KR102015177B1 - Apparatus for autofocusing and cross range scaling of isar image using compressive sensing and method thereof - Google Patents

Abstract

The present invention relates to an apparatus and method for auto focusing and vertical distance scaling of an ISAR image using compression sensing. According to the present invention, an autofocus and vertical distance scaling method of an ISAR image may include receiving a rare aperture signal for a target, a residual signal of a scattering point included in a distance bin for each distance bin of the rare aperture signal, and previously stored sensing Estimating parameters according to coordinates, translations, and irregular rotations for scattering points using an inter-matrix Pearson's correlation coefficient and calculating amplitudes corresponding to the parameters, using the estimated parameters and calculated amplitudes Reconstructing the ISAR video signal corresponding to the sparse aperture signal, removing signal components corresponding to translational and irregular rotation by using the reconstructed ISAR video signal, and then autofocusing through Fourier transform. Generating an image, and an angular velocity of the target calculated through the estimated parameters Calculating a vertical distance resolution and scaling the generated ISAR image according to the vertical distance resolution. Thus, according to the present invention, a sparse aperture signal is applied to a target's translational motion and irregular rotational motion. The resulting phase error signal can be reconstructed with the full ISAR video signal removed.

Description

Automatic focusing and vertical distance scaling apparatus of ISAR image using compression sensing and its method {APPARATUS FOR AUTOFOCUSING AND CROSS RANGE SCALING OF ISAR IMAGE USING COMPRESSIVE SENSING AND METHOD THEREOF}

The present invention relates to an apparatus and method for auto focusing and vertical distance scaling of an ISAR image using compression sensing, and more particularly, to reconstruct a rare aperture ISAR signal through compression sensing, thereby improving the throughput and the quality of the ISAR image. An apparatus and method for auto focusing and vertical distance scaling of an image.

High resolution radars are widely used in many military and civilian fields, including target classification and aircraft traffic control. This is because it has advantages such as robust performance, relatively high target identification capability, and interference suppression in all weather conditions compared to other remote sensing technologies.

In general, high-resolution target images can be obtained using inverse synthetic aperture radar (ISAR) techniques, while good distance resolution can be obtained by transmitting a wideband signal, while good vertical distance resolution can be obtained from targets at different aspect angles. Obtained by coherently processing the return echo signal.

However, if some of the data sets are missing from the observed echo data set, a correct ISAR image cannot be obtained using a two-dimensional (2D) imaging method based on Fourier transform (FT).

1 is a diagram illustrating a rare aperture signal.

As shown in FIG. 1, it is assumed that an nth distance bin is composed of M bursts in an ISAR video signal. In this case, vacant aperture data is generated due to interference such as other radar activity. That is, the received ISAR video signal receives data only in a partial interval (s _{1, n} , s _{2, n} ,..., S _{K, n} ), and thus the ISAR video signal becomes a rare aperture signal.

When generating FT-based ISAR images using such sparse-aperture (SA) signals, high side lobes regardless of translational and non-uniform rotational (RM) effects Occurs and the image quality is greatly degraded.

In order to solve the above problems, a study of reconstructing ISAR image from SA data set using compression sensing technique is underway. Compression sensing theory is well known that accurate recovery of unknown coarse signals can be achieved through limited measurements by solving the optimization problem of scarcity.

However, in the case of reconstructing the ISAR video signal using the conventional compression sensing method, all pixel values of the ISAR video are estimated. In this case, the computational cost is large and inefficient. In addition, the inner product of orthogonal matching tracking has a problem in that the resilience is poor because it is not sensitive to the similarity between the columns of the sensing dictionary matrix and the measurement vector.

Therefore, a new method for solving the problem of the ISAR image signal reconstruction algorithm using the conventional compression sensing technique is required.

The background technology of the present invention is disclosed in Korean Patent Registration No. 10-1617620 (2016.05.03.).

An object of the present invention is to provide an apparatus and method for auto focusing and vertical distance scaling of an ISAR image to improve the amount of computation and the quality of the ISAR image by reconstructing the rare aperture ISAR signal through compression sensing.

