Millimeter wave imaging real-time calibration method and device, computer device and storage medium

Abstract

The application relates to a millimeter wave imaging calibration method and device, computer equipment and a storage medium. The millimeter wave imaging calibration device comprises an antenna array and a calibration object parallel to the antenna array, an imaging channel is formed between the antenna array and the calibration object, an imaging object is arranged in the imaging channel, and the method is applied to the millimeter wave imaging calibration device. The method comprises the following steps: collecting echo data of the imaging object and the calibration object by transmitting and receiving step frequency signals through the antenna array to obtain first echo data; the second echo data is obtained by screening the first echo data according to the reference position of the calibration object relative to the antenna array, and the calibration parameter is obtained by matching filtering; and when the calibration parameter meets a preset condition, the first echo data is compensated and calibrated according to the calibration parameter. The application can obtain the calibration parameter in real time, compensate and calibrate the first echo data, and solve the problem that the consistency of the transmitting and receiving channels cannot be calibrated in real time, thereby improving the imaging quality.

Description

Technical Field

[0001] This application relates to the field of millimeter-wave imaging technology, and in particular to a millimeter-wave imaging calibration method, apparatus, computer equipment, and storage medium. Background Technology

[0002] In the field of security inspection, millimeter-wave-based human body imaging equipment can accurately image the human body. Combined with advanced artificial intelligence recognition algorithms, it can accurately identify dangerous items and their categories carried by the person. For millimeter-wave security imaging equipment, the antenna array contains numerous transceiver channels. However, imbalances in the amplitude and phase of these channels limit the image quality of the security imaging, thus affecting the accuracy of dangerous item detection. Therefore, it is necessary to calibrate the consistency of the transceiver channels.

[0003] Currently, phase compensation values ​​for each transmit / receive channel can be obtained by mutual calibration between the transmit and receive antennas, and the consistency of the transmit and receive channels can be calibrated before imaging. However, when inconsistencies between transmit and receive channels occur frequently, real-time calibration is not possible, resulting in poor image quality.

[0004] There is currently no effective solution to the problem that the inability to calibrate the consistency of the transmit and receive channels in real time in related technologies leads to poor image quality. Summary of the Invention

[0005] This embodiment provides a millimeter-wave imaging calibration method, apparatus, computer equipment, and storage medium to solve the problem in related technologies where the consistency of the transceiver channel cannot be calibrated in real time, resulting in poor imaging quality.

[0006] In a first aspect, this embodiment provides a millimeter-wave imaging calibration method applied to a millimeter-wave imaging calibration device, the millimeter-wave imaging calibration device including an antenna array and a calibration object parallel to the antenna array, forming an imaging channel between the antenna array and the calibration object; an imaging object is disposed in the imaging channel; the method includes:

[0007] By transmitting and receiving stepped frequency signals through the antenna array, echo data of the imaging object and the calibration object are collected to obtain the first echo data;

[0008] Based on the reference position of the calibrator relative to the antenna array, the second echo data is obtained by filtering from the first echo data, and the calibration parameters are obtained by matched filtering.

[0009] When the calibration parameters meet the preset conditions, the first echo data is compensated and calibrated according to the calibration parameters.

[0010] In some embodiments, the step of acquiring echo data of the imaging object and the calibration object by transmitting and receiving stepped-frequency signals through the antenna array to obtain first echo data includes:

[0011] The echo data reflected by the imaging object and the calibration object are collected through the transceiver channels of the antenna array and used as the first echo data; wherein, the first echo data is the echo data of the imaging object and the calibration object at each frequency point of each transceiver channel.

[0012] In some embodiments, the step of filtering second echo data from the first echo data based on the reference position of the calibrator relative to the antenna array, and obtaining calibration parameters through matched filtering, includes:

[0013] Based on the reference position of the calibrator relative to the antenna array, the distance range between the calibrator and the antenna array is obtained;

[0014] Based on the distance range, the second echo data reflected by the calibration object is obtained by filtering from the first echo data;

[0015] A matched filter model is established based on the reflection area of ​​the calibrator and the reference position, and the second echo data is subjected to matched filtering to obtain the calibration parameters.

[0016] In some embodiments, the method further includes:

[0017] The second echo data is calibrated based on the calibration parameters, and an imaging algorithm is used to obtain an image of the calibration object.

[0018] Based on the error between the size of the image of the calibration object and the size of the calibration object, the confidence level of the calibration parameter is calculated, and combined with a preset threshold, it is determined whether the calibration parameter meets the preset conditions.

[0019] When the confidence level is less than the preset threshold, it is determined that the calibration parameter does not meet the preset condition;

[0020] When the confidence level is greater than or equal to the preset threshold, it is determined that the calibration parameter meets the preset condition.

[0021] In some embodiments, the method further includes:

[0022] When the calibration parameters do not meet the preset conditions, the reference position of the calibrator relative to the antenna array is adjusted, the second echo data is obtained by re-filtering from the first echo data, and the calibration parameters are obtained by matched filtering.

[0023] In some embodiments, the method further includes:

[0024] Based on the reference position of the imaging object relative to the antenna array, the third echo data is obtained by filtering and processing from the calibrated first echo data;

[0025] The third echo data is reconstructed and imaged using the backpropagation algorithm to obtain an image of the imaging object.

[0026] Secondly, this embodiment provides a millimeter-wave imaging calibration device, characterized in that it includes: an antenna array, a calibration object parallel to the antenna array, and a calibration module; an imaging channel is formed between the antenna array and the calibration object; and an imaging object is disposed in the imaging channel.

[0027] The antenna array is used to transmit and receive stepped frequency signals, and to collect echo data of the imaging object and the calibration object to obtain the first echo data;

[0028] The imaging object and the calibration object are used to reflect the stepped frequency signal emitted by the antenna array;

[0029] The calibration module is used to filter out the second echo data from the first echo data according to the reference position of the calibrator relative to the antenna array, and obtain the calibration parameters through matched filtering;

[0030] When the calibration parameters meet the preset conditions, the first echo data is compensated and calibrated according to the calibration parameters.

[0031] In some embodiments, the calibrator includes a reflective region and a hollow region, and the area of ​​the hollow region is larger than the size of the imaging object;

[0032] The reflective region is made of diffuse reflective material; or, a metallic material.

[0033] In some embodiments, the above-described apparatus further includes: a determination module and an imaging module;

[0034] The judgment module is used to calibrate the second echo data based on the calibration parameters and obtain the calibration object image through the imaging algorithm;

[0035] Based on the error between the size of the image of the calibration object and the size of the calibration object, the confidence level of the calibration parameter is calculated, and combined with a preset threshold, it is determined whether the calibration parameter meets the preset conditions.

