NavIC and Global Navigation Satellite Systems

Comprehensive vocabulary flashcards covering the NavIC system, its technical components, historical development, and comparison with other global and regional navigation satellite systems.

NavIC (Navigation with Indian Constellation)

India's indigenous satellite-based positioning system, formally known as the Indian Regional Navigation Satellite System (IRNSS).

Primary Service Area

The region designated for NavIC coverage which includes all of India and extends up to $1,500$ kilometres beyond its borders.

Extended Service Area

The geographic reach of NavIC bounded by $30^{\circ}$ South to $50^{\circ}$ North latitude and $30^{\circ}$ East to $130^{\circ}$ East longitude.

Standard Positioning Service (SPS)

A NavIC service available to all civilian users providing a positioning accuracy of approximately $5-10$ metres within India.

Restricted Service (RS)

An encrypted, access-controlled NavIC service designated for authorized users, primarily for strategic and defense applications.

Atomic Clock

A precision timekeeping instrument that determines time by measuring the natural vibrational oscillations of atoms, significantly more accurate than mechanical or electronic clocks.

Caesium (Cs) Resonance Frequency

The frequency of $9,192,631,770$ hertz (cycles per second) of a caesium-133 atom which defines the international measure of one second.

SpectraTime

The Switzerland-based manufacturer from which the atomic clocks for the first-generation IRNSS satellites were procured.

NVS Series

The second generation of NavIC satellites designed with a mission life of $12$ years and featuring indigenously developed rubidium clocks.

L1 Frequency

A frequency band included in NVS-series satellites to improve interoperability with GPS and enable data reception by low-power wearable devices.

AJIT Microprocessor

The first microprocessor entirely conceptualized, designed, developed, and manufactured in India, attributed to IIT Bombay for future NavIC receivers.

IRNSS-1H

A satellite launched in $2017$ as a replacement for IRNSS-1A that failed to reach orbit because its heat shield did not separate.

NVS-02 Failure

A mission failure in January $2025$ caused by an electrical-path failure that prevented a control signal from reaching the engine's pyro valve.

Geostationary Orbit (GEO)

A special geosynchronous orbit in the plane of the equator at an altitude of approximately $35,786$ kilometres where satellites remain fixed relative to the Earth.

GAGAN

GPS Aided GEO Augmented Navigation; India's Satellite-Based Augmentation System (SBAS) developed by ISRO and the Airports Authority of India (AAI).

GPS (Global Positioning System)

The global navigation satellite system operated by the United States, which launched its first NAVSTAR satellite in $1978$.

GLONASS

Russia's global navigation satellite system (GLObalnaya NAvigatsionnaya Sputnikovaya Sistema) built around a $24$-satellite operational constellation.

Galileo

The European Union's civilian global navigation system designed as a $30$-satellite constellation.

BeiDou Navigation Satellite System (BDS)

China's global navigation system which became operational globally with a fleet eventually reaching $45$ in-orbit service satellites.

QZSS (Quasi-Zenith Satellite System)

Japan's regional satellite-navigation system, also known as Michibiki, operated under the Cabinet Office framework.