According to an embodiment of the present invention for achieving the above technical problem, a method for autofocusing and vertical distance scaling of an ISAR image comprises receiving a sparse aperture signal for a target, and scattering included in a distance bin for each distance bin of the sparse aperture signal Estimating a parameter according to the coordinates, translation, and irregular rotation of the scattering point using a residual signal of a point and a stored stored Pearson's correlation coefficient, and calculating an amplitude corresponding to the parameter. Reconstructing the ISAR video signal corresponding to the sparse aperture signal using the calculated parameters and the calculated amplitude, and using a reconstructed ISAR video signal to remove signal components corresponding to translation and irregular rotation, Generating an auto-focused ISAR image, and the estimation Using the angular velocity of the target calculated by the parameter calculating the perpendicular distance resolution, comprising the step of vertical distance scale the ISAR image of the generated according to the vertical distance resolution.

The calculating of the amplitude may include calculating a Pearson correlation coefficient between the first residual signal for the first scattering point and the basis function vector, and calculating the coefficients of the basis function vector at which the Pearson correlation coefficient is maximum, the coordinates, translations, and the like. Estimating a first parameter according to an irregular rotation, and performing a least square method on the first residual signal using a basis function vector corresponding to the first parameter, thereby performing a first amplitude of the signal corresponding to the first scattering point. It may include the step of calculating.

The reconstructing the ISAR image signal may include calculating a second residual signal using the first residual signal, the first parameter, and the first amplitude, and using the first and second residual signals. Comparing a function and a predetermined threshold value, and reconstructing the ISAR image signal or parameter estimation for the second scattering point according to the comparison result may include calculating the amplitude.

)를 추정할 수 있다. The calculating of the amplitude may be performed by using the following equation.

) Can be estimated.

이고,

는 i번째 산란점에 대한 신호 벡터이고,

는 상기 i번째 산란점에 대한 잔차 신호 벡터이고,

및

각각

와

의 표준 편차이고 E[

]는 예상 연산자이고,

와

는 각각

와

의 평균 벡터이다. here

ego,

Is the signal vector for the i th scattering point,

Is a residual signal vector for the i th scattering point,

And

each

Wow

Is the standard deviation of E [

] Is the expected operator,

Wow

Are each

Wow

Is the mean vector of.

)을 산출할 수 있다. The calculating of the amplitude corresponding to the parameter may be performed using the following equation.

) Can be calculated.

는 상기 추정된 매개 변수

에 기반한 기저 함수 벡터이다.here

Is the estimated parameter

Based function vector based on.

In the calculating of the second residual signal, the second residual signal may be calculated using the following equation.

는 n번째 거리빈의 i번째 산란점에 대한 잔차 신호 벡터이고,

는 n번째 거리빈의 i+1번째 산란점에 대한 잔차 신호 벡터이다.here

Is the residual signal vector for the i th scattering point of the n th distance bin,

Is the residual signal vector for the i + 1th scattering point of the nth distance bin.

The cost function C ₁ may be calculated using the following equation.

Δ is the preset threshold.

According to another embodiment of the present invention, an autofocus and vertical distance scaling apparatus of an ISAR image includes an input unit for receiving a sparse aperture signal for a target, and a residual signal of a scattering point included in a distance bin for each distance bin of the sparse aperture signal. A calculation unit for estimating a parameter according to coordinates, translation, and irregular rotation of scattering points using the stored Pearson's correlation coefficient between sensing matrices, and calculating an amplitude corresponding to the parameter, the estimated parameter and the calculation A reconstruction unit for reconstructing the ISAR image signal corresponding to the rare aperture signal using the amplitude, and removing the signal components corresponding to the translational and irregular rotation using the reconstructed ISAR image signal and then autofocusing through a Fourier transform. an image generator for generating a focused IRR image, and the estimated parameter And a scaling unit configured to calculate a vertical distance resolution using the calculated angular velocity and to vertically scale the generated ISAR image according to the vertical distance resolution.

Thus, according to the present invention, the sparse aperture signal can be reconstructed into a complete ISAR image signal from which phase error signals due to translational and irregular rotational movements of the target are removed. In addition, signal reconstruction and phase error elimination can be performed at the same time, and Fourier transform can be used to generate ISAR images, thus reducing the amount of computation.

In addition, the rotation speed of the target can be accurately calculated using the parameters estimated during the ISAR signal reconstruction process to obtain a well-balanced ISAR.

