CN-121978681-A - Millimeter wave living body detection radar system

CN121978681ACN 121978681 ACN121978681 ACN 121978681ACN-121978681-A

Abstract

The invention provides a millimeter wave living body detection radar system which comprises a millimeter wave receiving and transmitting antenna array, a receiving and transmitting front end, a frequency synthesis module, a radar control processing module and a display control computer. Aiming at the insect detection requirement carried in luggage, the invention adopts a technology of combining millimeter wave radar imaging and Doppler detection to realize the detection of insects, adopts Ka working frequency band, has the capability of penetrating materials such as foam, cartons, clothes and the like, realizes the detection of insects by acquiring micro Doppler information of targets and adopting a technology of combining millimeter wave radar imaging and Doppler detection, has the capability of two-dimensional radar imaging and the capability of storing original data, and uses a multiple-input multiple-output (MIMO) sparse array, wherein the number of antenna units used by the MIMO sparse array is far smaller than the number of image pixels compared with a real array, thereby reducing the cost and difficulty. The azimuth optimal resolution of the invention is less than or equal to 6mm, and the distance resolution is less than or equal to 30mm.

Inventors

ZHAO XU
SUN ZHAOYANG
QU XUANYU
ZHOU LIPING
LIU QIANG

Assignees

航天长征火箭技术有限公司

Dates

Publication Date: 20260505
Application Date: 20251215

Claims (10)

