NAVIC : Satellites for Navigation Services to Meet the Emerging Demands of Civil Aviation Requirements

Satellite navigation systems play a crucial role in meeting the emerging demands of civil aviation requirements, providing accurate positioning, navigation, and timing information to users. To cater to the specific needs of the aviation industry and fulfill user requirements, several satellite-based systems have been implemented. This article explores two prominent systems: GPS Aided Geo Augmented Navigation (GAGAN) and Navigation with Indian Constellation (NavIC).

NAVIC

Introduction

In today’s world, accurate navigation is essential for the safe and efficient operation of civil aviation. Satellites provide a reliable means of obtaining precise positioning and timing information, enabling pilots, air traffic controllers, and other aviation stakeholders to navigate with confidence. This article delves into the two satellite navigation systems, GAGAN and NavIC, which have been developed to meet the unique demands of the civil aviation sector in India.

GPS Aided Geo Augmented Navigation (GAGAN)

GAGAN Implementation

GAGAN, a collaboration between the Indian Space Research Organisation (ISRO) and the Airports Authority of India (AAI), serves as a satellite-based augmentation system (SBAS) designed to enhance navigation capabilities in Indian airspace. It ensures the accuracy, availability, and integrity of navigation information throughout all phases of flight, from en-route to approach, for all qualified airports within its service volume.

Interoperability and Certification

GAGAN is interoperable with other international SBAS systems, including the US Wide Area Augmentation System (WAAS), European Geostationary Navigation Overlay Service (EGNOS), and Japanese Multifunctional Transport Satellite (MSAS). This interoperability enables seamless navigation for aircraft operating across different regions.

GAGAN has undergone rigorous testing and certification by the Directorate General of Civil Aviation (DGCA). It has been certified to provide Required Navigation Performance (RNP) 0.1 services since December 30th, 2013, and Approach with Vertical Guidance (APV-1) services since April 21st, 2015.

Benefits and Applications

GAGAN offers significant benefits to the aviation industry. It enhances the accuracy of aircraft navigation, reduces the risk of accidents, and improves operational efficiency. Pilots can rely on GAGAN for precise guidance during critical maneuvers, such as approaches and landings.

Furthermore, GAGAN enables the implementation of advanced navigation procedures, such as Required Navigation Performance Authorization Required (RNP AR) approaches, which enhance safety and allow for optimized airspace utilization.

GAGAN’s services extend beyond aviation. They find applications in other sectors, including maritime navigation, surveying, mapping, and disaster management. The system’s accuracy, availability, and integrity make it a valuable asset for a wide range of users.

Navigation with Indian Constellation (NavIC)

Introduction to NavIC

NavIC, formerly known as the Indian Regional Navigation Satellite System (IRNSS), is a regional navigation satellite system developed by ISRO. It is designed to meet the positioning, navigation, and timing requirements of India.

Satellite Constellation and Ground Network

NavIC consists of a constellation of seven satellites and a network of ground stations. Three satellites are positioned in geostationary orbit at 32.5°E, 83°E, and 129.5°E, respectively, while four satellites operate in inclined geosynchronous orbits with equatorial crossing points at 55°E and 111.75°E. The ground network comprises control centers, precise timing facilities, monitoring stations, and ranging stations.

Services and Coverage

NavIC provides two services: the Standard Positioning Service (SPS) for civilian users and the Restricted Service (RS) for strategic users. Both services are available in the L5 (1176.45 MHz) and S-band (2498.028 MHz) frequencies. The coverage area of NavIC extends beyond India, reaching up to 1500 km beyond its boundaries.

The positioning accuracy provided by NavIC is better than 20 meters (2σ), while the timing accuracy exceeds 50 nanoseconds (2σ). The signals from NavIC satellites are interoperable with other global navigation satellite systems (GNSS), including GPS, Glonass, Galileo, and BeiDou.

Wide-ranging Applications

NavIC serves as a backbone for various applications. It is instrumental in transportation, including terrestrial, aerial, and marine navigation. Location-based services, personal mobility, resource monitoring, surveying, geodesy, scientific research, time dissemination, and synchronizations are some of the domains benefitting from NavIC’s precise positioning and timing capabilities.

International Recognition and Standards

NavIC has gained international recognition for its reliability and performance. The International Maritime Organization (IMO) has acknowledged NavIC as a component of the Worldwide Radio Navigation System (WWRNS) for maritime applications.

To ensure seamless integration and compatibility, NavIC adheres to international industry standards. The positioning service receiver data interface follows ISO 19116:2016, while the receiver interface is based on NMEA 0183, version 4.10 onwards. Navigation data logging uses RINEX v3.03 onwards, and vehicle location tracking complies with IS 16833:2018 amendment-2.

Differential GNSS follows RTCM 10403.3, and telecom standards include 3GPP TS 36.171 Rel. 16 for Assisted NavIC support in LTE. These standards ensure that NavIC can be easily integrated into various industries and applications worldwide.

Signal-in-Space Interface Control Document (SIS ICD)

The Signal-in-Space Interface Control Document (SIS ICD) provides essential information about NavIC’s signals in space. It facilitates the development of receiver systems and their associated applications by detailing the signal structure and other relevant parameters.

The SIS ICD is periodically updated to reflect the system’s enhancements and evolving requirements. It ensures that developers have access to accurate and up-to-date information to leverage NavIC’s signals effectively.

Week Number Rollover Event

NavIC’s system time is based on an epoch that began at 00:00 UT on Sunday, August 22nd, 1999. The first week number rollover event occurred on April 6th, 2019. Currently, NavIC’s system time is in the second epoch. These rollover events are crucial for maintaining accurate timing and synchronization in various applications reliant on NavIC.

Performance Monitoring and Reports

ISRO continually monitors the performance of NavIC’s Standard Positioning Service (SPS) signals using calibrated receivers. The performance reports, published quarterly, serve as a reference for receiver developers and provide valuable insights into the system’s performance and capabilities.

The performance reports include detailed information about signal availability, accuracy, integrity, and other performance metrics. They assist developers in optimizing their receiver designs and ensuring the reliable operation of NavIC-based applications.

Conclusion

The development of GAGAN and NavIC showcases India’s commitment to providing reliable and precise satellite navigation services. GAGAN enhances the navigation capabilities of civil aviation, ensuring the safety and efficiency of flights within Indian airspace. NavIC, on the other hand, caters to the positioning, navigation, and timing requirements of various sectors, including transportation, surveying, and scientific research.

These satellite navigation systems, with their interoperability, accuracy, and extensive coverage, contribute significantly to India’s technological advancements and provide a solid foundation for location-based services and critical applications across industries.

Also read  NAVIC.

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