scholarly journals Robust Statistics for GNSS Positioning under Harsh Conditions: A Useful Tool?

Sensors ◽  
2019 ◽  
Vol 19 (24) ◽  
pp. 5402 ◽  
Author(s):  
Daniel Medina ◽  
Haoqing Li ◽  
Jordi Vilà-Valls ◽  
Pau Closas
Keyword(s):  
Robust Regression ◽  
Robust Statistics ◽  
Single Point ◽  
Global Navigation Satellite Systems ◽  
Noise Model ◽  
Satellite Systems ◽  
Gnss Positioning ◽  
Global Navigation Satellite ◽  
Harsh Conditions ◽  
Real World Problems

Navigation problems are generally solved applying least-squares (LS) adjustments. Techniques based on LS can be shown to perform optimally when the system noise is Gaussian distributed and the parametric model is accurately known. Unfortunately, real world problems usually contain unexpectedly large errors, so-called outliers, that violate the noise model assumption, leading to a spoiled solution estimation. In this work, the framework of robust statistics is explored to provide robust solutions to the global navigation satellite systems (GNSS) single point positioning (SPP) problem. Considering that GNSS observables may be contaminated by erroneous measurements, we survey the most popular approaches for robust regression (M-, S-, and MM-estimators) and how they can be adapted into a general methodology for robust GNSS positioning. We provide both theoretical insights and validation over experimental datasets, which serves in discussing the robust methods in detail.

scholarly journals Code Single Point Positioning Using Nominal Gnss Constellations (Future Perception)

2007 ◽  
Vol 42 (3) ◽  
pp. 149-153
Author(s):  
A. Farah
Keyword(s):  
Single Point ◽  
Satellite System ◽  
Global Navigation Satellite Systems ◽  
Navigation Satellite ◽  
Satellite Systems ◽  
Performance Improvements ◽  
Single Point Positioning ◽  
Global Navigation ◽  
Point Positioning ◽  
Global Navigation Satellite

Code Single Point Positioning Using Nominal Gnss Constellations (Future Perception) Global Navigation Satellite Systems (GNSS) have an endless number of applications in industry, science, military, transportation and recreation & sports. Two systems are currently in operation namely GPS (the USA Global Positioning System) and GLONASS (the Russian GLObal NAvigation Satellite System), and a third is planned, the European satellite navigation system GALILEO. The potential performance improvements achievable through combining these systems could be significant and expectations are high. The need is inevitable to explore the future of positioning from different nominal constellations. In this research paper, Bernese 5.0 software could be modified to simulate and process GNSS observations from three different constellations (GPS, Glonass and Galileo) using different combinations. This study presents results of code single point positioning for five stations using the three constellations and different combinations.

scholarly journals Theoretical Upper Bound and Lower Bound for Integer Aperture Estimation Fail-Rate and Practical Implications

2012 ◽  
Vol 66 (3) ◽  
pp. 321-333 ◽  
Author(s):  
Tao Li ◽  
Jinling Wang
Keyword(s):  
Lower Bound ◽  
Upper Bound ◽  
Global Navigation Satellite Systems ◽  
Integer Ambiguity ◽  
Satellite Systems ◽  
Gnss Positioning ◽  
Integer Aperture Estimation ◽  
Ambiguity Validation ◽  
Global Navigation Satellite ◽  
Practical Implications

Integer ambiguity validation is pivotal in precise positioning with Global Navigation Satellite Systems (GNSS). Recent research has shown traditionally used ambiguity validation methods can be classified as members of the Integer Aperture (IA) estimators, and by the virtue of the IA estimation, a user controllable IA fail-rate is preferred. However, an appropriately chosen fail-rate is essential for ambiguity validation. In this paper, the upper bound and the lower bound for the IA fail-rate, which are extremely useful even at the designing stage of a GNSS positioning system, have been analysed, and numerical results imply that a meaningful IA fail-rate should be within this range.

