Real-Time PPP-RTK Performance Analysis Using Ionospheric Corrections from Multi-Scale Network Configurations

Psychas, Dimitrios; Verhagen, Sandra

doi:10.3390/s20113012

Cited by 59 publications

(32 citation statements)

References 36 publications

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“…In other words, Equation (2) is the so-called ionosphere-float model. However, one can easily augment Equation (2) with the external ionospheric delay corrections by making use of precise network-derived slant ionospheric corrections on the basis of the best linear unbiased prediction method [53]. It needs to be noted that satellite and receiver differential code biases (DCB) are lumped into the estimable ionospheric delay; therefore, one must carefully take into account the DCBs when implementing the external ionospheric delay corrections into the PPP-RTK model to ensure the absence of biases in the functional model of the ionosphere-corrected PPP-RTK user.…”

Section: Ppp-rtk Modelmentioning

confidence: 99%

Assessing the Performance of Multi-GNSS PPP-RTK in the Local Area

Zhao

Verhagen

et al. 2020

Remote Sensing

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The benefits of an increased number of global navigation satellite systems (GNSS) in space have been confirmed for the robustness and convergence time of standard precise point positioning (PPP) solutions, as well as improved accuracy when (most of) the ambiguities are fixed. Yet, it is still worthwhile to investigate fast and high-precision GNSS parameter estimation to meet user needs. This contribution focuses on integer ambiguity resolution-enabled Precise Point Positioning (PPP-RTK) in the use of the observations from four global navigation systems, i.e., GPS (Global Positioning System), Galileo (European Global Navigation Satellite System), BDS (Chinese BeiDou Navigation Satellite System), and GLONASS (Global’naya Navigatsionnaya Sputnikova Sistema). An undifferenced and uncombined PPP-RTK model is implemented for which the satellite clock and phase bias corrections are computed from the data processing of a group of stations in a network and then provided to users to help them achieve integer ambiguity resolution on a single receiver by calibrating the satellite phase biases. The dataset is recorded in a local area of the GNSS network of the Netherlands, in which 12 stations are regarded as the reference to generate the corresponding corrections and 21 as the users to assess the performance of the multi-GNSS PPP-RTK in both kinematic and static positioning mode. The results show that the root-mean-square (RMS) errors of the ambiguity float solutions can achieve the same accuracy level of the ambiguity fixed solutions after convergence. The combined GNSS cases, on the contrary, reduce the horizontal RMS of GPS alone with 2 cm level to GPS + Galileo/GPS + Galileo + BDS/GPS + Galileo + BDS + GLONASS with 1 cm level. The convergence time benefits from both multi-GNSS and fixing ambiguities, and the performances of the ambiguity fixed solution are comparable to those of the multi-GNSS ambiguity float solutions. For instance, the convergence time of GPS alone ambiguity fixed solutions to achieve 10 cm three-dimensional (3D) positioning accuracy is 39.5 min, while it is 37 min for GPS + Galileo ambiguity float solutions; moreover, with the same criterion, the convergence time of GE ambiguity fixed solutions is 19 min, which is better than GPS + Galileo + BDS + GLONASS ambiguity float solutions with 28.5 min. The experiments indicate that GPS alone occasionally suffers from a wrong fixing problem; however, this problem does not exist in the combined systems. Finally, integer ambiguity resolution is still necessary for multi-GNSS in the case of fast achieving very-high-accuracy positioning, e.g., sub-centimeter level.

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Section: Ppp-rtk Modelmentioning

confidence: 99%

Assessing the Performance of Multi-GNSS PPP-RTK in the Local Area

Zhao

Verhagen

et al. 2020

Remote Sensing

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“…Since the advent of PPP-RTK, efforts have been made to achieve fast (i.e., instantaneous or near-instantaneous) centimeter-level accuracy. Applying precise ionospheric corrections from regional networks with a station spacing of a few hundreds of kilometers has been shown to provide almost-instantaneous positioning solutions based on GPS dual-frequency data [2,[4][5][6]. The establishment of such dense networks, however, is not highly attractive because of the cost and complex operation requirements involved, and is also difficult or even impossible in certain areas.…”

Section: Introductionmentioning

confidence: 99%

A Multi-Frequency Galileo PPP-RTK Convergence Analysis with an Emphasis on the Role of Frequency Spacing

