Non-line-of-sight high-resolution microwave intensity coherent staring imaging device and method

Abstract

The present invention discloses a non-line-of-sight high-resolution microwave intensity coherent staring imaging device and method, comprising a transmitter, a random modulation plane, and a receiver; the transmitter comprises a signal generation module and a detection mechanism generation module; the receiver comprises a receiving module, a feature extraction and synthesis module, a data processing module, and a target positioning imaging module; the target positioning imaging module locates the target and reconstructs the image based on the first-order statistical feature comprehensive information of the target echo spatial distribution obtained by the feature extraction and synthesis module. This invention significantly improves the measurement accuracy of the target and realizes super-resolution imaging. It breaks through the aperture limitation of traditional staring imaging resolution and can also achieve high-precision detection of weak targets with low signal-to-noise ratio.

Description

Technical Field

[0001] The present invention relates to the field of computational imaging, and in particular to a non-line-of-sight high-resolution microwave intensity coherent staring imaging device and method. Background Art

[0002] Microwave radar imaging technology can be divided into two categories based on the relative motion between the radar and the target: relative static imaging and relative motion imaging. Relative static imaging, also known as microwave staring imaging, includes three types: real aperture imaging, phased array imaging, and focal plane imaging. Microwave staring imaging enables continuous, real-time monitoring of a specific area. However, because its azimuth resolution is determined by the antenna size, and therefore limited by the aperture size, its application is limited to close-range imaging scenarios or those requiring lower resolution. This significantly limits the application and development of microwave staring imaging technology.

[0003] The aforementioned relatively static imaging methods suffer from at least two issues: The antenna aperture is difficult to effectively expand, resulting in low system resolution. From the perspective of signal reception, information acquisition is limited by the aperture of the receiving array, making effective expansion difficult. Summary of the Invention

[0004] The purpose of the present invention is to provide a non-line-of-sight high-resolution microwave intensity coherent staring imaging device and method. The method is based on a secondary modulated radiation source and effectively expands the aperture of the secondary radiation source without increasing the radiation array, thereby greatly improving the resolution capability of the system.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] A non-line-of-sight high-resolution microwave intensity coherent staring imaging device comprises: a transmitter, a random modulation plane and a receiver;

[0007] The transmitter includes a signal generation module and a detection mechanism generation module;

[0008] The signal generation module is used to generate a transmission signal through parameter configuration, and the transmission signal is transmitted to the detection mechanism generation module;

[0009] The detection mechanism generation module is used to realize the generation of random or non-random detection beams, the monitoring of transmission power, and the transmission of transmission signals in the form of electromagnetic waves;

[0010] The random modulation plane is used to perform secondary random modulation on the amplitude and phase of the electromagnetic wave signal, so that the incident wave signal is scattered in all directions;

[0011] The receiver includes a receiving module, a feature extraction and synthesis module, a data processing module and a target positioning imaging module;

[0012] The receiving module is used to perform beam scanning and receive target reflected echoes, convert the reflected echoes into digital signals and output them to the feature extraction and synthesis module;

[0013] The feature extraction and synthesis module is used to complete the extraction of the first-order statistical features of the spatial distribution of the echo signal, and perform data synthesis on the features of multiple detection signals under the set number of detections, and transmit the data to the data processing module;

[0014] The data processing module uses a matched filter to filter the integrated data according to the prior information;

[0015] The target positioning imaging module is used to estimate the target orientation using the echo information and reconstruct the target image using a fast transformation method based on the data transmitted by the data processing module.

[0016] As a further improvement of the present invention, the signal generation module is also used to generate signal encoding with random or non-random amplitude and phase requirements by allocating random or non-random phases through a phased array antenna, thereby generating a single-channel or multi-channel signal.

[0017] As a further improvement of the present invention, the detection mechanism generation module includes a beamforming module, a power monitoring module and a transmission module;

[0018] The beamforming module is used to generate a detection pattern through a single source or a randomly modulated array excitation;

[0019] The power monitoring module is used to monitor the transmission power corresponding to the detection mode;

[0020] The transmitting module is used to transmit the transmission signal in the form of electromagnetic waves.

[0021] As a further improvement of the present invention, the beamforming module has a metamaterial planar coating.

[0022] As a further improvement of the present invention, the random modulation plane adopts an artificial random super surface or a rough surface in a natural environment.

[0023] As a further improvement of the present invention, the antenna used in the receiving module is a sparse large-aperture array, and the target echo is collected by an electromagnetic wave receiving device discretized in the frequency dimension.

[0024] As a further improvement of the present invention, the target positioning imaging module is further used to recover the phase of the first-order statistic of the integrated signal spatial distribution by using a phase recovery algorithm.

