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Step frequency inverse synthetic aperture radar (ISAR) imaging method based on coherent processing

A technology of stepping frequency and imaging method, applied in the field of radar, can solve the problems of poor side lobe, low operation efficiency, widening of the main lobe of target image, etc.

Active Publication Date: 2013-03-27
XIDIAN UNIV
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Problems solved by technology

[0005] 1. The minimum entropy method needs to use the search method to estimate the motion parameters, the search step size is difficult to control, and the operation efficiency is low
[0006] 2. Fitting the motion parameters of the target through the movement of the echo envelope, the estimation error is large, and the residual phase error is also large, which seriously affects the coherence between the sub-pulses in the pulse group and makes the synthesized target image appear Phenomenon of main lobe broadening and side lobe deterioration

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  • Step frequency inverse synthetic aperture radar (ISAR) imaging method based on coherent processing
  • Step frequency inverse synthetic aperture radar (ISAR) imaging method based on coherent processing
  • Step frequency inverse synthetic aperture radar (ISAR) imaging method based on coherent processing

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Embodiment Construction

[0037] The present invention will be further described below in conjunction with the accompanying drawings.

[0038] refer to figure 1 , the specific implementation steps of the present invention are as follows:

[0039] Step 1. Establish a stepped frequency ISAR echo signal model.

[0040] Assume that the waveform of the radar transmitting chirp signal is:

[0041] U(t)=u 1 (t)exp(j2π(f 0 +nΔf)t) 0≤n≤N-1

[0042] where u 1 (t)=rect(t / T 1 )exp(jπγt 2 ) is the chirp sub-pulse, exp is the base of the exponential function, j is an imaginary number, and f 0 is the fundamental frequency, n is the number of frequency modulation step sub-pulses, Δf is the frequency step amount, f 0 +nΔf is the carrier frequency of the nth FM step sub-pulse, t is time, N is the step frequency modulation number of sub-pulse in each pulse group, T 1 is the sub-pulse width, γ is the modulation frequency of the sub-pulse;

[0043] The distance between any scattering point P on the moving target...

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Abstract

The invention relates to a step frequency inverse synthetic aperture radar (ISAR) imaging method based on coherent processing. The method mainly solves the problems in a traditional parameter estimation method of being low in calculating efficiency and having large effects of phase error on frequency synthesis after envelope compensation. The method includes the steps: building a step frequency ISAR echo signal model; conducting motion parameter estimation according to the echo signal model; constructing a penalty function and compensating a sub-pulse envelope of echo signals; conducting frequency synthesis based on coherent processing on the compensated echo signals; conducting inverse fast Fourier transformation (IFFT) on the synthesized echo signals, and obtaining a high-resolution range profile; and conducting direction imaging through an RD algorithm or an RID algorithm to obtain a directional high-resolution image. Experiments prove that the method has the advantages of being high in phase error compensation precision and calculation efficiency and can be used for achieving two-dimensional high-resolution ISAR imaging of a target.

Description

technical field [0001] The invention belongs to the field of radar technology, in particular to an inverse synthetic aperture radar high-resolution imaging technology, which can be used to realize high-resolution two-dimensional imaging of targets. Background technique [0002] High-resolution ISAR imaging radar is widely used in modern radar systems because it can realize two-dimensional imaging of targets, obtain richer target scattering information, and facilitate target identification and classification. High-resolution ISAR imaging of targets requires increased vertical and lateral resolution of the radar. Lateral resolution is achieved by the rotation of the target relative to the radar, while vertical resolution is achieved by the large signal bandwidth emitted by the radar. [0003] The chirp signal is widely used in high-resolution imaging radar systems because it can synthesize large signal bandwidth and improve the longitudinal resolution of radar. There are gen...

Claims

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Application Information

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IPC IPC(8): G01S13/89
Inventor 李亚超全英汇邢孟道许斌周瑞雨
Owner XIDIAN UNIV
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