Pratibha Verma

Bio: Pratibha Verma is an academic researcher from National Institute of Technology Agartala. The author has contributed to research in topics: Surface plasmon & GNSS applications. The author has an hindex of 3, co-authored 19 publications receiving 45 citations. Previous affiliations of Pratibha Verma include University of Burdwan.

Visibility Anomaly of GNSS Satellite and Support from Regional Systems

Abstract: In a multi-GNSS (global navigation satellite system) environment with operational GPS, GLONASS and Galileo Satellites, the Asia–Oceania region is expected to get better benefits of a large number of GNSS satellites for use. However, it is witnessed that during some parts of the day, no GNSS satellite is present above 60° elevation angle from many parts of the earth, including India. Real-time data from India show the regular absence of usable GPS satellites above 60° elevation angles during some parts of the day; addition of GLONASS and Galileo satellites does not improve the situation much. From Burdwan, West Bengal, India at least twice a day, no GNSS satellite is found above 60° elevation angles for more than 30 min. Simulation study for scattered places of India and data from IGS Centres confirm similar observations, except for the extreme northern region. The global scenario also supports these observations, while the individual operator’s country is free from the problem using their own navigational system. The consequences of the problem affect GNSS-based solutions; for locations with obstruction of GNSS signals from low elevation angles, the concurrent occurrence of this incidence poses a threat for seamless GNSS-based navigation through intermittent loss of solution and degraded solution quality. Regional navigation satellite systems (RNSS) help mitigate this problem within the respective service regions. For a large part of the globe, the problem may be allayed using GNSS–RNSS hybrid operation. The result would be important for location-specific GNSS mission planning in strategic, life and safety-critical applications.

Evaluating PDOP in Multi-GNSS Environment

Abstract: Hybrid operation with two or more Global Navigation Satellite Systems (GNSS) together with (Multi-GNSS) is now popular in the enhanced Signal-in-Space (SiS) scenario that is expected to provide sev...

Wavelength dependence of impedance and quality factor for MIM surface plasmon structure

Abstract: In this paper, wavelength dependence of characteristic impedance and quality factor of MIM (Metal-Insulator-Metal) surface plasmon structure is analyzed. Structural parameters and damping ratio of the structure is tuned within allowable limit to analyze the variation after detailed analytical computation. Effect of wavelength on Faraday inductance and kinetic inductance are also studied, and it is found that resistive part dominates over the other impedances at higher frequency ranges, which suggests presence of symmetric and antisymmetric modes are not possible at high frequency range. Results will help to use of surface plasmon structure for detecting biological analytes and microfludic rate.

Performance Analysis of IRNSS-GPS Hybrid Operation: Study in Indian Metropolis Environment

Abstract: IRNSS/ NavIC is the Indian contribution in satellite based navigation scenario. Being a new system, it calls for performance analysis over various real-life environments. This paper presents the initial study results on IRNSS/ NavIC-GPS hybrid operation carried out during late October 2017 from Kolkata, a metropolis of India, where degradation of satellite visibility is common due to obstructions. The studies presented in this paper are carried out using a GNSS receiver mounted on a vehicle that moves through wide highways and dense residential areas having narrow roads. It is observed that, in both the cases, many situations are found when position solution cannot be acquired using the GNSS receiver. This is a serious impediment for seamless GNSS-based operations in such environments and needs to be properly taken care of while mission planning of safety-critical applications.

Global Positioning System Theory And Practice

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GNSS Vulnerabilities and Existing Solutions: A Review of the Literature

Abstract: This literature review paper focuses on existing vulnerabilities associated with global navigation satellite systems (GNSSs). With respect to the civilian/non encrypted GNSSs, they are employed for proving positioning, navigation and timing (PNT) solutions across a wide range of industries. Some of these include electric power grids, stock exchange systems, cellular communications, agriculture, unmanned aerial systems and intelligent transportation systems. In this survey paper, physical degradations, existing threats and solutions adopted in academia and industry are presented. In regards to GNSS threats, jamming and spoofing attacks as well as detection techniques adopted in the literature are surveyed and summarized. Also discussed are multipath propagation in GNSS and non line-of-sight (NLoS) detection techniques. The review also identifies and discusses open research areas and techniques which can be investigated for the purpose of enhancing the robustness of GNSS.

Precision of satellite based navigation position solution: A review using NavIC data

Abstract: Global Navigation Satellite System (GNSS) provides all-weather, precise Position, Velocity and Timing (PVT) solutions from any point on the surface or near to the surface of the earth. Accuracy and...

Positioning in the Arctic Region: State-of-the-Art and Future Perspectives

Abstract: The positioning systems’ high accuracy and reliability are crucial enablers for various future applications, including autonomous shipping worldwide. It is especially challenging for the Arctic region due to the lower number of visible satellites, severe ionospheric disturbances, scintillation effects, and higher delays than in the non-Arctic and non-Antarctic regions. In regions up North, conventional satellite positioning systems are generally proposed to be utilized, together with other situational awareness systems, to achieve the necessary level of accuracy. This paper provides a detailed review of the current state-of-the-art, satellite-based positioning systems’ availability and performance and reports high-level positioning requirements for the oncoming applications. In particular, the comparative study between three Global Navigation Satellite System (GNSS) constellations is executed to determine whether they are suitable for autonomous vessel navigation in the Arctics’ complex environment as the two most significant drivers for a reevaluation of the related satellite constellations. This work analyzes the ongoing research executed in different (inter-) national projects focused on Galileo, Global Positioning System (GPS), and GLObal NAvigation Satellite System (GLONASS). Based on the literature review and the simulation campaign, we conclude that all the convectional constellations achieve an accuracy of fewer than three meters in the analyzed Arctic scenarios. It is postulated that other complementary positioning methods should be utilized to improve accuracy beyond this limit. Finally, the study emphasizes existing challenges in the Arctic region regarding the localization and telecommunication capabilities and provides future research directions.

Visibility Anomaly of GNSS Satellite and Support from Regional Systems

Abstract: In a multi-GNSS (global navigation satellite system) environment with operational GPS, GLONASS and Galileo Satellites, the Asia–Oceania region is expected to get better benefits of a large number of GNSS satellites for use. However, it is witnessed that during some parts of the day, no GNSS satellite is present above 60° elevation angle from many parts of the earth, including India. Real-time data from India show the regular absence of usable GPS satellites above 60° elevation angles during some parts of the day; addition of GLONASS and Galileo satellites does not improve the situation much. From Burdwan, West Bengal, India at least twice a day, no GNSS satellite is found above 60° elevation angles for more than 30 min. Simulation study for scattered places of India and data from IGS Centres confirm similar observations, except for the extreme northern region. The global scenario also supports these observations, while the individual operator’s country is free from the problem using their own navigational system. The consequences of the problem affect GNSS-based solutions; for locations with obstruction of GNSS signals from low elevation angles, the concurrent occurrence of this incidence poses a threat for seamless GNSS-based navigation through intermittent loss of solution and degraded solution quality. Regional navigation satellite systems (RNSS) help mitigate this problem within the respective service regions. For a large part of the globe, the problem may be allayed using GNSS–RNSS hybrid operation. The result would be important for location-specific GNSS mission planning in strategic, life and safety-critical applications.