Subjects: Information Science and Systems Science >> Basic Disciplines of Information Science and Systems Science submitted time 2023-02-14 Cooperative journals: 《桂林电子科技大学学报》
Abstract： Aiming at the problem of blurred target position and high sidelobe when the back projection algorithm (BP algorithm)
is imaging multi-targets, after analyzing the accumulation characteristics of the FDA target echo amplitude, a target
imaging method of frequency diversity array radar based on clustering and coherent superposition is proposed. In the analysis
and Simulation of BP algorithm imaging process, it is found that the target point has the characteristics of energy concentration
and energy difference with the virtual image point. The K-means clustering algorithm can make full use of these characteristics
of the target point to extract and classify the target points in the radar imaging area, and only compensate the time
delay of the grid points of the specific cluster after classification, and then stack the echo amplitude, Thus, the energy value
of the time delay compensation grid points in the imaging region is obtained, and finally the multi-target clear two-dimensional
imaging is realized. The simulation results show that the proposed method can effectively solve the problems of fuzzy
position and high sidelobe when BP algorithm imaging multi-target, and improve the accuracy of imaging results.
Subjects: Information Science and Systems Science >> Basic Disciplines of Information Science and Systems Science submitted time 2023-02-14 Cooperative journals: 《桂林电子科技大学学报》
Abstract： Aiming at the problem of the large number of array elements and low utilization rate of the three-dimensional synthetic
aperture radar (3D-FDA-SAR) imaging method of frequency diversity arrays, a 3D-FDA-SAR imaging method based
on multiple input and multiple output arrays is proposed. The frequency diversity array of 3D-FDA-SAR tangent track direction
is changed to multiple input multiple output frequency diversity array. The multiple input multiple output frequency
diversity array moves with the moving platform to form a synthetic aperture along the track direction, combined with the
tangent track direction The real array is combined with a virtual two-dimensional frequency diversity array plane to obtain the
downward-looking three-dimensional imaging capability of the target. Firstly, a multi-input multi-output 3D-FDA-SAR imaging
model and signal model are established, using multi-input multi-output technology, the waveform quadrature signal
single-frequency narrowband signal is sent at the transmitting end, and all the transmitting arrays are received through the
full-frequency receiving mode at the receiving end. The echo signal reflected by the target is separated by a quadrature
matched filter to obtain the echo data of different receiving and sending channels, and then the echo data is imaged by the
backward projection algorithm, and finally the three-dimensional imaging result of the target is obtained. Experimental simulation
results show that the 3D-FDA-SAR imaging method based on multiple-input multiple-output arrays uses a small
number of array elements, improves the utilization of the array elements, and obtains the three-dimensional imaging capability
of downward-looking targets.
Subjects: Information Science and Systems Science >> Basic Disciplines of Information Science and Systems Science submitted time 2023-02-14 Cooperative journals: 《桂林电子科技大学学报》
Abstract： The hardware design of phased array three-dimension synthetic aperture radar (SAR) system based on wideband
transmission signals is complicated, and the received signals are difficult to separate. By applying the frequency diverse array
(FDA) to 3D-SAR, each array element only needs to transmit a single frequency signal to obtain wideband observation performance,
which greatly reduces the hardware requirements of system. However, due to the space-frequency sparseness of
FDA echo signals, the resolution is limited and the sidelobes of radar images are relatively high when using the back projection
(BP) algorithm based on matched filtering. To solve this problem, this paper proposes a random frequency diverse array
3D-SAR imaging method based on compressed sensing (CS). The array elements in the tangent-track and the observation
positions in the along-track are selected randomly and sparsely to realize two-dimensional sparse sampling of echo data.
In the imaging part, orthogonal matching pursuit (OMP) algorithm is used to reconstruct the scattering coefficient of targets.
Simulation and experimental results show that CS method not only reduces the data processing amount of FDA-3DSAR
system during imaging, but also effectively suppresses the sidelobes of radar images, and the imaging quality is significantly
improved. By using the compressed sensing algorithm, FDA-3D-SAR can accurately reconstruct the information of
space targets when the echo is sparse, which verifies the rationality and effectiveness of the proposed method.
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