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1

Support Vector Regression model to predict TEC for GNSS signals

Sivakrishna Kondaveeti, Ratnam Devanaboyina Venkata, Sivavaraprasad Gampala

Acta Geophysica

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2022

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Vol. 70, no 6

2827--2836

EN

Ionospheric Total Electron Content (TEC) predominantly affects the radio wave communication and navigation links of Global Navigation Satellite Systems (GNSS). The ionospheric TEC exhibits a complex spatial–temporal pattern over equatorial and low latitude regions, which are difficult to predict for providing early warning alerts to GNSS users. Machine Learning (ML) techniques are proven better for ionospheric space weather predictions due to their ability of processing and learning from the available datasets of solar-geophysical data. Hence, a supervised ML algorithm such as the Support Vector Regression (SVR) model is proposed to predict TEC over northern equatorial and low latitudinal GNSS stations. The vertical TEC data estimated from GPS measurements for the entire 24th solar cycle period, 11 years (2009–2019), is considered over Bengaluru and Hyderabad International GNSS Service (IGS) stations. The performance of the proposed SVR model with kernel Gaussian or Radial Basis Function (RBF) is evaluated over the two selected testing periods during the High Solar Activity (HSA) year, 2014 and the Low Solar Activity (LSA) year, 2019. The proposed model performance is compared with Neural Networks (NN) model, and International Reference Ionosphere (IRI-2016) model during both LSA and HSA periods. It is noticed that the proposed SVR model has well predicted the VTEC values better than NN and IRI-2016 models. The experimental results of the SVR model evidenced that it could be an effective tool for predicting TEC over low-latitude and equatorial regions.

2

Analysis of aircraft equipment requirements to conduct RNP APCH approach operation

Kwasiborksa Anna, Gładyś Sylwester, Banaszek Krzysztof, Manewrowski Jerzy, Roś Maciej

Systemy Logistyczne Wojsk

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2021

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Vol. 55, no. 2

101--120

PL

Ruch statków powietrznych jest ciągle analizowany z uwagi na problematykę pojemności przestrzeni powietrznej i przepustowości portów lotniczych. Ważnym obszarem jest podejście do lądowania statków powietrznych na dane lotnisko z wykorzystaniem pomocy nawigacyjnych. Urządzenia i systemy nawigacyjne są dostosowywane do wymagań prawnych organizacji europejskich i międzynarodowych. Do użytku operacyjnego podczas podejść do lądowania dopuszczono możliwość korzystania z systemu GNSS wraz z odpowiednią augmentacją (ABAS lub SBAS) określoną jako podejścia RNP APCH. Ich wprowadzenie skutkowało w pojawieniu się szeregu korzyści. Autorzy podjęli się analizy wymagań wyposażenia pokładowego statków powietrznych niezbędnego do wykonywania podejść RNP APCH. Celem naukowym jest ocena wyposażenia pokładowego RNAV statków powietrznych na przykładzie trzech przewoźników lotniczych (stan na grudzień 2018r.). Weryfikacji poddano hipotezę szacując wysoki stopień wyposażenia pokładowego RVAV statków powietrznych. Zastosowano metodę analizy wykorzystując aplikację CNS Dashboard udostępnionej przez Eurocentów. Wskazuje ona zadeklarowane możliwości nawigacyjne samolotów na podstawie planów lotu ICAO przesyłanych przez przewoźników do Network Managera skorelowanych z bazą danych statków powietrznych PRISME Fleet 2. W wyniku przeprowadzonej analizy, można zauważyć, że prawie wszystkie badane statki powietrzne miały wymaganą certyfikację do przeprowadzania podejść RNP APCH z użyciem systemu ABAS (96% badanych). Z drugiej strony żaden z samolotów nie miał wymaganego wyposażenia do wykorzystywania systemu SBAS podczas lądowania. Na podstawie badania dokumentów i obserwacji obszaru badawczego można stwierdzić, że przewoźnicy lotniczy coraz częściej wyposażają swoje statki powietrzne w wymagane moduły podejściach do lądowania typu RNP APCH.

EN

Aircraft traffic is constantly analyzed due to the issues of airspace and airport capacity. An important area is the approach to landing of aircraft at a given airport with the use of navigation aids. Navigation devices and systems are adapted to the legal requirements of European and international organizations. The use of the GNSS system with appropriate augmentation (ABAS or SBAS) defined as RNP APCH approaches is authorized for operational use during landing approaches. Their introduction resulted in the emergence of a number of benefits. The authors analyzed the requirements of the aircraft on-board equipment necessary to perform RNP APCH approaches. The research goal is to evaluate the RNAV on-board equipment of aircraft on the example of three air carriers (as of December 2018). The hypothesis was verified by estimating the high level of on-board RVAV equipment of the aircraft. The method of analysis was applied using the CNS Dashboard application provided by Eurocontrol. It indicates the declared navigational capabilities of airplanes based on ICAO flight plans sent by carriers to the Network Manager correlated with the PRISME Fleet 2 aircraft database. using the ABAS system (96% of respondents). On the other hand, none of the aircraft had the required equipment to use SBAS during landing. Based on the examination of documents and observation of the research area, it can be concluded that air carriers more and more often equip their aircraft with the required modules of RNP APCH landing approaches.

