Low-altitude weak target detection method and device based on synthetic wavelength

Abstract

The application provides a low-altitude weak target detection method and device based on a synthetic wavelength, which can be applied to the field of target detection. The method comprises: imaging echo data of a to-be-detected region without any to-be-detected target to obtain a first image; imaging echo data of a to-be-detected region with a to-be-detected target to obtain a second image; performing an interference operation on the first image and the second image to obtain a phase interference graph spectrum; cropping the phase interference graph spectrum to obtain a first wavelength phase interference graph and a second wavelength phase interference graph; generating a differential synthetic wavelength interference graph and an additive synthetic wavelength interference graph according to the first wavelength phase interference graph and the second wavelength phase interference graph; and unwrapping the additive synthetic wavelength interference graph by using the differential synthetic wavelength interference graph, and detecting the to-be-detected target based on the unwrapped additive synthetic wavelength interference graph. In this way, the target and clutter in the low-altitude environment are effectively identified, and the detection accuracy is improved.

Description

Technical Field

[0001] This application relates to the field of target detection, specifically to low-altitude target detection scenarios, and more specifically to a method, apparatus, equipment, medium, and program product for low-altitude weak target detection based on synthetic wavelength. Background Technology

[0002] The low-altitude economy refers to a comprehensive economic form that uses low-altitude airspace (usually below 1000 meters, extending to 3000 meters in some scenarios) as its carrier, and drones, electric vertical take-off and landing aircraft, and general aviation aircraft as its tools, encompassing manufacturing, operation, services, and derivative industries. Its core application scenarios include logistics and distribution, emergency rescue, agricultural plant protection, urban governance, and low-altitude tourism. Low-altitude economic activities are highly dependent on flight safety, and the illegal use of "low, slow, and small" targets (low-altitude, slow-speed, and small aircraft, such as consumer drones) poses a serious threat to public safety and airspace management. Therefore, the detection of "low, slow, and small" targets is particularly important.

[0003] At present, the detection methods for low-altitude weak targets (i.e., "low, slow and small" targets) can be mainly divided into three types: optical detection, radio detection and radar imaging. Among them, optical detection technology mainly uses optical sensors such as visible light and infrared to capture target images and achieve target recognition through image processing algorithms. For example, infrared thermal imaging technology can detect targets by the difference in thermal radiation between the target and the background. It is suitable for nighttime or low-light environments, but it is greatly affected by weather (such as rain and snow). Target features are easily interfered with by environmental noise. Radio detection technology is used to locate targets by analyzing the radio signals emitted by the target (such as drone remote control signals). It is suitable for scenarios without active echo signals, but it depends on the active communication of the target and is easily interfered with by electromagnetic environment. Radar-based detection technology has become the most widely used detection technology at present due to its advantages such as being less affected by weather and not relying on the active communication of the target. However, radar-based detection technology currently has the following problems: (1) It is easily interfered with by low-altitude clutter: In the low-altitude environment, radar signals are easily interfered with by clutter reflected by the ground, buildings, vegetation, etc., which causes the target echo to be submerged. For example, the intensity of ground clutter may be tens of times higher than the target echo, which is difficult for traditional radar to distinguish. (2) Difficult to detect slow-moving targets: The echo Doppler frequency shift of slow-moving or hovering targets is close to zero, making it difficult to distinguish from stationary clutter. Traditional moving target display technology will filter out such signals, resulting in missed detection. (3) Difficult to detect small targets: The radar cross section of slow-moving small targets is usually less than 2m². The echo energy of small targets is weak, and small targets may be made of non-metallic materials, which will further reduce the signal strength, making it even more difficult to detect weak small targets. Summary of the Invention

[0004] In view of the above problems, this application provides a method, apparatus, device, medium and program product for detecting weak low-altitude targets based on synthetic wavelengths, which can improve detection accuracy, especially the detection accuracy of low-altitude, slow-moving, small targets and reduce noise.

[0005] According to a first aspect of this application, a method for detecting weak low-altitude targets based on synthetic wavelengths is provided, comprising: imaging echo data of a region to be detected where no target exists to obtain a first image; imaging echo data of a region to be detected where a target exists to obtain a second image; performing an interferometric operation on the first image and the second image to obtain a phase interferogram spectrum; cropping the phase interferogram spectrum to obtain a first wavelength phase interferogram and a second wavelength phase interferogram; generating a differential synthetic wavelength interferogram and an additive synthetic wavelength interferogram based on the first wavelength phase interferogram and the second wavelength phase interferogram; unwrapping the additive synthetic wavelength interferogram using the differential synthetic wavelength interferogram; and detecting the target based on the unwrapped additive synthetic wavelength interferogram.

[0006] According to an embodiment of this application, before performing an interference operation on the first image and the second image, the method includes: registering the first image and the second image, including: calculating a cross-correlation function using the image features of the first image and the second image, determining the offset between the first image and the second image based on the cross-correlation function; adjusting the second image based on the offset, and calculating the offset between the adjusted second image and the first image; repeating the second image adjustment and offset calculation until the obtained offset is less than a preset threshold.

[0007] According to an embodiment of this application, cropping the spectrum of a phase interferogram to obtain a first wavelength phase interferogram and a second wavelength phase interferogram includes: cropping the high-frequency portion of the phase interferogram spectrum and performing linear phase compensation and inverse fast Fourier transform on the cropped spectrum to obtain a first wavelength phase interferogram; cropping the low-frequency portion of the phase interferogram spectrum and performing linear phase compensation and inverse fast Fourier transform on the cropped spectrum to obtain a second wavelength phase interferogram.

[0008] According to an embodiment of this application, generating a differential composite wavelength interferogram and an additive composite wavelength interferogram based on a first wavelength phase interferogram and a second wavelength phase interferogram includes: adding the first wavelength phase interferogram and the second wavelength phase interferogram to obtain an additive composite wavelength interferogram; and subtracting the first wavelength phase interferogram and the second wavelength phase interferogram to obtain a differential composite wavelength interferogram.

