How does satellite positioning work? How the GPS satellite positioning system works

Using the satellite as a reference point, that is, under the premise that the satellite position is known, the user receives the satellite signal and calculates the distance to the satellite and carries out three-ball cross measurement on the ground, so as to calculate the receiver position, and the positioning method is to measure the instantaneous distance between the unknown point and the satellite at the known position, and there are two measurement methods: virtual distance observation and carrier phase observation.

Obtain latitude and longitude information by interacting with satellites.

The working principle of GPS positioning is based on the built-in GPS hardware of the mobile phone to directly interact with the satellite to obtain the current latitude and longitude information, this positioning method is very accurate, the disadvantage is that it can only be used outdoors, and the satellite signal can not be received indoors.

The basic principle of network positioning is to measure the speed of three base stations according to the current network location of the mobile phone, calculate the distance between the mobile phone and each base station at one time, and determine an approximate position through triangulation.

GPS module positioning principle

Twenty-four GPS satellites orbit the Earth at an altitude of 12,000 kilometers above the ground in a 12-hour cycle, so that more than four satellites can be observed at any point on the ground at any time and at any time.

Due to the accurate position of the satellite, in GPS observation, the distance from the satellite to the receiver, using the distance formula in the three-dimensional coordinates, using three satellites, can form three equations to solve the position of the observation point (x, y, z). Considering the error between the clock of the satellite and the clock of the receiver, there are actually 4 unknowns, x, y, z and clock difference, so it is necessary to introduce the fourth satellite and form 4 equations to solve it, so as to obtain the latitude and longitude and elevation of the observation point.

In fact, the receiver can often lock more than 4 satellites, at this time, the receiver can be divided into several groups according to the distribution of satellite constellations, each group of 4, and then the algorithm selects the group with the smallest error for positioning, so as to improve the accuracy.

Due to the error of the satellite orbit and satellite clock, and the influence of the atmospheric troposphere and ionosphere on the signal, the positioning accuracy of the civilian GPS is only 10 meters. In order to improve the positioning accuracy, differential GPS (DGPS) technology is widely used, and a base station (differential station) is established for GPS observation, and the precise coordinates of the known base station are used to compare with the observed value, so as to obtain a correction and release it to the public. After receiving the correction, the receiver compares it with its own observations, eliminating most of the errors and obtaining a relatively accurate position.

Experiments show that the positioning accuracy can be improved to 5 meters by using differential GPS.

What is a GPS module

The GPS module is a GPS signal receiver, which can be connected to a computer or mobile phone in a wireless Bluetooth or wired way, and transmits the GPS signal it receives to the GPS software in the computer or mobile phone for processing. We often say that the GPS positioning module is called the user part, which is like a "radio" to receive, demodulate the satellite broadcast C A code signal, in the frequency as the module does not broadcast the signal, belongs to passive positioning.

The key to the application of GPS module lies in the formulation of serial communication protocol, that is, the relevant input and output protocol format of the module. It mainly includes data types and information formats, among which the data types mainly include binary information and data information of the National Marine Electronics Association of NMEA. These two types of information can be communicated with GPS receivers through serial ports.

The GPS module calculates the pseudo-distance with each satellite, and uses the distance intersection method to obtain the four parameters of longitude, latitude, altitude and time correction of the receiver, which is characterized by fast point speed but large error. The module of the initial positioning needs at least 4 satellites to participate in the calculation, which is called 3D positioning, and 3 satellites can achieve 2D positioning, but the accuracy is not good. The GPS module continuously outputs positioning information and auxiliary information in NMEA format through the serial communication port for the receiver to select the application.

The basic principle of GPS positioning is to determine the position of the point to be measured according to the instantaneous position of the high-speed moving satellite as the known starting data, and the method of the intersection of the rear of the space distance. At present, the positioning accuracy provided by GPS systems is better than 10 meters, and in order to obtain higher positioning accuracy, we usually use differential GPS technology: a GPS receiver is placed on the reference station for observation.

