A fast imaging method based on MIMO array equivalent phase center data reconstruction

Abstract

The application discloses a kind of based on MIMO array equivalent phase center data reconstruction fast imaging method, receive broadband signal after target scattering obtains original scattering echo signal;According to the criterion of high-precision reconstruction of multi-station data to single-station data in spatial domain, the space domain of imaging space is divided;According to the criterion of high-precision reconstruction, the reconstruction of multi-station data to single-station data is completed;According to the reconstruction criterion, the space domain is divided, and the high-precision reconstruction of multi-station data to single-station data in each subspace is completed;The scattering echo signal after reconstruction is respectively transformed to the spatial frequency domain corresponding to array direction and synthetic aperture direction in each space domain, and the original spatial spectrum is determined;The original spatial spectrum is determined final spatial spectrum according to the wave number domain interpolation of spatial frequency domain coordinate relationship;According to final spatial spectrum, the target imaging function of each sub-space is determined;According to the space domain divided, the target imaging function of each sub-space is clipped and spliced, and the final target imaging function is obtained.

Description

Technical Field

[0001] This invention relates to intelligent integrated recognition technology, and in particular to a fast imaging method based on MIMO array equivalent phase center data reconstruction. Background Technology

[0002] The most common approach for radar 3D real-time imaging devices is to use a 2D array for rapid azimuth focusing and a broadband signal for range focusing. However, in higher frequency applications, such as millimeter-wave and terahertz bands, the large number of elements in a 2D array significantly increases system cost under current conditions, especially since millimeter-wave and terahertz devices themselves are relatively expensive. Although a 3D focused image can be obtained by using a single element for point-by-point 2D scanning combined with a broadband signal, the data acquisition time is too long, making real-time imaging impossible. Combining MIMO arrays with synthetic aperture technology can reduce the number of elements and lower system cost. However, current imaging algorithms based on MIMO arrays and synthetic aperture technology, such as the BP algorithm and MIMO-RMA algorithm, generally have low imaging efficiency to ensure image quality and accuracy. The BP algorithm, which requires phase compensation in each dimension before superposition, cannot meet real-time requirements. While the MIMO-RMA algorithm is considered a computationally efficient imaging algorithm, it requires zero-padding operations on both the transmit and receive dimensions before transforming from the azimuth dimension to the spatial frequency dimension, significantly increasing the number of interpolation operations and thus affecting computational efficiency. Summary of the Invention

[0003] To address the problems existing in the prior art, this invention provides a fast imaging method based on MIMO array equivalent phase center data reconstruction, which can perform real-time imaging and has a high computational speed.

[0004] The objective of this invention is achieved through the following technical solutions.

[0005] A fast imaging method based on MIMO array equivalent phase center data reconstruction, comprising the following steps:

[0006] A criterion for high-precision reconstruction of multi-station data into single-station data in the spatial domain is defined;

[0007] The original scattered echo signal is obtained after the broadband signal is scattered by the target.

[0008] Based on the criteria for high-precision reconstruction of multi-station data into single-station data in the spatial domain, the imaging space is divided into spatial domains.

[0009] In the partitioned subspace, the reconstruction of multi-station data into single-station data is completed according to the criteria of high-precision reconstruction;

[0010] The spatial domain is divided according to the reconstruction criterion, and high-precision reconstruction of multi-station data into single-station data in each subspace is completed;

[0011] The reconstructed scattering echo signal is transformed into the spatial frequency domain corresponding to the array direction and the synthetic aperture direction in each spatial domain, and the original spatial spectrum is determined;

[0012] The original spatial spectrum is interpolated in the wave number domain according to the spatial frequency domain coordinate relationship to determine the final spatial spectrum;

[0013] The target imaging function of each subspace is determined according to the final spatial spectrum;

[0014] The target imaging function of each subspace is cropped and spliced according to the divided spatial domain to obtain the final target imaging function.

[0015] The original scattering echo signal is:

[0016] ;

[0017] The transmitting antennas of the MIMO array are located at , the receiving antennas are located at , is the wave number corresponding to different transmitting frequencies of the wideband signal, and the distance of the plane where the synthetic aperture of the MIMO array is located is located at z; the coordinate position of the center point of the imaging space is defined as , which is located at the geometric center of the imaging space.