[0036] When the confidence level is less than the preset threshold, it is determined that the calibration parameter does not meet the preset condition; when the confidence level is greater than or equal to the preset threshold, it is determined that the calibration parameter meets the preset condition.

[0037] The imaging module is used to filter and process the calibrated first echo data to obtain third echo data based on the reference position of the imaging object relative to the antenna array.

[0038] The third echo data is reconstructed and imaged using the backpropagation algorithm to obtain an image of the imaging object.

[0039] Thirdly, this embodiment provides a computer device including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the millimeter-wave imaging calibration method described in the first aspect above.

[0040] Fourthly, this embodiment provides a storage medium storing a computer program that, when executed by a processor, implements the millimeter-wave imaging calibration method described in the first aspect above.

[0041] Compared with related technologies, this embodiment provides a millimeter-wave imaging calibration method, apparatus, computer equipment, and storage medium. The method is applied to a millimeter-wave imaging calibration apparatus, which includes an antenna array and a calibration object parallel to the antenna array, forming an imaging channel between the antenna array and the calibration object. The imaging object is disposed in the imaging channel. The method includes: acquiring echo data of the imaging object and the calibration object by transmitting and receiving stepped-frequency signals through the antenna array to obtain first echo data; filtering second echo data from the first echo data according to the reference position of the calibration object relative to the antenna array, and obtaining calibration parameters through matched filtering; when the calibration parameters meet preset conditions, compensating and calibrating the first echo data according to the calibration parameters. This allows for real-time acquisition of calibration parameters during imaging to calibrate the first echo data, compensating for phase inconsistencies in the transmitting and receiving channels, reducing the impact of phase fluctuations in the transmitting and receiving channels on imaging, and solving the problem of poor imaging quality caused by the inability to calibrate the consistency of the transmitting and receiving channels in real time.

[0042] Details of one or more embodiments of this application are set forth in the following drawings and description to make other features, objects and advantages of this application more readily apparent. Attached Figure Description

[0043] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings:

[0044] Figure 1 This is a schematic diagram of the structure of a millimeter-wave imaging calibration device in one embodiment;

[0045] Figure 2 This is a schematic diagram of the frequency spacing in one embodiment;

[0046] Figure 3 This is a flowchart of a millimeter-wave imaging calibration method in one embodiment;

[0047] Figure 4 This is a schematic diagram of the structure of a millimeter-wave imaging calibration device in a preferred embodiment;

[0048] Figure 5 This is a flowchart of a millimeter-wave imaging calibration method in a preferred embodiment.

[0049] In the diagram: 10, antenna array; 11, transmitting antenna; 12, receiving antenna; 20, calibration object; 21, reflection area; 22, hollow area; 30, imaging object. Detailed Implementation

[0050] To better understand the purpose, technical solution, and advantages of this application, the application is described and illustrated below in conjunction with the accompanying drawings and embodiments.

[0051] Unless otherwise defined, the technical or scientific terms used in this application shall have the general meaning understood by one of ordinary skill in the art to which this application pertains. Words such as “a,” “an,” “an,” “the,” “the,” and “these” used in this application do not indicate quantitative limitation and may be singular or plural. The terms “comprising,” “including,” “having,” and any variations thereof used in this application are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or device that comprises a series of steps or modules (units) is not limited to the listed steps or modules (units) but may include steps or modules (units) not listed, or may include other steps or modules (units) inherent to these processes, methods, products, or devices. Words such as “connected,” “linked,” and “coupled” used in this application are not limited to physical or mechanical connections but may include electrical connections, whether direct or indirect. “Multiple” used in this application refers to two or more. “And / or” describes the relationship between related objects, indicating that three relationships may exist; for example, “A and / or B” can represent: A alone, A and B simultaneously, and B alone. Normally, the character " / " indicates that the objects before and after it are in an "or" relationship. The terms "first," "second," "third," etc., used in this application are merely to distinguish similar objects and do not represent a specific order of objects.

[0052] In the field of security inspection, human body security imaging equipment based on millimeter waves can accurately image the human body. At the same time, combined with advanced artificial intelligence recognition algorithms, it can accurately identify dangerous items and their categories carried by the human body.

[0053] Millimeter-wave security imaging equipment includes several working modes such as linear array flat scanning, linear array circular scanning, and area array scanning. Each working mode corresponds to a different imaging equipment structure. Among them, large antenna arrays contain a large number of transceiver channels. The imbalance of amplitude and phase of the transceiver channels limits the image quality of security imaging, which in turn affects the accuracy of dangerous item detection. Therefore, it is necessary to calibrate the consistency of the transceiver channels.

[0054] Currently, phase compensation values ​​for each transceiver channel can be obtained by mutual calibration between the transceiver antennas, referencing a reference channel. This allows for calibration of the consistency of the transceiver channels, followed by imaging in the time domain or wavenumber domain. For example, in the patent "Calibration System and Method for Active Millimeter-Wave Real-Time Three-Dimensional Imaging Security Inspection System," millimeter-wave antenna array apertures are configured on the left and right walls of the security inspection channel to collect echo signals from a calibration body placed on the floor. Calibration parameters are then obtained to compensate for phase inconsistencies in the transceiver channels, and these parameters are used in subsequent security inspection imaging. However, when transceiver channel inconsistencies occur frequently, using the previous calibration parameters for calibration during security inspection imaging may not achieve high-quality imaging. Therefore, real-time calibration is not possible, resulting in poor imaging quality.

[0055] To address the above issues, the following embodiments provide a millimeter-wave imaging calibration method, apparatus, computer device, and storage medium. These methods enable the formation of an imaging channel within an antenna array and a calibration object parallel to the antenna array, and the placement of the imaging object within the imaging channel. This allows for the acquisition of echo data from the calibration object and the imaging object, the real-time calculation of calibration parameters, and their use for imaging calibration of the imaging object.

[0056] This embodiment provides a millimeter-wave imaging calibration device. Figure 1 This is a schematic diagram of the device in this embodiment, as shown below. Figure 1 As shown, the device includes: an antenna array 10, a calibration object 20 parallel to the antenna array, and a calibration module (not shown in the figure); an imaging channel is formed between the antenna array and the calibration object; and an imaging object 30 is disposed in the imaging channel.

