GPS jammer shield triangulation
At present, the common positioning methods in the market are: satellite positioning, base station positioning, WIFI positioning. Each has its own characteristics and applies to the scene. The principle of localization is usually “triangulation“. That is, knowing the distance of the user to three fixed points, the user‘s position can be calculated.
1, GPS Global PosiTIoning System (GPS) is a positioning system studied by the United States. Its characteristics are as follows: it does not need a SIM card, does not need to connect to the network, as long as outdoors, you can basically accurately locate anywhere at any time. However, it takes a lot of time to search the satellite after GPS startup, which usually takes about 2 minutes (commonly known as cold start, cold start includes: 1. First use of GPS 2. The GPS battery is exhausted 3. Move more than 1000 km in the shutdown state or keep shutting down for more than 4 hours). Common satellite positioning systems: China‘s Beidou, America‘s GPS, Russia‘s GLONASS, Europe‘s Galileo Principle: The receiver receives the GPS satellite broadcast, through the analysis of visible GPS satellite position, distance and other information and the corresponding algorithm to get their own position information. Advantages: High positioning accuracy, as long as can receive the positioning signal of four satellites, can be positioned. Cons: GPS is greatly affected by weather and location. When the weather is bad, or under a viaduct/tree shade, or in the side corner of a tall building, underground garage, indoor or outdoor lower garage (or simply when the sky is not visible), the GPS location can be greatly affected, and even the location service can not be performed. Positioning accuracy: 5~10 meters
2, LBS(base station) positioning Base stations include mobile, Unicom and telecom base stations. Base station positioning is based on the signal difference of the base station in mobile communication, through the authentication of the nearest optimal base station when the mobile phone is turned on, turned off, and switched over the base station. Therefore, the location of the mobile phone is confirmed by the location of the base station where the user appears. In addition, different sectors within the range of the same base station will also be marked. The accuracy of base station positioning depends on the coverage density of the base station near the location. If there are more base stations, the positioning is accurate; if there are few base stations, the positioning is not so accurate. LBS positioning must be connected to the Internet, the phone is in the SIM card registration state (in flight mode open wifi and remove the SIM card is not possible). Principle: The location information of the cellular base station of the operator is fixed. By receiving one or more base station signal terminals, the operator can calculate its own position according to the signal strength and the location of the base station Advantages: Convenient, because it is through the SIM card to receive the base station signal for positioning. In theory, the location of a phone can be determined by calculating the difference between the signals of three base stations. Therefore, as long as the user‘s mobile phone is within the effective range of the mobile communication network, the location can be located at any time, and not affected by the weather, tall buildings, location and so on. Disadvantages: Through the calculation of base station signal differences of position coordinates, clearly inferior to the GPS positioning accuracy, are greatly influenced by the environment, located in suburban and rural mobile station can be within the scope of the 10 ~ 20 meters, the city due to the more tall buildings, radio waves propagation environment is bad, it is difficult to directly from the base station signal to the mobile station, generally go through refraction or reflection, Therefore, the positioning accuracy will be affected, the positioning range is 100~200 meters; The second is the narrow range of use. Although LBS will not be affected by weather, viaducts or tall buildings, if it is beyond the service range of the mobile phone, or the number of base stations where the mobile phone is located is insufficient, LBS positioning cannot be carried out. From this point, it is not suitable for field use.
3. WIFI positioning Wifi location, as the name implies, there must be wifi around it. The purpose of WiFi positioning is to solve the indoor accurate positioning, the principle is similar to base station positioning. The conditions for WiFi positioning are: 1. wifi must be enabled, whether connected to a hotspot or not. 2. You must have access to the Internet, either mobile data or wifi. Principle: Each wireless AP has a unique MAC address in the world. WiFi positioning relies on detecting the MAC addresses of all nearby WiFi Access points, comparing the coordinates of the MAC addresses in the database, and cross-calculating the location. GPS jammers are devices that block GPS signals. They can be divided into two types: simple and large. The simple type can effectively cover GPS satellite tracking, while the large type can even cover mobile phone and WIFI signals, so the simple type is usually selected in use. If you suspect that your vehicle has been fitted with a tracker, don‘t worry too much, let the professional personnel to solve the problem for you.
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