NAVIC India's Navigation System Gets a Simpler Name
Jun 08, 2016
ISRO put the seventh satellite of the Indian Regional Navigation Satellite System into orbit and promptly renamed the system Navigation with Indian Constellation or NAVIC.
India has launched six regional navigational satellites (IRNSS-1A, 1B, 1C, ID,1E and 1F) as part of a constellation of seven satellites to provide accurate position information service to users across the country and the region, extending up to an area of 1,500 km. With launch of 1G NAVIC will be functional completely.
About NAVIC/ IRNSS
IRNSS is an independent regional navigation satellite system designed to provide position information in the Indian region and 1500 km around the Indian mainland. IRNSS would provide two types of services, namely, Standard Positioning Services (SPS) - provided to all users - and Restricted Services (RS), provided to authorised users.
- With seven satellites, the Indian Regional Navigation Satellite System (IRNSS) will broadcast its signals primarily over India and to about 1,500 km beyond its borders.
- Like the GPS of US, the Indian satellites would continually transmit data that allowed suitably equipped receivers to establish their location with considerable precision.
- All seven IRNSS satellites will be at a height of about 36,000 km, taking a whole day to circle the Earth.
- Three of the satellites will be placed over the equator, in what is known as the geostationary orbit, where they match the Earth's rotation and therefore appear from the ground to remain at a fixed position in the sky.
- The remaining four satellites will be in pairs in two inclined geosynchronous orbits. From the ground, these satellites will appear to travel in figures of ‘8’ during the course of a day.
- IRNSS satellites transmit signals in two microwave frequency bands known as L5 and S. The system will provide two types of services, the ‘Standard Positioning Service’ that will be accessible to anyone and an encrypted ‘Restricted Service’ that will be available only to the military and other government-authorised users
Why only few Satellite in IRNSS
- The GPS requires a constellation of 24 orbiting satellites, supported by a global network of ground stations, to cover every part of the world. That kind of global system is expensive
- India had a more limited goal — creating a system wholly in India's control for providing navigation signals over this country and surrounding areas. The cost of such a system was a major consideration.
How object assess its Position through IRNSS:
Navigation satellites periodically transmit their precise position in orbit along with the exact time when each transmission takes place. Since these microwave signals travel at the speed of light, the delay between a signal’s transmission and its reception allows a receiving device to compute its distance from the satellite involved. With data from four satellites, the receiver can then work out its own position.
That’s why Navigation satellites need to carry extremely accurate clocks. Each IRNSS satellite is equipped with three rubidium atomic clocks, which keep precise time down to a few tenths of a trillionth of a second in an hour. Although currently these sophisticated clocks are imported, research efforts to make them indigenously are in progress.
Some Application of IRNSS:
- Terrestrial, Aerial and Marine Navigation
- Disaster Management
- Vehicle tracking and fleet management
- Integration with mobile phones
- Precise Timing
- Mapping and Geodetic data capture
- Terrestrial navigation aid for hikers and travellers
- Visual and voice navigation for drivers
GPS around the Globe
≈ The best known and currently the most widely used navigation satellite system is the U.S. Global Positioning System (GPS), which became operational two decades ago.
≈ Russia too offers global coverage with its Global Navigation Satellite System (GLONASS).
≈ Europe is establishing its own global system, Galileo. Although the full constellation will be ready only by 2019, it plans to begin some services with a reduced number of satellites by the end of next year.
≈ China announced operational services from its BeiDou Navigation Satellite System over that country and surrounding areas. It intends to launch more satellites and expand the system for global coverage by 2020. Japan has already launched the first of three satellites for its regional system that will augment GPS services.
Why India needed its own Navigation System
- It is essentially to ensure assured service. If one is dependent on a foreign navigation signal and then one is in dire need, there could be a situation not be available.
- Military operations rely heavily on satellite navigation, and India’s defence requirements appear to have played an important part in the decision to establish an independent system.
- Apart from signals that anyone can utilise free of cost, satellite navigation systems, including the Indian one, provide an encrypted service that is restricted to those authorised to receive it.
- As part of India’s modernisation of its armed forces, a satellite system of its own gave the country redundancy and reduced dependence on outside agencies for a key technology. To make defence forces self-reliant a Navigation system was need of hour
- Satellite navigation had huge civilian applications. With India developing both economically and technologically, this factor too would have influenced the decision to establish the IRNSS.
Source: the hindu, Deccan chronicle, indiandefensenews