[0057] The antenna array 10 is used to transmit and receive stepped frequency signals and to collect echo data of the imaging object 30 and the calibration object 20 to obtain the first echo data; wherein, the imaging object 30 and the calibration object 20 are used to reflect the stepped frequency signals transmitted by the antenna array 10.

[0058] Antenna array 10 includes several transmitting antennas and receiving antennas, with any one of the transmitting and receiving antennas forming a transceiver channel. The transmitting antennas radiate stepped-frequency signals outwards. Figure 2 This is a schematic diagram of the frequency spacing in this embodiment, as shown below. Figure 2As shown, the horizontal axis of the coordinate system represents the period T of the frequency point, and the vertical axis represents the frequency of the frequency point. The intervals between the frequency points can be equal or arranged according to a certain pattern. The number of frequency points is not limited to 32 or 64, etc., and can be selected based on the maximum unambiguous detectable distance and range resolution. The receiving antenna uses a superheterodyne structure for mixing. The intermediate frequency (IF) signal frequency depends on factors such as the ADC (analog-to-digital converter) sampling rate and the filtering characteristics of the RF chip. Furthermore, the ADC sampling rate must specifically meet the requirement of sampling the IF signal for an entire period.

[0059] Furthermore, the antenna array 10 is a sparse antenna array, and its antenna distribution is not limited to square arrays or circular arrays. An example layout of the transmitting and receiving antennas is provided, where both the transmitting and receiving antennas are linearly arranged, and two columns of transmitting antennas and two columns of receiving antennas are respectively arranged opposite to each other.

[0060] The calibration object 20, serving as a calibration reference, is positioned parallel to the antenna array 10 and is used to reflect the stepped-frequency signal transmitted by the antenna array 10. The shape of the calibration object 20 can correspond to the shape of the antenna array 10 and the arrangement of the transmitting and receiving antennas within the antenna array, in order to better obtain echo data from the antenna array 10. Preferably, in practical applications, the depth of the calibration object 20 from the antenna array 10 can be set to 2 meters.

[0061] In the field of security inspection, the imaging target 30 can specifically be a person or object to be detected, used to reflect the stepped-frequency signal emitted by the antenna array 10. Furthermore, the imaging target 30 is positioned in the imaging channel formed between the antenna array 10 and the calibration object 20. The imaging target 30 and the calibration object 20 have different depths (distances) relative to the antenna array 10. The antenna array 10 collects the echo data from the calibration object 20 and the imaging target 30, and when obtaining the first echo data, it distinguishes the echo data of the calibration object 20 and the imaging target 30 based on their different depths. Preferably, in practical applications, the depth of the imaging target 30 from the antenna array 10 can be set to 0.5m. The first echo data acquired by the antenna array 10 can be in multidimensional ADC data format.

[0062] The calibration module is connected to the antenna array 10 and is used to select the second echo data from the first echo data according to the reference position of the calibrator 20 relative to the antenna array 10, and obtain the calibration parameters through matched filtering; when the calibration parameters meet the preset conditions, the first echo data is compensated and calibrated according to the calibration parameters.

[0063] Specifically, the dimensions of the calibration object 20 can be obtained using high-precision measuring instruments, such as vernier calipers. An antenna coordinate system with XYZ axes is established using the plane of the antenna array 10. The aforementioned reference positions are the set of projections of the calibration object 20 onto the antenna coordinate system, which can be obtained by aligning the calibration object 20 with a laser and combining the dimensions of the calibration object 20.

[0064] Based on the reference position of the calibrator 20 relative to the antenna array 10, the maximum and minimum distances from the reflection point on the calibrator 20 to the antenna array 10 can be calculated to obtain the distance range between the calibrator 20 and the antenna array 10.

[0065] Since the imaging object 30 and the calibration object 20 are at different distances relative to the antenna array 10, the echo data reflected by the calibration object 20 is further selected from the first echo data based on the distance range and used as the second echo data. Matched filtering is then performed to obtain the calibration parameters. The calibration parameters are compensation values ​​for the phase of the transmit and receive channels.

[0066] Furthermore, by setting thresholds for the calibration parameters, specifically by calculating the confidence level of the calibration parameters and establishing preset conditions in conjunction with preset thresholds, the first echo data is calibrated in real time using the calibration parameters obtained above when the calibration parameters meet the preset conditions, in order to compensate for the phase inconsistency between the transmitting and receiving channels and reduce the impact on imaging quality.

[0067] The device provided in this embodiment forms an imaging channel between the antenna array and the calibration object parallel to the antenna array. The imaging object is placed in the imaging channel, and echo data of the imaging object and the calibration object are collected by the antenna array. Based on the reference position of the calibration object relative to the antenna array, the echo data reflected by the calibration object is filtered out, and calibration parameters are further calculated and used in imaging calibration. The device can obtain calibration parameters in real time and use them to compensate for the phase inconsistency of the transceiver channel, reduce the impact of the phase fluctuation of the transceiver channel on imaging, and solve the problem of poor imaging quality caused by the inability to calibrate the consistency of the transceiver channel in real time.

[0068] In some embodiments, the calibrator includes a reflective region and a hollow region, with the area of ​​the hollow region being larger than the size of the imaging object. The reflective region is made of a diffuse reflective material; or, a metallic material.

[0069] Specifically, the reflective area of ​​the calibrator is used to reflect the stepped-frequency signal transmitted by the antenna array. It can be a diffuse reflective material or other metallic material that can achieve reflection, depending on the actual reflection effect.

[0070] Furthermore, a hollow region is formed in the middle of the calibration object, and the area of ​​the hollow region is larger than the size of the imaging object. In this embodiment, the hollow structure of the calibration object can reduce the interference of echoes reflected multiple times between the calibration object and the imaging object. The echoes are reflected only through the reflection area at the edge of the calibration object, which can better distinguish the echo data reflected by the calibration object and the imaging object.

[0071] In some embodiments, the above-described apparatus further includes a determination module and an imaging module.

[0072] The judgment module is used to calibrate the second echo data based on the calibration parameters and obtain the calibration object image through the imaging algorithm; based on the error between the size of the calibration object image and the size of the calibration object, it calculates the confidence level of the calibration parameters and, in combination with a preset threshold, judges whether the calibration parameters meet the preset conditions; when the confidence level is less than the preset threshold, it is judged that the calibration parameters do not meet the preset conditions; when the confidence level is greater than or equal to the preset threshold, it is judged that the calibration parameters meet the preset conditions.