1. The millimeter wave living body detection radar system is characterized by comprising a millimeter wave receiving and transmitting antenna array (1), a receiving and transmitting front end (2), a frequency synthesis module (3), a radar control processing module (4) and a display control computer (5) which are electrically connected in sequence; The antenna array (1) comprises at least two millimeter wave radar antenna subarrays, each millimeter wave radar antenna subarray comprises at least two transmitting antenna units (11) and at least two receiving antenna units (12), the transmitting antenna units (11) transmit Ka frequency band signals, and the receiving antenna units (12) receive echo Ka frequency band signals after target reflection; The receiving and transmitting front end (2) comprises Ka frequency band receiving and transmitting modules, the number of which is the same as that of the millimeter wave radar antenna subarrays, each Ka frequency band receiving and transmitting module comprises a transmitting unit and a receiving unit, the transmitting unit multiplies the signals output by the frequency synthesizing module (3) to obtain Ka frequency band signals and then outputs the Ka frequency band signals to the transmitting antenna unit (11) in a branching mode, and the receiving units combine echo signals output by the receiving antenna unit (12) and then mix the echo signals with local oscillation signals to obtain intermediate frequency signals and output the intermediate frequency signals to the radar control processing module (4); The frequency synthesis module (3) comprises a C-band sweep frequency module (31) and a Ku frequency band up-conversion module (32) which are connected, the C-band sweep frequency module (31) generates a C-band Chirp signal, the Ku frequency band up-conversion module (32) multiplies the frequency of the C-band Chirp signal by 2 and then changes the frequency of the C-band Chirp signal into a 10.4 GHz-14 GHz signal, the frequency is outputted in a splitting way, one path of the signal is outputted to a local oscillator distribution network, the other path of signal is outputted to the transmitting antenna unit (11), and the frequency synthesis module (3) also carries out clock distribution; The radar control processing module (4) comprises a signal acquisition processing module (41) for performing distance pulse compression, BP core calculation, doppler information calculation and high-speed transmission and a control module (42) for performing receiving control, transmitting control, AD acquisition synchronization and data processing synchronization; The distance resolution of the millimeter wave living body detection radar system is less than or equal to 30mm, and a living body with the size smaller than or equal to 30mm is detected by acquiring BP imaging or Doppler information of a target.
2. A millimeter wave living body detection radar system according to claim 1, wherein each of said transmitting antenna units (11) corresponds to 1 transmitting channel, each of said receiving antenna units (12) corresponds to 1 receiving channel, each of said transmitting antenna units (11) and each of said receiving antenna units (12) are arranged in a mouth shape; The antenna array (1) is a MIMO sparse array, the antenna array (1) comprises 6 millimeter wave radar antenna subarrays, and each millimeter wave radar antenna subarray comprises 16 transmitting antenna units (11) and 16 receiving antenna units (12).
3. The millimeter wave living body detection radar system according to claim 1, wherein the maximum power of the receiving unit is: ; Wherein, G t is the unit gain of a transmitting antenna, G r is the unit gain of a receiving antenna, P t is the transmitting power, lambda is the working wavelength, sigma is the radar scattering cross section of a metal disc of the security check instrument, and R is the optical path difference of electromagnetic waves irradiated from the transmitting antenna to a target.
4. The millimeter wave living body detection radar system according to claim 1, wherein the C-band sweep frequency module (31) comprises an FPGA (field programmable gate array) connected with the signal acquisition processing module (41), a digital-to-analog converter, a VCO (voltage-to-analog converter) and a digital-to-analog converter, a band-pass filter and a frequency divider which are sequentially connected with one output end of the FPGA, wherein the digital-to-analog converter, the band-pass filter and the frequency divider are sequentially connected with the other output end of the FPGA, and the input end of the frequency divider is connected with the output end of the VCO and then connected with the Ku frequency band up-conversion module (32); the range resolution is: ; Wherein c is the speed of light, B is the system bandwidth, and κ is the main lobe broadening coefficient caused by the distance pulse compression time window function; regulating main lobe widening coefficient kappa by reducing side lobes below-40 dB and adding Taylor window function during pulse compression; obtaining the sweep frequency bandwidth of the VCO according to the system bandwidth B and the frequency multiplication times; pulse repetition period of C-band Chirp signal Wherein, T scan is the acquisition time of single-frame imaging data, and N TR is the total number of equivalent receiving and transmitting antenna units; The generation of the C-band Chirp signal is used for realizing a single-path linear frequency modulation continuous wave signal with the bandwidth of 1.8GHz, the output power of more than or equal to 0dBm, the frequency sweep period of 6 mu s-16 mu s and the spurious emission of-50 dBc.
5. The millimeter wave living body detection radar system as set forth in claim 1, wherein the BP kernel calculation method comprises the steps of: s1, for each received signal Pulse compression is carried out to obtain Wherein k is the wave number, For the coordinates of the transmit channel m, For receiving the coordinates of channel n, Z is the Z coordinate of the projection position; S2, pair Performing BP focusing imaging to obtain : ; Wherein, the For the distance of the emission channel to the projection position, For the distance of the receive channel to the projection position, j is the imaginary part.
6. The millimeter wave living body detection radar system as recited in claim 5, wherein in step S1, Wherein delta i is located at The scattering coefficient of the target unit is determined, Is the optical path difference of electromagnetic waves irradiated from the transmitting antenna unit to the target.
7. The millimeter wave living body detection radar system as set forth in claim 6, wherein in step S1, pulse compression of the ideal signal is: ; Wherein IFT is Fourier transform, and k is wave number; On the basis of ideal pulse compression, the dispersion of the channel is also compensated by mixing with the reference channel, and the delay is compensated by multiplying the linear phase.
8. The millimeter wave living body detection radar system as set forth in claim 1, wherein the Doppler information analysis method by the signal acquisition processing module (41) comprises the following steps: SI, processing the received mixed signal by using a set of matched filters on the receiving antenna of each millimeter wave receiving antenna array (1) Each filter matches a particular transmit waveform , Is the first Orthogonal signals transmitted by the transmitting channels from each physical receiving channel according to the energy magnitude Is separated from Signals from different transmission channels ; SII, will all Indexing according to virtual array elements Arranged to form a length of Data vector of (2) The data vector A received signal that is a virtual array; SIII, collecting continuous pulse or time domain snapshot of specified time to obtain a pulse with length of Is a slow time sequence of (2) , For the number of coherent processing intervals, Time for the L th coherent treatment; SIV, vs. slow time series And (3) FFT (fast Fourier transform) is carried out to obtain: ; The method for detecting the living body with the size smaller than or equal to 30mm by Doppler information is that when the target with the speed v exists, the target is detected in all M multiplied by N virtual channels In all at the same Doppler frequency Peak occurs at which lambda is the operating wavelength.
9. The millimeter wave living body detection radar system as set forth in claim 8, wherein in step SI, in the first step On the receiving channels, the echo signals from the target are subjected to down-conversion to baseband, and then are: ; Wherein alpha is complex amplitude and comprises a target scattering coefficient and path loss; delay is passed for transmitting waveform A subsequent waveform; is Doppler frequency shift term, wherein ; Is the transmit spatial phase from the mth transmit antenna to the target; For the received spatial phase from the target to the nth receive antenna: ; wherein, the Convolution, because of waveform orthogonality, the output energy is maximum when the filter matches its own waveform, and zero when it matches other waveforms.
10. The millimeter wave living body detection radar system of claim 1, wherein the display control computer (5) is connected with the radar control processing module (4) through an optical fiber interface, and carries out living body detection by issuing a detection instruction and receiving returned living body detection information.