[0009] According to an embodiment of this application, unwrapping an additive composite wavelength interferogram using a differential composite wavelength interferogram includes: calculating the distance difference corresponding to the differential phase based on the differential composite wavelength corresponding to the differential composite wavelength interferogram and the differential phase contained in the differential composite wavelength interferogram; calculating the distance difference between the differential phase and the ideal differential phase based on the distance difference corresponding to the differential phase and the differential composite wavelength interferogram; and obtaining the unwrapped additive composite wavelength interferogram based on the distance difference between the differential phase and the ideal differential phase and the composite phase contained in the additive composite wavelength interferogram.

[0010] According to an embodiment of this application, the distance difference between the differential phase and the ideal differential phase is calculated based on the distance difference between the differential phase and the differential synthesized wavelength interferogram. This includes: unwrapping the differential phase contained in the differential synthesized wavelength interferogram to obtain the ideal differential phase corresponding to the differential phase; and calculating the distance difference of the ideal differential phase based on the ideal differential phase, the ideal differential synthesized wavelength corresponding to the ideal differential phase, and the distance difference between the differential phase and the differential phase corresponding to the ideal differential phase.

[0011] According to an embodiment of this application, obtaining an unwrapped additive composite wavelength interferogram based on the distance difference between the differential phase and the ideal differential phase, and the composite phase contained in the additive composite wavelength interferogram, includes: unwrapping the corresponding composite phase in the additive composite wavelength interferogram based on the distance difference between the differential phase and the ideal differential phase, and obtaining the unwrapped composite phase; and generating an unwrapped additive composite wavelength interferogram based on the unwrapped composite phase.

[0012] According to an embodiment of this application, detecting a target based on an unwrapped additive composite wavelength interferogram includes: extracting features from the unwrapped additive composite wavelength interferogram; wherein the features include phase statistical features, interference fringe features, and multi-scale features, and the multi-scale features include phase statistical features and / or interference fringe features extracted at different resolutions; and based on the features, using a preset target detection algorithm to detect the target.

[0013] A second aspect of this application provides a low-altitude weak target detection device based on synthetic wavelength, comprising:

[0014] The radar imaging module is used to image the echo data of the area to be detected where there is no target to be detected, to obtain a first image; and to image the echo data of the area to be detected where there is a target to be detected, to obtain a second image.

[0015] The phase interferogram spectrum acquisition module is used to perform interferometry on the first image and the second image to acquire the phase interferogram spectrum.

[0016] The phase interferogram spectrum clipping module is used to clip the phase interferogram spectrum to obtain a first wavelength phase interferogram and a second wavelength phase interferogram.

[0017] The wavelength synthesis module is used to generate differential synthesized wavelength interferograms and additive synthesized wavelength interferograms based on the first wavelength phase interferogram and the second wavelength phase interferogram.

[0018] The target detection module is used to unwrap the additive composite wavelength interferogram using the differential composite wavelength interferogram, and detect the target to be detected based on the unwrapped additive composite wavelength interferogram.

[0019] A third aspect of this application provides an electronic device comprising: one or more processors; and a memory for storing one or more computer programs, wherein the one or more processors execute the one or more computer programs to implement the steps of the method described above.

[0020] A fourth aspect of this application also provides a computer-readable storage medium having a computer program or instructions stored thereon, which, when executed by a processor, implement the steps of the above-described method.

[0021] The fifth aspect of this application also provides a computer program product, including a computer program or instructions that, when executed by a processor, implement the steps of the above-described method.

[0022] The above-described one or more embodiments have the following beneficial effects: Phase interferometry can effectively distinguish noise, thereby effectively identifying targets and clutter in low-altitude environments. It can also accurately identify slow-moving and small targets. Compared with the traditional amplitude interferometry, phase interferometry can also effectively avoid false alarms and missed alarms caused by improper detection threshold division, thereby improving detection accuracy and reducing the probability of false detection and missed detection. The wavelength synthesis method, which uses differential synthesized wavelength interferograms to unwrap additive synthesized wavelength interferograms, can greatly reduce the error propagation problems existing in traditional unwrapping methods, thereby greatly reducing the impact of noise on target detection. Attached Figure Description

[0023] The above-mentioned contents, other objects, features and advantages of this application will become clearer from the following description of embodiments with reference to the accompanying drawings, in which:

[0024] Figure 1 The illustration shows an application scenario of the low-altitude weak target detection method, apparatus, device, medium, and program product based on synthetic wavelength according to embodiments of this application;

[0025] Figure 2 A flowchart illustrating a low-altitude weak target detection method based on synthetic wavelength according to an embodiment of this application is shown schematically.

[0026] Figure 3 A schematic diagram illustrating an image registration method according to an embodiment of this application is shown.

[0027] Figure 4 This illustration schematically shows a process for obtaining an additive composite wavelength interferogram after unpacking, according to an embodiment of this application.

[0028] Figure 5 This schematic diagram illustrates a structural block diagram of a low-altitude weak target detection device based on synthetic wavelength according to an embodiment of this application;

[0029] Figure 6 A block diagram of an electronic device suitable for implementing a low-altitude weak target detection method based on synthetic wavelength, according to an embodiment of this application, is shown schematically. Detailed Implementation

[0030] The embodiments of this application will now be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of this application. In the following detailed description, numerous specific details are set forth to provide a thorough understanding of the embodiments of this application for ease of explanation. However, it will be apparent that one or more embodiments may be implemented without these specific details. Furthermore, descriptions of well-known structures and technologies are omitted in the following description to avoid unnecessarily obscuring the concepts of this application.

[0031] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of this application. The terms “comprising,” “including,” etc., as used herein indicate the presence of the stated features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.

[0032] All terms used herein (including technical and scientific terms) have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein are to be interpreted in a manner consistent with the context of this specification, and not in an idealized or overly rigid way.

[0033] When using expressions such as "at least one of A, B and C", they should generally be interpreted in accordance with the meaning that is commonly understood by those skilled in the art (e.g., "a system having at least one of A, B and C" should include, but is not limited to, a system having A alone, a system having B alone, a system having C alone, a system having A and B, a system having A and C, a system having B and C, and / or a system having A, B and C, etc.).

