BazTech - Yadda

1

A combined iCEEMDAN and VMD method for mitigating the impact of ionospheric scintillation on GNSS signals

Dey Abhijit, Chhibba Rohan, Ratnam Devananboyina Venkata, Sharma Nitin

Acta Geophysica

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2021

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Vol. 69, no. 5

1933--1948

EN

Severe amplitude and phase scintillation induced by the ionospheric plasma density irregularities degrades the performance of global navigation satellite system (GNSS) receivers. Scintillation typically has adverse effects at the tracking process and thus adversely affects the raw GNSS measurements used in a number of applications. Hence, it is important to develop robust methodologies for detecting and mitigating ionospheric effects on the GNSS signals. In this paper, we propose a novel method based on the combination of improved complete ensemble empirical mode decomposition with adaptive noise (iCEEMDAN) and variational mode decomposition (VMD) methods. The proposed method employs a detrended fuctuation analysis (DFA)-based metric for robust thresholding between the scintillation-free and amplitude scintillated GNSS signals. The major contribution of the proposed method is development of novel approaches for selection of intrinsic mode functions (IMFs) based on DFA and optimised selection of [K, 훼] parameters of the VMD. The performance of the proposed method was evaluated and was observed that it is better than existing ionospheric scintillation effects mitigation algorithms for both simulated and real-time GPS scintillation datasets. The proposed method can denoise approximately 9.23–15.30 dB scintillation noise from the synthetic and 0.2–0.48 from the real scintillation index (S4) values. Therefore, the proposed (iCEEMDAN-VMD) method is appropriate for mitigating the ionospheric scintillation effects on the GNSS signals.

2

Lotniczy skaning laserowy (LiDAR-ALS) jako źródło danych do obliczeń stateczności skarp na terenach zadrzewionych i zakrzewionych

Piechota A.

Przegląd Geologiczny

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2017

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Vol. 65, nr 10/2

811--816

EN

The paper discusses the problem of quick acquire height data for calculation of escarpment stability. In past the slope of profile was obtainedfrom classical land survey methods (like Total Station, GNSS, etc.), carto- metric measurement on maps or measurements based on a Digital Terrain Modelfrom aerial photography. Now we have a new method that is Airborne Laser Scanning (LiDAR-ALS). In 2011-2014 almost all country was measured in this method. The declared accuracy of height measurement on the durable surfaces is about 0.10-0.15 m. Author compared this method with classical method Global Navigation Satellite System - Real Time Network (GNSS-RTN) on two wooded and bushy areas. The comparison was based on the measurement characteristic points on the profiles and acquisition of height data from LiDAR-ALS data. Data in this method were obtained in two ways: from point cloud and from DTM createdfrom this point cloud. In the next step, height differences were calculated and these data were subjected to basic statistical calculations. The result of the study was a mean error of height data from LiDAR-ALS and conclusions about its usefulness in acquire height data for calculation of escarpment stability.

3

Comparative analysis of three ionospheric broadcast models for global navigation satellite systems

Li S., Li L., Wang S., Peng J., Xu Y., Zhao Y.

Acta Geophysica

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2017

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Vol. 65, no. 2

395--410

EN

An ionospheric model and corresponding coefficients broadcasted via GNSS navigation message are generally used to estimate the time delay for single-frequency GNSS users. In this article, the capabilities of three ionospheric models, namely, Klobuchar model, NeQuick Galileo version (NeQuick G), and Neustrelitz TEC broadcast model (NTCM-BC), were assessed. The models were examined in two aspects: total electron content (TEC) prediction and ionospheric delay correction effects in single-point positioning. Results show that both NeQuick G and NTCM-BC models outperformed Klobuchar model for predicting global TEC values during all the test days. Compared with Slant TEC (STEC) along the receiver-to-satellite ray path derived from IGS global ionosphere map (GIMs), STEC from NeQuick G and NTCM-BC models tend to have less bias than those from Klobuchar model in most situations. The point positioning results were improved by applying ionospheric broadcast models especially at the mid- and low-latitude stations.

4

Transport safety : the GNSS spoofing detecting using two navigators

Dobryakova L., Lemieszewski Ł., Ochin E.

Logistyka

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2014

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nr 3

1328--1331

EN

The purpose of this paper is to introduce the principles of GNSS spoofing detection theory using two navigators. With that in mind, some of the theoretical treatment has been simplified to provide a starting point for a mathematically literate user of GNSS who wishes to understand how GNSS spoofing detection theory using two navigators works, and to get a basic grasp of GNSS spoofing detection theory and terminology.

PL

Celem tego artykułu jest przedstawienie zasad teorii detekcji GNSS spoofingu za pomocą dwóch nawigatorów. Mając to na uwadze, niektórzy z leczenia teoretyczne zostałi uproszczony, aby stanowić punkt wyjścia dla matematycznie literat użytkownika GNSS, który chce zrozumieć, jak działa teoria wykrywania GNSS spoofingu za pomocą dwóch nawigatorów i uzyskać podstawowe zrozumienie teorii wykrywania GNSS spoofingu.

5

Testing and measuring GNSS parameters

Novak A., Novak Sedlackova A., Nemec V.

TTS Technika Transportu Szynowego

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2013

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R. 20, nr 10

1225--1232, CD

EN

This paper describes the consistent preview of the testing and measuring GNSS parameters. The Measuring and testing GNSS requires three essential components: aircraft with flight crews, procedures or navigation aid requiring validation, and a Flight Inspection System (FIS). A Global Navigation Satellite System (GNSS), as a source of position information available worldwide is considered as a key enabler to future navigation.