Satellite antenna phase center errors: magnified threat to multi-frequency PPP ambiguity resolution

Geng, Jianghui; Guo, Jiang; Wang, Chen; Zhang, Qiyuan

doi:10.1007/s00190-021-01526-4

Cited by 12 publications

(4 citation statements)

References 30 publications

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“…We inferred that there were some frequency-dependent biases (e.g., IFCB, multi-frequency PCO errors) left in the data processing model. It has been demonstrated that these frequency-dependent biases could be magnified after forming combined observables (i.e., PPP-WAR) [34]. In this case, even a bias of several millimeters can threaten PPP-AR.…”

Section: Discussionmentioning

confidence: 99%

“…Ref. [34] demonstrated that multi-frequency PPP-AR solutions were more vulnerable than float solutions to some frequency-specific errors (e.g., antenna phase centers, IFCB); they demonstrated that even a bias of several millimeters could deteriorate multi-frequency PPP-AR convergence performance. In this case, we further implemented PPP-WAR using dual satellite clocks (refer to ( 5)), which is shown in the right panel.…”

Section: Ppp-warmentioning

confidence: 99%

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Assessment of Multi-Frequency PPP Ambiguity Resolution Using Galileo and BeiDou-3 Signals

Guo

Zhang

et al. 2021

Remote Sensing

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From network RTK to PPP-RTK, it is highly expected that high-precision positioning within a few minutes can be achieved with a sparse reference network. In this study, we investigate a rapid multi-frequency PPP convergence strategy based on Galileo E1/E5a/E6 and BeiDou-3 B1C/B2a/B3I signals, whose unambiguous wide-lane observables can efficiently assist in speeding up narrow-lane ambiguity resolution. Furthermore, frequency-specific biases existing on the third-frequency observables have been observed to slow down multi-frequency PPP-AR convergence. In this study, we partially mitigated their effects by estimating a second satellite clock for the third frequency of signals. We validated this approach with one month of data collected from 22 stations. On average, it took about 18 min for PPP wide-lane ambiguity resolution (PPP-WAR) to converge, while 32 min were required for ambiguity-float PPP. Compared with dual-frequency PPP-AR, which needed nearly 12 min to converge, multi-frequency PPP-AR required 6 min only. Once there were more than 10 satellites involved in PPP, the convergence could be achieved within 3 min on average. Meanwhile, 81% and 62% of multi-frequency PPP-AR solutions converged successfully within 5 and 1 min, respectively. Finally, we carried out a vehicle-borne experiment to validate this approach in a kinematic environment. Owing to frequent cycle slips during the movement of vehicle, it took 14 min for B1C/B2a/B3I and E1/E5a/E6 PPP-AR to obtain reliable positions, and 19 min for those using the other signal combinations B1C/B2a/B2b and E1/E5a/E5b, owning to higher noise. Overall, these results are promising for achieving high-precision PPP positioning globally within a few minutes if multi-frequency biases can be handled well in the data processing.

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Section: Discussionmentioning

confidence: 99%

Section: Ppp-warmentioning

confidence: 99%

Assessment of Multi-Frequency PPP Ambiguity Resolution Using Galileo and BeiDou-3 Signals

Guo

Zhang

et al. 2021

Remote Sensing

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“…It is important to note that when using the MW combination to obtain the float WL ambiguity, the antenna phase center correction of the receiver and satellite must be taken into account [29,30]. The formula is as follows:…”

Section: Ppp-ar Processmentioning

confidence: 99%

Evaluation of Real-time Precise Point Positioning with Ambiguity Resolution Based on Multi-GNSS OSB Products from CNES

