Ship target ISAR imaging method based on fractional Fourier transform

A technology of fractional Fourier transform and imaging method, which is applied in the field of ship target ISAR imaging, and can solve the problems of irregular time-varying Doppler frequency, complex movement, and serious three-dimensional rotation of the target.

Active Publication Date: 2018-06-01
BEIJING INSTITUTE OF TECHNOLOGYGY +1
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Problems solved by technology

In the case of complex sea conditions, the movement of the ship target is also complex, the three-dimensional rotation of the target is very serious, and the time-varying Doppler frequency is even more irregular. At thi

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  • Ship target ISAR imaging method based on fractional Fourier transform
  • Ship target ISAR imaging method based on fractional Fourier transform
  • Ship target ISAR imaging method based on fractional Fourier transform

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[0093] In order to better understand the present invention, the content of the present invention will be further described below in conjunction with the accompanying drawings and examples.

[0094] The present invention provides a kind of ship target ISAR imaging method based on fractional Fourier transform, such as figure 1 and Figure 16 shown, including:

[0095] (1) Obtain the radar echo signal of the scattered point of the ship target in each range unit:

[0096] Among them, the distance unit is divided into distance units according to the distance resolution of the radar. In the radar image, when two targets are located at the same azimuth, but the distance from the radar is different, the minimum distance between the two is distinguished by the radar. Rate. It is usually defined as the distinguishable limit when the falling edge of the echo pulse of the closer target coincides with the rising edge of the echo pulse of the farther target. The distance between the two...

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Abstract

The invention provides a ship target ISAR imaging method based on fractional Fourier transform. The ship target ISAR imaging method comprises the steps of: acquiring a radar echo signal of a scattering point of a ship target in each distance unit; modeling the acquired radar echo signals in the distance units into multi-component secondary frequency modulation signals through pulse compression andmotion compensation; determining estimated parameters of scattering point echo signals in the distance units according to the secondary frequency modulation signals; updating radar echo signals in the distance units by adopting the estimated parameters of the scattering point echo signals in the distance units; and acquiring an ISAR image of a ship target by utilizing the updated radar echo signals. The ship target ISAR imaging method adopts a symmetrical correlation function, fractional Fourier transform and multi-product processing for the radar echo signals in sequence, avoids the couplingof time and time delay, estimates a quadratic term phase coefficient and a cubic term phase coefficient with high precision, adopts a range-instantaneous-Doppler imaging technology combining with parameter estimation, and obtains a high-quality and high-precision ISAR image of a moving target.

Description

technical field [0001] The invention relates to microwave imaging technology, in particular to a fractional-order Fourier transform-based ISAR imaging method for ship targets. Background technique [0002] Synthetic Aperture Radar (SAR) is the most common imaging radar, which is usually installed on moving platforms such as aircrafts and satellites, and is used to image delicate targets, that is, to the ground. Its essence is to synthesize a huge and effective antenna aperture equivalently in the azimuth direction through the relative motion between the radar and the target, thereby breaking through the limitation of the radar's real aperture antenna on the azimuth resolution, and making the radar imaging technology move towards A new level. Inverse Synthetic Aperture Radar (ISAR) is another radar imaging technology developed on the basis of SAR, aiming at solving the imaging problem of moving targets. ISAR is mostly placed in a fixed position to image moving targets, main...

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Application Information

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IPC IPC(8): G01S13/90
CPCG01S13/90G01S13/9064
Inventor 辛红彩白霞宋玉娥李炳照陶然
Owner BEIJING INSTITUTE OF TECHNOLOGYGY
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