[0025] An imaging method using a non-line-of-sight high-resolution microwave intensity coherent staring imaging device comprises the following steps:

[0026] The transmitter generates the transmission signal, creates the detection pattern, monitors the power of each detection pattern, and sends the transmission signal in the form of electromagnetic waves;

[0027] The transmitted signal propagates through space to form a far-field radiation field distribution. After random modulation and reflection by the random modulation plane, it is radiated into the target area. The target area generates a scattered field, which is then randomly modulated and reflected by the random modulation plane twice and propagated to the receiver.

[0028] The receiver completes the collection of target echoes, positioning of the target, integration of the first-order statistical characteristics of the spatial distribution of the echo signal, filtering with a matched filter, and fast transformation method to achieve target imaging.

[0029] As a further improvement of the present invention, the detection mode includes a single beam or a random detection beam.

[0030] As a further improvement of the present invention, the receiver adopts sparse large-aperture array beam scanning to receive secondary modulated echo signals, and designs a matched filter based on prior knowledge of the target; and also recovers the phase of the first-order statistic of the integrated signal spatial distribution through a phase recovery algorithm.

[0031] Compared with the prior art, the present invention has the following technical effects:

[0032] The encoding method of the transmission signal generated by the device of the present invention at the transmitting end is not limited and can be a random or non-random signal. The only difference is the detection coding efficiency. After secondary modulation of the random modulation plane, the aperture of the secondary radiation source is effectively expanded, and the two-dimensional random radiation field in time and space can be irradiated on the target plane, thereby greatly improving the resolution capability of the system; a sparse large-aperture array beam scanning is used to receive the secondary modulated echo signal, with a narrow beam width and higher sampling accuracy; after the first-order statistics of the signal space distribution are integrated, the result is more accurate and stable, effectively eliminating the interference of the random modulation plane on the echo signal; a matched filter is designed based on prior knowledge such as the target size and orientation, greatly reducing the number of detections, improving detection efficiency, and realizing target detection imaging under low signal-to-noise ratio; a phase recovery algorithm recovers the phase of the first-order statistics of the signal space distribution after integration, resists phase disturbances, and improves image quality. The incoherent detection feature of the invention provides a basis for realizing super-resolution computational imaging. Based on the secondary modulated radiation source, this method effectively expands the aperture of the secondary radiation source without increasing the radiation array, thereby greatly improving the resolution capability of the system. In addition, to address the interference of the target echo by the secondary random modulation plane, an intensity coherent imaging method based on the first-order statistical characteristics of the radiation field is proposed, and robust high-resolution imaging is achieved with the help of a large-aperture sparse receiving array.

[0033] This non-line-of-sight high-resolution microwave intensity coherent staring imaging device and method first uses a detection mode to emit electromagnetic waves that meet target detection requirements. This then enables beyond-line-of-sight propagation of these electromagnetic waves. Simultaneously, the target's scattering field undergoes secondary random modulation, generating a two-dimensional random radiation field in both time and space, providing more information for feature extraction and synthesis modules. This method then locates the target and reconstructs its scattering coefficient distribution image, resulting in super-resolution imaging of the target. A matched filter is used to improve detection efficiency, and a phase recovery algorithm is employed to combat phase disturbances and enhance image quality.

[0034] Furthermore, the device of the invention makes the detection process highly anti-interference, and the imaging algorithm can significantly improve the imaging resolution by more than 3 times; the lower the signal-to-noise ratio, the higher the number of detections required, and the time cost will increase accordingly; the present invention can achieve the above effects for both slow-moving targets and stationary targets. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 Schematic diagram of a non-line-of-sight high-resolution microwave intensity coherent staring imaging device according to an embodiment of the present invention;

[0036] Figure 2 Schematic diagram of the imaging scene of the example of the present invention;

[0037] Figure 3 This is a flow chart of a non-line-of-sight high-resolution microwave intensity coherent staring imaging device and method provided by an embodiment of the present invention;

[0038] Figure 4 The imaging result of the static target scene given in the example of the present invention. DETAILED DESCRIPTION

[0039] The following is a clear and complete description of the technical solutions in the embodiments of the present invention, in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0040] By applying the intensity interferometry imaging method in optics, and from the statistical characteristics of the two-dimensional random radiation field in time and space, it is concluded that the Fourier transform of the autocorrelation of the radiation source target and its far-field scattering field is proportional. The non-line-of-sight high-resolution microwave intensity coherent staring imaging device scenario refers to a non-line-of-sight scenario in which the target scattering field undergoes secondary random modulation and reflection on a random modulation plane, extracts the first-order statistical characteristics of the spatial distribution of the received signal, and synthesizes multiple samples to quickly transform and invert the target image. At the same time, matched filtering is used for filtering to improve detection efficiency and achieve detection of weak targets with low signal-to-noise ratio. The phase recovery algorithm is used to solve the phase disturbance problem and improve the image reconstruction quality. The invention has the super-resolution imaging characteristics of the non-coherent computational imaging system and good anti-interference characteristics.