scholarly journals Intelligent Urban Positioning: Integration of Shadow Matching with 3D-Mapping-Aided GNSS Ranging

2017 ◽  
Vol 71 (1) ◽  
pp. 1-20 ◽  
Author(s):  
Mounir Adjrad ◽  
Paul D. Groves
Keyword(s):  
Urban Areas ◽  
Three Dimensional ◽  
Covariance Matrices ◽  
Global Navigation Satellite Systems ◽  
3D Mapping ◽  
Deterministic Approach ◽  
Satellite Systems ◽  
Gnss Positioning ◽  
Error Covariance ◽  
Global Navigation Satellite

In dense urban areas, conventional Global Navigation Satellite Systems (GNSS) positioning can exhibit errors of tens of metres due to the obstruction and reflection of the signals by the surrounding buildings. By using Three-Dimensional (3D) mapping of the buildings, the accuracy can be significantly improved. This paper demonstrates the first integration of GNSS shadow matching with 3D-mapping-aided GNSS ranging. The integration is performed in the position domain, whereby separate ranging and shadow matching position solutions are computed, then combined using direction-dependent weighting. Two weighting strategies are compared, one based on the computation of ranging-based and shadow matching position error covariance matrices, and a deterministic approach based on the street azimuth. Using experimental data collected from a u-blox GNSS receiver, it is shown that both integrated position solutions are significantly more accurate than either shadow matching or 3D-mapping-aided ranging on their own. The overall Root Mean Square (RMS) horizontal accuracy obtained using covariance-based weighting was 6·1 m, a factor of four improvement on the 25·9 m obtained using conventional GNSS positioning. Results are also presented using smartphone data, where shadow matching is integrated with conventional GNSS positioning.

scholarly journals GPS/Galileo Multipath Detection and Mitigation Using Closed-Form Solutions

2009 ◽  
Vol 2009 ◽  
pp. 1-20 ◽  
Author(s):  
Khaled Rouabah ◽  
Djamel Chikouche
Keyword(s):  
High Performance ◽  
High Accuracy ◽  
Global Navigation Satellite Systems ◽  
Line Of Sight ◽  
Satellite Systems ◽  
Closed Form Solutions ◽  
Gnss Positioning ◽  
Simulation Results ◽  
Multipath Detection ◽  
Global Navigation Satellite

We propose an efficient method for the detection of Line of Sight (LOS) and Multipath (MP) signals in global navigation satellite systems (GNSSs) which is based on the use of virtual MP mitigation (VMM) technique. By using the proposed method, the MP signals' delay and coefficient amplitudes can be efficiently estimated. According to the computer simulation results, it is obvious that our proposed method is a solution for obtaining high performance in the estimation and mitigation of MP signals and thus it results in a high accuracy in GNSS positioning.

scholarly journals Intersystem Bias in GPS, GLONASS, Galileo, BDS-3, and BDS-2 Integrated SPP: Characteristics and Performance Enhancement as a Priori Constraints

2021 ◽  
Vol 13 (22) ◽  
pp. 4650
Author(s):  
Lin Pan ◽  
Zhehao Zhang ◽  
Wenkun Yu ◽  
Wujiao Dai
Keyword(s):  
Performance Enhancement ◽  
Low Cost ◽  
Single Point ◽  
A Priori ◽  
Global Navigation Satellite Systems ◽  
Satellite Systems ◽  
Term Stability ◽  
Long Term Stability ◽  
And Performance ◽  
Global Navigation Satellite

