The millimeter wave radar sensor that keeps “out of the circle” has a promising market prospect

How to monitor basic vital signs such as heartbeat and breathing? For this demand, I believe that the first response of most people is the hospital’s electrocardiograph and other professional medical monitoring equipment. In recent years, with the rise of wearable devices, many smart watches and bracelets can also obtain the user’s pulse, blood oxygen and other physical parameters in real time through the photoelectric method, which has brought great convenience to people.

Author: Avnet

How to monitor basic vital signs such as heartbeat and breathing? For this demand, I believe that the first response of most people is the hospital’s electrocardiograph and other professional medical monitoring equipment. In recent years, with the rise of wearable devices, many smart watches and bracelets can also obtain the user’s pulse, blood oxygen and other physical parameters in real time through the photoelectric method, which has brought great convenience to people.

But these methods above have one thing in common. They are all “contact” measurement schemes, which is to connect the sensor directly to the body of the measured object. If I want to find a “non-contact” measurement method, is it feasible to complete the real-time monitoring of heartbeat and respiration in an empty space? Such a measurement scheme already exists! It uses millimeter wave radar technology.

“Latecomer” with good performance

As we all know, the earliest application of radar is in the military. The principle is to generate and send a signal with a frequency that gradually increases with time through the transmitter. When this signal encounters an object, it will be reflected back. The delay is 2 of the distance/speed of light value. Times, and there is a frequency difference between the returned waveform and the transmitted waveform. This frequency difference has a linear relationship with the time delay. By subtracting these two frequencies, you can get the difference between the two frequencies (beat frequency). ), from which the distance between the object and the radar can be calculated. On this basis, not only can it know whether the measured target exists, but also accurate information such as the target’s position, direction, distance, and speed can be calculated.

Later, the application of radar gradually expanded to some other special fields, and finally entered the civilian market with millimeter wave radar. Automobiles have become an important entry point for millimeter-wave radar in the civilian field. In recent years, with the rise of autonomous driving, the development momentum has been strong. At present, millimeter-wave radar has basically become a standard configuration in automatic driving systems above L2.5.

Millimeter wave radar is essentially to sense the position and movement of objects. In the wider civil field, there are already mature applications of mature sensing technologies (such as PIR and ultrasonic) before the arrival of radar. In this new field, millimeter-wave radar must face the challenges of these technologies directly.

Table 1: Comparison of millimeter wave radar and other sensor technologies

 

Millimeter wave radar

Infrared sensor

camera

Ultrasonic radar

Induction mechanism

Electromagnetic wave

infrared

Visible light

Ultrasound

Temperature effect

no effect

Affected above 40℃

no effect

no effect

Penetration ability

Can penetrate non-metallic objects

No penetration

No penetration

No penetration

Application Environment

Any environment

Not suitable for smoke, dust, high temperature environment

Need better light conditions

Any environment

life

long life

≈1000h

long life

long life

stability

Stable and reliable

The sensing distance decreases with the use time

Greatly affected by the environment

relatively stable

Detection distance

100 metres

8 meters

Depends on the optical lens

5 meters

cost

Moderate

Lower

Higher

Lower

Technical bottleneck

scanning frequency

Static human detection is inaccurate

privacy protection

The distance is short, the accuracy is not high

However, in terms of technical characteristics, millimeter-wave radars are still very confident in their own in the civilian market. Specifically, millimeter-wave radar is not easily affected by the environment (temperature, light, etc.), and can penetrate non-metallic materials such as plastics, wall panels and clothes, which determines that it can occupy the C position in some specific application scenarios; On the other hand, compared with other sensors, millimeter-wave radar can not only detect the presence of an object, but also determine the direction, speed, and distance of the moving object, and even determine the exact position of the moving object according to the antenna configuration. These high-precision Data and abundant information will undoubtedly win new development space for millimeter-wave radar in the industrial and consumer markets, especially in fields related to the Internet of Things.

Millimeter wave radar “three brothers”

According to the working frequency band, millimeter wave radars for the civilian market can be divided into three categories:

24GHz millimeter wave radar. This is also the first millimeter wave radar put into civilian use, with a wavelength of 1.25cm (barely millimeter wave). Because the frequency of the frequency band is relatively low and the bandwidth is relatively narrow (only 250MHz), the 24GHz millimeter-wave radar is limited in measurement accuracy, which also limits the expansion of its application range to a certain extent. However, due to its mature technology and low cost, there is still plenty of room for development.