[0034] This application provides a method for detecting weak low-altitude targets based on synthetic wavelengths. The method uses a first image as a base image and performs an interferometric operation on the first image and a second image to obtain a phase interferogram spectrum. The first image is generated from echo data of a region where no target is detected, and the second image is generated from echo data of a region where a target is detected. By cropping the phase interferogram spectrum, two phase interferograms corresponding to single wavelengths are obtained. These two phase interferograms are added together to obtain an additive synthetic wavelength interferogram, and subtracted to obtain a differential synthetic wavelength interferogram. The differential synthetic wavelength interferogram is used to unwrap the additive synthetic wavelength interferogram to obtain an unwrapped additive synthetic wavelength interferogram, which is then used to detect the target. In this way, noise can be reduced, the probability of target echoes being submerged by clutter in low-altitude environments can be decreased, the detection capability of slow and small targets can be improved, thereby reducing the probability of missed detections and false detections and improving detection accuracy. When performing target detection, using phase interferometry instead of the traditional amplitude interferometry can effectively reduce false alarms and missed alarms caused by improper detection threshold division, thus significantly improving the robustness of dynamic noise and making it more conducive to detecting weak targets.

[0035] Figure 1 The illustration shows an application scenario of a low-altitude weak target detection method based on synthetic wavelength according to an embodiment of this application.

[0036] like Figure 1 As shown, application scenario 100 according to this embodiment may include a first terminal device 101, a second terminal device 102, a third terminal device 103, a network 104, and a server 105. The network 104 serves as a medium for providing a communication link between the first terminal device 101, the second terminal device 102, the third terminal device 103, and the server 105. The network 104 may include various connection types, such as wired or wireless communication links, or fiber optic cables, etc.

[0037] Users can use the first terminal device 101, the second terminal device 102, and the third terminal device 103 to interact with the server 105 via the network 104 to receive or send messages, etc. Various communication client applications can be installed on the first terminal device 101, the second terminal device 102, and the third terminal device 103, such as shopping applications, web browser applications, search applications, instant messaging tools, email clients, social media platform software, etc. (for example only).

[0038] The first terminal device 101, the second terminal device 102, and the third terminal device 103 can be various electronic devices with displays and support web browsing, including but not limited to smartphones, tablets, laptops, and desktop computers.

[0039] Server 105 can be a server that provides various services, such as a backend management server that supports websites browsed by users using the first terminal device 101, the second terminal device 102, and the third terminal device 103 (this is just an example). The backend management server can analyze and process data such as received user requests, and feed back the processing results (such as web pages, information, or data obtained or generated according to user requests) to the terminal devices.

[0040] It should be noted that the low-altitude weak target detection method based on synthetic wavelength provided in this application embodiment can generally be executed by server 105. Correspondingly, the low-altitude weak target detection device based on synthetic wavelength provided in this application embodiment can generally be installed in server 105. The low-altitude weak target detection method based on synthetic wavelength provided in this application embodiment can also be executed by a server or server cluster that is different from server 105 and capable of communicating with the first terminal device 101, the second terminal device 102, the third terminal device 103, and / or server 105. Correspondingly, the low-altitude weak target detection device based on synthetic wavelength provided in this application embodiment can also be installed in a server or server cluster that is different from server 105 and capable of communicating with the first terminal device 101, the second terminal device 102, the third terminal device 103, and / or server 105.

[0041] It should be understood that Figure 1 The number of terminal devices, networks, and servers shown is merely illustrative. Depending on implementation needs, any number of terminal devices, networks, and servers can be included.

[0042] The following will be based on Figure 1 The described scene, through Figures 2-4 A detailed description is provided of a low-altitude weak target detection method based on synthetic wavelength according to embodiments of this application.

[0043] Figure 2 A flowchart illustrating a low-altitude weak target detection method based on synthetic wavelength according to an embodiment of this application is shown.

[0044] like Figure 2 As shown, the low-altitude weak target detection method 200 based on synthetic wavelength in this embodiment includes operations S210 to S250.

[0045] In operation S210, the echo data of the area to be detected where there is no target is imaged to obtain a first image; the echo data of the area to be detected where there is a target is imaged to obtain a second image.

[0046] In operation S220, an interference operation is performed on the first image and the second image to obtain the phase interferogram spectrum.

[0047] In operation S230, the phase interferogram spectrum is cropped to obtain the first wavelength phase interferogram and the second wavelength phase interferogram.

[0048] In operation S240, a differential composite wavelength interferogram and an additive composite wavelength interferogram are generated based on the first wavelength phase interferogram and the second wavelength phase interferogram.

[0049] When operating the S250, the differential composite wavelength interferogram is used to unwrap the additive composite wavelength interferogram, and the target to be detected is based on the unwrapped additive composite wavelength interferogram.

[0050] In some embodiments, during operation S210, a multiple-input multiple-output (MIMO) radar can be used to detect the detection area where there is no target and the detection area where there is a target, respectively, to obtain corresponding multi-channel echo data, and to perform imaging based on the acquired multi-channel echo data to obtain a first image and a second image, respectively.

[0051] In some embodiments, during operation S210, the target to be detected can be a small object such as a stone, ore, or micro drone, or a larger object such as steel or wood.

[0052] According to the embodiments of this application, the phase interferometry method can effectively distinguish noise, thereby effectively identifying targets and clutter in low-altitude environments. It can also accurately identify slow-moving and small targets. Compared with the traditional amplitude interferometry method, the phase interferometry method can also effectively avoid false alarms and missed alarms caused by improper detection threshold division, thereby improving detection accuracy and reducing the probability of false detection and missed detection. The wavelength synthesis method uses differential synthesized wavelength interferograms to unwrap additive synthesized wavelength interferograms, which can greatly reduce the error propagation problems existing in traditional unwrapping methods, thereby greatly reducing the impact of noise on target detection.

