Accurate navigation

It is with high hopes and aspirations that Indians will be looking out for the proposed launch of the Indian heavy-lift Geostationary Satellite Launch Vehicle (GSLV) in June this year to put a satellite into orbit that will mark another major step towards creating a Indian Regional Navigational Satellite System (IRNSS).

It is intended to dovetail the on-going program of the GPS aided geo augmented navigation or GPS and geo-augmented navigation system (GAGAN) with the planned implementation of a regional satellite-based augmentation system (SBAS) by India.

It is a system to improve the accuracy of a GNSS receiver by providing reference signals. The effort currently underway is the first step towards introduction of modern communication, navigation, surveillance/Air Traffic Management system over Indian airspace.

When the seven-satellite system is in place it will allow for both civilian applications and a dedicated military component that will not be amenable to foreign tinkering during times of hostilities as are the US-made Global Positioning System (GPS), the Russian Global Navigation Satellite System (GLONASS) or the European Galileo network with which India is also associated.   
 
IRNSS satellite

The Indian Regional Navigational Satellite System (IRNSS) is visualized as an autonomous regional satellite navigation system being developed by Indian Space Research Organisation (ISRO) and the Defence Research and Development Organisation laboratories to cover the whole Indian subcontinent and the oceans around it. The government approved the project in May 2006 with plans to complete it by 2014.

It will consist of a constellation of 7 navigational satellites in geostationary orbit to have a larger signal footprint and lower number of satellites to map the region. It is intended to provide an all-weather absolute position accuracy of better than 7.6 meters throughout India and within a region extending approximately 1,500 km around it. A goal of complete Indian control has been stated, with the space segment, ground segment and user receivers all being built in India.

The American company Raytheon won a contract to set up 15 reference stations scattered across the country. Two mission control centres, along with associated uplink stations, have been set up at Kundalahalli in Bangalore. One more control centre and uplink station is to come up at Delhi.

This was preceded by  a network of 18 total electron content (TEC) monitoring stations all over the country to study and understand the behavior of the ionosphere over the Indian region which has a peculiarity all its own and affects navigation within the aerospace around India.

The GSAT-4 satellite is intended to be the technology demonstrator of the project. The failure of the GSLV launch in April, 2010 was a setback to the IRNSS project even though later launches using the French Ariane rocket have put the GSAT-8 in orbit last year and it is ready to be switched on most probably next month. This is because all other launch-capable nations are hesitant to send aloft a satellite of another nation which has a spy capability.  

The first GAGAN transmitter was integrated into the GSAT-4 geostationary satellite and was supposed to be operational by 2008. Following a series of delays, GSAT-4 was launched on 15 April 2010, however it failed to reach orbit after the third stage of the Geosynchronous Satellite Launch Vehicle Mk.II that was carrying it malfunctioned much to the consternation of both the civil aviation sector as well as the military establishment that was keen to utilise its services.

The GAGAN system on which the whole Indian Regional Navigation Satellite System is to be based will be compatible with other SBAS systems such as the Wide Area Augmentation System (WAAS), the European Geostationary Navigation Overlay Service (EGNOS) and the Multi-functional Satellite Augmentation System (MSAS) and will provide seamless air navigation service across regional boundaries.

While the ground segment consists of reference stations and a master control centre, which will have sub systems such as data communication network, SBAS correction and verification system, operations and maintenance system, performance monitoring display and payload simulator, Indian land uplinking stations will have dish antenna assembly. The space segment will consist of one geo-navigation transponder.

Improving effectiveness

To improve the effectiveness of flight-management systems (FMS) within the country the  GAGAN will be packed with algorithms created to save air operators both civil and military time and money by setting up standard operating procedures for climb, descent and engine performance profiles at every airport given its location, altitude and other relevant parameters.

It needs to be remembered that it is during takeoff and landing that aircraft both civil and military guzzle the most fuel. The FMS will improve the efficiency and flexibility by increasing the use of operator-preferred trajectories. It will improve airport and airspace access in all weather conditions, and the ability to meet the environmental and obstacle clearance constraints.

Environmentally too it needs to be kept in mind that aircraft are even worse polluters of the atmosphere than terrestrially operated cars, trucks and heavy vehicles It will also enhance reliability and reduce delays by defining more precise terminal area procedures that feature parallel routes and environmentally optimized airspace corridors.

GAGAN project

Its creators claim the following characteristics: GAGAN will increase safety by using a three-dimensional approach operation with course guidance to the runway, which will reduce the risk of controlled flight into terrain i.e., an accident whereby an airworthy aircraft, under pilot control, inadvertently flies into terrain, an obstacle, or water.

GAGAN will also offer high position accuracies over a wide geographical area like the Indian airspace. These positions accuracies will be simultaneously available to 80 civilian and more than 200 non-civilian airports and airfields and will facilitate an increase in the number of airports to 500 as planned. These position accuracies can be further enhanced with ground based augmentation system. Raytheon has set up 15 reference stations scattered across the country. Two mission control centres, along with associated uplink stations, have been set up at Kundalahalli in Bangalore. One more control centre and uplink station is to be established at Delhi.

Among its other claimed advantages are that it will greatly reduce congestion and enhance communications to meet India’s growing air traffic management needs.

Equally, if not more interestingly, in 2012 the Defence Research and Development Organisation came up with a miniaturized version of the data receiving device with all the features from global positioning systems (GPS) and global navigation satellite systems (GNSS) incorporated within one gadget.

The module weighing just 17 gm, can be used in multiple platforms ranging from aircraft (e.g. winged or rotor-craft) to small boats, ships. Reportedly, it can also assist “survey applications”. It is a cost-efficient device and can be of “tremendous” civilian use, according to its creators.

The navigation output is composed of GPS, GLONASS and GPS+GLONASS position, speed and time data. According to a statement released by the DRDO, G3oM is a state-of-the-art technology receiver, integrating Indian GAGAN as well as both global positioning system and GLONASS systems. The product is said to bring about a quantum leap in the area of GNSS technology and has paved the way for highly miniaturized GNSS systems for the future

For the sphere of military aviation among the many advantages claimed for the new system is a more accurate missile targeting system.

It needs to be recalled that the whole idea of satellite navigation was born for military applications because it was recognized very early in its development that it can help weapons cruise most accurately to their targets. The first thing that comes to mind is that it would help reduce the much-maligned collateral damage through precision strikes.

As part of network centricity, the knowledge about where all members of a fighting group are located would also reduce what is known as the “fog of war” on which all tactical errors are blamed.