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Journal ArticleDOI: 10.1080/02564602.2020.1723445

Case Study: Performance Observation of NavIC Ionodelay and Positioning Accuracy

04 Mar 2021-Iete Technical Review (Informa UK Limited)-Vol. 38, Iss: 2, pp 256-266
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...

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Journal ArticleDOI: 10.1007/S40328-020-00316-2
Mehul V. Desai1, Shweta Shah1Institutions (1)
Abstract: The solar flares and geomagnetic storms are considered a potential threat for the upcoming Indian Regional Navigation Satellite System or Navigation with Indian Constellation (NavIC). Therefore, we investigated in detail the occurrence of tracking failure and effects on the positional accuracy of the NavIC L5-band and S-band system under direct exposure of X2.2 and X9.3 solar flare on September 6, 2017, X9.3 is the strongest event since the NavIC signals are in the service. The regional NavIC data (5–6 September 2017) from the equatorial region Trivandrum station and the Equatorial Ionization Anomaly area in India (Surat, Bombay, Hyderabad and Gandhinagar stations), are collected using the accord NavIC dual-frequency (L5-band and S-band) receivers. We have shown that the 1G NavIC signals remain in loss of lock condition for 1 h on September 6, 2017 (X2.2 and X9.3 solar flares), and as a result, positioning accuracy deviated on September 6, 2017. Hence, the solar flare event considered a potential threat for future NavIC based autonomous navigation technologies.

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2 Citations


Journal ArticleDOI: 10.1016/J.ASR.2020.09.038
Abstract: The Indian Regional Navigation Satellite System (IRNSS/NavIC) is fully operational and broadcasting radio signals at L5 (1176.45 MHz) and S-band (2492.028 MHz). When these signals pass through the ionosphere, carrier phase delay, which depends on Total Electron Content (TEC), causes error in positioning. Corrections are applied in the augmented navigation system to minimize the position error due to TEC; however, 100% removal of error is practically impossible. Thus, a study has been carried out to understand the role of ionospheric determinants, such as TEC and scintillation S4, on the accuracy of augmented navigation over low latitude region using a dual-frequency NAVigation with Indian Constellation (NavIC) receiver installed at BITS-Pilani K.K. Birla Goa Campus (Geog. Lat. 15.39 ° N, Geog. Long. 73.87 ° E). Data collected using the Indian Space Research Organization (ISROs) NavIC receiver (make DataPattern) during the low solar period between March 2019 to December 2019 is utilized for this study. The important findings of the study are as follows: (a) Mean position error was in the range of 2–4 m. (b) Diurnal variation of the position error indicated a maximum at afternoon hours, coinciding with the time of maximum TEC over the EIA crest region. (c) Mean position error in afternoon hours indicated a linear relation with mean TEC, in a scatter-plot analysis. (d) Statistically, the position error during the scintillation nights was found to be similar to non-scintillation nights, indicating that the post-sunset equatorial density depletions during low solar do not significantly impact navigation accuracy. Absolute position error during the active phase of a moderate geomagnetic storm of 14 May 2019 was found to be significantly higher compared to a quiet period, which also depends on the mode of operation of the augmented navigation system. It was found that a hybrid NavIC (Dual) + GPS (SBAS) augmented navigation was more accurate than NavIC with dual- ionospheric corrections or NavIC with grid corrections, alone. Besides, the dynamic behavior of the ionosphere, i.e., diurnal, monthly, and seasonal variations of ionospheric TEC, have also been studied using the iono-delay values derived from the NavIC receiver.

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Topics: TEC (61%), Total electron content (56%)

2 Citations


Journal ArticleDOI: 10.1080/03772063.2021.1939801
Somnath Mahato1, Somnath Mahato2, Atanu Santra1, Atanu Santra2  +4 moreInstitutions (2)
Abstract: Global Navigation Satellite System (GNSS) provides precise Position, Velocity, and Timing (PVT) information. Various types of receivers of varying cost and complexity are used for collection and us...