[0073] Specifically, the second echo data obtained from the above screening is multiplied with the corresponding calibration parameters, and then a fast imaging algorithm such as K-space is used to image the calibrated object to obtain the calibration object image.

[0074] The dimensions of the images of the calibration objects are compared with the actual measured dimensions of the calibration objects, and the overall error is obtained by summing the squares of the differences. During the summation process, different weights can be assigned to the square of each difference; the specific weight values ​​are determined based on experimental analysis.

[0075] After obtaining the comprehensive error, a Bayesian network can be used to calculate the confidence level, or the comprehensive error can be stratified for judgment. For example, when the comprehensive error is greater than a certain threshold (set according to actual results), the confidence level is 0; when the comprehensive error is less than the threshold, a linear equation is used to calculate the confidence level. Preset conditions are established by combining the preset threshold obtained through theoretical simulation with the confidence level.

[0076] The imaging module is used to filter and process the calibrated first echo data to obtain the third echo data based on the reference position of the imaging object relative to the antenna array; and to reconstruct the imaging of the third echo data based on the backpropagation algorithm to obtain the image of the imaging object.

[0077] Specifically, the calibration parameters are multiplied pairwise with the first echo data to obtain the compensated and calibrated first echo data.

[0078] By performing an inverse Fourier transform on the compensated first echo data to obtain the range-power spectrum, echo data with a distance less than or equal to D (minimum distance between the calibration object and the antenna array) and greater than or equal to L (depth of the imaging object relative to the antenna array) are selected based on the reference position of the imaging object relative to the antenna array. These echoes are then subjected to another Fourier transform. Furthermore, to ensure uniform radar echoes and reduce the influence of specular radiation, the third echo data is optimized by adding a window function, such as a Hamming window, to obtain the third echo data reflected by the imaging object. This is based on the BP (backpropagation) algorithm... Perform reconstructed imaging.

[0079] The judgment module and imaging module provided in this embodiment can be used to image the calibration object, calculate the confidence level of the calibration parameters with the size of the calibration object, and judge the confidence level of the calibration parameters. In this way, non-compliant calibration parameters can be corrected online to improve the accuracy of the calibration parameters. Then, the echo data reflected by the imaging object can be obtained from the first echo data after calibration, and combined with the imaging algorithm, higher quality imaging can be obtained.

[0080] It should be noted that the above modules can be functional modules or program modules, and can be implemented through software or hardware. For modules implemented through hardware, the above modules can reside in the same processor; or the above modules can be located in different processors in any combination.

[0081] This embodiment provides a millimeter-wave imaging calibration method, applied to the millimeter-wave imaging calibration device described in the above embodiment. Figure 3 This is a flowchart of the method in this embodiment, as follows: Figure 3 As shown, the method includes the following steps:

[0082] Step S310: The first echo data is obtained by transmitting and receiving stepped frequency signals through the antenna array to collect the echo data of the imaging object and the calibration object.

[0083] Specifically, in the aforementioned millimeter-wave imaging device, the antenna array includes several transmitting antennas and receiving antennas, with any one of the transmitting and receiving antennas forming a transceiver channel. The transmitting antennas radiate a stepped-frequency signal outwards, reflecting the imaging object and calibration object. This reflected signal is then received by the receiving antennas, acquiring first echo data in a multi-dimensional ADC data format. The first echo data includes echo data reflected from the imaging object and calibration object.

[0084] Step S320: Based on the reference position of the calibrator relative to the antenna array, the second echo data is obtained by filtering from the first echo data, and the calibration parameters are obtained by matched filtering.

[0085] Specifically, the dimensions of the calibration object can be obtained using high-precision measuring instruments, such as vernier calipers. An antenna coordinate system with XYZ axes is established using the plane of the antenna array. The aforementioned reference positions are the set of calibration objects projected onto the antenna coordinate system, which can be obtained by aligning the calibration object with a laser and combining this with its dimensions.

[0086] Based on the reference position of the calibrator relative to the antenna array, the maximum and minimum distances from all reflection points on the calibrator to the antenna array can be calculated to obtain the distance range between the calibrator and the antenna array.

[0087] Since the imaging object and the calibration object are at different distances relative to the antenna array, the echo data reflected by the calibration object is further selected from the first echo data based on the distance range, and used as the second echo data. Matched filtering is then performed to obtain the calibration parameters. These calibration parameters are compensation values ​​for the phase of the transmit and receive channels.

[0088] Step S330: When the calibration parameters meet the preset conditions, the first echo data is compensated and calibrated according to the calibration parameters.

[0089] Specifically, by setting thresholds for calibration parameters, specifically by calculating the confidence level of the calibration parameters and establishing preset conditions in combination with preset thresholds, the first echo data is calibrated in real time using the calibration parameters obtained above when the calibration parameters meet the preset conditions, in order to compensate for the phase inconsistency between the transmitting and receiving channels and reduce the impact on imaging quality.

[0090] The above steps form an imaging channel between the antenna array and the calibration object parallel to the antenna array. The imaging object is placed in the imaging channel, and echo data of the imaging object and the calibration object are collected by the antenna array. Based on the reference position of the calibration object relative to the antenna array, the echo data reflected by the calibration object is filtered out, and calibration parameters are further calculated and used in imaging calibration. Compared with the prior art, where the calibration parameters used for security inspection imaging may not necessarily achieve high-quality imaging, this embodiment can acquire calibration parameters in real time and use them to compensate for the phase inconsistency of the transceiver channel, reduce the impact of the phase fluctuation of the transceiver channel on imaging, and solve the problem of poor imaging quality caused by the inability to calibrate the consistency of the transceiver channel in real time.

[0091] In some embodiments, the process of obtaining the first echo data in step S310 above can be specifically implemented through the following steps:

[0092] The echo data reflected by the imaging object and the calibration object are collected through the transceiver channels of the antenna array as the first echo data; wherein, the first echo data is the echo data of the imaging object and the calibration object at each frequency point of each transceiver channel.

[0093] Specifically, the antenna array includes several transmitting and receiving antennas, with each transmitting and receiving antenna forming a transceiver channel. The acquired first echo data specifically refers to the echo data of the imaging object and the calibration object received by each transceiver channel of the antenna array at each frequency point.

[0094] In one example, the data format of the first echo data can be set as Data[TxNum][RxNum][FreNum], where TxNum is the number of transmitting antennas, RxNum is the number of receiving antennas, and FreNum is the number of frequency points. The set of echo data corresponding to each transmit and receive channel (assuming the transmitting antenna ID is TxIdx and the receiving antenna ID is RxIdx) is {Data[TxIdx][RxIdx][0], Data[TxIdx][RxIdx][1], ..., Data[TxIdx][RxIdx][FreNum-1]}.