Global navigation satellite systems (GNSSs) have been booming in recent years, and the space segment of all four of the GNSSs, including BDS (BDS-3/BDS-2), Galileo, GPS, and GLONASS, has almost been fully deployed at present. The single point positioning (SPP) technology, which is widely used in satellite navigation and low-accuracy positioning, can benefit from the multi-GNSS integration, but the additional intersystem bias (ISB) parameters should be introduced to ensure the compatibility among different GNSSs. In this study, the ISB estimates derived from four-system integrated SPP are carefully characterized, and the performance enhancement attributed to a priori ISB constraints by prediction for position solutions under open sky and constrained visibility environments is rigorously evaluated. The results indicate that the ISB between BDS-3 and BDS-2 cannot be ignored. The daily ISBs show step changes when encountering the replacement of receiver types, while it is not the case for the receiver firmware versions. The daily ISBs are roughly consistent for the stations equipped with the same type of receivers. The short-term stability of epochwise ISBs for GLONASS, Galileo, BDS-2, and BDS-3 with respect to GPS can be 2.335, 1.262, 1.741, and 1.532 ns, respectively, whereas the corresponding long-term stability for daily ISBs can be 1.258, 1.288, 2.713, and 2.566 ns, respectively. The single-day prediction accuracy of daily ISBs for GLONASS, Galileo, BDS-2, and BDS-3 with respect to GPS can be 1.055, 0.640, 1.242, and 0.849 ns, respectively. The improvements on positioning accuracy after introducing a priori ISB constraints can be over 20% at an elevation mask of 40° and 50° with a time span of ISB prediction of a day. As to the availability, it is only 64.0% for traditional four-system SPP under a cutoff elevation of 50°, while the corresponding availability is increased to approximately 90.0% after considering a priori ISB constraints. For completeness, the characteristics of ISBs estimated with the low-cost u-blox M8T receiver and the Xiaomi Mi8 smartphone as well as the contribution of a priori ISB constraints to the multisystem SPP solutions with these devices are also investigated.

scholarly journals Low-Cost GNSS Software Receiver Performance Assessment

Geosciences ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 79 ◽  
Author(s):  
Matteo Cutugno ◽  
Umberto Robustelli ◽  
Giovanni Pugliano
Keyword(s):  
Low Cost ◽  
Single Point ◽  
Tall Buildings ◽  
Global Navigation Satellite Systems ◽  
Satellite Systems ◽  
Front End ◽  
Systems Software ◽  
Steering Mechanism ◽  
Differential Positioning ◽  
Global Navigation Satellite

The Software-Defined Receiver (SDR) is a rapidly evolving technology which is a useful tool for researchers and allows users an extreme level customization. The main aim of this work is the assessment of the performance of the combination consisting of the Global Navigation Satellite Systems Software-Defined Receiver (GNSS-SDR), developed by CTTC (Centre Tecnològic de Telecomunicacions de la Catalunya), and a low-cost front-end. GNSS signals were acquired by a Nuand bladeRF x-40 front-end fed by the TOPCON PG-A1 antenna. Particular attention was paid to the study of the clock-steering mechanism due to the low-cost characteristics of the bladeRF x-40 clock. Two different tests were carried out: In the first test, the clock-steering algorithm was activated, while in the second, it was deactivated. The tests were conducted in a highly degraded scenario where the receiver was surrounded by tall buildings. Single-Point and Code Differential positioning were computed. The achieved results show that the steering function guarantees the availability of more solutions, but the DRMS is quite the same in the two tests.

scholarly journals GEOSPATIAL DATA QUALITY OF THE SERVIR CORS NETWORK

2015 ◽  
Vol II-3/W5 ◽  
pp. 285-290 ◽  
Author(s):  
J. Santos ◽  
R. Teodoro ◽  
N. Mira ◽  
V. B. Mendes
Keyword(s):  
Quality Control ◽  
Geospatial Data ◽  
Global Navigation Satellite Systems ◽  
Positional Accuracy ◽  
Worst Case ◽  
Static Mode ◽  
Satellite Systems ◽  
Gnss Positioning ◽  
Global Navigation Satellite