[0041] like Figure 1 As shown, an embodiment of the present invention provides a non-line-of-sight high-resolution microwave intensity coherent staring imaging device, comprising: a transmitter 1, a random modulation plane 2, and a receiver 3; the transmitter 1, the random modulation plane 2, and the receiver 3 are connected via an air interface or a physical interface;

[0042] The transmitter 1 includes a signal generation module 11 and a detection mechanism generation module 12;

[0043] The signal generation module 11 is used to complete the generation of the transmission signal through parameter configuration, and transmit the generated transmission signal data to the detection mechanism generation module 12; specifically:

[0044] The signal generation module 11 completes signal generation through parameter configuration, etc. The configuration parameters include bandwidth, duration, frequency, signal encoding method, and the relationship between channel data in a multi-channel case; the generated signal data is transmitted to the detection mechanism generation module 12; in an embodiment of the present invention, a pulse signal with high coding gain and short duration is generated, and polarization, bandwidth, frequency and other information are designed through single-channel excitation to generate a certain number of detection modes.

[0045] The signal generation module 11 specifically designs signal encoding that meets the requirements of random or non-random amplitude and phase through a phased array antenna distribution random or non-random phase method, and generates a single-channel or multi-channel signal.

[0046] The detection mechanism generation module 12 is used to realize the generation of random or non-random detection beams, the monitoring of transmission power, and the transmission of transmission signals in the form of electromagnetic waves; specifically:

[0047] The detection mechanism generation module 12 is used to generate a detection mode (single beam or random detection beam), which corresponds to the monitoring of the transmission power and the transmission of the signal in the form of electromagnetic waves; the detection mechanism generation module completes the generation and transmission of a large number of detection modes on the aperture composed of single-path excited signal radiation units by designing discrete frequency, time, phase and other information.

[0048] Specifically, the detection mechanism generation module 12 includes a beamforming module 121, a power monitoring module 122 and a transmitting module 123; the beamforming module 121 completes the generation of the detection mode through single-channel excitation or random modulation array; the power monitoring module 122 completes the monitoring of the transmission power corresponding to the detection mode; the transmitting module 123 transmits the transmission signal in the form of electromagnetic waves.

[0049] The number of detection modes formed by the beamforming module 121 is huge, and the correlation between the detection modes is adjusted as needed; the power monitoring module 122 completes the monitoring of the transmission power corresponding to the detection mode; and the transmitting module 123 completes the transmission signal transmission drive and beamforming.

[0050] In an optional embodiment of the present invention, the function of the beamforming module 121 is performed by a planar coating of a metamaterial (a combination of units having polarization-sensitive properties).

[0051] In an optional embodiment of the present invention, the random modulation plane 2 is an artificial random metasurface or a naturally occurring random variation modulation medium, which is used to perform secondary random modulation on the amplitude and phase of the incident wave signal so that the incident wave signal is scattered in all directions.

[0052] The random modulation plane 2 refers to an artificial random modulation plane or a rough surface in a natural environment, such as plasma.

[0053] The receiver 3 includes a receiving module 31, a feature extraction and synthesis module 32, a data processing module 33 and a target positioning imaging module 34; the modules of the transmitter 1 are connected through an internal interface; the modules of the receiver 3 are connected through an internal interface;

[0054] The receiving module 31 is a sparse large-aperture array used for beam scanning, thereby receiving the target reflected echo, converting it into a digital signal and outputting it to the feature extraction and synthesis module 32; specifically:

[0055] The receiving module 31 receives electromagnetic wave signals via an antenna and converts them into digital signals using a signal processing device. The receiving module 31 converts electromagnetic wave signals into digital signals. The antenna used by the receiving module has a single beam or a random radiation beam with the same frequency (polarization, bandwidth, encoding, etc.) as the transmitting detection mode. The receiving module 31 uses a sparse large-aperture array to collect target echoes through electromagnetic wave receiving devices discretized in the frequency (polarization, bandwidth, encoding, etc.) dimension. This maximizes the temporal and spatial distribution characteristics of the target echo signals, providing as much information as possible for subsequent target feature extraction. The echo signal data is then transmitted to the feature extraction and synthesis module 32.

