I know that there is a question asking "What other sensor positioning technologies are there besides GPS and base station positioning?", just doing some research and research in this area recently, so I sorted out the information I learned and answered it. After that, I know that there are other pages that have corrected and supplemented my answer. Here I will sort it out and send it back to backup.
Affirmation: The following contents are grateful to Xu Zhe, Yan Hu, Maggie, Mu Rong, and Zhutou Xinyu for their knowledge.
Currently commonly used positioning methods include: GPS positioning, base station positioning, wifi positioning, IP positioning, RFID/QR code identification and positioning, Bluetooth positioning, sound wave localization, scene recognition and positioning. Technically one or more of the following combinations can be employed.
About GPS and A-GPS positioning :
The principle of common GPS positioning can be easily understood as follows: It consists of 24 working satellites, allowing more than 4 satellites to be observed anywhere in the world and at any time, measuring the satellite between the known location and the receiver. Distance, and then combine the data of multiple satellites to know the specific location of the receiver. Finding satellites across the sky is inefficient, so when you are positioning via GPS, the first start can take several minutes. This is also why we often use a large circle before we use the map, and then we will be precise to a certain point. However, if we know our rough position before we can locate it, the speed of finding the satellite can be greatly shortened.
There are two kinds of pseudo-codes used in the GPS system, namely the civil C/A code and the military P (Y) code. The civil precision is about 10 meters and the military precision is about 1 meter. The advantage of GPS is that it has no radiation, but its penetration is very weak and it cannot penetrate reinforced concrete. It is usually only necessary to look at the sky outside. When the signal is blocked or cut, the GPS positioning will drift and it will not be used indoors or in a relatively closed space.
Because of this shortcoming of GPS, it is often necessary to assist the positioning system to help complete the positioning, which is what we call A-GPS.
For example, the iPhone uses A-GPS, that is, after the base station or WiFi AP is initially positioned, it quickly finds stars according to the GPS satellite table stored in the machine, and then performs GPS positioning. For example, in the field of civil vehicle navigation equipment, the more mature GPS + acceleration sensor correction algorithm is currently positioned. The car navigation market in Japan was first introduced in volume production by Sony's portable car navigation system Nav-U1. For example, in the iphone4 with the addition of the three-axis gyroscope, a three-axis gyroscope can be used to assist in the positioning. For details, please refer to the introduction of this article, but the error of the positioning of the three-axis gyroscope will gradually accumulate over time.
About base station positioning (cell ID positioning) :
The cell identification code ?-ell ID determines the user location by identifying which cell in the network transmits the user call and translates the information into latitude and longitude. Cell ID implements the basic principle of positioning: that is, the cell number in which the wireless network reports the terminal (estimated according to the base station of the service), and the location service platform translates the cell number into latitude and longitude coordinates.
Basic positioning process: The device first obtains the current location from the base station?-ell ID). (First Positioning) - 》 The device transmits the location to the agps location server via the network - 》 The Agps server queries the currently available satellite information in the area based on the location and returns the device. —— †The GPS receiver in the device quickly finds available GPS satellites based on available satellites and returns GPS positioning information.
About Wifi AP Location :
The device only needs to listen to the hot spots in the vicinity, detect the signal strength of each hotspot, and then send the information to the server on the network. Based on this information, the server queries the coordinates recorded by each hotspot in the database, and then performs operations to know the specific location of the client. A successful positioning requires two prerequisites: the client can access the Internet, and the coordinates of the detected hotspots are in the database.
PS: Apple's WIFI location service http://; this website can obtain location information via MAC address http://samy.pl/mapxss/
About RFID, QR code positioning :
By setting a certain number of card readers and erecting antennas, the signals are positioned according to the strength, arrival time, and angle of the signals received by the card reader. At present, it is impossible to accurately locate, and it is difficult to install a card reader and an antenna with a large amount of engineering practice experience. In addition, WIFI is economical and practical in terms of cost.
In addition, indoor positioning can not rely on GPS satellites, mainly relying on indoor equipment. It can be implemented using WLAN and RFID.
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