1 is a diagram illustrating a rare aperture signal.
2 is a block diagram of a device for auto focusing and vertical distance scaling of an ISAR image according to an exemplary embodiment of the present invention.
3 is a flowchart of a method for auto focusing and vertical distance scaling of an ISAR image according to an exemplary embodiment of the present invention.
4 is a flowchart for describing in detail the steps S320 and S330 of FIG. 3.
FIG. 5 is a flowchart for describing operation S340 of FIG. 3 in detail.
FIG. 6 is a flowchart for describing operation S350 of FIG. 3 in detail.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. In the drawings, parts irrelevant to the description are omitted in order to clearly describe the present invention, and like reference numerals designate like parts throughout the specification.

Throughout the specification, when a part is said to "include" a certain component, it means that it may further include other components, except to exclude other components unless specifically stated otherwise.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention.

2 is a block diagram of a device for auto focusing and vertical distance scaling of an ISAR image according to an exemplary embodiment of the present invention.

As shown in FIG. 2, the apparatus 200 for auto focusing and vertical distance scaling of an ISAR image according to an exemplary embodiment of the present invention includes an input unit 210, a calculator 220, a reconstructor 230, and an image generator 240. ) And the scaling unit 250.

First, the input unit 210 receives a rare opening signal for a target.

Next, the calculation unit 220 coordinates and translates the scattering point by using the Pearson's correlation coefficient between the residual signal of the scattering point included in the distance bin and the previously stored sensing matrix for each distance bin of the rare opening signal. And estimating a parameter according to the irregular rotation and calculating an amplitude corresponding to the parameter.

In detail, the calculator 220 calculates a Pearson correlation coefficient between the first residual signal and the basis function vector for the first scattering point. The calculator 220 estimates the coefficient of the basis function vector at which the Pearson correlation coefficient is maximum as the first parameter according to the coordinates, translation, and irregular rotation. The calculator 220 calculates a first amplitude of the signal corresponding to the first scattering point by performing a least square method on the first residual signal using the basis function vector corresponding to the first parameter.

Next, the reconstruction unit 230 reconstructs the ISAR image signal corresponding to the rare aperture signal using the estimated parameter and the calculated amplitude.

In detail, the reconstruction unit 230 calculates a second residual signal using the first residual signal, the first parameter, and the first amplitude. The reconstructor 230 compares the cost function calculated using the first and second residual signals with a predetermined threshold value, reconstructs the ISAR image signal or estimates the amplitude of the second scattering point according to the comparison result, and amplitude. To calculate.

Next, the image generator 240 removes signal components corresponding to translation and irregular rotation by using the reconstructed ISAR image signal, and then generates an auto-focusing ISAR image through Fourier transform.

Next, the scaling unit 250 calculates the vertical distance resolution by using the angular velocity of the target calculated through the estimated parameters and vertically scales the generated ISAR image according to the vertical distance resolution.

Hereinafter, an autofocus and vertical distance scaling method of an ISAR image according to an embodiment of the present invention will be described with reference to FIGS. 3 to 6.

3 is a flowchart of a method for auto focusing and vertical distance scaling of an ISAR image according to an exemplary embodiment of the present invention.

First, as shown in FIG. 3, the input unit 210 receives a rare opening signal for a target (S310).

In this case, the rare opening signal may be represented by Equation 1 below.

Where Ln is the number of scattering points in the nth distance bin, A _i 'is the amplitude of the ith scattering point, c is the speed of light, f ₀ is the carrier frequency, and R ₀ is the initial distance from the radar to the center of rotation of the target. X ₀ is the initial position on the x-axis of the target in two-dimensional coordinates starting from the center of rotation of the target, v _R is the target's eye velocity, a _R is the target's acceleration, j _R is the target's jerk , w is the target's rotational speed, w _d is the target's rotational acceleration, x _n is the x-coordinate of the nth scattering point, y _i is the y-coordinate of the i-th scattering point, and l is the n-th distance bin of the sparse number signal. Index number of the burst involved.

As shown in Equation 1, the sparse aperture signal is composed of signals for a plurality of distance bins.

If Equation 1 is expressed as a vector, it can be expressed as Equation 2 below.

이고, l, q, c는 각각 1차, 2차, 3차 위상항에 대응하는 기저 함수를 의미한다. 기저 함수 l은 시간에 대한 순수 선형 함수로서 산란점의 좌표값에 대응하는 함수이며,

이다. 기저 함수 q는 산란점의 병진 운동에 대응하는 함수이며,

이다. 기저함수 c는 산란점의 불균일 회전 운동에 대응하는 함수이며,

이다. here

Where l, q, and c represent the basis functions corresponding to the first, second and third phase terms, respectively. The basis function l is a pure linear function of time and corresponds to the coordinates of the scattering point,

to be. The basis function q is a function corresponding to the translational motion of the scattering point,

to be. The basis function c is a function corresponding to the nonuniform rotation of the scattering point,

to be.