[0056] The feature extraction and synthesis module 32 uses digital signal processing devices to complete the first-order statistical feature extraction of the spatial distribution of the echo signal, and synthesizes the features of multiple detection signals under the set number of detection times, and then transmits the data to the data processing module 33; the data processing module 33 uses a matched filter to filter the integrated data according to prior information such as the target size and orientation, thereby improving the detection efficiency, and finally transmits the data to the target positioning imaging module 34; the target positioning imaging module 34 uses the echo information to complete the estimation of the target orientation, and uses a fast transformation method to reconstruct the target image for the data transmitted by the data processing module 33, and uses a phase recovery algorithm to solve the phase disturbance problem, improve the anti-interference performance, and improve the image reconstruction quality.

[0057] The target positioning and imaging algorithm used by the target positioning and imaging module 34 is adjusted according to the system requirements. Accordingly, the imaging algorithm can simultaneously achieve fast high-resolution imaging of a small area and fast imaging of a large area.

[0058] The present invention also provides an imaging method based on the above-mentioned microwave staring imaging device based on intensity coherence under secondary modulation.

[0059] use Figure 3 The imaging scene shown in the figure is a scene in which the target is stationary or moving slowly during the imaging process. The embodiment of the present invention is further described in detail below with reference to the accompanying drawings. Figure 2 FIG2 is a flow chart of a microwave staring imaging method based on intensity coherence under secondary modulation provided by an embodiment of the present invention. The method includes the following steps:

[0060] In step 201, the transmitter 1 generates a transmission signal through the signal generation module 11, generates paired detection modes using the detection mechanism generation module 12, accurately monitors the power of each detection mode, and finally sends the transmission signal in the form of electromagnetic waves.

[0061] The detection pattern has random or non-random characteristics in spatial and temporal (phase, encoding, etc.) dimensions, and the correlation between the detection patterns is adjusted as needed. Power monitoring can obtain the precise power value of the detection pattern.

[0062] The detection mode includes a single beam or a group of random detection beams.

[0063] Step 202: The transmitted signal propagates through space to form a far-field radiation field distribution. After random modulation and reflection by random modulation plane 2, it is radiated into the target area. The target area generates a scattered field, which is then randomly modulated and reflected by random modulation plane 2 again and propagates to the receiver.

[0064] The random modulation plane 2 performs random modulation on the amplitude and phase of the signal.

[0065] The random modulation plane 2 can randomly modulate the incident beam, so that the incident beam is randomly scattered in various directions, forming diffuse reflection.

[0066] In step 203, the receiver 3 uses the receiving module 31 to complete the collection of the target echo, the feature extraction and synthesis module 32 completes the extraction and synthesis of the first-order statistical features of the spatial distribution of the echo signal, the data processing module 33 uses the matched filter to complete the filtering of the synthesized data according to the prior information such as the target size and orientation, and the target positioning and imaging module 34 completes the positioning of the target, the rapid transformation method realizes the imaging of the target, and the phase recovery algorithm improves the image quality.

[0067] The design of the matched filter is based on the available information before detection, or information that can be quickly extracted through detection. The characteristics of the detection process can be modified by obtaining the detection data.

[0068] Among them, sparse large-aperture array beam scanning is used to receive secondary modulated echo signals; a matched filter is designed based on prior knowledge of the target such as target size and orientation; and a phase recovery algorithm is used to recover the phase of the first-order statistics of the integrated signal spatial distribution, thereby improving accuracy and image quality.

[0069] This invention significantly improves the measurement accuracy of targets and achieves super-resolution imaging, breaking through the aperture limitation of traditional staring imaging resolution while also enabling high-precision detection of faint targets with low signal-to-noise ratio.

[0070] This imaging method can effectively resist random noise and interference, significantly improve imaging resolution, and break through the diffraction limit. At the same time, this imaging method has similar imaging effects for stationary targets and slow-moving targets, and the improvement in imaging resolution depends on the imaging algorithm.

[0071] In an optional embodiment of the present invention, the transmitted signal is a zero-mean complex Gaussian signal, the center frequency of the transmitted signal is 3 GHz, the imaging distance is 1 km, the length of the random modulation plane is not less than 1.3 km, and the width is 0.17 km. The minimum interval between discrete points in the imaging target domain is 0.25 m, and the scanning range of the receiving array is as follows: Figure 3 Shown: Azimuth angle range The pitch angle range θ∈(50°,70°); Figure 3 As shown, σ is the target plane scattering coefficient, S t is the target scattered field, S I is the signal of the target scattered field after secondary random modulation, S r The signal received by the large aperture sparse array is -30dB, and the detection samples are accumulated 1000 times. The imaging results of the stationary target are as follows: Figure 4 As shown, the imaging resolution is significantly improved compared to the traditional imaging resolution which is limited by the aperture of the transmitting radar array.