[0095] In this embodiment, a millimeter-wave imaging calibration device is used to place the imaging object in the imaging channel between the antenna array and the calibration object, and to make the calibration object and the imaging object have different depths relative to the antenna array. This allows the echo data of the calibration object and the imaging object to be acquired at the same time, and then the echo data of the calibration object and the imaging object can be distinguished by their respective distances from the antenna array.

[0096] In some embodiments, step S320 above, which involves filtering the second echo data from the first echo data based on the reference position of the calibrator relative to the antenna array and obtaining calibration parameters through matched filtering, includes the following steps:

[0097] Step S321: Obtain the distance range between the calibrator and the antenna array based on the reference position of the calibrator relative to the antenna array.

[0098] Specifically, the dimensions of the calibration object, including parameters such as its height, are obtained using high-precision measuring instruments, such as vernier calipers. In an antenna coordinate system established on the plane of the antenna array, all reflection points on the calibration object are projected onto the set of the antenna coordinate system using laser alignment, thus obtaining the reference position of the calibration object relative to the antenna array.

[0099] In the above reference position, the minimum distance between the calibration object and the antenna array is known to be D. Then, the distance from the reflection point on the calibration object to the antenna is greater than or equal to D. Then, based on the height of the calibration object and the minimum distance D, the maximum distance DMax from the reflection point on the calibration object to the antenna array is obtained by using the Pythagorean theorem, and thus the distance range between the calibration object and the antenna array is obtained.

[0100] Step S322: Based on the distance range, filter the second echo data reflected by the calibration object from the first echo data.

[0101] Specifically, for the first echo data mentioned above, an inverse Fourier transform is performed to convert it to the range-power spectrum. Then, based on the range range, targets outside the range range [D, DMax] are filtered out on the range-power spectrum. Finally, a Fourier transform is performed to convert it to the time domain to obtain the second echo data reflected by the calibration object. The format of the second echo data is also multidimensional ADC data Data[TxNum][RxNum][FreNum].

[0102] Step S323: Establish a matched filter model based on the reflection area and reference position of the calibration object, and perform matched filtering on the second echo data to obtain the calibration parameters.

[0103] Specifically, the location set of the reflection area of ​​the calibration object is defined as P, combined with the reference position in the antenna coordinate system. After transformation, a matched filter model of the following form is established:

[0104] ,

[0105] Where j indicates that the current expression is a complex expression, and k represents the wave number. , Indicates wavelength. Represents the spatial location of a certain transmitting antenna. This represents the spatial location of a specific receiving antenna. Let P represent the set of locations of the calibrated objects.

[0106] Furthermore, each transceiver channel ( , Assuming the target reflection point is considered, each reflection point on the calibration object is regarded as an equivalent antenna. The second echo data is subjected to time-domain matched filtering as follows:

[0107] ,

[0108] in, For the transmitting channel T, the additional amplitude and phase compensation value for the receiving channel R at frequency point F; The transmitted channel T and the received channel R are the ADC sampling values ​​(i.e., the second echo data) at frequency point F after distance filtering.

[0109] The above additional amplitude and phase compensation values ​​were obtained. Subsequently, since the impact of phase error in the transmit / receive channel on imaging is greater than the impact of amplitude inconsistency in the transmit / receive channel on imaging quality, the phase compensation value was calculated. = abs( ) / The phase compensation value is used as the calibration parameter.

[0110] In this embodiment, since the calibration object and the imaging object have different depths relative to the antenna array, the second echo data reflected by the calibration object can be obtained by converting the first echo data to the range-power spectrum and filtering it from the range of distances between the calibration object and the antenna array. Furthermore, the phase compensation value for the transmit and receive channels can be calculated through matched filtering as a calibration parameter.

[0111] After obtaining the calibration parameters, in order to improve their accuracy, in some embodiments, the confidence level of the calibration parameters can be determined by imaging the calibration object, and non-compliant calibration parameters can be corrected online. This can be achieved through the following steps:

[0112] Step S410: The second echo data is calibrated based on the calibration parameters, and the calibration object image is obtained through the imaging algorithm.

[0113] Specifically, the second echo data obtained from the above screening is multiplied with the corresponding calibration parameters, and then a fast imaging algorithm such as K-space is used to image the calibrated object to obtain the calibration object image.

[0114] Step S420: Based on the error between the size of the calibration object image and the size of the calibration object, calculate the confidence level of the calibration parameters, and combine it with a preset threshold to determine whether the calibration parameters meet the preset conditions.

[0115] Specifically, the dimensions of the calibration object in the calibration object imaging are calculated, such as the outer length and width of the calibration object. In the case where the calibration object includes a reflective area and a hollow area in the above embodiments, the inner length and width of the calibration object, as well as the contrast between the reflective area and the hollow area in the calibration object, are further calculated. The contrast can be obtained by taking the logarithm of the ratio of the average power of the solid part (reflective area) to the average power of the hollow part (hollow area).

[0116] The dimensions of the images of the calibration objects are compared with the actual measured dimensions of the calibration objects, and the overall error is obtained by summing the squares of the differences. During the summation process, different weights can be assigned to the square of each difference; the specific weight values ​​are determined based on experimental analysis.

[0117] After obtaining the comprehensive error, a Bayesian network can be used to calculate the confidence level, or the comprehensive error can be stratified for judgment. For example, when the comprehensive error is greater than a certain threshold (set according to actual results), the confidence level is 0; when the comprehensive error is less than the threshold, a linear equation is used to calculate the confidence level. Preset conditions are established by combining the preset threshold obtained through theoretical simulation with the confidence level.

[0118] Step S430: When the confidence level is less than the preset threshold, the calibration parameters do not meet the preset conditions; when the confidence level is greater than or equal to the preset threshold, the calibration parameters meet the preset conditions.

[0119] Specifically, when the confidence level is greater than or equal to the preset threshold, the calibration parameter meets the preset conditions and can be used to compensate for the phase of the transmit and receive channels.

[0120] When the confidence level is less than a preset threshold, the calibration parameter does not meet the preset conditions. Further considering the computation time requirements, a reasonable upper limit for the number of iterations is set (obtained from the system's allowed computation time). If the confidence level is less than the preset threshold and the current number of calculations is less than the upper limit for the number of iterations, the calibration parameter that does not meet the preset conditions continues to be corrected online to improve the accuracy of the calibration parameter.