2021

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The single-receiver integer ambiguity resolution-enabled variant of precise point positioning (PPP), namely PPP-RTK, has proven to be crucial in reducing the long convergence time of PPP solutions through the recovery of the integerness of the user-ambiguities. The proliferation of global navigation satellite systems (GNSS) supports various improvements in this regard through the availability of more satellites and frequencies. The increased availability of the Galileo E6 signal from GNSS receivers paves the way for speeding up integer ambiguity resolution, as more frequencies provide for a stronger model. In this contribution, the Galileo-based PPP-RTK ambiguity resolution and positioning convergence capabilities are studied and numerically demonstrated as a function of the number and spacing of frequencies, aiming to shed light on which frequencies should be used to obtain optimal performance. Through a formal analysis, we provide insight into the pivotal role of frequency separation in ambiguity resolution. Using real Galileo data on up to five frequencies and our estimated PPP-RTK corrections, representative kinematic user convergence results with partial ambiguity resolution are presented and discussed. Compared to the achieved performance of dual-frequency fixed solutions, it is found that the contribution of multi-frequency observations is significant and largely driven by frequency separation. When using all five available frequencies, it is shown that the kinematic user can achieve a sub-decimeter level convergence in 15.0 min (90% percentile). In our analysis, we also show to what extent the provision of the estimable satellite code biases as standard PPP-RTK corrections accelerates convergence. Finally, we numerically demonstrate that, when integrated with GPS, the kinematic user solution achieves convergence in 3.0 and 5.0 min on average and at 90%, respectively, in the presence of ionospheric delays, thereby indicating the single-receiver user’s fast-convergence capabilities.

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“…Results indicate that centimetre-level positioning accuracy can be achieved based on GPS-or BDS-only observations, and performance can be further improved by realizing PPP AR method. Psychas et al (2020) analysed the real-time PPP-RTK user performance using ionospheric corrections from multi-scale regional networks during a day with medium ionospheric disturbance. Results showed that sub-10 cm horizontal accuracy can be achieved within 1 min and 2 min based on corrections from a network with 68 km and 115 km spacing.…”

Section: Introductionmentioning

confidence: 99%

Accuracy evaluation of ionospheric delay from multi-scale reference networks and its application for fast PPP ambiguity resolution

Zhao¹,

Douša²,

Václavovic³

2021

Proceedings of Conference GIS Ostrava 2021 Advances in Localization and Navigation

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The Precise Point Positioning (PPP) can achieve a fast ambiguity resolution (PPP-RTK) when augmented with precise ionospheric delays derived from regional GNSS networks. In this study, the accuracy of the ionospheric delay derived from multi-scale networks are assessed and used for the GPS and Galileo PPP-RTK demonstration. First, the convergence time of the GPS-only PPP are evaluated based on the GFZ final and CNES real-time products. Results indicated that an average convergence time of 30 min and 20 min is needed for the CNES and GFZ float solutions, respectively, in order to achieve a decimetre level horizontal position accuracy. After applying the ambiguity resolution method, 20% and 35% improvements are observed reaching 24min and 13min, respectively. Then, the accuracy of ionospheric delays derived from the ambiguity-fixed PPP and the CODE global products are assessed. A short-baseline comparison indicated that the mean bias and standard deviation of the derived multi-day ionospheric errors are within 0.15 TECU and 0.06 TECU, respectively, with a presence of a daily periodic term. The accuracy of the interpolated ionospheric delay from global models are more related to the location of the stations, ranging from 1 TECU to 3 TECU. Finally, precise ionospheric delays derived from the EUREF permanent network with the inter-station distance larger than 73 km are selected for ionospheric modelling at the user location. Results indicated that the PPP ambiguity resolution can be achieved within a minute. After enlarging the inter-station distance to 209 km, ambiguity resolution can be achieved within several epochs with improved fixing rate as well.

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Real-Time PPP-RTK Performance Analysis Using Ionospheric Corrections from Multi-Scale Network Configurations

Cited by 59 publications

References 36 publications

Assessing the Performance of Multi-GNSS PPP-RTK in the Local Area

Assessing the Performance of Multi-GNSS PPP-RTK in the Local Area

A Multi-Frequency Galileo PPP-RTK Convergence Analysis with an Emphasis on the Role of Frequency Spacing

Accuracy evaluation of ionospheric delay from multi-scale reference networks and its application for fast PPP ambiguity resolution

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