GPS Current Affairs
The ISRO Telemetry Tracking and Command Network (ISTRAC) and CSIR-National Physical Laboratory (NPL) have signed MoU to make indigenous regional positioning system-NavIC independent from the US clock system.
Until now, the satellites on NavIC (Navigation with Indian Constellation) managed by the ISRO relied on the US GPS to ensure that the clocks aboard were working at the high-precision required in satellite-based communication.
Significance of MoU
The MoU will help the NAVIC to get formally synchronized with the Indian Standard Time (IST) which is being maintained by the Delhi-based NPL – the timekeeper of India. It will also help in making NAVIC to get fully operational in the market for commercial purposes as time synchronisation is essential for all kinds of services such as financial transactions, digital archiving, stock handling, time stamping, national security or prevention of cyber-crimes etc.
Formally called the Indian Regional Navigation Satellite System (IRNSS) is designed to provide accurate position information service to users in India as well as the region extending up to 1500 km from its boundary. NavIC System consists of constellation of seven satellites (namely IRNSS-1A, 1B, 1C, 1D, 1E, 1F and 1G) of which three are geostationary and four are non-geostationary.
National Physical Laboratory (NPL)
The NPL is part of the Council of Scientific & Industrial Research (CISR). It is the measurement standards laboratory of India. It maintains standards of SI units in India and calibrates the national standards of weights and measures. It is only agency in India authorised to maintain Indian Standard Time (IST) and hosts most accurate clocks in the country with accuracy of ±20 nanoseconds through the Primary Time Scale (PTS), an ensemble of five caesium clocks and one hydrogen maser.
The atomic clocks on the first satellite IRNSS-1A of the NavIC (Navigation with Indian Constellation), the indigenously built satellite-based positioning system, has developed a technical snag.
One of the three crucial rubidium timekeepers (atomic clock) on IRNSS-1A satellites failed six months ago and the other two followed subsequently. ISRO will soon launch one of its back up navigation satellites as a replacement to IRNSS-1A satellite.
- Remaining satellites of NavIC constellation (having total 7 satellites) are performing their core function of providing accurate position, navigation and time.
- Each satellite has three clocks and a total of 27 clocks for the navigation satellite system. These clocks are supplied same foreign vendor. These clocks are important to provide precise data.
- The troubled IRNSS-1A spacecraft was put in space in July 2013 and has an expected life span of 10 years. The seventh navigation satellite, IRNSS-1G, was launched in April 2016.
Atomic clock: It is an extremely accurate type of clock regulated by the vibrations of an atomic or molecular system. Its principle of operation is not based on nuclear physics, but rather on atomic physics. It uses the microwave signal that electrons in atoms emit when they change energy levels. The accuracy of an atomic clock depends on two factors, temperature of the sample atoms and frequency and intrinsic width of the electronic transition (higher frequencies and narrow lines increase the precision).
About NavIC (Navigation with Indian Constellation)
- NavIC also known as the Indian Regional Navigation Satellite System (IRNSS) is similar to the GPS (Global Positioning System) of US, Glonass of Russia and Galileo of Europe as well as China’s Beidou.
- Starting in July 2013, ISRO had launched all the seven navigation satellites of the IRNSS by April 2016. Each satellite has a life span of 10 years.
- IRNSS is said to be the “Indian GPS” that will give accurate real-time positioning and timing services over India and the region around it extending to 1,500km. Thus, NAVIC’s reach is regional.
- Applications of IRNSS: terrestrial, aerial and marine navigation, terrestrial navigation for hikers and travellers, vehicle tracking and fleet management, disaster management, integration with mobile phones, mapping and geodetic data capture and visual and voice navigation for drivers. Apart from the civilian applications, it will be used for defence purposes as well.
For more Information: IRNSS