Description

Millimeter wave living body detection radar system Technical Field The invention relates to the technical field of measurement and test, in particular to a millimeter wave living body detection radar system. Background Customs will measure insects in import and export quarantine, mainly to identify species, assess risk, and prevent invasion of foreign pests. But now lack effective detection means. Millimeter wave radar is a radar that operates in the millimeter wave band (MILLIMETER WAVE) for detection. Millimeter wave generally means that the wavelength of the frequency domain (the wavelength is 1-10 mm) of 30-300 GHz is between microwave and centimeter wave, and millimeter wave radar has the advantages of microwave radar and photoelectric radar. Therefore, a system for detecting insects using millimeter wave radar is needed. Disclosure of Invention The invention provides a millimeter wave living body detection radar system for solving the problem of insect detection, which comprises a millimeter wave receiving and transmitting antenna array, a receiving and transmitting front end, a frequency synthesis module, a radar control processing module and a display control computer. Aiming at the insect detection requirement carried in luggage, the invention adopts a technology of combining millimeter wave radar imaging and Doppler detection to realize the detection of insects, adopts Ka working frequency band, has the capability of penetrating materials such as foam, cartons, clothes and the like, realizes the detection of insects by acquiring micro Doppler information of targets and adopting a technology of combining millimeter wave radar imaging and Doppler detection, has the capability of two-dimensional radar imaging and the capability of storing original data, and uses a multiple-input multiple-output (MIMO) sparse array, wherein the number of antenna units used by the MIMO sparse array is far smaller than the number of image pixels compared with a real array, thereby reducing the cost and difficulty. The azimuth optimal resolution of the invention is less than or equal to 6mm, and the distance resolution is less than or equal to 30mm. The invention provides a millimeter wave living body detection radar system, which comprises a millimeter wave receiving and transmitting antenna array, a receiving and transmitting front end, a frequency synthesis module, a radar control processing module and a display control computer which are electrically connected in sequence; The antenna array comprises at least two millimeter wave radar antenna subarrays, wherein each millimeter wave radar antenna subarray comprises at least two transmitting antenna units and at least two receiving antenna units, the transmitting antenna units transmit Ka frequency band signals, and the receiving antenna units receive echo Ka frequency band signals reflected by a target; the receiving and transmitting front end comprises Ka frequency band receiving and transmitting modules the same as the millimeter wave radar antenna subarrays in number, each Ka frequency band receiving and transmitting module comprises a transmitting unit and a receiving unit, the transmitting unit multiplies the signals output by the frequency synthesizing module to obtain Ka frequency band signals and then shunts the Ka frequency band signals to the transmitting antenna unit, and the receiving unit combines echo signals output by the receiving antenna unit and then mixes the echo signals with local oscillation signals to obtain intermediate frequency signals and outputs the intermediate frequency signals to the radar control processing module; The frequency synthesis module comprises a C-band sweep module and a Ku frequency band up-conversion module which are connected, wherein the C-band sweep module generates a C-band Chirp signal, the Ku frequency band up-conversion module converts the C-band Chirp signal into a 10.4 GHz-14 GHz signal after frequency multiplication by 2, the C-band Chirp signal is output in a two-way mode, one way is output to a local oscillator distribution network, the other way is output to a transmitting antenna unit, and the frequency synthesis module also carries out clock distribution; The radar control processing module comprises a signal acquisition processing module for performing distance pulse compression, BP core calculation, doppler information calculation and high-speed transmission, and a control module for performing receiving control, transmitting control, AD acquisition synchronization and data processing synchronization; The distance resolution of the millimeter wave living body detection radar system is less than or equal to 30mm, and a living body with the size smaller than or equal to 30mm is detected by acquiring BP imaging or Doppler information of a target. According to the millimeter wave living body detection radar system, as an optimal mode, each transmitting antenna unit corresponds to 1 transmitting channel, each r