Satellite Navigation Systems

Satellite navigation systems, sometimes abbreviated as satnav, are systems that utilize satellites to provide autonomous geo-spatial positioning. To do this, these systems allow small electronic receivers to determine their location to high precision using time signals transmitted along a line of sight by radio from satellites. The system can be used for providing position, navigation or for tracking the position of something fitted with a receiver, which use the signals to calculate the time for precise time synchronization. These satellite navigation systems operate independently of any telephonic or internet reception, though these technologies can enhance the usefulness of the positioning information generated.

The term that has been coined and used to describe a satellite navigation system that has global coverage is global navigation satellite system. There are different classifications for these systems, which are discussed below. For more information about the types of orbits that these systems utilize, check out our article on satellite orbits.

The different types of Satellite Navigation Systems that are in some stage of development include the United States’ Global Positioning System, Russia’s Global Navigation Satellite System, China’s BeiDou Navigation Satellite System, European Union’s Galileo, Japan’s Quasi-Zenith Satellite System, and India’s Indian Regional Navigation Satellite System. We will take a quick look at these different types below and then take a different look at the different types of Satellite Navigation Implementations.

To learn more about how GPS works, check out these links from GPS.gov, the FAA, and the Smithsonian.

Classifications

The classification types for these types of systems that provide enhanced accuracy and integrity monitoring that usable for civil navigation are classified into 2 groups. The acronym GNSS means Global Navigation Satellite System.

GNSS-1 is the first generation system and is the combination of existing satellite navigation systems, which are GPS and GLONASS, with Satellite Based Augmentation Systems or Ground Based Augmentation Systems.
GNSS-2 is the second generation of systems that independently provides a full civilian satellite navigation system, exemplified by the European Galileo positioning system.

Satellite Navigation Implementations

There are several different satellite navigation implementations by several different countries. Several of these systems are currently available and active; whereas, several of the implementations below are currently being built.

GPS

The system called GPS consists of up to 32 medium Earth orbit satellites in six different orbital planes. The GPS system is an acronym for Global Positioning System, which was built in the 1970s with an eye on military use. However, as time has passed, US leadership has made GPS more available to the entire world since 1994 and is the world’s most utilized satellite navigation system. The current accuracy of the system depends on which bands are being used, but the general accuracy is said to be around 500 to 30 cm. There are currently 31 active satellites, but this number changes as satellites get constantly updated.

GLONASS

The GLONASS satnav system, which is an acronym for GLObal NAvigation Satellite System, is the second system to be put into place. Development of GLONASS began in the Soviet Union in 1976 and was completed in 1995, before the system was restored to capacity in 2001 after capacity declined in the mid 1990s. This system operates using 24 satellites in orbit, which is able to provide global coverage. There are plans to update the satellite constellation going forward. The GLONASS accuracy is up to 2.8 metres for use.

Galileo

This alternative to the US GPS system is named after Galileo Galilei and went live in 2016. The Galileo satnav system was started with a chief aim being able to provide an independent high-precision positioning system so European nations do not have to rely on the GPS, or the GLONASS systems. The Galileo System will be able to provide worldwide coverage and be a network of 30 satellites. Of the 30 total satellites, 24 of these will be actively in service and 6 satellites will be spares. That said, the free version Galileo is free and open to all, but has an accuracy of 1 meter. The paid version is encrypted and has an accuracy of 1 centimeter.

BeiDou

BeiDou, otherwise known as the BeiDou Navigation Satellite System (BDS), is a Chinese satellite navigation system consisting of 2 separate satellite constellations. The first generation of satellites was launched in 2000 before being decommissioned in 2012, consisted of 3 satellites that provided coverage and navigation services for Chinese and neighboring country users. The goal of the 2nd generation of BeiDou satellites is to expand access to the system from the Asia-Pacific region to global coverage. The expectation was for this global coverage to be completed by 2020, with several launches in the summer of 2020 to finish the network. It is worth noting that the accuracy of the system depends on the users utilizing the system as for the Chinese military, the system is very accurate up to 10 centimeters. But for civilian use, the accuracy is 10-meters, which is much worse than other competitor satnav systems, which can have a 5 meter accuracy for GPS L4 band and 30 centimeters for the L5 band. This is worth discussing more in depth and detail in a later article.

Indian Regional Navigation Satellite System

The Indian Regional Navigation Satellite System is an autonomous regional satellite navigation system that provides accurate real-time positioning and timing services. The system was built by India to cover India and has further plans for its expansion. With 7 active satellites in orbit, the system can provide accuracy of 1 meter for the public version and 0.1 meters of accuracy for the encrypted version.

Japanese Quasi-Zenith Satellite System

The Quasi-Zenith Satellite System was developed by the Japanese government to enhance GPS accuracy in the Asia-Oceania region of the world with a focus on Japan. To achieve this enhanced accuracy, the new satellite system was developed as a four-satellite regional time transfer system and a satellite-based augmentation system. The system is made up of 7 satellites and has an accuracy of 0.01 to 1 meters. There are future plans to expand the system and launch more satellites.