Human breathing Human breathing 24ghz millimeter wave radar Human body sensor module personnel detection new way, launched the indoor personnel detection solution based on human breathing 24GHz millimeter wave radar module for accurate positioning and stable tracking of indoor personnel. At the same time, combined with the scheme of vital signs detection function, we can judge whether indoor personnel are in the state of vital signs. On this basis, the new scheme based on millimeter-wave radar takes the lead in realizing 3D target tracking, room area measurement and other functions, providing a new direction and choice for the smart home, consumer electronics, elderly care and other markets.

3D object tracking

The human respiratory 24ghz millimeter wave radar human sensor module has a high range resolution, and can simultaneously measure the direction Angle and pitch Angle of the target, so as to obtain abundant point cloud information of the measured target. By using the obtained point cloud information, the distribution state of the target in the three-dimensional space (horizontal, vertical, height) can be obtained, and the posture of the target (such as standing, sitting, lying, falling) can be judged according to the mutual relationship of the target in the three-dimensional distribution, as well as the relationship between the target's height and time, so as to distinguish the needs of adults, children, people and pets.

Human breathing 24ghz millimeter wave radar human sensor module 3D target tracking function combined with vital signs detection function, can make people's life more intelligent and safe. For example, by judging the posture and position of the human body, adjust the air volume and direction of the air conditioner; Detection of falls, breathing abnormalities, timely notification; Monitoring breathing rate can determine whether the state of sleep, so as to adjust the intensity of light; A timely warning when children and pets are left in the car or at home... Millimeter wave radar point cloud imaging can avoid privacy disclosure, more suitable for family, pension and other private space.

Measuring house area

According to the human breathing 24ghz millimeter wave radar human body sensor module has the characteristics of high range resolution. A practical room area measurement method is proposed by combining the estimation algorithm of the Angle of reach, the detection of constant false alarm rate and the corresponding boundary search method.

Through the accurate judgment of the housing area, it can provide an important basis for the rational use of smart home. For example, by measuring the room area, the air conditioner can better control the cooling capacity and improve the operation efficiency; TV, stereo and other household appliances can adjust the volume according to the house area and personnel...

Let millimeter wave work for you

Through continuous exploration of the application of human breathing 24ghz millimeter wave radar human body sensor module, it has realized the functions of personnel stability tracking, vital signs monitoring, adult, child and pet identification, human posture recognition, house area measurement and so on, providing a guarantee for intelligent life and safe life. Millimeter wave radar will become an indispensable helper in your life.

How to avoid interference between radars? Advanced driving assistance systems (ADAS) AdvancedDriverAssistanceSystems, as in recent years, with the rapid development of millimeter wave radar in car assembly rate is increasing day by day. Imagine that after street vehicles are equipped with millimeter wave radars, interference between radars will become an increasingly significant problem.

The radar SoC provides an effective solution to the problem of DRE interference. Before going any further, let's look at common signal jamming between radars: a typical example of FMCW radar signal jamming. If the radar receives chirp signals from other surrounding radars during operation, the interference signal frequency is similar to the current radar operating frequency, and the interference source enters the effective intermediate band bandwidth (IFbandwidth) of the radar. Display the situation after the interference signal enters the effective IF bandwidth of the radar. It can be seen that the interference signal has a great impact on the effective signal waveform, which can easily lead to the failure to detect useful target signals or generate false target points.

In order to solve the interference problems mentioned above, the baseband accelerator of human respiratory 24ghz millimeter wave radar has integrated several anti-interference functions, including frequencyhopping mode, chirpshifting mode, phasescrambling mode and interferencemental navigation function.

Frequencyhopping mode

This mode randomly changes the initial chirp emission frequencies of different frames by means of a random number generator - XOR chain.

When the XOR chain state is 0, do not change chirp. When the XOR chain state is 1, the chirp initial frequency changes.

When there are interference signals in the environment with the same sweep band width, the IF signal generated by mixing the random chirp starting frequency with the interference signal will be in the Alps except for the analog bandwidth.

The IF signal will be filtered by a filter, so the entire IF signal will be filtered by the filter and the energy of the interference signal received by the frame will be reduced by about half (assuming the same number of Chirps at the changing frequency and the same number of Chirps at the constant frequency).

For the interference signal entering the band, because its chirp frequency is random in the incoming band, its energy will be distributed to the whole 2D-FFT in the spectrum, so it will not gather and cause false target interference.

The Chirpshifting pattern

Similar to the mode of frequencyhopping, random number generators-XOR chains are used to randomly change different chirp start time points in the frame.

When the XOR chain state is 1, the chirp start time point is changed; when the state is 0, the chirp start time point is not changed.

When there are interference sources of similar radar frequency in the environment, the random change chirp at the initial time point, mixing with the interference signal to generate the IF signal will also be in addition to the analog bandwidth, thus achieving the effect of harmonious frequencyhopping similar mode.

Phasescrambling mode

In this mode, the random number generator randomly changes the starting phase of different CHIRps in the frame. When the interference signal appears, due to phase random modulation, its energy will be distributed throughout the 2D-FFT in the spectrum, so it will not gather and produce false target interference.

In the above three modes, different chirp states are required for phase compensation, so as to reduce the phase error caused by chirp modulation. If the compensation is not proper, it is easy to cause 2D-FFT false targets along the velocity dimension to appear in the spectrum. The exclusive Baseband accelerator automatically compensates for the first two anti-jamming modes, while the accelerator automatically compensates for the first two anti-jamming modes phasescrambling In mode allows users to more accurately compensate for the 180 degree phase during the radar calibration phase to get the best results in the three modes, That is, speed dimension spur is not generated (Currently SDK calibration instructions have been integrated, and it is very easy for users to call in the calibration link).

Interferencemitic navigation mode

In addition to the first three anti-jamming methods, baseband accelerator also integrates an interference removal algorithm. When the time domain signal waveform is collected by the radar, the amplitude change rate of the signal is determined. If sampling points with an abnormal rate of amplitude change are found in the signal, these signals are recognized as interference. In this case, these signals will be deleted to reduce the noise floor of the 2D-FFT.

To sum up, for the mutual interference of multiple radars in human respiratory 24ghz MMW radar human sensor module, it provides a variety of means for users to select and use, and has a positive effect on the suppression and removal of interference.