[0121] Furthermore, the following steps are used to perform online correction on calibration parameters that do not meet the preset conditions:

[0122] When the calibration parameters do not meet the preset conditions, the second echo data is obtained by adjusting the reference position of the calibrator relative to the antenna array, and the calibration parameters are obtained by matching filtering.

[0123] Specifically, the reference position can be adjusted by using methods such as genetic algorithms, gradient descent algorithms, or coarse-fine search. In order to further reduce the number of calculations in the algorithm, the search range of the relative reference position can be predetermined, for example, by combining the measurement uncertainty of the laser measurement mentioned above.

[0124] After adjusting the reference position, the second echo data reflected by the calibration object is re-screened, and the calibration parameters are calculated using the method in the above embodiments. The confidence level of the calibration parameters is then determined.

[0125] In this embodiment, the confidence level of the calibration parameters is calculated by imaging the calibration object and comparing it with the size of the calibration object. The confidence level of the calibration parameters is then judged, thereby correcting non-compliant calibration parameters online to improve the accuracy of the calibration parameters and achieve better imaging in the future.

[0126] In some embodiments, the above method further includes an imaging process for the imaging object, specifically implemented through the following steps:

[0127] Based on the reference position of the imaging object relative to the antenna array, the third echo data is obtained by filtering and processing the calibrated first echo data; the third echo data is then reconstructed and imaged using the backpropagation algorithm to obtain the image of the imaging object.

[0128] Specifically, the calibration parameters Compared with the first echo data By performing pairwise multiplication, the first echo data after compensation and calibration is obtained. .in, and This represents the ADC sampling values ​​of the transmitting channel T and the receiving channel R at frequency point F.

[0129] By performing an inverse Fourier transform on the compensated first echo data to obtain the range-power spectrum, echo data with a distance less than or equal to D (minimum distance between the calibration object and the antenna array) and greater than or equal to L (depth of the imaging object relative to the antenna array) are selected based on the reference position of the imaging object relative to the antenna array. These echoes are then subjected to another Fourier transform. Furthermore, to ensure uniform radar echoes and reduce the influence of specular radiation, the third echo data is optimized by adding a window function, such as a Hamming window, to obtain the third echo data reflected by the imaging object. .

[0130] Based on the BP (backpropagation) algorithm The specific steps for reconstructing the image are as follows:

[0131] ,

[0132] Where NK is the number of wavenumbers, NT is the number of transmitting antennas, and NR is the number of receiving antennas. This represents the spatial location of the corresponding transmitting antenna. This represents the spatial location of the corresponding receiving antenna. k represents the wave number, and λ represents the wavelength. .

[0133] The above equation can be transformed as follows:

[0134]

[0135] .

[0136] Two-dimensional convolution can be implemented using the following two-dimensional Fourier method:

[0137] .

[0138] In this embodiment, the echo data reflected by the imaging object can be obtained by filtering from the calibrated first echo data, and combined with the imaging algorithm, higher quality imaging can be obtained.

[0139] The method embodiments provided in the above examples can be executed in a terminal, computer, or similar computing device. For example, when running on a terminal, the terminal may include one or more processors and a memory for storing data, wherein the processor may include, but is not limited to, a microprocessor (MCU) or a programmable logic device (FPGA). The terminal may also include transmission devices for communication functions and input / output devices. Those skilled in the art will understand that the above description is merely illustrative and does not limit the structure of the terminal. For example, the terminal may include more or fewer components, or have different configurations.

[0140] The memory can be used to store computer programs, such as application software programs and modules, like the computer program corresponding to the millimeter-wave imaging calibration method in this embodiment. The processor executes various functional applications and data processing by running the computer program stored in the memory, thereby implementing the aforementioned method. The memory may include high-speed random access memory (RAM) and non-volatile memory, such as one or more magnetic storage devices, flash memory, or other non-volatile solid-state memory. In some instances, the memory may further include memory remotely located relative to the processor, and these remote memories can be connected to the terminal via a network. Examples of such networks include, but are not limited to, the Internet, corporate intranets, local area networks (LANs), mobile communication networks, and combinations thereof.

[0141] The transmission device is used to receive or send data via a network. This network includes a wireless network provided by the terminal's communication provider. In one example, the transmission device includes a Network Interface Controller (NIC), which can connect to other network devices via a base station to communicate with the Internet. In another example, the transmission device may be a Radio Frequency (RF) module, used for wireless communication with the Internet.

[0142] The present embodiment will now be described and illustrated through preferred embodiments.

[0143] Figure 4 This is a schematic diagram of the structure of the millimeter-wave imaging calibration device according to a preferred embodiment, as shown below. Figure 4 As shown, the millimeter-wave imaging calibration device includes: an antenna array 10, a calibration object 20 parallel to the antenna array, and a calibration module ( Figure 4 (not shown in the image); an imaging channel is formed between the antenna array and the calibration object; the imaging object 30 is disposed in the imaging channel.

[0144] The antenna array 10 described above is used to transmit and receive stepped frequency signals, and to collect echo data of the imaging object 30 and the calibration object 20 to obtain the first echo data.

[0145] The antenna array 10 includes several transmitting antennas 11 and receiving antennas 12, which are linearly arranged, with two rows of transmitting antennas 11 and two rows of receiving antennas 12 respectively positioned opposite each other. A calibration object 20, serving as a calibration reference, is positioned parallel to the antenna array 10 at a distance of 2m and is used to reflect the stepped-frequency signal transmitted by the antenna array 10.

[0146] In the field of security inspection, the imaging target 30 can specifically be a person or object to be inspected, used to reflect the stepped frequency signal emitted by the antenna array 10. Furthermore, the imaging target 30 is positioned in the imaging channel formed between the antenna array 10 and the calibration object 20. The imaging target 30 and the calibration object 20 have different depths (distances) relative to the antenna array 10; for example, the depth of the imaging target 30 from the antenna array 10 can be set to 0.5m.

[0147] The calibration object 20 includes a reflective region 21 and a hollow region 22, with the area of ​​the hollow region 22 being larger than the size of the imaging object 30. The reflective region 21 is made of a diffuse reflective material; or, a metallic material.

[0148] The calibration module is connected to the antenna array 10 and is used to select the second echo data from the first echo data according to the reference position of the calibrator 20 relative to the antenna array 10, and obtain the calibration parameters through matched filtering; when the calibration parameters meet the preset conditions, the first echo data is compensated and calibrated according to the calibration parameters.