The SERVIR Continuous Operation Reference Stations (CORS) network was implemented in 2006 to facilitate land surveying with Global Navigation Satellite Systems (GNSS) positioning techniques. Nowadays, the network covers all Portuguese mainland. The SERVIR data is provided to many users, such as surveyors, universities (for education and research purposes) and companies that deal with geographic information. By middle 2012, there was a significant change in the network accessing paradigm, the most important of all being the increase in the responsibility of managing the network to guarantee a permanent availability and the highest quality of the geospatial data. In addition, the software that is used to manage the network and to compute the differential corrections was replaced by a new software package. These facts were decisive to perform the quality control of the SERVIR network and evaluate positional accuracy. In order to perform such quality control, a significant number of geodetic monuments spread throughout the country were chosen. Some of these monuments are located in the worst location regarding the network geometry in order to evaluate the accuracy of positions for the worst case scenarios. Data collection was carried out using different GNSS positioning modes and were compared against the benchmark positions that were determined using data acquired in static mode in 3-hour sessions. We conclude the geospatial data calculated and provided to the users community by the network is, within the surveying purposes, accurate, precise and fits the needs of those users.

scholarly journals Partial Carrier-Phase Integer Ambiguity Resolution for High Accuracy GNSS Positioning

2020 ◽  
Author(s):  
Andreas Brack
Keyword(s):  
Ambiguity Resolution ◽  
Carrier Phase ◽  
Real Data ◽  
Global Navigation Satellite Systems ◽  
Integer Ambiguity ◽  
Phase Measurements ◽  
Satellite Systems ◽  
Partial Ambiguity Resolution ◽  
Gnss Positioning ◽  
Global Navigation Satellite

Global navigation satellite systems provide ranging based positioning and timing services. The use of the periodic carrier-phase signals is the key to fast and accurate solutions, given that the inherent ambiguities of the carrier-phase measurements are correctly resolved. The idea of partial ambiguity resolution is to resolve a subset of all ambiguities, which enables faster solutions but does not fully exploit the high precision of the carrier-phase measurements. Theory, methods, and algorithms for partial ambiguity resolution are discussed and analyzed with simulated and real data.

scholarly journals GNSS Positioning Security: Automatic Anomaly Detection on Reference Stations

2021 ◽  
pp. 60-76
Author(s):  
Stéphanie Lebrun ◽  
Stéphane Kaloustian ◽  
Raphaël Rollier ◽  
Colin Barschel
Keyword(s):  
Anomaly Detection ◽  
Historical Data ◽  
Global Navigation Satellite Systems ◽  
Navigation Satellite ◽  
Satellite Systems ◽  
Gnss Positioning ◽  
Detection Approach ◽  
Normal Behavior ◽  
Global Navigation Satellite ◽  
Statistical Rule

AbstractThe dependency of critical infrastructures on Global Navigation Satellite Systems (GNSS) keeps increasing over the years. This over-reliance brings concerns as those systems are vulnerable and consequently prone to human-made perturbations, such as jamming and spoofing attacks. Solutions for detecting such disturbances are therefore crucially needed to raise GNSS users’ awareness and protection. This paper suggests an approach for detecting anomalous events (i.e., potentially an attack attempt) based on measurements recorded by Continuously Operating GNSS Reference Stations (CORS). Precisely, the anomaly detection process first consists in modeling the normal behavior of a given signal thanks to a predictive model which combines the Seasonal and Trend decomposition using LOESS and ARIMA algorithms. This model can then be used to predict the upcoming measurement values. Finally, we compare the predictions to the actual observations with a statistical rule and assess if those are normal or anomalous. While our anomaly detection approach is intended for real-time use, we assess its effectiveness on historical data. For simplicity and independence, we also focus on the Carrier-to-Noise Ratio only, though similar methods could apply to other observables. Our results prove the sensitivity of the proposed detection on a reported case of unintentional disturbance. Other anomalies in the historical data are also uncovered using that methodology and presented in this paper.

Sign in / Sign up

Export Citation Format

Share Document