[0018] The criterion for high-precision reconstruction of multi-station data into single-station data in the defined spatial domain is as follows:

[0019] ;

[0020] wherein is the equivalent center of the transmitting and receiving antennas,

[0021]

[0022] are the distances of the transmitting and receiving antennas from the center point of the imaging space, respectively;

[0023]

[0024] is the distance of the equivalent center of the transmitting and receiving antennas from the center point of the imaging space;

[0025] The premise for high-precision reconstruction of multi-station data into single-station data is as follows:

[0026]

[0027] wherein, ,

[0028] ,

[0029] , respectively representing the distance between the transmitting and receiving antennas located at Target distance. After subspace partitioning and reconstruction from multi-station data to single-station data, the reconstructed subspace data undergoes further imaging algorithm processing. Specifically, this includes transforming the reconstructed scattered echo signals in each spatial domain to the spatial frequency domain corresponding to the array direction and synthetic aperture direction, respectively, to determine the original spatial spectrum; interpolating the original spatial spectrum in the wavenumber domain based on the spatial frequency domain coordinate relationship to determine the final spatial spectrum; and determining the target imaging function for each subspace domain based on the final spatial spectrum.

[0030] .

[0031] Based on the divided spatial domains, the target imaging functions of each sub-spatial domain are cropped and stitched together to obtain the final target imaging function.

[0032] Compared with the prior art, the advantages of this invention are:

[0033] 1. Compared to the classic BP algorithm, which can be used for any array configuration, the imaging speed has been improved.

[0034] 2. Compared to the MIMO-RMA algorithm, which requires zero padding and causes a significant increase in the number of interpolation operations, thus affecting computational efficiency, the imaging efficiency is significantly improved. Moreover, since the phase error is controlled within a reasonable range during the reconstruction of multi-station data into single-station data, the imaging efficiency is improved without reducing the imaging quality. Attached Figure Description

[0035] Figure 1 This is a schematic diagram illustrating the steps of a fast imaging method based on MIMO array equivalent phase center data reconstruction according to an embodiment of the present invention.

[0036] Figure 2 This is a schematic diagram of the structure of the fast imaging method device based on MIMO array equivalent phase center data reconstruction according to an embodiment of the present invention.

[0037] Figure 3 This is a schematic diagram of a MIMO linear array example. Detailed Implementation

[0038] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0039] Figure 1 This is a schematic diagram illustrating the steps of a fast imaging method based on MIMO array equivalent phase center data reconstruction according to an embodiment of the present invention, as shown below.Figure 1 As shown, the method includes the following steps:

[0040] S1, Receive the original scattered echo signal obtained after the broadband signal is scattered by the target.

[0041] In this system, the broadband signal is transmitted by the transmitting element of the MIMO array, and the receiving element of the MIMO array receives the original scattered echo signal.

[0042] In this embodiment of the invention, the MIMO array is selected as a linear array with the transmitter at both ends of the receiver array. It is understood that other forms of MIMO arrays may also be selected in other embodiments. Figure 2 This is a schematic diagram of a MIMO linear array synthetic aperture simulation scenario according to an embodiment of the present invention. Figure 3 This is a schematic diagram of a MIMO linear array example according to an embodiment of the present invention, as shown below. Figure 2 and Figure 3 As shown, in this MIMO linear array, the receiving elements are spaced at intervals of d. R Arranged such that at the ends of the first and last receiving elements, there are transmitting elements at intervals of d. T arrangement.

[0043] The original scattered echo signal is:

[0044] ;

[0045] The transmit antenna of the MIMO array is located at The receiving antenna is located at [location]. place, The wavenumbers corresponding to different transmission frequencies of the broadband signal are given, and the distance to the plane containing the MIMO array synthetic aperture is located at z; the coordinates of the center point of the imaging space are defined as follows: Its position is located at the geometric center of the imaging space.

[0046] S2. Based on the criteria for high-precision reconstruction of multi-station data into single-station data in the spatial domain, the imaging space is divided into spatial domains.

[0047] Subspace partitioning must satisfy the following conditions:

[0048]

[0049] in, ,

[0050] ,

[0051] , respectively representing the distance between the transmitting and receiving antennas located at Distance to the target;

[0052]

[0053]

[0054] respectively are the distances from the transceiver antenna to the center point of the imaging space.

[0055]

[0056] is the distance from the equivalent center of the transceiver antenna to the center point of the imaging space.

[0057] S3, in the divided subspaces, according to the high-precision reconstruction criterion, the multi-station data is reconstructed to single-station data:

[0058]

[0059] wherein is the equivalent center of the transceiver antenna,

[0060]

[0061]

[0062] respectively are the distances from the transceiver antenna to the center point of the imaging space.