[0053] In some embodiments, during operation S210, the echo data of the area to be detected where there is no target to be detected (belonging to multi-channel echo data) can be represented as follows: ,in, Indicates the first The echo data received by each antenna element Fast time refers to the time it takes for the radar to sample the echo within a single pulse signal. This indicates the return time of the radar echo; echo data of the area to be detected where the target exists (belonging to multi-channel echo data) can be represented as: Overlay Each echo data point is processed and SAR imaging is performed to obtain the first image. , superimposed Each echo data point is processed and SAR imaging is performed to obtain a second image. Furthermore, and The calculation formulas are as follows:

[0054]

[0055]

[0056] in, Indicates the wavelength of the echo. Indicates the azimuth and location. Distance to position is The position of the pixel unit, Indicates time Time The azimuth position of each antenna element Indicates time Time The range position of each antenna element.

[0057] Figure 3 A schematic diagram of an image registration method according to an embodiment of this application is shown.

[0058] like Figure 3 As shown, before performing the interferometry operation on the first and second images, the following steps are included:

[0059] The registration of the first image and the second image specifically includes operations S310 to S340.

[0060] In operation S310, the cross-correlation function is calculated using the image features of the first image and the second image.

[0061] In operation S320, the offset between the first image and the second image is determined based on the cross-correlation function.

[0062] In operation S330, the second image is adjusted according to the offset, and the offset between the adjusted second image and the first image is calculated.

[0063] In operation S340, the second image adjustment and offset calculation are repeated until the obtained offset is less than the preset threshold.

[0064] For example, when the target size is small, the detection process is easily affected by noise, resulting in poor coherence between the first and second images. This can lead to unsatisfactory results when using phase interferometry for target detection. Therefore, it is necessary to improve the coherence between the first and second images. Suppose the target is a small pebble. Due to its small size and non-metallic nature, its echo energy is very weak and easily drowned out by echoes reflected from vegetation, buildings, and other objects. If the echo reflected by the pebble is drowned out by these objects, the echo at the pebble's location in the second image is actually the echo reflected by the vegetation, buildings, and other objects at that location. Conversely, the echo at the location corresponding to the pebble in the first image is the echo reflected by the vegetation, buildings, and other objects at that location. Therefore, the reflection intensity of the echo at the pebble's location in the second image is significantly different from that in the first image. The reflection intensity of the echo at corresponding locations is approximately equal, making it impossible to accurately detect small stones. Furthermore, the correlation between the first and second images is relatively poor. To address this issue, the first and second images need to be registered. For example, image features such as reflection intensity can be extracted from both images. Based on these features, a cross-correlation function between the first and second images can be calculated. This cross-correlation function can then be used to estimate the offset between the first and second images. The second image is then adjusted based on the calculated offset, and the cross-correlation function between the adjusted second image and the first image is recalculated to estimate the offset again. This process of adjusting the second image and calculating the offset is repeated until the calculated offset is less than a preset threshold. When the offset is less than the preset threshold, the coherence between the first and second images is considered to be at its maximum.

[0065] In some embodiments, the registered first image is represented as The second image is represented as .

[0066] In some embodiments, during operation S220, an interference operation is performed on the first image and the second image to obtain a phase interferogram. It can be represented as:

[0067]

[0068] in, for The conjugate operation, This is a phase acquisition operation; a Fourier transform is performed on the obtained phase interferogram to obtain the phase interferogram spectrum.

[0069] According to the embodiments of this application, phase interferometry is used to perform interferometric imaging on echo data, which can effectively avoid false alarms and missed alarms caused by improper threshold division. For example, assuming that the target to be detected is a very small object, the traditional amplitude interferometry cannot clearly show the amplitude change when a small target is present. However, through phase interferometry, the phase change when a small target is present can be clearly found from the phase interferogram, thereby accurately detecting the small target, thereby improving the robustness to dynamic noise and reducing the probability of misjudgment.

[0070] In some embodiments, during operation S230, cropping the phase interferogram spectrum to obtain a first wavelength phase interferogram and a second wavelength phase interferogram includes: cropping the high-frequency portion of the phase interferogram spectrum and performing linear phase compensation and inverse fast Fourier transform on the cropped spectrum to obtain the first wavelength phase interferogram; cropping the low-frequency portion of the phase interferogram spectrum and performing linear phase compensation and inverse fast Fourier transform on the cropped spectrum to obtain the second wavelength phase interferogram.

[0071] Furthermore, the high-frequency portion of the phase interferogram spectrum can be zeroed out first. Assuming the high-frequency portion occupies half the width of the entire phase interferogram spectrum, the phase interferogram after zeroing out the high-frequency portion is shifted towards the center by one-quarter of the phase interferogram spectrum width. If the high-frequency portion occupies one-third of the entire phase interferogram spectrum width, then the zeroed-out phase interferogram spectrum needs to be shifted towards the center by one-sixth of the phase interferogram spectrum width. Linear phase compensation is then performed on the zeroed-out phase interferogram spectrum in this way to move it to the center. Then, an inverse fast Fourier transform is performed on the linearly compensated phase interferogram spectrum to obtain the first wavelength phase interferogram. The frequency of the first wavelength corresponding to the first wavelength phase interferogram is low-frequency, and the first wavelength is greater than the echo wavelength. Next, the low-frequency portion of the phase interferogram spectrum is set to zero. Assuming the low-frequency portion occupies half the width of the entire phase interferogram spectrum, the phase interferogram after zeroing the low-frequency portion is shifted towards the center by one-quarter of the phase interferogram spectrum width. If the low-frequency portion occupies one-third of the entire phase interferogram spectrum width, the zeroed phase interferogram spectrum needs to be shifted towards the center by one-sixth of the phase interferogram spectrum width. Linear phase compensation is then performed on the zeroed phase interferogram spectrum in this way to move it to the center. Finally, an inverse fast Fourier transform is performed on the linearly compensated phase interferogram spectrum to obtain the second-wavelength phase interferogram. The frequency of the second wavelength corresponding to the second-wavelength phase interferogram is high-frequency, and the second wavelength is smaller than the echo wavelength. .

