GNSS 101: General Knowledge About Global Positioning Systems

How many satellite navigation, positioning systems, are there in the world nowadays?

To define, a global satellite navigation system can be termed as Global Navigation Satellite System (GNSS), which includes the United States' Global Positioning System (GPS), Russia's GLONASS, China's BeiDou Navigation Satellite System (BDS) and the European Union's Galileo. India’s Regional Navigation Satellite System (IRNSS), France’s Doppler Orbitography and Radiopositioning Integrated by Satellite (DORIS) and Japan’s Quasi-Zenith Satellite System (QZSS) are in the process of developing regional navigation and augmentation systems.

Comparison of geostationary, GPS, GLONASS, Galileo, Compass (MEO), International Space Station, Hubble Space Telescope, Iridium constellation and graveyard orbits (Reference from: https://en.wikipedia.org/wiki/Satellite_navigation)

The original motivation for satellite navigation was for military applications: satellite navigation enables the accurate delivery of weapons to targets. In May 2000, the U.S government discontinued its use of Selective Availability in order to make GPS more responsive to civil and commercial users worldwide. Commercial and consumer-grade GPS-enabled devices were soon been widely marketed worldwide for land, air and sea navigation and longitude, latitude, and altitude geospatial measurement. GNSS receivers decode time signals, that enables users to determine the time precision to within 100 billionths of a second. These time tagging and time synchronization features have been effectively used in energy or water grids, telecommunication networks and financial activities.

By integrated with wireless communications like 4G LTE networks, Wi-Fi, or ISM bands modules, GNSS-enabled devices provide real-time logistics, various location-based services and vehicle, assets and personal tracking, which includes law enforcement and pets tracking. Higher positioning precision can be achieved for the receivers by including multi constellations or reference differential signals from ground segment. As the technology emerges, GPS satellites evolves with Block IIR(M), Block IIF and Block III programs for the space-based segment while the Architecture Evolution Plan, AEP, and the Advanced Control Segment, OCX, are improved for the ground segment.

For more information about GPS/GNSS-related applications, please refer to this web link: https://grindgis.com/50-uses-or-applications-of-gps/