Shu

Xie

et al. 2022

Remote Sensing

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Ambiguity resolution (AR) is a core technology that helps to speed up convergence time and increase positioning accuracy for precise point positioning (PPP), and the performance of PPP-AR is based on the quality of ambiguity resolution products. Real-time PPP-AR becomes a reality as users can now obtain publicly accessible real-time observable-specific signal bias (OSB) products from the Centre National d’Etudes Spatiales (CNES). Therefore, an analysis of the quality of OSB products and an evaluation of the performance of PPP-AR are required to promote the application of real-time positioning. For a total of 31 days between day of year (DOY) 121 and 151 in 2021, observation data were collected from 90 stations, and the OSB products were used to assess the experiments. As for the quality of the OSB products, the data availability (DA) of the GPS and Galileo satellites was greater than 97%, whereas that of BDS was less than 60%; the maximum fluctuation value (MAX) and standard deviation (STD) of the GPS, Galileo, and BDS satellites were 0.045 and 0.012; 0.081 and 0.028; and 0.292 and 0.085 cycles, respectively. In terms of ambiguity residuals using the OSB products, the wide-lane (WL) residual percentages within ±0.25 cycles for the GPS, Galileo, BDS-2, and BDS-3 systems were more than 92%, and the narrow-lane (NL) residual percentages within ±0.25 cycles for the four systems were 92%, 89%, 79%, and 60%, respectively. With regard to the performance of PPP-AR, the GPS+Galileo solution showed the best performance in the kinematic positioning mode, in which the mean root mean square (RMS) of positioning accuracy was 1.06, 1.27, and 2.85 cm for the east (E), north (N), and up (U) components, respectively, and the mean convergence time reached 9.6 min. In the static positioning mode, the mean convergence times of the GPS-only and GPS+Galileo solutions were 11.4 min and 8.0 min, respectively, and both of their mean RMS for positioning accuracy reached 0.79, 0.95, and 1.48 cm for the E, N, and U components, respectively. However, the addition of BDS did not further enhance the performance of multi-GNSS PPP-AR in either the kinematic or static positioning mode due to the poor quality of the real-time BDS products. More importantly, a prediction method was proposed to avoid re-convergence and to enhance the reliability of PPP-AR in the event of short-time missing real-time OSB products and to improve the positioning accuracy and the ambiguity fixed rate.

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“…These errors include LEO satellite orbital and clock errors, ground receiver clock errors, tropospheric delays, ionospheric delays, phase ambiguities, phase center offsets (PCOs) and phase center variations (PCVs), and various hardware delays. For instance, the errors of GNSS satellite PCO for PPP can reach the centimeter level [13], and the hardware delay of the differential code biases (DCBs) can reach more than ten nanoseconds [14].…”

Section: Introductionmentioning

confidence: 99%

PCO and hardware delay calibration for LEO satellite antenna downlinking navigation signals

Liu,

Wang,

El-Mowafy

et al. 2024

Meas. Sci. Technol.

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Augmentation of the GNSS by Low Earth Orbit (LEO) satellites is a promising approach benefiting from the advantages of LEO satellites. This, however, requires errors and biases in the satellite downlink navigation signals to be calibrated, modeled, or eliminated. This contribution introduces an approach for in-orbit calibration of the Phase Center Offsets (PCOs) and code hardware delays of the LEO downlink navigation signal transmitter/antenna. Using the satellite geometries of Sentinel-3B and Sentinel-6A as examples, the study analyzed the formal precision and bias influences for potential downlink antenna PCOs and hardware delays of LEO satellites under different ground network distributions, and processing periods. It was found that increasing the number of tracking stations and processing periods can improve the formal precision of PCOs and hardware delay. Less than 3.5 mm and 3 cm, respectively, can be achieved with 10 stations and 6 processing days. The bias projections of the real-time LEO satellite orbital and clock errors can reach below 3 mm in such a case. For near-polar LEO satellites, stations in polar areas are essential for strengthening the observation model.

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Satellite antenna phase center errors: magnified threat to multi-frequency PPP ambiguity resolution

Cited by 12 publications

References 30 publications

Assessment of Multi-Frequency PPP Ambiguity Resolution Using Galileo and BeiDou-3 Signals

Assessment of Multi-Frequency PPP Ambiguity Resolution Using Galileo and BeiDou-3 Signals

Evaluation of Real-time Precise Point Positioning with Ambiguity Resolution Based on Multi-GNSS OSB Products from CNES

PCO and hardware delay calibration for LEO satellite antenna downlinking navigation signals

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