[0072] In some embodiments, during operation S240, generating a differential composite wavelength interferogram and an additive composite wavelength interferogram based on the first wavelength phase interferogram and the second wavelength phase interferogram includes: adding the first wavelength phase interferogram and the second wavelength phase interferogram to obtain an additive composite wavelength interferogram; and subtracting the first wavelength phase interferogram and the second wavelength phase interferogram to obtain a differential composite wavelength interferogram.

[0073] Furthermore, pixel units in the additive composite wavelength interferogram The corresponding composite phase is represented as Pixel unit in differential synthesis wavelength interferogram The corresponding differential phase is represented as ,

[0074] and The calculation methods are as follows:

[0075]

[0076]

[0077] in, For pixel units in the second wavelength phase interferogram The corresponding entanglement phase, For the pixel unit in the first wavelength phase interferogram The corresponding entanglement phase, The noise is low, and the corresponding additive synthesis wavelength is , , The noise is relatively high, and its corresponding differential synthesis wavelength is , ,in, Indicates the first wavelength. This indicates the second wavelength.

[0078] Figure 4 The illustration shows a schematic diagram of the process for obtaining the additive composite wavelength interferogram after unpacking according to an embodiment of this application.

[0079] like Figure 4 As shown, the differential synthesized wavelength interferogram is used to wrap the additive synthesized wavelength interferogram, including operations S410 to S430.

[0080] In operation S410, the distance difference corresponding to the differential phase is calculated based on the differential synthesis wavelength corresponding to the differential synthesis wavelength interferogram and the differential phase contained in the differential synthesis wavelength interferogram.

[0081] In operation S420, the distance difference between the differential phase and the ideal differential phase is calculated based on the distance difference corresponding to the differential phase and the differential composite wavelength interferogram.

[0082] In operation S430, based on the distance difference between the differential phase and the ideal differential phase, and the composite phase contained in the additive composite wavelength interferogram, the unwrapped additive composite wavelength interferogram is obtained.

[0083] In some embodiments, during operation S410, the distance difference corresponding to the differential phase is calculated using the following formula. :

[0084]

[0085] Although It contains a lot of noise, leading to It contains a high level of noise, but It can reflect phase fluctuations caused by tiny targets, so it can be used Calculate the distance difference corresponding to the differential phase under ideal conditions (i.e., ideal differential phase), where, Represents pixel unit The corresponding differential phase belongs to the low-wound differential phase.

[0086] In some embodiments, during operation S420, the distance difference between the differential phase and the ideal differential phase is calculated based on the distance difference between the differential phase and the differential synthesized wavelength interferogram. This includes: unwrapping the differential phase contained in the differential synthesized wavelength interferogram to obtain the ideal differential phase corresponding to the differential phase; and calculating the distance difference between the ideal differential phase and the differential phase corresponding to the ideal differential phase based on the ideal differential phase, the ideal differential synthesized wavelength corresponding to the ideal differential phase, and the distance difference between the differential phase and the differential phase corresponding to the ideal differential phase.

[0087] Furthermore, we define a pixel unit under ideal conditions. The distance difference corresponding to the ideal differential phase is The ideal differential phase corresponding to this distance difference is The corresponding ideal differential synthesis wavelength is The corresponding distance difference parameter is First, the differential phases contained in the differential synthesized wavelength interferogram are unwrapped, that is, for Untangling yields pixel units. Corresponding ideal differential phase Since the ideal situation refers to both the differential composite wavelength interferogram and the additive composite wavelength interferogram being unenclosed, theoretically... Therefore, it can be based on , and ,calculate Corresponding distance difference Specifically, first calculate the pixel unit. The corresponding ideal distance difference parameter is ,Right now, Then according to , and ,calculate ,Right now, ,in, This indicates the operation of retrieving the nearest integer.

[0088] In some embodiments, during operation S430, obtaining an unwrapped additive composite wavelength interferogram based on the distance difference between the differential phase and the ideal differential phase and the composite phase contained in the additive composite wavelength interferogram includes: unwrapping the corresponding composite phase in the additive composite wavelength interferogram based on the distance difference between the differential phase and the ideal differential phase to obtain the unwrapped composite phase; and generating an unwrapped additive composite wavelength interferogram based on the unwrapped composite phase.

[0089] Furthermore, relative to , Although it reduces noise while reflecting the distribution of the target to be detected, It is still limited to the single-wavelength level, therefore, it needs to be based on right To unpack the package, first, according to , and Calculate the distance difference parameter corresponding to the additive synthesis wavelength. ,Right now, Then according to and Calculate the synthesized phase after unwrapping ,Right now, According to each pixel unit corresponding Generate an additive composite wavelength interferogram after unwrapping, because The noise contained is very low, so the detection accuracy of the resulting additive composite wavelength interferogram after unwrapping is very high.

[0090] According to the embodiments of this application, this application uses a synthetic wavelength unwrapping method to unwrap the additive synthetic wavelength interferogram, which solves the problems of high error probability in dense residual point areas, the need for manual intervention, and path interruption and error propagation in noise or low coherence areas of existing unwrapping methods, thereby greatly reducing noise and improving detection accuracy.

[0091] In some embodiments, during operation S250, the target to be detected is detected based on the unwrapped additive composite wavelength interferogram, including: extracting features from the unwrapped additive composite wavelength interferogram; wherein the features include phase statistical features, interference fringe features, and multi-scale features, and the multi-scale features include phase statistical features and / or interference fringe features extracted at different resolutions; and based on the features, a preset target detection algorithm is used to detect the target.

[0092] For example, by extracting phase statistical features (such as the mean, variance, and gradient of the phase), interference fringe features (such as fringe spacing, direction, and curvature), and multi-scale features (such as the target features at different resolutions obtained by using wavelet transform, pyramid transform, and other scaling analysis methods) from the unwrapped additive composite wavelength interferogram, the target can be detected using a detection threshold-based method. For example, when the change value of the interference fringes is greater than a preset detection threshold, the target is considered to exist in the detection area. Alternatively, matched filtering can be used to detect the target. For instance, based on the extracted features, a corresponding matched filter can be designed and convolved with the phase interferogram. If the output of the matched filter exceeds a preset threshold, the target is considered detected. Machine learning algorithms can also be used to detect the target. By training the machine learning model with sample data from various detection areas, the model can learn the deep features in the phase interferogram and the relationships between them, thereby effectively identifying the target. Machine learning algorithms can include artificial neural networks, convolutional neural networks, and support vector machines.

