Which countries have GPS?

Four global positioning systems

American GPS: It was designed and developed by the US Department of Defense in the early 1970s and completed by 1993. 1994, the United States announced that it would provide global free GPS access within 10, but the United States only provided low-precision satellite signals to foreign countries. It is believed that the system has a "back door" set by the United States. In the event of war, the United States can shut down information services to a certain area.

Galileo: 1999, Europe put forward a plan to launch 30 satellites to form Galileo satellite positioning system. The plan was officially launched.

Russia "GLONASS": Not yet deployed. Since 1970s, at least 65,438+08 satellites are needed to ensure the coverage of the whole of Russia. In order to provide global positioning service, 24 satellites are needed.

China Beidou: In 2003, China Beidou No.1 was built and put into operation. Unlike GPS, Beidou's commander and terminal can communicate in both directions. After the Sichuan earthquake on May 6, 2008, 5438+02, Beijing Armed Police Command Center and Sichuan Armed Police Force exchanged hundreds of times with Beidou. Beidou-2 series satellites will enter the peak of networking, and it is expected that a global system consisting of more than 30 satellites will be formed in 20 15 years.

The satellite positioning system is a global positioning system. Simply put, this is a satellite system consisting of 24 satellites covering the whole world. This system can ensure that four satellites can be observed at any point on the earth at any time, thus ensuring that satellites can collect the latitude, longitude and height of observation points, thus realizing the functions of navigation, positioning and timing. This technology can be used to guide planes, ships, vehicles and individuals to reach their destinations safely and accurately along selected routes.

Global Positioning System (GPS) is a new generation of space satellite navigation and positioning system jointly developed by the United States Army, Navy and Air Force in 1970s. Its main purpose is to provide real-time, all-weather and global navigation services for land, sea and air, and it is also used for some military purposes such as intelligence gathering, nuclear explosion monitoring and emergency communication. It is an important part of America's global dominant strategy. After more than 20 years of research and experiments, it cost 30 billion dollars. By1March 1994, 24 GPS satellite constellations with global coverage of 98% had been deployed.

The GPS global positioning system consists of three parts: the space part-GPS constellation; Ground control part-ground monitoring system; User equipment part-GPS signal receiver.

GPS positioning technology has the advantages of high precision, high efficiency and low cost, which makes it widely used in strengthening and establishing various geodetic control networks, as well as highway engineering survey and deformation measurement of large structures.