77GHz millimeter wave radar. The millimeter wave radar in this frequency band has a wavelength of only 3.9mm, a relatively high frequency, and a bandwidth of up to 4GHz. Generally speaking, the shorter the wavelength of the radar, the higher the resolution/accuracy (of course the cost will be higher), and the overall system will be smaller. Therefore, the 77GHz millimeter-wave radar will gradually take over 24GHz products and become the automotive industry. Mainstream, and many countries and regions also allocate this frequency band as a dedicated frequency band for automobiles.

With the maturity of 77GHz millimeter-wave radar technology, the cost-effective advantage of the 24GHz solution in vehicle applications is not so significant. Therefore, in recent years, the 24GHz millimeter-wave radar has gradually shifted the focus of subsequent development to the industrial and consumer markets.

60GHz millimeter wave radar. The radar wavelength of this frequency band is 5mm and has a license-free bandwidth of up to 7GHz that can be used for short-range applications, so it can provide better resolution. Its appearance is mainly to deal with the problem of limited bandwidth, insufficient accuracy, and limitation of the sensing of objects used by the 24GHz radar. Because of this, the competition of various major technology manufacturers around the millimeter wave radar in the non-automotive field has gradually shifted from the 24GHz to the 60GHz frequency band.

Obviously, 60GHz millimeter-wave radar is better at detecting subtle movements. The 60GHz radar has a wavelength of 5mm, and a 0.5mm micro motion is equivalent to 10% of the wavelength. This “looks” on the radar is already an obvious shift.

The “new track” in the non-automotive sector

It can be said that with 24GHz radar as the front stop, 77GHz radar’s key breakthrough in the automotive field, and the reinforcement of 60GHz radar, the millimeter-wave radar “three brothers” have broken new ground in the civilian market. Especially in the non-automotive field, the performance of millimeter wave radar in the four fields is very worth looking forward to.

The first is the field of building automation and smart home. As a human body and motion sensor, millimeter wave radar can accurately perceive the number and location of people in the area, and use this as a basis to control lighting, air conditioning and other systems to achieve more efficient energy saving. There are also developers exploring the combination of millimeter-wave radar and elevator control, and accurately calculate the number of passengers waiting in the elevator room based on the algorithm-even able to accurately determine irrelevant passengers and real passengers-and then rationally dispatch and upgrade the elevator Operating efficiency.

The second is the field of health care. The heartbeat and breathing monitoring mentioned above is a typical use case. And with the acceleration of the aging process, the combination of millimeter wave radar and smart elderly care can also evolve more new use cases such as fall alarm and sleep monitoring. The future prospects of this field are also very worthy of attention. For example, Avnet has developed a breathing and heartbeat detection solution based on Infineon’s BGT60TR1X series of millimeter-wave radar chips. It can be processed on a low-cost MCU that can automatically detect and capture the subtle movements caused by breathing and heartbeat in a large range.

The millimeter wave radar sensor that keeps “out of the circle” has a promising market prospect
Figure 2: Schematic diagram of Avnet’s millimeter wave radar function

The millimeter wave radar sensor that keeps “out of the circle” has a promising market prospect
Figure 3: Measured diagram of Avnet’s millimeter-wave radar breathing and heartbeat detection program,
The upper left and upper right images show changes in chest displacement caused by breathing and heartbeat

The third is the field of security monitoring. Although the camera is currently the mainstream solution in this field, personal privacy has always been a sensitive topic accompanying visual solutions. Therefore, on certain occasions, millimeter-wave radar can be used as an alternative to replace cameras for traffic analysis and intrusion detection. In addition, the use of a “camera + millimeter-wave radar” solution that interacts with each other can also enhance the performance and reliability of the original solution, which is conducive to achieving a higher recognition rate, a lower false alarm rate, and a lower labor cost.

Finally, there is the field of human-computer interaction (HMI). With precise motion detection, millimeter-wave radar can achieve finer gesture and body recognition, providing users with a more natural HMI experience. This will bring a brand new user experience in terms of non-contact gesture control, real-time game interaction, and home appliance control on small screens or short-range screens.

In short, from military to special purpose, to automobiles, to industrial and consumer IoT applications, millimeter-wave radar continues to “out of the circle” and expands its application landscape. Data from MarketsandMarkets shows that by 2023 the total market for radar sensors will reach 20.6 billion U.S. dollars, with a compound annual growth rate of 19.5% from 2017 to 2023. Among them, vehicle-mounted radar is the biggest driving force for this wave of growth. It is foreseeable that the Internet of Things market will become another wheel driving the millimeter-wave radar market, driving it to fly forward with higher acceleration.

The Links:   MG400H1FL1 LP150X05-A2M2

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