How many satellites does GPS satellite positioning need?

It takes at least three satellites to form a triangle to get the approximate position. The more satellites, the more accurate.

GPS is the abbreviation of English Global Positioning System. GPS was started as a project of the US military in 1958 and put into use in 1964. In 1970s, the United States army, navy and air force jointly developed a new generation of satellite positioning system GPS. The main purpose is to provide real-time, all-weather and global navigation services for land, sea and air, and to be used for some military purposes such as intelligence gathering, nuclear explosion monitoring and emergency communication. After more than 20 years of research and experiments, it cost 30 billion dollars. By 1994, 24 GPS satellite constellations with global coverage of 98% have been deployed. In the field of machinery, GPS has another meaning: geometric product specifications (GPS for short). Another meaning is G/s(GB per second). GPS (General Processor Sharing) is a special term in processor sharing and network service quality control.

Basic introduction

Global Positioning System (English: global positioning system, usually abbreviated as GPS), also known as global positioning system, is a medium-range circular orbit satellite navigation system. It can provide accurate positioning, speed measurement and high-precision time standard for most areas (98%) of the earth's surface. Developed and maintained by the US Department of Defense, the system can meet the needs of military users located anywhere in the world or in near-earth space to continuously and accurately determine the three-dimensional position, three-dimensional movement and time. The system includes 24 GPS satellites in space; There are 1 master control stations, 3 data injection stations and 5 monitoring stations on the ground, and the users are GPS receivers. At least three satellites are needed to quickly determine the position and height of the client on the earth; The more satellites that can be connected, the more accurate the decoded position will be.

The system was developed by American government in 1960s+0970s, and was fully built in 1960s +0994. Users only need a GPS receiver to use this service, and there is no extra charge. GPS signals can be divided into two categories: civil standard positioning service (SPS) and military precise positioning service (PPS). Because SPS can be used at will without any authorization, the United States initially artificially added selective error (that is, selective availability) to civil signals to reduce its accuracy, so that its final positioning accuracy is about 100 meters. The accuracy of capture is below ten meters. After 2000, the Clinton administration decided to cancel the interference with civil signals. So now the positioning accuracy of civil GPS can reach 10 meter.

GPS system has the following advantages: using low-frequency signals, it can maintain considerable signal penetration even in bad weather; Global coverage (up to 98%); High-precision three-dimensional constant-speed timing; Fast, time-saving and efficient; Wide range of uses and diverse functions; Movable positioning; Different from the double-star positioning system, the receiver does not need to send out any signals during use, which increases the concealment and improves its military application efficiency.