Ultra wideband (UWB), a technology proposed in the 1960s, has been favored again in recent years. Originally, UWB was pushed out in the direction of communication application technology, but now it is grandly pushed out with high-precision positioning technology, especially indoor positioning, that is, non exposed space positioning technology. It integrates positioning and communication functions, which is particularly fashionable, gratifying and attractive. Especially in September 2019, Apple's iPhone 11 press conference announced that it was equipped with U1 chip, and UWB quietly entered the consumer market. What is quiet? Because Apple did not make any introduction to the mysterious chip at the press conference. However, this may be an epoch-making event for indoor positioning. It is estimated that UWB will play a great role in the next five to ten years.

How does UWB positioning work? Here might as well make a brief introduction. UWB (ultra wide band) is ultra wideband technology. It is a carrier free communication technology. It uses nanosecond non sinusoidal narrow pulses to transmit data, so it occupies a wide spectrum range. UWB positioning adopts broadband pulse communication technology, which has strong anti-interference ability to reduce the positioning error. The emergence of UWB indoor positioning technology fills the gap in the field of high-precision positioning. It has the advantages of insensitive to channel fading, low power spectral density of transmitted signal, low interception ability, low system complexity, and can provide positioning accuracy of 0.1M level.

Different from traditional wireless communication, UWB does not use carrier, but transmits data by transmitting and receiving low-energy pulse signals. The ranging method is realized by measuring the transmission time of the signal, that is, the distance is determined by calculating the transmission time difference between the two devices. Therefore, in a small area, UWB can provide more accurate positioning results than Wi Fi and Bluetooth. Apple also called it "GPS system used in the living room" on the English product introduction page.

UWB indoor positioning system usually consists of three parts: one is UWB positioning label. The positioning label is an active label, which can be made into different forms, fixed on objects, vehicles or worn on personnel, and has variability in different application environments. Its positioning accuracy can reach up to 5-10cm. The UWB pulse signal sent by the tag is received and transmitted through the positioning base station (positioning sensor). Each tag has a unique ID number, which can be used to connect the positioning objects, so that the positioning base station (positioning sensor) can find the actual positioning position through the tag. The duration of tag transmission signal is very short, which can allow hundreds of tags to be located at the same time; Second, UWB positioning base station. The positioning base station (positioning sensor) can determine the position of the label through the time difference of arrival (TDOA) measurement technology, and transmit the data to the network controller and positioning engine software, with the positioning measurement accuracy of centimeter level; Third, application software. Application software is mainly embodied in system functions. The basic functions of UWB indoor positioning system can include: personnel distribution, displaying the distribution of personnel wearing positioning labels; Personnel movement track, displaying one or more personnel movement tracks in real time through electronic map; Track the designated person, and the map will automatically switch with the movement of the label. Move the mouse over the label to see the current status of the label; The electronic fence displays the alarm position status of personnel through different colors and shapes on the plane electronic map.

UWB indoor positioning process: first, each positioning tag repeatedly sends data frames with UWB pulses; Second, the UWB pulse train sent by the positioning tag is received by the positioning base station; Third, each positioning base station uses a high-sensitivity short pulse detector to measure the time when the data frame of each positioning tag reaches the receiver antenna; Fourth, the positioning engine refers to the calibration data sent by the tag, determines the time difference between the tag reaching different positioning base stations, and uses three-point positioning technology and optimization algorithm to calculate the tag position; Fifth, AOA (angle of arrival) algorithm is generally used for single base station positioning, and TDOA (time difference of arrival) algorithm is mostly used for multi base station positioning.

UWB indoor positioning is mainly applicable to: first, tunnel / pipe gallery / subway. Carry out real-time automatic tracking of construction personnel, and master the position and activity track of each employee in the tunnel and the position distribution of personnel in the whole tunnel at any time. When encountering an emergency, we can quickly find the reliable location information of the trapped people, so as to improve the efficiency of rescue and relief and safety rescue; Second, vehicle storage. Track assets and inventory in real time, improve process, improve search efficiency and reduce resource waste; Third, petrochemical industry. Zero time delay can accurately locate the real-time position of people, vehicles and objects, intuitively and timely reflect the on-site situation and personnel status of the chemical industry, and improve the strength and efficiency of safety guarantee in the petrochemical industry; Fourth, hospitals / nursing homes. 24-hour intelligent management and control, all-weather security guard, real-time analysis of the behavior of caregivers, visitors, patients / the elderly, and improve the fine management efficiency of hospitals / nursing homes; Fifth, prison / public security / justice. UWB indoor positioning system can carry out personnel access management, real-time position query, restricted area supervision, isolation distance control and personnel scheduling, and can monitor and count personnel position, travel route, distance and speed. In fact, UWB precision positioning applications and services are far more than the above aspects. Due to its precise positioning and tracking of all personnel, animals, assets, objects and event processes, it has broad development prospects in the industrial Internet, mass consumer goods and data networking. UWB can essentially become a space-time sensor and an indispensable partner of the Internet of things and big data. It has the aura of a rising star in multiple fields of high-precision indoor positioning, indoor and outdoor integrated positioning and navigation and communication integration innovation.