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Topics: GNSS applications (64%), Satellite system (50%)

1 Citations


Open accessDissertationDOI: 10.24377/LJMU.T.00015733
01 Nov 2021-
Abstract: The prevalence of wearable technology in association football (or soccer) has been prominent in top professional teams for over a decade and is employed by coaches and sport science practitioners to quantify and help improve the performance of either the individual player or team. Educational settings have also witnessed an exponential rise in the application of wearable technology in formal learning environments. The increased number of football industry related qualifications offered by Further Education (FE) and Higher Education (HE) establishments has probably been the driver for this expansion. There is, however, a dearth of research on the educational application of wearable technology in FE and HE. There is also some conjecture as to whether the current wearable technology products on the market, are designed for an educational purpose. The aim therefore of this professional doctorate project was to investigate the use of wearable technology in football related further and higher education settings, and to develop a wearable technology product tool that was deemed appropriate for a FE environment. Thus, the aim of Study 1 (Chapter 4) was to establish the extent, wearable technology was being used in FE and HE environments. Using a mixed-method research design the initial survey established the type of technology and how they were being employed in FE and HE settings. The study identified that Global Positioning System (GPS) vests and Heart rate chest strap are the most prominent wearable technology. Qualitative findings suggested there are pedagogic challenges and barriers to using this kind of technology, a lack of understanding, and poor feedback and communication. Having established some preliminary findings Study 2 (Chapter 5) explored these barriers and challenges within contextualised settings in more depth. It identified a disconnect between coaching performance and coaching education, highlighting a lack of knowledge surrounding the uses and capabilities of wearable technology used in football related FE settings. Furthermore, participant responses suggested the current wearable technology products on the market were not fit for educational purposes. By designing and developing (Study 3) a bespoke wearable technology product (Chapter 6) provided an industry-specific solution to the issues presented in Chapter 5. Adopting a unique collaboration between academia and industry, recruiting experts in various fields, thus enabled the design and development of a novel bespoke system, including the hardware and software requirements reported in Chapter 4 and Chapter 5. Since the purpose of Study 3 was the development of the wearable technology hardware and software, the aim of Study 4 (Chapter 7) was to evaluate the product and system in an applied real-world setting. Findings suggest student engagement increased, and attainment improved. Additionally, it also demonstrated a more accessible and user-friendly platform for use in FE by eliminating technological features captured in Chapter 5. By using a mobile application and cloud-based system that enabled cross pollination to other curriculum areas suggested college staff and coaches were becoming more engaged with wearable technology. Evidence also suggested students displayed attributes of independent learning and demonstrated engagement outside of formal learning environments. In summary, the research data and product development presented in this thesis suggest the wearable technology system is fit for purpose and can be deployed in FE environments. From a practitioner perspective, this doctoral thesis has also laid the foundations for education, football, and wearable technology communities the impetus to work in collaboration. This doctoral thesis demonstrates that it is possible for academia, business and commercial enterprise to work collectively to elucidate and solve real world industry problems

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Topics: Wearable technology (64%), Further education (52%), New product development (51%) ... show more

Open accessDOI: 10.1109/ICORT52730.2021.9581415
05 Aug 2021-
Abstract: The navigation and positioning system is vital in both civil and military applications. It has become an integral part of our day-to-day life. Navigation with Indian Constellation (NavIC) is the latest addition in the area of satellite-based navigation systems. To achieve the required positioning accuracy of any satellite-based navigation system, the performance accuracy of an individual satellite is more important. The effect of artificial or natural error sources on satellite signals depends on their location, traveling path. In this paper, the NavlC L5-band and S-band signals are considered. The digital IF data is used, which is logged from NavIC receiver, and the performance analysis of NavlC signals has been evaluated in terms of Power Spectral Density, acquisition and post-processing parameters like C / No, elevation angle, pseudoranges, ionospheric delay and troposphere delay concerning the location of NavIC receiver at low latitude SVNIT, Surat Station (21 °9'50.04” N, 72° 47’1.26” E). This kind of analysis can be useful for future applications of the NavlC.

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Topics: Navigation system (58%), Positioning system (56%)

References
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18 results found


Journal ArticleDOI: 10.1109/TAES.1987.310829
Abstract: The goal in designing an ionospheric time-delay correctionalgorithm for the single-frequency global positioning system userwas to include the main features of the complex behavior of theionosphere, yet require a minimum of coefficients and usercomputational time, while still yielding an rms correction of at least50 percent. The algorithm designed for this purpose, andimplemented in the GPS satellites, requires only eight coefficientssent as part of the satellite message, contains numerousapproximations designed to reduce user computationalrequirements, yet preserves the essential elements required to obtaingroup delay values along multiple satellite viewing directions.