[0149] Specifically, the dimensions of the calibration object 20 can be obtained using high-precision measuring instruments, such as vernier calipers. An antenna coordinate system with XYZ axes is established using the plane of the antenna array 10. The aforementioned reference positions are the set of projections of the calibration object 20 onto the antenna coordinate system, which can be obtained by aligning the calibration object 20 with a laser and combining the dimensions of the calibration object 20.

[0150] Based on the reference position of the calibrator 20 relative to the antenna array 10, the maximum and minimum distances from the reflection point on the calibrator 20 to the antenna array 10 can be calculated to obtain the distance range between the calibrator 20 and the antenna array 10.

[0151] Since the imaging object 30 and the calibration object 20 are at different distances relative to the antenna array 10, the echo data reflected by the calibration object 20 is further selected from the first echo data based on the distance range and used as the second echo data. Matched filtering is then performed to obtain the calibration parameters. The calibration parameters are compensation values ​​for the phase of the transmit and receive channels.

[0152] Furthermore, by setting thresholds for the calibration parameters, specifically by calculating the confidence level of the calibration parameters and establishing preset conditions in conjunction with preset thresholds, the first echo data is calibrated in real time using the calibration parameters obtained above when the calibration parameters meet the preset conditions, in order to compensate for the phase inconsistency between the transmitting and receiving channels and reduce the impact on imaging quality.

[0153] Furthermore, the above-mentioned device also includes: a judgment module and an imaging module ( Figure 4 (Not shown in the image). The judgment module is used to calibrate the second echo data based on the calibration parameters and obtain the calibration object image through the imaging algorithm; based on the error between the size of the calibration object image and the size of the calibration object, the confidence level of the calibration parameters is calculated, and combined with the preset threshold, it is determined whether the calibration parameters meet the preset conditions; when the confidence level is less than the preset threshold, it is determined that the calibration parameters do not meet the preset conditions; when the confidence level is greater than or equal to the preset threshold, it is determined that the calibration parameters meet the preset conditions.

[0154] The imaging module is used to filter and process the calibrated first echo data to obtain the third echo data based on the reference position of the imaging object relative to the antenna array; and to reconstruct the imaging of the third echo data based on the backpropagation algorithm to obtain the image of the imaging object.

[0155] The device provided in this preferred embodiment can acquire echo data of the imaging object and the calibration object through the antenna array, and filter the echo data reflected by the calibration object according to the reference position of the calibration object relative to the antenna array. It can further calculate calibration parameters and use them in imaging calibration. It can acquire calibration parameters in real time and use them to compensate for the phase inconsistency of the transceiver channel, reduce the impact of the phase fluctuation of the transceiver channel on imaging, and solve the problem of poor imaging quality caused by the inability to calibrate the consistency of the transceiver channel in real time.

[0156] In this embodiment, the hollow structure of the calibration object reduces interference from multiple reflections between the calibration object and the imaging object. Reflection is only performed through the reflection area at the edge of the calibration object, which allows for better differentiation of the echo data reflected by the calibration object and the imaging object.

[0157] Figure 5 This is a flowchart of the millimeter-wave imaging calibration method according to a preferred embodiment, as follows: Figure 5 As shown, this method, applied to the aforementioned preferred millimeter-wave imaging calibration device, specifically includes the following steps:

[0158] Step S510: Collect echo data reflected by the imaging object and the calibration object through the transceiver channel of the antenna array, as the first echo data.

[0159] Step S520: Based on the distance and size of the calibration object relative to the antenna array, obtain the distance range between the calibration object and the antenna array, and based on the distance range, filter the second echo data reflected by the calibration object from the first echo data.

[0160] Step S530: The calibration parameters are obtained by performing matched filtering on the second echo data; the second echo data is calibrated based on the calibration parameters, and the calibration object image is obtained through the imaging algorithm.

[0161] Step S540: Based on the error between the size of the calibration object image and the size of the calibration object, calculate the confidence level of the calibration parameters, and combine it with a preset threshold to determine whether the calibration parameters meet the preset conditions.

[0162] In step S550, when the calibration parameters do not meet the preset conditions, the second echo data is obtained by adjusting the reference position of the calibrator relative to the antenna array, and the calibration parameters are obtained by matching filtering.

[0163] Step S560: When the calibration parameters meet the preset conditions, the first echo data is compensated and calibrated according to the calibration parameters, and the third echo data reflected by the imaging object is obtained by filtering and processing according to the reference position of the imaging object relative to the antenna array; the third echo data is reconstructed and imaged based on the back propagation algorithm to obtain the image of the imaging object.

[0164] It should be noted that the steps shown in the above process or the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions. Furthermore, although a logical order is shown in the flowchart, in some cases, the steps shown or described may be executed in a different order than that shown here. For example, steps S550 and S560 are executed respectively based on whether the calibration parameters meet preset conditions, without distinguishing the order of execution.

[0165] The method provided in this preferred embodiment can acquire echo data of the imaging object and the calibration object through an antenna array, and filter the echo data reflected by the calibration object according to the reference position of the calibration object relative to the antenna array. The calibration parameters are then calculated and used in imaging calibration. Compared with the prior art, where the calibration parameters used for security inspection imaging may not necessarily achieve high-quality imaging, this embodiment can acquire calibration parameters in real time and use them to compensate for the phase inconsistency of the transceiver channel, reduce the impact of the phase fluctuation of the transceiver channel on imaging, and solve the problem of poor imaging quality caused by the inability to calibrate the consistency of the transceiver channel in real time.

[0166] Furthermore, by imaging the calibration object and calculating the confidence level of the calibration parameters based on the size of the calibration object, and judging the confidence level of the calibration parameters, the non-compliant calibration parameters are corrected online to improve the accuracy of the calibration parameters and achieve better imaging in the future.

[0167] This embodiment also provides a computer device, including a memory and a processor, wherein the memory stores a computer program and the processor is configured to run the computer program to perform the steps in any of the above method embodiments.

[0168] Optionally, the computer device may further include a transmission device and an input / output device, wherein the transmission device is connected to the processor and the input / output device is connected to the processor.

[0169] It should be noted that the specific examples in this embodiment can refer to the examples described in the above embodiments and optional implementations, and will not be repeated in this embodiment.

[0170] Furthermore, in conjunction with the millimeter-wave imaging calibration methods provided in the above embodiments, this embodiment can also provide a storage medium for implementation. This storage medium stores a computer program; when executed by a processor, the computer program implements any of the millimeter-wave imaging calibration methods described in the above embodiments.