[0093] Based on the above-mentioned method for detecting weak low-altitude targets based on synthetic wavelength, this application also provides a device for detecting weak low-altitude targets based on synthetic wavelength. The following will be combined with... Figure 5 The device is described in detail.

[0094] Figure 5 A schematic block diagram of a low-altitude weak target detection device based on synthetic wavelength according to an embodiment of this application is shown.

[0095] like Figure 5 As shown, the low-altitude weak target detection device 500 based on synthetic wavelength in this embodiment includes a radar imaging module 510, a phase interferogram spectrum acquisition module 520, a phase interferogram spectrum clipping module 530, a wavelength synthesis module 540, and a target detection module 550.

[0096] The radar imaging module 510 is used to image the echo data of a target area where no target is present to obtain a first image, and to image the echo data of a target area to obtain a second image. In one embodiment, the radar imaging module 510 can be used to perform the operation S210 described above, which will not be repeated here.

[0097] The phase interferogram spectrum acquisition module 520 is used to perform an interference operation on the first image and the second image to acquire the phase interferogram spectrum. In one embodiment, the phase interferogram spectrum acquisition module 520 can be used to perform the operation S220 described above, which will not be repeated here.

[0098] The phase interferogram spectrum trimming module 530 is used to trim the phase interferogram spectrum to obtain a first wavelength phase interferogram and a second wavelength phase interferogram. In one embodiment, the phase interferogram spectrum trimming module 530 can be used to perform the operation S230 described above, which will not be repeated here.

[0099] The wavelength synthesis module 540 is used to generate a differentially synthesized wavelength interferogram and an additively synthesized wavelength interferogram based on the first wavelength phase interferogram and the second wavelength phase interferogram. In one embodiment, the wavelength synthesis module 540 can be used to perform the operation S240 described above, which will not be repeated here.

[0100] The target detection module 550 is used to unwrap the additive composite wavelength interferogram using a differential composite wavelength interferogram, and detect the target to be detected based on the unwrapped additive composite wavelength interferogram. In one embodiment, the target detection module 550 can be used to perform the operation S250 described above, which will not be repeated here.

[0101] In some embodiments, the apparatus 500 further includes an image registration module, which is used to register the first image and the second image before performing an interference operation on the first image and the second image. Specifically, the image registration module is used to: calculate a cross-correlation function using the image features of the first image and the second image, determine the offset between the first image and the second image based on the cross-correlation function; adjust the second image based on the offset, and calculate the offset between the adjusted second image and the first image; repeat the second image adjustment and offset calculation until the obtained offset is less than a preset threshold.

[0102] In some embodiments, the phase interferogram spectrum clipping module 530 is specifically used to: clip the high-frequency part of the phase interferogram spectrum, and perform linear phase compensation and inverse fast Fourier transform on the clipped spectrum to obtain a first wavelength phase interferogram; clip the low-frequency part of the phase interferogram spectrum, and perform linear phase compensation and inverse fast Fourier transform on the clipped spectrum to obtain a second wavelength phase interferogram.

[0103] In some embodiments, the wavelength synthesis module 540 is specifically used to: add the first wavelength phase interferogram and the second wavelength phase interferogram to obtain an additive synthesized wavelength interferogram; and subtract the first wavelength phase interferogram and the second wavelength phase interferogram to obtain a differential synthesized wavelength interferogram.

[0104] In some embodiments, the target detection module 550 is specifically used to: calculate the distance difference corresponding to the differential phase based on the differential composite wavelength corresponding to the differential composite wavelength interferogram and the differential phase contained in the differential composite wavelength interferogram; calculate the distance difference between the differential phase and the ideal differential phase based on the distance difference corresponding to the differential phase and the differential composite wavelength interferogram; and obtain the unwrapped additive composite wavelength interferogram based on the distance difference between the differential phase and the ideal differential phase and the composite phase contained in the additive composite wavelength interferogram.

[0105] In some embodiments, the target detection module 550 is further configured to: unwrap the differential phase contained in the differential synthesized wavelength interferogram to obtain the ideal differential phase corresponding to the differential phase; and calculate the distance difference of the ideal differential phase based on the ideal differential phase, the ideal differential synthesized wavelength corresponding to the ideal differential phase, and the distance difference with the differential phase corresponding to the ideal differential phase.

[0106] In some embodiments, the target detection module 550 is further configured to: unwrap the corresponding composite phase in the additive composite wavelength interferogram according to the distance difference between the differential phase and the ideal differential phase, and obtain the unwrapped composite phase; and generate the unwrapped additive composite wavelength interferogram according to the unwrapped composite phase.

[0107] In some embodiments, the target detection module 550 is further configured to: extract features of the unwrapped additive composite wavelength interferogram; wherein the features include phase statistical features, interference fringe features and multi-scale features, and the multi-scale features include phase statistical features and / or interference fringe features extracted at different resolutions; and based on the features, use a preset target detection algorithm to detect the target to be detected.

[0108] According to the embodiments of this application, the device 500 can effectively avoid false alarms and missed alarms caused by improper threshold division. By using differential synthesized wavelength interferogram to unwrap the additive synthesized wavelength interferogram, noise is greatly reduced and detection accuracy is improved.

