Augmentation of GNSS Utility by IRNSS/ NavIC Constellation Over the Indian Region

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.

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Visibility Anomaly of GNSS Satellite and Support from Regional Systems

In this paper, the potentials of using Global Navigation Satellite System (GNSS) techniques in the complex calibration procedure of the tracking sensors for missile test range applications have been presented. The frequently used tracking sensors in test range applications are- electro-optical tracking stations (EOTS) and tracking radars. Over the years, the EOTS are used as the reference for bias estimation of the radars. With the introduction of GPS in test range applications, especially the DGPS, the reference for bias estimation got shifted to DGPS from the EOTS. However, the achievable position solution accuracy is limited to the order of a few meters for DGPS, EOTS, and Radars. With the evolution of Multi-constellation GNSS and carrier-phase based measurement techniques in satellite navigation, achievable position solution accuracies may be improved to sub-meter level. New navigation techniques like real time kinematic (RTK) and precise point positioning have the potentials for use in the calibration procedures of the missile test ranges to the accuracies of centimeter-level. Moreover, because of the availability of a large number of navigation signals over the Indian region, multi-constellation GNSS receivers can enhance signal availability, reliability, and accuracies during the calibration of missile test ranges. Currently available compact, low-cost GNSS modules also offer the possibilities of using these for cost-effective, networked RTK for dynamic calibration of test ranges reducing cost and resource requirements.

https://publications.drdo.gov.in/ojs/index.php/dsj/article/download/15570/7374

Potential of Multi constellation Global Navigation Satellite System in Indian Missile Test Range Applications

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...

Evaluating PDOP in Multi-GNSS Environment

GLONASS is declared fully operational in its revitalized form since late 2011. This generated interest for using it for redundancy and system independence and for a robust Multi-GNSS navigation environment. This paper discusses the accuracy capabilities of revitalized GLONASS in standalone and in mixed mode of operation with GPS on basis of studies made using real-life data from different parts of India collected over 2012–2014. The results show the potentials of GLONASS as an independent global navigation system and the advantages of it as an active component of usable Multi-GNSS from India and the surrounding regions.

Studies on solution accuracy of GLONASS from India

Abstract GLONASS, successfully operating during 1990s became unusable by early 2000s. Following a revitalization and modernization plan since 2004, GLONASS constellation has been completed again by the end of 2011 and the use of GLONASS is gaining popularity. Because of the previous experience, some scepticism exists among the stakeholders in using GLONASS for reliable solution and application development. This paper critically reviews the operational lifespan of GLONASS satellites launched between 2004 and 2016, as this is an important contributor towards reliability and sustained operation of the system. For popularization and extracting full benefits of GLONASS as stand-alone system or as an active component of multi-GNSS, major issues of assuring the minimum sufficient GLONASS constellation (of 24…23 satellites), efficient design implementation and the modernized ground control segment development and operation need to be properly taken care of by the system operators.

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Lifetime Performances of Modernized GLONASS Satellites: A Review

Satellite navigation (satnav) systems are now popular with different usable satnav systems. Accuracy of navigation solution depends on satellite geometry; an integrated mode of operation using more than one system is now possible that is supposed to provide better satellite geometry. This paper presents a study on obtainable satellite geometry involving GPS and GLONASS in stand-alone and mixed modes of operation based on collected data from different parts of India.

A Study on Satellite Geometry Variation for Multi-GNSS from India

Since its initial operation in 1982, GLONASS has completed 35 years of service and has passed through eventful journey. Being the first global alternative to GPS, it generated interest among users worldwide. After initiation, the system declined to a period of unstable constellation status; the system has been revitalized and modernized since the end of 2012. This paper presents a concise discussion on initiation, development, decline and revitalization phases of the system and a review on the available research reports which presented the development and advantages of GLONASS as a stand-alone system and as a multi-GNSS component. The paper reviews the experiences of using the advantages of GLONASS from India during its complete service period based on real-time, long-term systematic analysis of data collected over the Indian region both for the initial and the revitalized and modernized phases. Finally, considering the longterm experience of using GLONASS, the paper presents a few issues towards popularization and quality enhancement of GLONASS services from India. This review may be useful in understanding the need, advantages and challenges of using GLONASS from the region.

Shreya Sarkar

Papers

Studies on solution accuracy of GLONASS from India

Lifetime Performances of Modernized GLONASS Satellites: A Review

A Study on Satellite Geometry Variation for Multi-GNSS from India

A Review of 36 Years of GLONASS Service from India

GLONASS-NavIC Hybrid Operation from India Towards Seamless and Improved Performance