GPS positioning principle

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The full name of GPS is Global Positioning System. The global positioning system originated from military projects in the United States. This type of system in the United States is called GPS. It is a medium-distance circular orbit satellite navigation system developed and maintained by the US Department of Defense. It can be used on the surface of the earth. Most areas (98%) provide accurate positioning, speed measurement and high-precision standard time.

The global positioning system can meet the needs of military users located in any place on the global ground or in near-Earth space to continuously and accurately determine the three-dimensional position, three-dimensional motion and time.

The GPS system has the following advantages: using low-frequency signals, it can maintain considerable signal penetration even in bad weather; up to 98% global coverage; high-precision three-dimensional fixed-speed timing; fast, time-saving, and high-efficiency; application Extensive, multifunctional; movable positioning. Unlike the dual-star positioning system, the receiver does not need to send out any signals during use; this increases the concealment and improves its military application efficiency.

China also has a global positioning system called Beidou; a fighting nation also has it called GLONASS; the EU also has it called Galileo. The positioning principles of these four sets of global positioning systems are basically the same, and apart from positioning, GPS can also provide time, which means that you can tell you the accurate time. Accurate positioning is inextricably linked to time. There is actually a certain connection between coordinates and time. We can calculate the distance between the GPS receiver and the satellite through the coordinates and time. Moreover, the GPS receiver must pass at least 4 satellites to determine its own space and time coordinates.

The most difficult problem with satellite positioning is the error, because when the signal is transmitted, due to the influence of the atmosphere and other factors, even if the speed is a little slow, the impact is relatively large. Because the speed of light is extremely fast, the error of GPS is generally a few meters. For tens of meters, if we want to reduce the error, we have to use the differential GPS technology, which can greatly improve the positioning accuracy of GPS. It is to deploy a GPS reference station on the relatively close known coordinate point of the drone.

It can also receive the signals of 4 satellites that provide position information for the drone, calculate the coordinate value based on these signals, and then compare it with The known coordinates are compared to obtain the deviation of the coordinates, and then the deviation or the real-time measured carrier phase is sent to the UAV through the data transmission link or mobile communication network, and the UAV makes corrections based on the received information . You can also purchase positioning services for drones from professional precision positioning service providers, and receive error correction information through the mobile communication network to correct the position.

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