[0171] It should be noted that the user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data used for analysis, data stored, data displayed, etc.) involved in this application are all information and data authorized by the user or fully authorized by all parties.

[0172] It should be understood that the specific embodiments described herein are merely illustrative of the application and not intended to limit it. All other embodiments derived by those skilled in the art based on the embodiments provided in this application without inventive effort are within the scope of protection of this application.

[0173] Obviously, the accompanying drawings are merely some examples or embodiments of this application. Those skilled in the art can apply this application to other similar situations based on these drawings without any creative effort. Furthermore, it is understood that although the work done in this development process may be complex and lengthy, for those skilled in the art, certain design, manufacturing, or production modifications made based on the technical content disclosed in this application are merely conventional technical means and should not be considered as insufficient disclosure of this application.

[0174] The term "embodiment" in this application refers to a specific feature, structure, or characteristic described in connection with an embodiment that may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily imply the same embodiment, nor does it imply that it is mutually exclusive with or alternative to other embodiments. It will be clearly or implicitly understood by those skilled in the art that the embodiments described in this application may be combined with other embodiments without conflict.

[0175] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of patent protection. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the appended claims.

Claims

1. A millimeter-wave imaging calibration method, characterized in that, An imaging calibration device for millimeter-wave imaging is used, the millimeter-wave imaging calibration device including an antenna array and a calibration object parallel to the antenna array, forming an imaging channel between the antenna array and the calibration object; The object to be imaged is positioned in the imaging channel; The calibration object includes a reflective region and a hollow region, wherein the area of ​​the hollow region is larger than the size of the imaging object; the method includes: By transmitting and receiving stepped frequency signals through the antenna array, echo data of the imaging object and the calibration object are collected to obtain the first echo data; Based on the reference position of the calibrator relative to the antenna array, second echo data is obtained by filtering from the first echo data, and calibration parameters are obtained by matched filtering; the matched filtering is based on the reflection area of ​​the calibrator and the reference position. When the calibration parameters meet the preset conditions, the first echo data is compensated and calibrated according to the calibration parameters.

2. The millimeter-wave imaging calibration method according to claim 1, characterized in that, The first echo data is obtained by acquiring the echo data of the imaging object and the calibration object through the antenna array transmitting and receiving stepped frequency signals, including: The echo data reflected by the imaging object and the calibration object are collected through the transceiver channels of the antenna array and used as the first echo data; wherein, the first echo data is the echo data of the imaging object and the calibration object at each frequency point of each transceiver channel.

3. The millimeter-wave imaging calibration method according to claim 1, characterized in that, The step of filtering second echo data from the first echo data based on the reference position of the calibrator relative to the antenna array, and obtaining calibration parameters through matched filtering, includes: Based on the reference position of the calibrator relative to the antenna array, the distance range between the calibrator and the antenna array is obtained; Based on the distance range, the second echo data reflected by the calibration object is obtained by filtering from the first echo data; A matched filter model is established based on the reflection area of ​​the calibrator and the reference position, and the second echo data is subjected to matched filtering to obtain the calibration parameters.

4. The millimeter-wave imaging calibration method according to claim 1, characterized in that, Also includes: The second echo data is calibrated based on the calibration parameters, and an imaging algorithm is used to obtain an image of the calibration object. Based on the error between the size of the image of the calibration object and the size of the calibration object, the confidence level of the calibration parameter is calculated, and combined with a preset threshold, it is determined whether the calibration parameter meets the preset conditions. When the confidence level is less than the preset threshold, the calibration parameter does not meet the preset condition; When the confidence level is greater than or equal to the preset threshold, the calibration parameter satisfies the preset condition.

5. The millimeter-wave imaging calibration method according to claim 4, characterized in that, Also includes: When the calibration parameters do not meet the preset conditions, the reference position of the calibrator relative to the antenna array is adjusted, the second echo data is obtained by re-filtering from the first echo data, and the calibration parameters are obtained by matched filtering.

6. The millimeter-wave imaging calibration method according to claim 1, characterized in that, Also includes: Based on the reference position of the imaging object relative to the antenna array, the third echo data is obtained by filtering and processing from the calibrated first echo data; The third echo data is reconstructed and imaged using the backpropagation algorithm to obtain an image of the imaging object.

7. A millimeter-wave imaging calibration device, characterized in that, include: An antenna array, a calibration object parallel to the antenna array, and a calibration module; an imaging channel is formed between the antenna array and the calibration object; The object to be imaged is positioned in the imaging channel; The antenna array is used to transmit and receive stepped frequency signals, and to collect echo data of the imaging object and the calibration object to obtain first echo data; the calibration object includes a reflective area and a hollow area, and the area of ​​the hollow area is larger than the size of the imaging object; The imaging object and the calibration object are used to reflect the stepped frequency signal emitted by the antenna array; The calibration module is used to filter out the second echo data from the first echo data according to the reference position of the calibrator relative to the antenna array, and obtain the calibration parameters through matched filtering; The matched filtering is based on the reflection region of the calibrator and the reference position; When the calibration parameters meet the preset conditions, the first echo data is compensated and calibrated according to the calibration parameters.

8. The millimeter-wave imaging calibration device according to claim 7, characterized in that, The reflective region is made of diffuse reflective material; or, a metallic material.

9. The millimeter-wave imaging calibration device according to claim 7, characterized in that, Also includes: Judgment module and imaging module; The judgment module is used to calibrate the second echo data based on the calibration parameters and obtain the calibration object image through the imaging algorithm; Based on the error between the size of the image of the calibration object and the size of the calibration object, the confidence level of the calibration parameter is calculated, and combined with a preset threshold, it is determined whether the calibration parameter meets the preset conditions. When the confidence level is less than the preset threshold, it is determined that the calibration parameter does not meet the preset condition; When the confidence level is greater than or equal to the preset threshold, it is determined that the calibration parameter satisfies the preset condition; The imaging module is used to filter and process the calibrated first echo data to obtain third echo data based on the reference position of the imaging object relative to the antenna array. The third echo data is reconstructed and imaged using the backpropagation algorithm to obtain an image of the imaging object.

10. A computer device, comprising a memory and a processor, characterized in that, The memory stores a computer program, and the processor is configured to run the computer program to perform the millimeter-wave imaging calibration method according to any one of claims 1 to 6.

11. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the steps of the millimeter-wave imaging calibration method according to any one of claims 1 to 6.

Images