[0109] According to embodiments of this application, any multiple modules among the radar imaging module 510, phase interferogram spectrum acquisition module 520, phase interferogram spectrum trimming module 530, wavelength synthesis module 540, and target detection module 550 can be combined into one module, or any one of these modules can be split into multiple modules. Alternatively, at least some of the functions of one or more of these modules can be combined with at least some of the functions of other modules and implemented in one module. According to embodiments of this application, at least one of the radar imaging module 510, phase interferogram spectrum acquisition module 520, phase interferogram spectrum trimming module 530, wavelength synthesis module 540, and target detection module 550 can be at least partially implemented as hardware circuitry, such as a field-programmable gate array (FPGA), a programmable logic array (PLA), a system-on-a-chip, a system-on-a-substrate, a system-on-package, an application-specific integrated circuit (ASIC), or any other reasonable means of integrating or packaging the circuitry, or implemented in software, hardware, or firmware, or in any suitable combination of any of these three implementation methods. Alternatively, at least one of the radar imaging module 510, the phase interferogram spectrum acquisition module 520, the phase interferogram spectrum clipping module 530, the wavelength synthesis module 540, and the target detection module 550 may be at least partially implemented as a computer program module, which can perform corresponding functions when the computer program module is run.

[0110] Figure 6 A block diagram of an electronic device suitable for implementing a low-altitude weak target detection method based on synthetic wavelength, according to an embodiment of this application, is shown schematically.

[0111] like Figure 6 As shown, an electronic device 600 according to an embodiment of this application includes a processor 601, which can perform various appropriate actions and processes according to a program stored in a read-only memory (ROM) 602 or a program loaded from a storage portion 608 into a random access memory (RAM) 603. The processor 601 may include, for example, a general-purpose microprocessor (e.g., a CPU), an instruction set processor and / or an associated chipset and / or a special-purpose microprocessor (e.g., an application-specific integrated circuit (ASIC)), etc. The processor 601 may also include onboard memory for caching purposes. The processor 601 may include a single processing unit or multiple processing units for performing different actions of the method flow according to an embodiment of this application.

[0112] RAM 603 stores various programs and data required for the operation of electronic device 600. Processor 601, ROM 602, and RAM 603 are interconnected via bus 604. Processor 601 executes various operations of the method flow according to embodiments of this application by executing programs in ROM 602 and / or RAM 603. It should be noted that the programs may also be stored in one or more memories other than ROM 602 and RAM 603. Processor 601 may also execute various operations of the method flow according to embodiments of this application by executing programs stored in said one or more memories.

[0113] According to embodiments of this application, the electronic device 600 may further include an input / output (I / O) interface 605, which is also connected to a bus 604. The electronic device 600 may also include one or more of the following components connected to the input / output (I / O) interface 605: an input section 606 including a keyboard, mouse, etc.; an output section 607 including a cathode ray tube (CRT), liquid crystal display (LCD), etc., and a speaker, etc.; a storage section 608 including a hard disk, etc.; and a communication section 609 including a network interface card such as a LAN card, modem, etc. The communication section 609 performs communication processing via a network such as the Internet. A drive 610 is also connected to the input / output (I / O) interface 605 as needed. A removable medium 611, such as a disk, optical disk, magneto-optical disk, semiconductor memory, etc., is installed on the drive 610 as needed so that computer programs read from it can be installed into the storage section 608 as needed.

[0114] This application also provides a computer-readable storage medium, which may be included in the device / apparatus / system described in the above embodiments; or it may exist independently and not assembled into the device / apparatus / system. The computer-readable storage medium carries one or more programs, which, when executed, implement the method according to the embodiments of this application.

[0115] According to embodiments of this application, the computer-readable storage medium can be a non-volatile computer-readable storage medium, such as including but not limited to: portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), portable compact disk read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination thereof. In this application, the computer-readable storage medium can be any tangible medium containing or storing a program that can be used by or in conjunction with an instruction execution system, apparatus, or device. For example, according to embodiments of this application, the computer-readable storage medium may include ROM 602 and / or RAM 603 and / or one or more memories other than ROM 602 and RAM 603 described above.

[0116] Embodiments of this application also include a computer program product comprising a computer program containing program code for performing the methods shown in the flowchart. When the computer program product is run on a computer system, the program code enables the computer system to implement the low-altitude weak target detection method based on synthetic wavelength provided in the embodiments of this application.

[0117] When the computer program is executed by the processor 601, it performs the functions defined in the system / apparatus of this application embodiment. According to the embodiments of this application, the systems, apparatuses, modules, units, etc., described above can be implemented by computer program modules.

[0118] In one embodiment, the computer program may rely on a tangible storage medium such as an optical storage device or a magnetic storage device. In another embodiment, the computer program may also be transmitted and distributed in the form of signals over a network medium, and downloaded and installed via the communication section 609, and / or installed from the removable medium 611. The program code contained in the computer program can be transmitted using any suitable network medium, including but not limited to: wireless, wired, etc., or any suitable combination thereof.

[0119] In such an embodiment, the computer program can be downloaded and installed from a network via the communication section 609, and / or installed from the removable medium 611. When the computer program is executed by the processor 601, it performs the functions defined in the system of this application embodiment. According to the embodiments of this application, the systems, devices, apparatuses, modules, units, etc., described above can be implemented by computer program modules.

[0120] According to embodiments of this application, program code for executing the computer programs provided in the embodiments of this application can be written in any combination of one or more programming languages. Specifically, these computational programs can be implemented using high-level procedural and / or object-oriented programming languages, and / or assembly / machine languages. Programming languages ​​include, but are not limited to, languages ​​such as Java, C++, Python, "C", or similar programming languages. The program code can be executed entirely on the user's computing device, partially on the user's device, partially on a remote computing device, or entirely on a remote computing device or server. In cases involving remote computing devices, the remote computing device can be connected to the user's computing device via any type of network, including a local area network (LAN) or a wide area network (WAN), or it can be connected to an external computing device (e.g., via the Internet using an Internet service provider).

[0121] The flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of this application. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of code containing one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions indicated in the blocks may occur in a different order than those indicated in the drawings. For example, two consecutively indicated blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in a block diagram or flowchart, and combinations of blocks in a block diagram or flowchart, may be implemented using a dedicated hardware-based system that performs the specified function or operation, or using a combination of dedicated hardware and computer instructions.

