The UWB positioning system is currently the industry’s most accurate commercial wireless positioning system, which can achieve high real-time positioning accuracy and positioning capacity and can usually obtain a two-dimensional positioning accuracy of up to 10cm~20cm in a real environment. The application of UWB has begun on a large scale worldwide.
1. How can the UWB indoor positioning system achieve such high accuracy?
UWB positioning with positioning accuracy up to centimeter-level, GPS positioning should be widely known by everyone, because we cannot do without positioning and navigation!
Different from GPS, UWB positioning is mainly used for indoor high-precision positioning to obtain the location information of people or objects within a certain space.
In recent years, indoor positioning has shown broad market prospects in retail, catering, logistics, manufacturing, chemical, power, medical and other industries.
In this context, technologies such as Bluetooth positioning, Wi-Fi positioning, UWB positioning, and RFID positioning have entered the market one after another, contributing many effective location service solutions to the indoor positioning needs of different industries.
Among them, the market attention and acceptance of UWB positioning (ultra-wideband) has increased significantly in recent years.
The application scenarios of UWB positioning are becoming wider and wider, and the demand for positioning and navigation in places such as prison detention centers, general hospitals, factories, airports, and parking lots is gradually increasing.
Ultra Wide-Band (UWB) is a new type of wireless communication technology. According to the specifications of the Federal Communications Commission, the working frequency band of UWB is 3.1~10.6GHz, and the ratio of the system -10dB bandwidth to system center frequency is greater than 20% Or the system bandwidth is at least 500MHz.
UWB signal generation can be realized by modulating the narrow pulse (such as the second Gaussian pulse) with a very short transmission time (such as 2ns) to the UWB working frequency band through up-conversion methods such as differentiation or mixing.
The main advantages of UWB positioning are low power consumption, insensitivity to channel fading (such as multipath, non-line-of-sight channels, etc.), strong anti-interference ability, no interference to other devices in the same environment, and strong penetration (It can be positioned in an environment penetrating a brick wall), with high positioning accuracy and positioning accuracy.
Why can the positioning accuracy of UWB positioning reach the centimeter level?
1.1. UWB-TDOA positioning principle
The UWB positioning system adopts TDOA (Time Difference of Arrival Principle) and uses UWB technology to measure the time difference of radio signal propagation between the positioning tag and two different positioning base stations, thereby obtaining the distance difference between the positioning tag and the four sets of positioning base stations.
The use of TDOA technology does not require reciprocating communication between the positioning tag and the positioning base station, only the positioning tag only needs to transmit or receive only UWB signals, so higher positioning dynamics and positioning capacity can be achieved.
1.2.UWB positioning index
In addition, high-precision positioning requires not only high-precision time measurement technology but also a stable and reliable reference time. Due to the uncertainty of analog circuits such as crystal oscillators and phase-locked loops, high-precision synchronization technology is required to solve the problem of UWB-TDOA positioning. Frequency synchronization and time synchronization issues.
In layman’s terms, time synchronization is similar to adjusting the time of two watches to the same time, but due to the mechanical differences between the two watches, the running speed will cause the two watches to run for a period of time. This means that solving frequency synchronization is required.
At present, synchronization technology is divided into two types: wired synchronization and wireless synchronization. Wired synchronization refers to the use of optical fibers, network cables, and other cables to directly connect positioning base stations to each other or access a synchronization controller to achieve synchronization between positioning base stations; wireless synchronization refers to positioning via radio Synchronization between base stations.
Generally, the accuracy of wired synchronization is higher than that of wireless synchronization, and the cost of wired synchronization is higher than that of wireless synchronization due to the need to lay additional cables.
The wireless synchronization technology penetrates into the nature of the factors that cause asynchrony in the radio transmission and reception link so that wireless synchronization can achieve the same positioning accuracy as wired synchronization.
Why centimeter-level high-precision positioning is more inclined to UWB?
Firstly, the positioning accuracy that can be achieved by other positioning technologies is limited. Even if the same positioning accuracy as the UWB positioning technology can be achieved, the complexity and cost of the system are too high.
Secondly, although there are many scenarios for positioning such as RFID and ibeacon, many companies are already doing it. UWB is a relatively new technology with many advantages and many potential application markets to be developed.
2. Three major uses of ultra-wideband UWB technology
Ultra-wideband UWB technology first appeared in the 1960s and was mainly used for military radars. After the FCC lifted the restrictions on UWB technology in the civilian field, UWB technology has developed rapidly.
Because UWB technology has many advantages such as good concealment, high transmission rate, large system capacity, low power consumption, and strong anti-interference ability, it is gradually applied in the fields of communication and regional positioning. Ultra-wideband UWB technology has the following three common uses.
2.1. Communication
1) UWB technology transmits large data, up to several hundred Mnit/s.
2) The transmission distance can reach hundreds of meters, but the transmission capacity will be greatly attenuated after the transmission distance is long.
3) High-security performance. For general communication systems, UWB signals are equivalent to white noise signals, which are difficult to obtain by other devices.
UWB technology application note
It can be used for video transmission of home multimedia devices; it combines the security performance of UWB with NFC to ensure that wireless payments are more secure.
2.2. Radar
1) UWB technology has high spatial resolution capabilities.
2) UWB technology has strong target recognition capabilities.
UWB application note
Ground-penetrating radar, wall penetrating radar, road detection, etc.
2.3. Regional positioning
1) UWB positioning accuracy is high, positioning accuracy can reach centimeter level.
2) In the positioning system, the UWB tag has a large capacity, which is larger than other wireless positioning technologies.
3) UWB positioning has low latency and low power consumption.
UWB indoor positioning application scenarios
Positioning management of personnel in prisons, hospitals, substations, power plants, underground mines, tunnels; positioning management of mobile items such as raw materials, production equipment, electronic fences, etc. in factories, warehouses and logistics; valuable assets such as positioning of workers and elderly in nursing homes, and dispatching of security personnel Positioning management.
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