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Rotating speed estimation and calibration method for near-field turntable target

A rotation speed and target technology, applied in the radar field, can solve the problems of near-field ISAR imaging distortion, estimation of near-field target motion parameters not involved, and achieve the effect of improving computing efficiency

Pending Publication Date: 2021-06-15
HARBIN INST OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0003] The purpose of the present invention is to solve the problem that the existing near-field ISAR imaging method assumes that the motion parameters of the target are known and does not involve the estimation of the motion parameters of the near-field target, resulting in distortion of near-field ISAR imaging, and proposes a near-field target Rotation Speed ​​Estimation and Calibration Method

Method used

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  • Rotating speed estimation and calibration method for near-field turntable target
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  • Rotating speed estimation and calibration method for near-field turntable target

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specific Embodiment approach 1

[0037] Specific implementation mode 1: In this implementation mode, a method for estimating and calibrating the rotational speed of a near-field turntable target has a specific process as follows:

[0038] The radar receives the echo signal of the near-field target, performs motion compensation on the signal, converts the target into a turntable target, uses the R-D algorithm to image, and obtains the one-dimensional range image and R-D image of the target respectively. Use the one-dimensional range image of the target to estimate the target rotation speed, calculate the normalized amplitude variance of each distance unit corresponding to the slow time signal, and select the distance unit with distinctive points; integrate the cubic polynomial phase signal of the distance unit The parameters of the generalized cubic phase function (IGCPF) are estimated to obtain the phase coefficients of each order of the signal; the rotation speed of the target is estimated by using each order...

specific Embodiment approach 2

[0047] Specific embodiment two: the difference between this embodiment and specific embodiment one is: in the step two, calculate the one-dimensional distance image S(k n , each distance unit in m) corresponds to the slow time signal The normalized amplitude variance of , to judge whether there is a distinctive point in the distance unit;

[0048] The specific process is:

[0049] Calculate the one-dimensional range image S(k n , each distance unit in m) corresponds to the slow time signal The normalized magnitude variance of , the normalized magnitude variance is defined as

[0050] Among them, E represents the mean value operation; k is the number of certain distance units;

[0051] When the normalized magnitude variance value is less than 0.12, it is preliminarily considered that there are isolated characteristic points in the corresponding distance unit, and the 8- 10 distance units (8, 9 or 10 distance units corresponding to the smallest normalized magnitude vari...

specific Embodiment approach 3

[0053] Specific embodiment three: the difference between this embodiment and specific embodiment one or two is that in the step three, select the distance unit that has a characteristic point in the step two, and use the integral type generalized cubic phase function IGCPF to correspond slowly to the distance unit time signal k (m) Carry out cubic polynomial phase signal parameter estimation, obtain the estimated value of each phase coefficient of signal; Concrete process is:

[0054] Step 31. Assume that the discrete form of the slow-time cubic polynomial phase signal corresponding to the distance unit is s k (m) = σ 0 exp[j(a 1 m+a 2 m 2 +a 3 m 3 )],

[0055] in, M is the length of the azimuth signal, σ 0 is the signal amplitude, a p Indicates the phase coefficient of each order, p=1,2,3; j is the imaginary unit, j 2 =-1;

[0056] Signal s in step 32 and step 31 k The generalized cubic phase function GCPF of (m) is defined as

[0057]

[0058] in,(·) * is ...

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Abstract

The invention discloses a rotating speed estimation and calibration method for a near-field turntable target, and relates to a rotating speed estimation and calibration method for a near-field turntable target. The objective of the invention is to solve the problem of near-field ISAR imaging distortion caused by the fact that the existing near-field ISAR imaging method assumes that the motion parameter of a target is known and does not involve the estimation of the motion parameter of a near-field target. The method comprises the following steps: 1, obtaining an R-D image of a target; 2, calculating a normalized amplitude variance of a slow time signal corresponding to each distance unit in the one-dimensional distance image, and judging whether each distance unit has a dominant display point or not; 3, obtaining an estimated value of each phase coefficient of the signal; 4, estimating an estimated value of the rotating speed of the target; and 5, according to the estimated value of the rotating speed of the target, determining the mapping relation of a target scattering point on the R-D image, and performing interpolation operation on the target R-D image to obtain an ISAR image reflecting the real shape and size of the target. The method is applied to the technical field of radars.

Description

technical field [0001] The invention belongs to the technical field of radar and relates to a method for estimating and calibrating the rotation speed of a near-field turntable target. Background technique [0002] Traditional ISAR works under the assumption of far-field plane waves. The distance between the target and the radar is much greater than the lateral size of the target. Through the approximation of the distance formula, the imaging results obtained by the far-field ISAR imaging method can reflect the real shape of the target, and then the horizontal calibration technology The motion parameters of the target can be estimated from the echo or image, the actual physical size represented by the azimuth unit can be calculated, and the size information of the target can be obtained. However, as new ISAR application scenarios continue to emerge, radars may work in near-field conditions, that is, the distance between the target and the radar is relatively close, which is ...

Claims

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Application Information

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IPC IPC(8): G01S13/58G01S13/90
CPCG01S13/58G01S13/9021
Inventor 王勇周兴宇
Owner HARBIN INST OF TECH
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