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GNSS Constellations

GNSS (Global Navigation Satellite System) constellations refer to a system of satellites orbiting the Earth that provides global positioning and timing information to users. The most common GNSS constellations include GPS (Global Positioning System) operated by the United States, GLONASS (Global Navigation Satellite System) operated by Russia, Galileo operated by the European Union, BeiDou operated by China, and IRNSS (Indian Regional Navigation Satellite System) operated by India. 

Each satellite in the constellation orbits around the Earth at a specific altitude and transmits signals that can be picked up by a receiver on the ground. By measuring the time delay between the transmission and reception of the signal, the receiver can calculate its distance from the satellite and determine its precise location. GNSS constellations are becoming increasingly important for a variety of applications, from GPS navigation in smartphones to precision farming and self-driving cars.

Click on any of the GNSS Constellations below to learn more about the different satellites in each constellation and their launch dates, status and more.

GNSS constellations operates by utilizing a network of satellites that orbits around the Earth to provide location and time information to users on the ground. Each satellite in the constellation transmits signals that can be received by a GNSS receiver on the ground. By measuring the time delay between the transmission and reception of these signals, the receiver can calculate its distance from the satellite. By measuring distances from multiple satellites, the receiver can triangulate its position and determine its precise location. This process allows GNSS receivers to provide accurate positioning information by leveraging signals from multiple satellites in the constellation.

GNSS constellations differ from each other due to several reasons such as their origin, frequency bands, launch date, number of satellites, and accuracy.

Origin: GNSS constellations are developed by different countries and organizations, such as GPS by the US, GLONASS by Russia, Galileo by the European Union, BeiDou by China, IRNSS by India, and QZSS by Japan.

Launch Date: The launch dates of the constellations vary, with GPS being the oldest and operational since 1978, GLONASS since 1982, Galileo since 2016, BeiDou since 2000, QZSS since 2010, and IRNSS since 2013.

Frequency Bands: The frequency bands used by the constellations differ, with GPS using L1 and L2 bands, GLONASS using L1 and L2 bands, Galileo using E1, E5a, E5b, and E6 bands, BeiDou using B1, B2, B3, and B5 bands, QZSS using L1 and L2 bands, and IRNSS using L5 and S bands.

Number of Satellites: The number of satellites in each constellation also varies, with GPS having 31 satellites, GLONASS having 24 satellites, Galileo having 24 satellites, BeiDou having 35 satellites, IRNSS having 9 satellites, and QZSS having 4 satellites.

Accuracy: The accuracy of the constellations also varies, with GPS providing a real-time positioning accuracy in the centimeter range and a long-term accuracy in the millimeter range, GLONASS providing positional accuracy in the 5-10 meters range, Galileo providing horizontal and vertical position accuracy in the meter range, BeiDou providing millimeter-level accuracy with post-processing, IRNSS providing a positioning accuracy of 5-10 meters, and QZSS providing a positioning accuracy of better than 1 meter.