As shown in the sparse aperture signal above, the second and third phase terms of the signal must be removed to produce a well-focused (autofocused) ISAR image.

The calculation unit 220 then uses the Pearson's correlation coefficient between the residual signal of the scattering point included in the distance bin and the stored sensing matrix for each distance bin of the sparse aperture signal, and the translation and After estimating the parameter according to the irregular rotation, the amplitude corresponding to the parameter is calculated (S320).

The reconstruction unit 230 reconstructs the ISAR image signal corresponding to the rare aperture signal using the estimated parameter and the calculated amplitude (S330).

4 is a flowchart for describing in detail the steps S320 and S330 of FIG. 3.

First, the calculation unit 220 calculates a Pearson correlation coefficient between the first residual signal for the first scattering point and the basis function vector included in the previously stored sensing matrix (S321). In this case, when the first scattering point is the first scattering point of the corresponding distance bin, the calculator 220 sets the first residual signal as a rare opening signal of the corresponding distance bin.

Then, the calculation unit 220 estimates the coefficient of the basis function vector at which the Pearson correlation coefficient is maximum as the first parameter according to the coordinates, translation, and irregular rotation (S322).

)를 추정한다. In detail, the calculation unit 220 uses the following equation (3) to determine the parameters of the scattering point coordinates, translation and irregular rotation (

Estimate).

이고,

는 i번째 산란점에 대한 파라미터이고,

는 상기 i번째 산란점에 대한 잔차 신호이고,

및

는 각각

와

의 표준 편차이고 E[

]는 예상 연산자이고,

와

는 각각

와

의 평균 벡터이다. here

ego,

Is the parameter for the i th scattering point,

Is a residual signal for the i th scattering point,

And

Are each

Wow

Is the standard deviation of E [

] Is the expected operator,

Wow

Are each

Wow

Is the mean vector of.

And α _i is a parameter corresponding to the coordinate of the i-scattering point, β _i is a parameter corresponding to the translational motion of the i-scattering point, and γ _i is a parameter corresponding to the irregular rotational motion of the i-scattering point.

)를 추정할 수 있다. For example, assume that the first scattering point is the second scattering point of the third distance bin. Then, the calculation unit 220 is a first parameter for the first scattering point (Equation 4 below)

) Can be estimated.

Next, the calculator 220 calculates a first amplitude of the signal corresponding to the first scattering point by performing a least square method on the first residual signal using the basis function vector corresponding to the first parameter (S323). In detail, the calculator 220 calculates a first amplitude by using Equation 5 below.

는 추정된 파라미터

에 대응하는 기저 함수 벡터를 의미한다. 예를 들어 n번째 거리빈에서 값을 가지는 버스트의 개수가

개인 경우

은

의 기저 함수 벡터가 된다. here

Is an estimated parameter

The base function vector corresponding to. For example, if the number of bursts with values in the nth

Personal case

silver

Is the basis function vector of.

Next, the reconstruction unit 230 calculates a second residual signal using the first residual signal, the first parameter, and the first amplitude (S331).

In detail, the reconstruction unit 230 calculates a second residual signal by using Equation 6 below.

The reconstruction unit 230 compares the cost function calculated using the first and second residual signals with a preset threshold value (S332).

In detail, the reconstruction unit 230 calculates a cost function using Equation 7 below and compares it with a threshold.

는 제1 잔차 신호이고,

는 제2 잔차 신호이고, δ는 임계값이다. here

Is the first residual signal,

Is the second residual signal and δ is the threshold.

Then, the reconstruction unit 230 reconstructs the ISAR signal according to the comparison result (S333) or calculates the amplitude by parameter estimation with respect to the second scattering point.

In detail, if the cost function is smaller than the threshold value, the reconstruction unit 230 reconstructs the ISAR image signal using the estimated parameter and amplitude. At this time, the reconstruction unit 230 reconstructs the ISAR image signal using Equation 8 below.

Where s _n ^re (t _l ) is the reconstructed ISAR video signal and T _obs is the concatenated processing interval (CPI), that is, radar observation time.