3

Broadcast ionospheric delay correction algorithm using reduced order adjusted spherical harmonics function for single frequency GNSS receivers

Abhigna M. S. R., Sridhar M., Harsha P. Babu Sree, Krishna K. Siva, Ratnam D. Venkata

Acta Geophysica

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2021

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Vol. 69, no. 1

335--351

EN

Single-frequency Global Navigation Satellite System (GNSS) users require an efcient ionospheric delay correction model for improving their positional accuracy. GPS satellite range signals undergo time delay through the inhomogeneous and dynamic state of the ionosphere. The ionospheric delay is inverse proportional to the signal frequency square due to the dispersive nature of the ionospheric medium. There is a need for aid regional ionospheric broadcast correction model that is necessary for low-latitude ionospheric conditions. In this paper, a reduced order adjusted spherical harmonics function (ROASHF) ionospheric broadcast correction model with order and degree 2 is proposed for the Indian region. A dense GPS receiver network of 14 GPS receivers over the Indian region is analyzed to derive nine ROASHF broadcast coefcients. The performance of the proposed ionospheric broadcast correction model is compared with Klobuchar, NeQuickG, BDS-2, CODEKlob, and CODEGIM TEC models during March and September equinox and June and December solstice days in 2015 and 2016. The mean root mean square error (RMSE) of ROASHF, Klobuchar, NeQuickG, BDS-2, CODEKlob, and CODEGIM TEC models is 7.13 TECU, 9.52 TECU, 15.52 TECU, 11.44 TECU, 13.47 TECU, and 11.97 TECU, respectively. The results demonstrated that the proposed ROASHF ionospheric broadcast model could better predict the ionospheric delays for single-frequency GNSS users. The proposed ionospheric broadcast model is suitable for the Indian regional navigation system known as Navigation with Indian Constellation (NavIC).

4

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.

5

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.

6

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.

7

The test programme concerning aircraft positioning and traffic monitoring – part II

Jafernik H.

Zeszyty Naukowe. Transport / Politechnika Śląska

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2016

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z. 93

41--48

EN

This paper presents the results of studies on the determination of an aircraft’s trajectory and positioning accuracy. The PPP method was applied to determine the aircraft’s position in kinematic mode for code observations in the GPS system. Computations were executed in the “PPP_KINEMTIC” software, whose source code was written using the Scilab 5.3.2 platform. The PPP_KINEMTIC software allows for the latitude coordinate to be estimated with accuracy between 1 and 6 m, the longitude coordinate to be estimated with accuracy between 0.5 and 2.5 m, and the ellipsoidal height to be estimated with accuracy between 1 and 7 m. The average value of the MRSE term equals 5 m with a magnitude between 1 and 8.5 m. In the paper, general libraries of the PPP_KINEMTIC application were presented and the PPP method was characterized too.

8

Perspektywy rozwoju nawigacyjnych i wspomagających systemów satelitarnych w bliskiej i dalszej przyszłości

Januszewski J.

Przegląd Telekomunikacyjny + Wiadomości Telekomunikacyjne

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2014

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nr 5

116--123

PL

Opisano szczegóły modernizacji dwóch nawigacyjnych systemów satelitarnych (NSS), GPS i GLONASS, zmiany w ich segmencie kosmicznym i naziemnym, dwa NSS, Galileo i BeiDou, znajdujące się w budowie, dwa nowe satelitarne systemy wspomagające (SBAS), SDCM i GAGAN. Omówiono problem kompatybilności i międzyoperacyjności wszystkich tych systemów, w szczególności trzech parametrów - sygnałów emitowanych przez satelity, czasów systemów i układów odniesienia współrzędnych. Przedstawiono również perspektywy stworzenia w przyszłości globalnego nawigacyjnego systemu satelitarnego GNSS.

EN

The details about two Satellite Navigation Systems (SNS), GPS and GLONASS modernization progressing, the changes in their spatial and terrestrial segments, two new global SNS, Galileo and BeiDou under construction, two new Satellite Based Augmentation Systems (SBAS), SDCM and GAGAN, the problem of compatibility and interoperability of all these systems, in particular three parameters - signal in space, system time and coordinate reference frame, and finally the perspectives of future Global Navigation Satellite System (GNSS) are described in this paper.

9

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.

10

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.