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Ultra Wide Band (UWB) technology
UWB because its channel bandwidth is generally more than 500MHz, when the data is sent and received, it can obtain higher time
accuracy, so it can be located by ToF or TDoA, but this mode requires the target to be located also has UWB functions, so this is a
cooperative positioning mode.
Of course, since UWB has a bandwidth of 500MHz, it can also work in radar mode, sending through one antenna while receiving
by another or more antennas to achieve radar functions and achieve motion detection and other functions. When working in this
mode, non-cooperative targets can be located.
At the same time, UWB can carry out effective data transmission, the current UWB typical transmission rate is 110Kbps, 850Kbps,
6.8Mbps, 27Mbps, 54Mbps, the most commonly used is 6.8Mbps, with the development of technology, you can use 27Mbps and
other rates.
At present, UWB is most commonly used for wireless positioning and data transmission based on time measurement, which realizes
the function of solving a small amount of data transmission while positioning.
Millimeter wave radar
Millimeter wave refers to its wavelength is millimeter level, generally refers to the wireless operating in the frequency band of about
100GHz, for example, now the typical 60GHz, 77GHz, 120GHz, 240GHz, can be called millimeter wave, millimeter wave positioning,
is the device emits millimeter wave, through the reflection of the target echo analysis, to judge the size of the target, the position of
the target. Speed, in a way, millimeter wave is somewhat similar to a very low pixel camera, see only about, see not clearly.
A few typical applications of millimeter wave are:
1) Short-distance accurate ranging, such as a few centimeters away, can reach the measurement accuracy of um level, can also be
used to measure the depth of liquid and solid 10+ meters, such as the height of the liquid level of the container, the height of the
grain bin;
2) millimeter-wave radar for cars, this kind of radar is mainly to solve the problem of target detection, understand the distance, speed,
size, etc., of multiple targets in front of the car to provide protection for the safety of the car;
3) Perimeter protection, used for perimeter intrusion detection, for example, theft behavior, the most typical is used with the camera,
as the perimeter management of the camera equipped with millimeter wave radar, you can alarm on the server to remind the manager,
it is longer than the camera work distance, less sensitive to night and bad antenna cameras, has better reliability;
4) Other applications, when the wavelength is short enough, can penetrate the fabric to see if there is a gun hidden under the clothing;
So, this function is also used for airport security; The accurate ranging of the target radar can reach the mm level. Material analysis
can be achieved, for example, the water content of wood; Medical applications can be realized, such as the irradiation of fractures,
which can be used in place of X-ray machines, and the energy level of mw can be satisfied.
The front end of a MMwave radar system is a perception unit, and a specialized business processing unit is required at the back end for
analysis and decision making. Millimeter wave radar is not effective at identifying who the target is.
Millimeter wave here is only limited to say that it is the function of radar, of course, it can also be used to transmit data, because the
bandwidth of millimeter wave is very wide, each channel can reach 4GHz or higher, so combined with multiple antennas, OFDM
modulation mode, data transmission can also reach tens of Gbps rate, to download a large number of data in a short time. This is a
good passage.
Video technology
Video technology is one of the most widely used technologies in recent years, in the city, basically can be said to be everywhere. In the
early days, there were TV walls that required managers to keep an eye on multiple cameras. But with the development of AI technology,
this work is gradually handed over to machines.
The biggest advantage of video technology is clear, can clearly see all the operators' every move, but the biggest problem is also clear,
there is a violation of privacy suspicion;
The three core units of the video system are camera front end +NVR data storage +AI processing. Therefore, only the camera can not,
need a special AI processing unit.
The video system can identify who the target is under limited conditions, but this depends on the camera is directly towards the target,
the distance from the target, the illumination, etc., otherwise it is difficult to achieve.
Comparison of three techniques
Compare project UWB millimeter wave radar vision
Wireless technology yes yes no
(Non) Cooperation goal Cooperation goal, with Tag non-cooperation goal, without Tag non-cooperation goal, without Tag
Data transfer Supported No Supported No
Working distance typical 0~50 m Typical 0~50 m Typical 0.5~10 m
We can identify stationary targets. We can't
Target occlusion Partial occlusion is OK partial occlusion is not OK partial occlusion is not OK
Vital signs detection terminal tags are configured with sensors
Heart rate/oxygen target is close, relatively static
Respiratory rate/heart rate is not working
The maximum non-conformity of target-free static and partial occlusion can not effectively detect the target privacy problem
Improvement of light environment
Back-end data processing complexity
