GPS Aided Geo Augmented Navigation

GPS Aided Geo Augmented Navigation
Name	GPS Aided Geo Augmented Navigation
Country	India
Type	Satellite-based augmentation system
Status	Operational

GPS Aided Geo Augmented Navigation is a satellite-based augmentation system developed by the Indian Space Research Organisation and operated by the Airports Authority of India. It is designed to improve the accuracy, integrity, and availability of Global Positioning System signals for civil aviation and other users over India and the surrounding region. The system provides crucial safety-of-life navigation services, making it a key component of India's modern air traffic management infrastructure and a significant achievement for the nation's space program.

Overview

The system was conceived to enhance the performance of the Global Positioning System for precision approaches over the Indian subcontinent. Its development was driven by the need for a reliable air navigation service across the challenging terrain of the Himalayas and the expansive maritime regions of the Indian Ocean. The project represents a major collaboration between Indian Space Research Organisation and the Airports Authority of India, with support from various other national laboratories. It became operational in the early 21st century, following a series of successful tests and validations, and has since been certified for use in aviation.

System Architecture

The architecture consists of a ground segment, a space segment, and user receivers. The ground segment includes a network of precisely surveyed Indian Regional Navigation Satellite System reference stations spread across India that continuously monitor Global Positioning System and GLONASS signals. Data from these stations is processed at master control centers located in Bangalore and New Delhi, which generate integrity and correction messages. These messages are then uplinked to geostationary satellites in the space segment, which broadcast them to users over a wide coverage area. The user segment comprises certified receivers installed in aircraft, used by the Indian Air Force, and deployed in various terrestrial applications.

Signal Structure and Augmentation

The system broadcasts its augmentation signals on the same L-band frequencies as the standard Global Positioning System, specifically using the L1 and L5 bands. It transmits correction data for ionospheric delays, satellite clock errors, and ephemeris inaccuracies measured by its ground network. A key feature is the transmission of integrity information, providing timely warnings to users if any Global Positioning System signal is unreliable. The signal structure is compatible with international standards set by organizations like the International Civil Aviation Organization and the Radio Technical Commission for Aeronautics, ensuring interoperability with other global and regional systems like the Wide Area Augmentation System.

Performance and Accuracy

The system is designed to meet stringent requirements for precision approach operations, such as Localizer Performance with Vertical guidance. It typically provides horizontal accuracy better than 1.5 meters and vertical accuracy better than 2.5 meters throughout its service area. The system's integrity guarantees that the time to alert users of any anomaly is within six seconds, a critical parameter for safety-of-life services in aviation. Its availability exceeds 99.9% over the designated service volume, which covers India and extends approximately 1500 kilometers beyond its borders, supporting operations over the Bay of Bengal and parts of the Arabian Sea.

Applications

Its primary application is in civil aviation for all phases of flight, particularly for precision approaches and landing at airports across India, including major hubs like Indira Gandhi International Airport and Chhatrapati Shivaji Maharaj International Airport. It is also extensively used for helicopter operations in remote and difficult terrain. Beyond aviation, it supports maritime navigation in the Indian Ocean, surveying and geodetic activities by the Survey of India, and disaster management operations coordinated by the National Disaster Management Authority. The Indian Army and other defense services utilize it for precise positioning and navigation.

Regional Implementations

As a regional system, it serves as the satellite-based augmentation system for the Flight Information Regions of India. It is a cornerstone of India's strategic Navigation with Indian Constellation program, which also includes the Indian Regional Navigation Satellite System. The system's success has fostered discussions on expanding its coverage through collaboration with neighboring countries. It operates alongside other independent regional systems globally, such as the European Geostationary Navigation Overlay Service in Europe and the Multi-functional Satellite Augmentation System in Japan, contributing to the worldwide framework of Global Navigation Satellite System augmentation.

Category:Satellite navigation systems Category:Indian Space Research Organisation Category:Aviation in India