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992 Citations


Journal ArticleDOI: 10.1029/RS006I003P00357
01 Mar 1971-Radio Science
Abstract: Knowledge of the height integral of atmospheric refractivity (n — 1), where n is the refractive index, is essential for prediction of atmospheric range effect at any elevation angle. Observed values of the height integral for the lower, nonionized atmosphere can be obtained from weather balloon ascent data. Year-long collections of data from widely separated locations were used to relate this integral to surface data. Although (n — 1) at any point in a dry atmosphere depends on both pressure and temperature (the ratio P/T), the height integral of the observed dry part of (n — 1) is a linear function of surface pressure only, not of temperature. This is theoretically correct since P/T is equivalent to density, and the integral of density with height yields surface pressure. By application of this finding, the equivalent height for a (theoretically justified) quartic (n — 1) model (dry part) should be found to vary directly as surface temperature; the value obtained (least-squares fit to observed data) is 40.1 km for surface T = 0°C with a height expansion coefficient of 0.149 km per surface degree C. This would reduce the equivalent height to zero near 0° Kelvin. This theoretical model matches observed height integrals with an rms error of a few millimeters out of 2.3 meters (far less than 1%). Agreement between stations is excellent. A study of the more variable but much smaller wet part is in progress. The wet part is significant at radio but not at optical frequencies.

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Topics: Surface pressure (54%), Atmospheric pressure (52%)

255 Citations



Journal ArticleDOI: 10.1049/IET-RSN.2009.0022
Abstract: Several countries have been developing satellite-based augmentation systems (SBAS) for improving positional accuracy of global positioning system (GPS). India is also developing one such system popularly known as GPS aided geo augmented navigation (GAGAN) system. Modelling of ionospheric effects is one of the major challenges in developing precise and reliable GAGAN. The high values of total electron content (TEC), the large diurnal and seasonal variability and intense irregularities present in the low-latitude ionosphere, lead to unacceptable positional errors in GAGAN service region. Todd Walter et al. of Stanford University, USA have made significant contribution in the area of SBAS ionospheric grid modelling by developing the popularly known planar fit model. It is reported by Walter et al. (2000) that a constant decorrelation value of 35 cm was proposed over the wide area augmentation system (WAAS) service region. To provide accurate estimation of ionospheric delays at user ionospheric pierce points (IPP) during a storm or intense irregularities, an irregularity detector and a decorrelation adaptor are incorporated in the modelling. As planar fit model is not adequate to model intense irregularities of Indian ionosphere, a modified planar fit model is applied for GAGAN data on similar lines as was done for WAAS and the results are encouraging.

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Topics: Wide Area Augmentation System (57%), Total electron content (52%), GNSS augmentation (51%) ... show more

50 Citations


Open access
Rajat Acharya1, Neha Nagori, Nishkam Jain, Surendra Sunda  +3 moreInstitutions (1)
01 Oct 2007-
Abstract: Satellite Based Augmentation System (SBAS), being developed by Indian Space Research Organization (ISRO) in collaboration with Airports Authority of India (AAI) is known as “GPS Aided GEO Augmented Navigation” (GAGAN). It is expected to offer better accuracy and integrity of navigation service than with GPS alone by providing correction terms to the GPS signals. This is achieved by modelling a Near Real Time Grid Based Ionospheric Delay Model for correcting propagation delay at 1575.42 MHz (L1) using measurements at 1575.42 and 1227.6 MHz (L2). Existing algorithms are replaced by Kriging based model to meet the requirement of correction with 0.5 m maximum residue over Indian region. Details of the data collection and pre-processing, including estimation of the Total Electron Content (TEC), which is a measure of ionospheric delay, has been described. Kriging algorithm and some preliminary results of studies are also presented in this paper. This includes the spatial decorrelation of the stochastic random field over the deterministic variation of ionospheric TEC. Its variation with time and locations are investigated and a temporal dependence found to exist. Large scale ionospheric irregularities and depletions that cause severe amplitude and phase scintillations are also studied. Their impacts on GAGAN are also shown. Some major scientific studies required to be carried out over Indian region to improve the GAGAN performance is discussed.

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Topics: GPS signals (57%), Global Positioning System (54%), GNSS augmentation (53%) ... show more

36 Citations


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