On the other hand, if the cost function is greater than or equal to the threshold value, the reconstruction unit 230 calculates the amplitude by estimating the parameter for the second scattering point.

For example, assume that the second scattering point is the third scattering point of the third distance bin.

Since the residual signal for the third scattering point of the third distance bin was calculated in step S331, the calculation unit 220 estimates the parameter for the third scattering point of the third distance bin through steps S322 and S323 and estimates the estimated parameter. Calculate the amplitude through.

In operation S331, a residual signal for the fourth scattering point is calculated, and in operation S332, a cost function is calculated and compared with a threshold.

If the cost function calculated at the fourth scattering point is less than the threshold, the set of estimated parameters and amplitudes has a total of four sets.

Next, the image generator 240 removes signal components corresponding to translation and irregular rotation from the reconstructed ISAR image signal and generates an autofocus ISAR image through a Fourier transform (S340).

FIG. 5 is a flowchart for describing operation S340 of FIG. 3 in detail.

In detail, the image generator 240 removes a signal component due to translation and non-uniform rotation from the reconstructed ISAR image signal (S341).

In the reconstructed ISAR image signal, a signal s _n ^lin (t) from which signal components due to translation and non-uniform rotation are removed may be represented by Equation 9 below.

The image generator 240 generates a vertical distance profile by performing Fourier transform on the signal from which the signal components due to translation and non-uniform rotation are removed from the reconstructed ISAR image signal (S342).

The image generator 240 generates a vertical distance profile CRP _n (v) through Equation 10 below.

The image generator 240 generates an ISAR image using the vertical distance profile in operation S343.

Next, the scaling unit 250 calculates the vertical distance resolution by using the angular velocity of the target calculated through the estimated parameter and scales the ISAR image vertical distance according to the vertical distance resolution (S350).

FIG. 6 is a flowchart for describing operation S350 of FIG. 3 in detail.

As shown in FIG. 6, the scaling unit 250 calculates an angular velocity of the target by using the estimated parameter (S351).

As described above, the parameters α _{n, 1} and γ _{n, 1} corresponding to the i th scattering circle of the n th distance bin may be expressed by Equations 11 and 12 below.

Then, the relationship with the i'-th scattering circle of the n-th distance bin may be expressed by Equation 13 below.

Therefore, the scaling unit 250 calculates the angular velocity of the target by using Equation 14 according to the relationship between the two scattering points of Equation 11.

는 추정된 각속도이다. here

Is the estimated angular velocity.

Next, the scaling unit 250 calculates the vertical distance resolution of the ISAR image using the calculated angular velocity (S352).

)를 산출한다. In detail, the scaling unit 250 uses the following equation 15 to determine the vertical distance resolution of the ISAR image signal (

) Is calculated.

In operation S353, the scaling unit 250 scales the generated ISAR image by using the calculated vertical distance resolution.

As described above, according to the exemplary embodiment of the present invention, the auto-focused ISAR image may be restored from the sparse aperture signal from the complete ISAR image signal from which the phase error signal due to the translational and irregular rotational motions of the target is removed. In addition, signal reconstruction and phase error cancellation can be performed simultaneously, and Fourier transforms can be used to generate ISAR images, thus reducing the amount of computation.

In addition, the rotation speed of the target can be accurately calculated using the parameters estimated during the ISAR signal reconstruction process, thereby obtaining a well-balanced ISAR image.

Although the present invention has been described with reference to the embodiments shown in the drawings, this is merely exemplary, and it will be understood by those skilled in the art that various modifications and equivalent other embodiments are possible. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

200: vertical distance scaling apparatus of ISAR image
210: input unit 220: calculator
230: reconstruction unit 240: image generation unit
250: scaling unit

Claims (14)

In the auto focus and vertical distance scaling method using the auto focus and vertical distance scaling device of the ISAR image,
Receiving a sparse aperture signal for the target,
The Pearson's correlation coefficient between the residual signal of the scattering point included in the distance bin and the stored sensing matrix is calculated for each distance bin of the sparse aperture signal, and the coefficient of the basis function vector at which the Pearson correlation coefficient is maximized is calculated. Estimating the parameters according to the coordinates of the scattering point, translation and irregular rotation, and calculating an amplitude corresponding to the parameters;
Reconstructing an ISAR video signal corresponding to the rare aperture signal using the estimated parameter and the calculated amplitude,
Generating an auto-focusing ISAR image through Fourier transform after removing signal components corresponding to translation and irregular rotation using the reconstructed ISAR image signal; and
Calculating a vertical distance resolution by using the angular velocity of the target calculated through the estimated parameter, and vertically scaling the generated ISAR image according to the vertical distance resolution,
The step of calculating the amplitude,
The parameter (