[0122] Those skilled in the art will understand that the features described in the various embodiments of this application can be combined and / or combined in various ways, even if such combinations or combinations are not explicitly described in this application. In particular, the features described in the various embodiments of this application can be combined and / or combined in various ways without departing from the spirit and teachings of this application. All such combinations and / or combinations fall within the scope of this application.

Claims

1. A method for detecting weak low-altitude targets based on synthetic wavelength, characterized in that, The method includes: Image the echo data of the area to be detected where there is no target to be detected to obtain a first image; image the echo data of the area to be detected where there is a target to be detected to obtain a second image; Interference operations are performed on the first image and the second image to obtain the phase interferogram spectrum; The phase interferogram spectrum is cropped to obtain a first wavelength phase interferogram and a second wavelength phase interferogram; Based on the first wavelength phase interferogram and the second wavelength phase interferogram, a differential composite wavelength interferogram and an additive composite wavelength interferogram are generated. The additive composite wavelength interferogram is unwrapped using the differential composite wavelength interferogram, and the target to be detected is based on the unwrapped additive composite wavelength interferogram.

2. The method according to claim 1, characterized in that, Before performing the interference operation on the first image and the second image, the following steps are included: The registration of the first image and the second image includes: calculating a cross-correlation function using the image features of the first image and the second image, determining the offset between the first image and the second image based on the cross-correlation function; adjusting the second image based on the offset, and calculating the offset between the adjusted second image and the first image; repeating the second image adjustment and offset calculation until the obtained offset is less than a preset threshold.

3. The method according to claim 1, characterized in that, The step of cropping the phase interferogram spectrum to obtain a first wavelength phase interferogram and a second wavelength phase interferogram includes: The high-frequency portion of the phase interferogram spectrum is cropped, and the cropped spectrum is subjected to linear phase compensation and inverse fast Fourier transform to obtain the first wavelength phase interferogram. The low-frequency portion of the phase interferogram spectrum is cropped, and the cropped spectrum is subjected to linear phase compensation and inverse fast Fourier transform to obtain a second wavelength phase interferogram.

4. The method according to claim 1, characterized in that, The step of generating a differential composite wavelength interferogram and an additive composite wavelength interferogram based on the first wavelength phase interferogram and the second wavelength phase interferogram includes: The first wavelength phase interferogram and the second wavelength phase interferogram are added together to obtain the additive composite wavelength interferogram; Subtracting the first wavelength phase interferogram from the second wavelength phase interferogram yields the differential composite wavelength interferogram.

5. The method according to claim 1, characterized in that, The step of using the differential synthesized wavelength interferogram to de-wrap the additive synthesized wavelength interferogram includes: Calculate the distance difference corresponding to the differential phase based on the differential synthesized wavelength corresponding to the differential synthesized wavelength interferogram and the differential phase contained in the differential synthesized wavelength interferogram; Based on the distance difference corresponding to the differential phase and the differential synthesized wavelength interferogram, calculate the distance difference between the differential phase and the ideal differential phase. Based on the distance difference between the differential phase and the ideal differential phase, and the composite phase contained in the additive composite wavelength interferogram, the unwrapped additive composite wavelength interferogram is obtained.

6. The method according to claim 5, characterized in that, The step of calculating the distance difference between the differential phase and the ideal differential phase based on the distance difference corresponding to the differential phase and the differential synthesized wavelength interferogram includes: The differential phase contained in the differential synthesized wavelength interferogram is unwrapped to obtain the ideal differential phase corresponding to the differential phase; The distance difference of the ideal differential phase is calculated based on the ideal differential phase, the ideal differential synthesis wavelength corresponding to the ideal differential phase, and the distance difference between the ideal differential phase and the differential phase corresponding to the ideal differential phase.

7. The method according to claim 5, characterized in that, The step of obtaining the unwrapped additive composite wavelength interferogram based on the distance difference between the differential phase and the ideal differential phase, and the composite phase contained in the additive composite wavelength interferogram, includes: Based on the distance difference between the differential phase and the ideal differential phase, the corresponding composite phase in the additive composite wavelength interferogram is unwrapped to obtain the unwrapped composite phase; Based on the unwrapped synthetic phase, an additive synthetic wavelength interferogram is generated.

8. The method according to claim 1, characterized in that, The detection of the target based on the additive composite wavelength interferogram after unpacking includes: Extract features from the unwrapped additive composite wavelength interferogram; wherein, the features include phase statistical features, interference fringe features and multi-scale features, and the multi-scale features include phase statistical features and / or interference fringe features extracted at different resolutions; Based on the aforementioned features, a preset target detection algorithm is used to detect the target to be detected.

9. A low-altitude weak target detection device based on synthetic wavelength, characterized in that, The device includes: The radar imaging module is used to image the echo data of the area to be detected where there is no target to be detected, to obtain a first image; and to image the echo data of the area to be detected where there is a target to be detected, to obtain a second image. The phase interferogram spectrum acquisition module is used to perform an interference operation on the first image and the second image to acquire the phase interferogram spectrum. The phase interferogram spectrum clipping module is used to clip the phase interferogram spectrum to obtain a first wavelength phase interferogram and a second wavelength phase interferogram. The wavelength synthesis module is used to generate a differentially synthesized wavelength interferogram and an additively synthesized wavelength interferogram based on the first wavelength phase interferogram and the second wavelength phase interferogram. The target detection module is used to unwrap the additive composite wavelength interferogram using the differential composite wavelength interferogram, and detect the target to be detected based on the unwrapped additive composite wavelength interferogram.

10. An electronic device, comprising: One or more processors; Memory, used to store one or more computer programs. The characteristic feature is that the one or more processors execute the one or more computer programs to implement the steps of the method according to any one of claims 1 to 8.

11. A computer-readable storage medium having a computer program or instructions stored thereon, characterized in that, When the computer program or instructions are executed by a processor, they implement the steps of the method according to any one of claims 1 to 8.

12. A computer program product, comprising a computer program or instructions, characterized in that, When the computer program or instructions are executed by a processor, they implement the steps of the method according to any one of claims 1 to 8.

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