[0063]

[0064] is the distance from the equivalent center of the transceiver antenna to the center point of the imaging space.

[0065] S4, the reconstructed scattering echo signal is transformed into the spatial frequency domain corresponding to the array direction and the synthetic aperture direction in each airspace respectively, and the original spatial spectrum is determined;

[0066] S5, the original spatial spectrum is determined according to the spatial frequency domain coordinate relationship in the wave number domain, and the final spatial spectrum is determined by interpolation;

[0067] S6, according to the final spatial spectrum, the target imaging function of each sub-space is determined;

[0068] S4-S6 calculation formula is as follows:

[0069]

[0070] According to the divided airspace, the target imaging function of each sub-space is cropped and spliced to obtain the final target imaging function.

[0071] It can be seen that the fast imaging method based on MIMO array equivalent phase center data reconstruction has high-precision reconstruction criterion from multi-station data to single-station data, avoids zero padding operation in multiple space dimensions, further reduces interpolation calculation, and in turn shortens imaging time; since the phase error is controlled within a reasonable range in the process of reconstructing multi-station data into single-station data, the imaging quality can be guaranteed without being reduced.

[0072] In conclusion, compared with the classic BP algorithm which can be used for any array form, the fast imaging method and device based on MIMO array equivalent phase center data reconstruction has improved imaging speed; compared with the MIMO-RMA algorithm which needs zero padding operation, causes the number of interpolation operations to increase significantly, and in turn affects the calculation efficiency, the imaging efficiency is obviously improved, and since the phase error is controlled within a reasonable range in the process of reconstructing multi-station data into single-station data, the imaging efficiency is improved without reducing the imaging quality.

Claims

1. A fast imaging method based on MIMO array equivalent phase center data reconstruction, characterized by the following steps: include: A criterion for high-precision reconstruction of multi-station data into single-station data in the spatial domain is defined; The original scattered echo signal is obtained after the broadband signal is scattered by the target. Based on the criteria for high-precision reconstruction of multi-station data into single-station data in the spatial domain, the imaging space is divided into spatial domains. In the partitioned subspace, the reconstruction of multi-station data into single-station data is completed according to the criteria of high-precision reconstruction; The spatial domain is divided according to the reconstruction criteria, and high-precision reconstruction of multi-station data to single-station data is completed in each subspace. The reconstructed scattered echo signal is transformed into the spatial frequency domain corresponding to the array direction and the synthetic aperture direction in each spatial domain to determine the original spatial spectrum. The original spatial spectrum is interpolated in the wavenumber domain based on the spatial frequency domain coordinate relationship to determine the final spatial spectrum; The target imaging function for each sub-spatial domain is determined based on the final spatial spectrum. Based on the divided spatial domains, the target imaging functions of each sub-spatial domain are cropped and stitched together to obtain the final target imaging function; The original scattered echo signal is: ； The transmit antenna of the MIMO array is located at The receiving antenna is located at [location]. place, The wavenumbers corresponding to different transmission frequencies of the broadband signal are given, and the distance to the plane containing the MIMO array synthetic aperture is located at z; the coordinates of the center point of the imaging space are defined as follows: The location is at the geometric center of the imaging space; the criteria for high-precision reconstruction of multi-station data from single-station data in the defined spatial domain are as follows: ； in It is the equivalent center of the transmitting and receiving antennas. ， ； These are the distances from the transmitting and receiving antennas to the center point of the imaging space; ; is the distance from the equivalent center of the transmitting and receiving antennas to the center point of the imaging space; The prerequisite for high-precision reconstruction of multi-station data into single-station data is the following: ； in, , ， , respectively representing the distance between the transmitting and receiving antennas located at Distance to the target.

2. The fast imaging method based on MIMO array equivalent phase center data reconstruction according to claim 1, characterized in that... After subspace partitioning and reconstruction from multi-station data to single-station data, the reconstructed subspace data undergoes further imaging algorithm processing. Specifically, this includes transforming the reconstructed scattered echo signals in each spatial domain to the spatial frequency domain corresponding to the array direction and synthetic aperture direction, respectively, to determine the original spatial spectrum; interpolating the original spatial spectrum in the wavenumber domain based on the spatial frequency domain coordinate relationship to determine the final spatial spectrum; and determining the target imaging function for each subspace domain based on the final spatial spectrum. 。 3. The fast imaging method based on MIMO array equivalent phase center data reconstruction according to claim 2, characterized in that... Based on the divided spatial domains, the target imaging functions of each sub-spatial domain are cropped and stitched together to obtain the final target imaging function.

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