How is the positioning principle of GPS navigation positioning?

1. How is the GPS positioning system positioning

The 24 GPS satellites run around the earth at a high altitude of 12,000 kilometers from the ground, so that at any moment at any time, any at all at the ground can be observed at the same time.

Because the position of the satellite is accurate, in the GPS observation, we can get the distance from the satellite to the receiver. Using the distance formula in the three -dimensional coordinates, the three satellites can be used to form three equations to solve the position of the observation point (x X, y, z).Considering the error between the clock of the satellite and the receiver clock, there are actually 4 unknown, X, Y, Z, and clock difference, so the 4th satellite needs to be introduced to form 4 squares to solve, so as to obtain the observation point of the observation pointLavels and heights.

In fact, the receiver can often lock more than 4 satellites. At this time, the receiver can be distributed into several groups according to the satellite constellation, and each group is 4, and then the group with the smallest error is selected by the algorithm for positioning, thereby positioning, so asImprove accuracy.

Due to the errors of satellite Running tracks and satellite clocks, the impact of atmosphere on the signal of the flow layer, the ionization layer on the signal, and the artificial SA protection policy, the positioning accuracy of the civil GPS is only 100 meters.In order to improve the positioning accuracy, the differential GPS (DGPS) technology is generally adopted to establish a reference station (differential table) for GPS observation. The accurate coordinates of the known benchmark station are used to compare the observation values to obtain a correction number and release it outside the outside world.EssenceAfter receiving the correction number, the receiver compares it with its own observation value, eliminates most of the errors, and obtains a more accurate position.Experiments show that the positioning accuracy can be increased to 5 meters by using differential GPS.

vehicle navigation system is mainly composed of navigation hosts and navigation display terminals.The built -in GPS antenna will receive at least 3 data information transmitted from 24 GPS satellites surrounding the earth, thereby determining the current location of the car.The navigation host is matched with the electronic map data determined by the GPS satellite signal to determine the accurate location of the car in the electronic map.

On this basis, various functions such as driving navigation, route recommendation, information query, and playback AV/TV will be realized.Drivers only need to watch the screens on the display and listen to voice prompts, and manipulate the remote control in the hand to achieve the above functions, so as to drive easily and freely.

Global Positioning System is the second -generation satellite navigation system in the United States.It was developed on the basis of the Ziwuyi satellite navigation system, and it adopted the successful experience of the Wuwuyi system.Like the Ziwuyi system, the global positioning system consists of three parts: space part, ground monitoring, and user receiving machines.

According to the current plan, the space part of the global positioning system uses 24 satellites with a height of about 20,200 kilometers to form a satellite constellation.21 3 satellites are near -circular orbit, and the operating cycle is about 11 hours and 58 minutes. It is distributed on the six orbit planes (four on the surface of the orbit), and the orbital inclination angle is 55 degrees.The distribution of satellites allows more than four satellites at any time around the world at any time, and can maintain a good positioning and solving geometric graphics (DOP).This provides continuous global navigation capabilities in time.

The ground monitoring section includes four monitoring stations, one upward injection station and a main control station.The monitoring station has a GPS user receiver, atomic clock, a sensor collected by local weather data, and a computer that processes preliminary data.The main task of the monitoring station is to obtain satellite observation data and send these data to the main control station.The main control station is located at the Vanden Fort Air Force Base.It implements comprehensive control of the ground monitoring department.The main task of the main control station is to collect all observation data of the GPS satellites in each monitoring station, and use these data to calculate the orbit and satellite clock of each GPS satellite.The upward injection station is also located at the Vanden Fort Air Force Base.Its task is mainly to inject such navigation data and the instructions of the main control station into the satellite when each satellite runs to the sky.This injection is performed once a day for each GPS satellite and the final injection before the satellite leaves.

The global positioning system has the characteristics of good performance, high accuracy, and wide application. It is by far the best navigation positioning system.With the continuous improvement of the global positioning system and the continuous improvement of software and software, the application fields are continuously developing. At present, the various departments of the national economy have begun to gradually penetrate people's daily life.

2. Positioning principle of GPS navigation

d1 = [(x1-x2)^2 (y1-y2)^2 (Z1-Z2)^2]^1/2 c (vt1-vt0)

d2 = [(x2-x)^2 (y2-y)^2 (Z2-Z)^2]^1/2 c (vt2-vt0)

d3 = [(x3-x)^2 (y3-y)^2 (Z3-Z)^2]^1/2 c (vt3-vt0)

d4 = [(x4-x)^2 (y4-y)^2 (Z4-Z)^2]^1/2 c (vt4-vt0)

In the above four equations, the coordinates of the measuring point X, Y, Z, and VTO are unknown parameters, where DI = C TI (i = 1, 2, 3, 4).

DI (i = 1, 2, 3, 4) is satellite 1. Satellite 2, satellite 3. Satellite 3. Satellite 3, satellite 4 to receiver.

TI (i = 1, 2, 3, 4) is satellite 1. Satellite 1. Satellite 2. Satellite 2, satellite 3, and satellite 4 signals to reach the time of the receiving machine.

C is the speed of transmission of GPS signal (ie, the speed of light).

The meaning of each parameter in the four equations is as follows:

X, Y, and Z is the spatial right -angle coordinates of the coordinates to be tested.

XI, Yi, Zi (i = 1, 2, 3, 4) are satellite 1. Satellite 1. Satellite 2. Satellite 2, Satellite 3, Satellite 4's spatial right -angle coordinates at the time of T, can be obtained by satellite navigation.

VT I (i = 1, 2, 3, 4) is satellite 1, satellite 2, satellite 3. Satellite 3, and satellite 4 satellite clocks, which are provided by the satellite star calendar.

VTO is the bell of the receiver.

From the above four equations, the clock vTO of the coordinates of X, Y, Z and the receiver at the above four equations.

The basic positioning principle of GPS is: satellite sends its own star parameters and time information uninterrupted. After receiving this information, the user receives the three -dimensional position, three -dimensional direction, and time information of the receiver.

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