According to the known precise coordinates of the base station, the distance correction number from the base station to the satellite is calculated, and the base station sends this data in real time. While the user receiver conducts GPS observation, it also receives the correction number sent by the base station and corrects its positioning results, thereby improving the positioning accuracy. Differential GPS is divided into two main categories:

Pseudorange difference and carrier phase difference.

When a satellite sends its own location information to the receiver, it will attach the time when the information was sent, and after receiving the information, the GPS terminal subtracts the sending time from the current time to obtain the time for information propagation. Multiplying the propagation time by the speed of propagation (the speed of light) gives us the distance between the terminal and the satellite.

Location service refers to the mobile communication system through specific positioning technology to obtain the geographic location information of the mobile terminal (such as latitude and longitude coordinates), to provide the mobile user himself, the communication system Paixian or the third-party positioning client, and with the support of a certain electronic brother sedan chair map information, to provide mobile users with location-related call or non-call services.

The working principle of the satellite is as follows:

When the satellite is working, the image signal or sound signal or data signal on the ground is transmitted to the geosynchronous satellite through the high-frequency transmitting device, and after the satellite is received, it is transmitted to the earth through signal amplification and frequency distribution, and then the satellite receiver on the earth receives the satellite signal through the satellite receiving antenna, and then separates the signal through the frequency division, and then displays or broadcasts through the amplification circuit and terminal equipment, etc.

Features of the satellite:

When the satellite is in operation, the ground image signal or sound signal or data signal shall be transmitted to the geosynchronous satellite through a high-frequency transmission device. After receiving the satellite, it is transmitted to Earth through signal amplification and frequency distribution. Satellite receivers on the earth receive satellite signals by receiving satellite lines in the sky, and then separate the base signals through frequency division, and then visualize or transmit jujube calls through amplification circuits and terminal equipment.

The principle of satellite communication is to launch the satellite into a geostationary orbit 36,000 kilometers above the equator, use the satellite communication device to receive the signal sent from the ground station, amplify and convert the signal and send it to other ground stations, and complete the transmission between the two ground stations. In fact, a communications satellite is a microwave transmitting station <>

1.What is Satellite Positioning.

Satellite positioning is a technique that measures the spatial position of a target object through a satellite system and displays it on a map. At present, the more common satellite positioning systems include GPS system, GLONASS system, Beidou system, etc.

2.How to locate people.

Through mobile phones or other GPS devices, real-time location of individuals can be realized. These devices contain a GPS chip that can receive signals from satellites, calculate the current location of the device based on the time of the signal, and display it on a map.

3.Whether a person's location can be accurately located through satellite positioning.

Satellite positioning can find a person's location relatively accurately, and its error is generally not more than 10 meters, and can even reach an accuracy of a few centimeters. However, to achieve this accuracy, a sufficient number of satellites and suitable reception conditions are required.

4.The application of satellite positioning in daily life.

Satellite positioning has many applications in daily life, such as navigation, positioning services, logistics and distribution, etc. In addition, in the location service of the mobile phone, there are some social apps, such as WeChat, etc., which can query the location information of friends and family members through the location sharing function, so that everyone can pay attention to each other's dynamics.

5.Privacy issues with satellite positioning.

Although satellite positioning is convenient and fast, it also brings some privacy issues. For example, some apps will actively or passively collect personal location information, and then use it for commercial purposes, and will analyze the collected personal data, and finally can infer a person's living habits, preferences and other private information. Therefore, when using satellite positioning, it is necessary to pay attention to the protection and privacy of personal information.

6.How to protect the privacy of personal satellite positioning.

To protect personal privacy, you need to start with the essence briefly, including setting permissions, streamlining app permissions, and rejecting redundant permissions. At the same time, you can also turn off the location function, regularly clean up cached data, turn off wifi and other operations. If you don't want other people in the pants to be able to access their location, you can set yourself to private mode, not sharing your location and only sharing it in certain situations.

7.Summary.

Satellite positioning plays an increasingly important role in modern life, but while enjoying the convenience of satellite positioning, you also need to pay attention to your privacy and security. In order to make better use of satellite positioning technology and protect personal privacy, it is necessary to enhance the awareness of self-protection and privacy protection.