triple-frequency code measurements (especially the low-noise of the code on the B3 signal) to minimize the total noise level and achieve the largest AR success rate (model-driven) under different ionosphere residual situations (data-driven), thus speeding up the AR by directly rounding. With the triple-frequency Beidou Navigation Satellite System (BDS) data collected at five stations from a continuously-operating reference station network in Guangdong Province of China, different testing scenarios are defined (a medium baseline, whose distance is between 20 km and 50 km; a medium-long baseline, whose distance is between 50 km and 100 km; and a long baseline, whose distance is larger than 100 km). The efficiency of the optimal code-phase combination on the AR success rate was compared with that of the geometry-free and ionosphere-free (GIF) combination and the Hatch-Melbourne-Wübbena (HMW) combination. Results show that the optimal combinations can always achieve better results than the HMW combination with B2 and B3 signals, especially when the satellite elevation angle is larger than 45 • . For the wide-lane AR which aims to obtain decimeter-level kinematic positioning service, the standard deviation (STD) of ambiguity residuals for the suboptimal combination are only about 0.2 cycles, and the AR success rate by directly rounding can be up to 99%. Compared with the HMW combinations using B1 and B2 signals and using B1 and B3 signals, the suboptimal combination achieves the best results in all baselines, with an overall improvement of about 40% and 20%, respectively. Additionally, the STD difference between the optimal and the GIF code-phase combinations decreases as the baseline length increases. This indicates that the GIF combination is more suitable for long baselines. The proposed optimal code-phase combination determination method can be applied to other multi-frequency global navigation satellite systems, such as new-generation BDS, Galileo, and modernized GPS.

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A new ionosphere-free ambiguity resolution method for long-range baseline with GNSS triple-frequency signals

Cited by 21 publications

References 24 publications

GPS/BDS Medium/Long-Range RTK Constrained with Tropospheric Delay Parameters from NWP Model

GPS/BDS Medium/Long-Range RTK Constrained with Tropospheric Delay Parameters from NWP Model

A New GNSS Single-Epoch Ambiguity Resolution Method Based on Triple-Frequency Signals

Triple-Frequency Code-Phase Combination Determination: A Comparison with the Hatch-Melbourne-Wübbena Combination Using BDS Signals

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