Mehul V. Desai

Bio: Mehul V. Desai is an academic researcher from Sardar Vallabhbhai National Institute of Technology, Surat. The author has contributed to research in topics: Navigation system & Global Positioning System. The author has an hindex of 6, co-authored 10 publications receiving 62 citations.

The GIVE Ionospheric Delay Correction Approach to Improve Positional Accuracy of NavIC/IRNSS Single-Frequency Receiver

Abstract: The Navigation with Indian Constellation (NavIC)/Indian Regional Navigation Satellite System (IRNSS) is an independent navigation system developed for the Indian subcontinent by the Indian Space Research Organisation (ISRO). The positional accuracy of this system is mainly affected by the ionosphere of the low-latitude equatorial Indian subcontinent, as large ionospheric gradients and intense irregularities are present in it. The objective of this study is to improve the positional accuracy of NavIC/IRNSS systems by applying ionospheric correction using the most suitable single-frequency model. The data to be analysed were collected from the NavIC/IRNSS receiver provided by the Space Applications Centre, ISRO. A comparative analysis between the dual-frequency model and single-frequency model (e.g. GIVE model, coefficient-based model) was performed on the data from the NavIC/IRNSS receiver. Different ionospheric models were applied to compute ionospheric delay (ionodelay) on a quiet day (3 < K P < 5). Our result shows that both the single-frequency Grid Ionosphere Vertical Error (GIVE) model and dual frequency model outperform remarkably compared to the traditional coefficient-based model. The GIVE model was also analysed on FAR categorized satellites for different stormy days of different months. It was observed that during stormy days also, the 3D position computed by applying the GIVE model was nearly the same as the dual-frequency model.

Impact of dilution of precision for position computation in Indian regional navigation satellite system

Abstract: The System of seven satellites, Indian Regional Navigation Satellite System (IRNSS) will provide Special Positioning Service (SPS) and Precision Service (PS) towards the Indian subcontinent. In Positioning Navigation Timing (PNT) application, measurement is affected by some intentional and unintentional sources of error. This Measurement also depends on the volume of tetrahedron created by the geometry of measuring satellites. The Satellites geometry is measured by single dimensionless numbers called GDOP. Lower the GDOP value, the better the satellite Geometry, hence the position measured by the system is more precise. Currently, IRNSS system has six active satellites in an orbit. In this paper performance analysis of IRNSS, GPS and IRNSS+GPS are investigated by computing the GDOP due to all satellites in view. The performance analysis is done using ACCORD IRNSS receiver which is provided by SAC, ISRO, Ahmedabad. The dual frequency IRNSS receiver of SVNIT, SURAT (21.16° Lat., 72.78° Long.) is explored for best GDOP configuration and position determination over the Indian subcontinent.

An Observational Review on influence of Intense Geomagnetic Storm on Positional Accuracy of NavIC/IRNSS System

Abstract: The positional accuracy of Navigation with the Indian Constellation (NavIC)/Indian Regional Navigation Satellite System (IRNSS) in the low latitudes of the Indian region during the intense geomagne...

Estimation of ionospheric delay of NavIC/IRNSS signals using the Taylor Series Expansion

Abstract: The delay in Navigation with Indian Constellation (NavIC)/Indian Regional Navigation Satellite System (IRNSS) signals due to the ionosphere are decisive because it leads to significant changes in the positional accuracy of the system. In this paper, we try to estimate the ionospheric time delay (ionodelay) precisely using the local Taylor Series Expansion (TSE) algorithm for a single frequency NavIC/IRNSS system. The performance of the local TSE algorithm is examined by considering two cases. In case I, the TSE was validated under the influence of an intense geomagnetic storm (8 September 2017) by considering NavIC/IRNSS data from the Indian equatorial and Equatorial Ionization Anomaly (EIA) regions. In case II, based on the quiet and disturbed days data, the local TSE model was examined at different locations in the local area (<10 km) using two NavIC/IRNSS receivers (i.e. reference and rover). The results of ionodelay and positional accuracy (Three Dimensional Distance Root Mean Square [3DRMS], Circular Error Probability [CEP], and Spherical Error Probability [SEP]) of NavIC/IRNSS for both the cases indicates that the single frequency local TSE algorithm performs the same as the reference dual frequency model, where as the global eight coefficient Klobuchar and the regional Grid Ionospheric Vertical Error (GIVE) model behaves differently. Therefore, the single-frequency TSE model improves the performance of the NavIC/IRNSS receiver in the local area, and the mathematical coefficient computation and additional frequency hardware cost have been reduced, with the acceptance of a maximum 0.8 m of errors.

Case Study: Performance Observation of NavIC Ionodelay and Positioning Accuracy

Abstract: The NavIC is an Indian satellite based navigation system uses the L5 and S-band signals to provide 10 m (metres) and 0.1 m positioning accuracy services for civilian and military users respectively...

The GIVE Ionospheric Delay Correction Approach to Improve Positional Accuracy of NavIC/IRNSS Single-Frequency Receiver

Abstract: The Navigation with Indian Constellation (NavIC)/Indian Regional Navigation Satellite System (IRNSS) is an independent navigation system developed for the Indian subcontinent by the Indian Space Research Organisation (ISRO). The positional accuracy of this system is mainly affected by the ionosphere of the low-latitude equatorial Indian subcontinent, as large ionospheric gradients and intense irregularities are present in it. The objective of this study is to improve the positional accuracy of NavIC/IRNSS systems by applying ionospheric correction using the most suitable single-frequency model. The data to be analysed were collected from the NavIC/IRNSS receiver provided by the Space Applications Centre, ISRO. A comparative analysis between the dual-frequency model and single-frequency model (e.g. GIVE model, coefficient-based model) was performed on the data from the NavIC/IRNSS receiver. Different ionospheric models were applied to compute ionospheric delay (ionodelay) on a quiet day (3 < K P < 5). Our result shows that both the single-frequency Grid Ionosphere Vertical Error (GIVE) model and dual frequency model outperform remarkably compared to the traditional coefficient-based model. The GIVE model was also analysed on FAR categorized satellites for different stormy days of different months. It was observed that during stormy days also, the 3D position computed by applying the GIVE model was nearly the same as the dual-frequency model.

An Observational Review on influence of Intense Geomagnetic Storm on Positional Accuracy of NavIC/IRNSS System

Abstract: The positional accuracy of Navigation with the Indian Constellation (NavIC)/Indian Regional Navigation Satellite System (IRNSS) in the low latitudes of the Indian region during the intense geomagne...