[0072] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A non-line-of-sight high-resolution microwave intensity coherent staring imaging device based on secondary modulation, characterized in that: include: Transmitter (1), random modulation plane (2) and receiver (3); The transmitter (1) comprises a signal generating module (11) and a detection mechanism generating module (12); The signal generation module (11) is used to generate a transmission signal through parameter configuration, and the transmission signal is transmitted to the detection mechanism generation module (12); The detection mechanism generation module (12) is used to realize the generation of random or non-random detection beams, the monitoring of transmission power, and the transmission of transmission signals in the form of electromagnetic waves; The random modulation plane (2) is used to perform secondary random modulation on the amplitude and phase of the electromagnetic wave signal, so that the incident wave signal is scattered in all directions; The receiver (3) includes a receiving module (31), a feature extraction and synthesis module (32), a data processing module (33) and a target positioning imaging module (34); The receiving module (31) is used to perform beam scanning and receive target reflected echoes, convert the reflected echoes into digital signals and output them to the feature extraction and synthesis module (32); The feature extraction and synthesis module (32) is used to extract the first-order statistical features of the spatial distribution of the echo signal, and to perform data synthesis on the features of multiple detection signals under a set number of detection times, and transmit the data to the data processing module (33); The data processing module (33) uses a matched filter to filter the integrated data according to the prior information; The target positioning imaging module (34) is used to estimate the target orientation using echo information and reconstruct the target image using a fast transformation method based on the data transmitted by the data processing module.

2. The non-line-of-sight high-resolution microwave intensity coherent staring imaging device according to claim 1, characterized in that: The signal generation module (11) is also used to generate signal encoding with random or non-random amplitude and phase requirements by allocating random or non-random phases through a phased array antenna, thereby generating a single-channel or multi-channel signal.

3. The non-line-of-sight high-resolution microwave intensity coherent staring imaging device according to claim 1, characterized in that: The detection mechanism generation module (12) includes a beamforming module (121), a power monitoring module (122) and a transmitting module (123); The beamforming module (121) is used to generate a detection pattern through a single source or a random modulation array excitation; The power monitoring module (122) is used to monitor the transmission power corresponding to the detection mode; The transmitting module (123) is used to transmit a transmission signal in the form of electromagnetic waves.

4. The non-line-of-sight high-resolution microwave intensity coherent staring imaging device according to claim 1, characterized in that: The beamforming module (121) has a metamaterial planar coating.

5. The non-line-of-sight high-resolution microwave intensity coherent staring imaging device according to claim 1, characterized in that: The random modulation plane (2) adopts an artificial random super surface or a rough surface in a natural environment.

6. The non-line-of-sight high-resolution microwave intensity coherent staring imaging device according to claim 1, characterized in that: The antenna used by the receiving module (31) is a sparse large-aperture array, and the target echo is collected through an electromagnetic wave receiving device discretized in the frequency dimension.

7. The non-line-of-sight high-resolution microwave intensity coherent staring imaging device according to claim 1, characterized in that: The target positioning imaging module (34) is further used to recover the phase of the first-order statistic of the integrated signal spatial distribution using a phase recovery algorithm.

8. An imaging method using the non-line-of-sight high-resolution microwave intensity coherent staring imaging device according to any one of claims 1 to 7, characterized in that: The following steps are involved: The transmitter (1) generates a transmission signal, produces a detection pattern, monitors the power of each detection pattern, and sends the transmission signal in the form of electromagnetic waves; The transmitted signal propagates through space to form a far-field radiation field distribution, undergoes random modulation and reflection by the random modulation plane (2), and is radiated in the target domain. The target domain generates a scattered field, which undergoes secondary random modulation and reflection by the random modulation plane and propagates to the receiver (3). The receiver (3) completes the collection of target echoes, the positioning of the target, the synthesis of the first-order statistical characteristics of the spatial distribution of the echo signals, the filtering of the matched filter, and the imaging of the target using a fast conversion method.

9. The imaging method according to claim 8, characterized in that The detection mode includes a single beam or a random detection beam.

10. The imaging method according to claim 8, characterized in that The receiver (3) adopts sparse large-aperture array beam scanning to receive the secondary modulated echo signal, and designs a matched filter based on prior knowledge of the target; and also recovers the phase of the first-order statistic of the integrated signal spatial distribution through a phase recovery algorithm.

Images