Journal ArticleDOI
Estimation of ionospheric gradients and vertical total electron content using dual-frequency NAVIC measurements
TLDR
In this article, an ionospheric temporal gradient analysis is carried out in east, west, north and south directions using a Weighted Least Squares (WLS) algorithm for NAVIC L5 signals.Abstract:
Indian Space Research Organization is being developing a regional satellite radio navigation system known as Navigation with Indian Constellation (NAVIC) satellite system to cater positioning, navigation and timing application. NAVIC has the capability to transmit dual frequency measurements on L5 and S band signals. Ionospheric gradients are one of the pre-dominant error sources with huge impact at the time of geomagnetic disturbed ionospheric conditions in low-latitude region. The large ionospheric gradients can degrade the positional accuracy of NAVIC system. In this paper, ionospheric temporal gradient analysis is carried out in east, west, north and south directions using a Weighted Least Squares (WLS) algorithm for NAVIC L5 signals. The ionospheric gradient algorithm is tested with NAVIC receiver data located at Koneru Lakshmaiah Education Foundation (KLEF) University campus, Guntur, India (16.42∘ N, 80.62∘ E) during geomagnetic storm time conditions (27th–29th May 2017). The results confirmed the increments in VTEC along with longitudinal (E-W) and latitudinal (N-S) gradient magnitudes accordingly with geomagnetic storm effects. The WLS based VTEC model is able to detect E and W ionospheric gradients during the transition period from main phase to recovery phase of the geo-magnetic storm.read more
Citations
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Journal ArticleDOI
A New Ionospheric Model for Single Frequency GNSS User Applications Using Klobuchar Model Driven by Auto Regressive Moving Average (SAKARMA) Method Over Indian Region
TL;DR: The experimental results of SAKARMA for NavIC have revealed that the MAPE for proposed SAKarMA model is 9-17% (accuracy: 83-91%), while 34-53% (Accuracy: 47-66%) for the Klobuchar model, illustrating that the proposed SakARMAmodel is capable of predicting the ionospheric delays for single frequency GNSS/NavIC users.
Journal ArticleDOI
Performance of NavIC for studying the ionosphere at an EIA region in India
TL;DR: In this article, NavIC's performance in ionospheric studies over the Indian subcontinent region was analyzed using data of one year (2017-2018) at IIT Indore, a location near the northern crest of Equatorial Ionization Anomaly (EIA).
Journal ArticleDOI
Performance Evaluation of Adjusted Spherical Harmonics Ionospheric Model Over Indian Region
Kondaveeti Siva Krishna,Devanaboyina Venkata Ratnam,M. Sridhar,P. Babu Sree Harsha,G. Sivavaraprasad +4 more
TL;DR: The results confirm that the 4th order ASHF ionospheric model can identify the northern Equatorial Ionization Anomaly (EIA) TEC crest patterns over the Indian region.
Journal ArticleDOI
Evaluation of Ionospheric Delays Based on Orthogonal Dimensionality Reduction Approach
TL;DR: The results show that the SVD–SHF approach is more efficient in estimating ionospheric delays than the Weighted Least Square (WLS) method, and can be implemented in Global Navigation Satellite System (GNSS) and surveying applications.
Journal ArticleDOI
Total electron content prediction using singular spectrum analysis and autoregressive moving average approach
J. R. K. Kumar Dabbakuti,Mallika Yarrakula,Sampad Kumar Panda,Punyawi Jamjareegulgarn,Mohd Anul Haq +4 more
TL;DR: An integrated approach by combining the signal extraction technique Singular Spectrum Analysis (SSA) with Autoregressive Moving Average (ARMA) is presented in this work to predict the ionospheric Total Electron Content (TEC) values that are responsible for causing ionsospheric delays in the trans-ionospheric signal propagation associated with satellite-based communication, navigation, and timing applications.
References
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Journal ArticleDOI
Ionospheric Time-Delay Algorithm for Single-Frequency GPS Users
TL;DR: The algorithm designed for this purpose, and implemented in the GPS satellites, requires only eight coefficients sent as part of the satellite message, and contains numerous approximations designed to reduce user computational requirements, yet preserves the essential elements required to obtaingroup delay values along multiple satellite viewing directions.
Journal ArticleDOI
The International Reference Ionosphere 2012 – a model of international collaboration
Dieter Bilitza,Dieter Bilitza,David Altadill,Yongliang Zhang,Chris Mertens,Vladimir Truhlik,P. G. Richards,Lee-Anne McKinnell,Bodo W. Reinisch +8 more
TL;DR: A brief history of the IRI project is given, the latest version of the model, IRI-2012, is described and efforts to develop a real-time IRI model are discussed.
Proceedings ArticleDOI
A new method for fast carrier phase ambiguity estimation
TL;DR: In this paper, the authors used an ambiguity reparametrization that allows one to reformulate the original ambiguity estimation problem into a new problem that becomes much easier to solve, and demonstrated that a significant reduction in both the correlation between the ambiguities and in the elongation of the corresponding confidence ellipsoid can be reached.
Journal ArticleDOI
TEC variations during low solar activity period (2005–2007) near the Equatorial Ionospheric Anomaly Crest region in India
TL;DR: In this paper, the authors analyzed the ionospheric variations in terms of Total Electron Content (TEC) for the low solar activity period from April 2005 to December 2007, and found that TEC at Rajkot is at its maximum during Equinoctial months (March, April, September, October), and minimum during the Winter months (November, December, January, February), with intermediate values during Summer months (May, June, July, August), showing a semi annual variation.
Journal ArticleDOI
An improved model of the variation of electron concentration with height in the ionosphere
TL;DR: In this paper, an empirical model of the variation of electron concentration with height is described which overcomes some limitations found in practice with a previous widely used model (Bradley and Dudeney, 1973).