) And the amplitude (

Auto focus and vertical distance scaling method of ISAR image

here

ego,

Is the signal vector for the i th scattering point,

Is a residual signal vector for the i th scattering point,

And

each

Wow

Is the standard deviation of E [

] Is the expected operator,

Wow

Are each

Wow

Is the mean vector of,

Is the estimated parameter

Based function vector based on. The method of claim 1,
The step of calculating the amplitude,
Calculating a Pearson correlation coefficient between the first residual signal and the basis function vector for the first scattering point,
Estimating a coefficient of the basis function vector at which the Pearson correlation coefficient is maximum as a first parameter according to the coordinates, translation, and irregular rotation, and
Calculating a first amplitude of a signal corresponding to the first scattering point by performing a least square method on the first residual signal using a basis function vector corresponding to the first parameter; Vertical distance scaling method. The method of claim 2,
Reconstructing the ISAR video signal,
Calculating a second residual signal using the first residual signal, the first parameter and the first amplitude, and
Comparing the cost function calculated using the first and second residual signals with a predetermined threshold value, and reconstructing the ISAR image signal or estimating a parameter with respect to a second scattering point according to a comparison result to calculate an amplitude. Auto focus and vertical distance scaling methods for ISAR images, including. delete delete The method of claim 3,
Computing the second residual signal,
A method of auto focusing and vertical distance scaling of an ISAR image calculating the second residual signal by using the following equation:

here

Is the residual signal vector for the i th scattering point of the n th distance bin,

Is the residual signal vector for the i + 1th scattering point of the nth distance bin. The method of claim 6,
The cost function (C ₁ ) is,
Auto Focus and Vertical Distance Scaling Method for ISAR Image Calculated Using Equation

Δ is the preset threshold. An input unit for receiving a rare opening signal for a target,
The Pearson's correlation coefficient between the residual signal of the scattering point included in the distance bin and the stored sensing matrix is calculated for each distance bin of the sparse aperture signal, and the coefficient of the basis function vector at which the Pearson correlation coefficient is maximized is calculated. A calculator for estimating a parameter according to the coordinates of the scattering point, translation and irregular rotation, and calculating an amplitude corresponding to the parameter;
A reconstruction unit for reconstructing an ISAR video signal corresponding to the rare aperture signal using the estimated parameter and the calculated amplitude;
An image generator which removes signal components corresponding to translation and irregular rotation by using the reconstructed ISAR image signal and generates an auto-focusing ISAR image through Fourier transform, and
A scaling unit configured to calculate a vertical distance resolution using the angular velocity of the target calculated through the estimated parameters and to vertically scale the generated ISAR image according to the vertical distance resolution;
The calculation unit,
The parameter (

) And the amplitude (

Auto focus and vertical distance scaling device of ISAR image

here

ego,

Is the signal vector for the i th scattering point,

Is a residual signal vector for the i th scattering point,

And

each

Wow

Is the standard deviation of E [

] Is the expected operator,

Wow

Are each

Wow

Is the mean vector of,

Is the estimated parameter

Based function vector based on. The method of claim 8,
The calculation unit,
Compute the Pearson correlation coefficient between the first residual signal and the basis function vector for the first scattering point, and estimate the coefficient of the basis function vector at which the Pearson correlation coefficient is maximum as the first parameter according to the coordinates, translation, and irregular rotation. And performing a least square method on the first residual signal using the basis function vector corresponding to the first parameter to calculate a first amplitude of the signal corresponding to the first scattering point and to autofocus and vertical distance of the ISAR image. Scaling device. The method of claim 9,
The reconstruction unit,
Compute a second residual signal using the first residual signal, the first parameter, and the first amplitude, compare the cost function calculated using the first and second residual signals with a preset threshold, and compare the result. And reconstructing the ISAR image signal or estimating a parameter with respect to a second scattering point to calculate an amplitude. delete delete The method of claim 10,
The calculation unit,
An apparatus for auto focusing and vertical distance scaling of an ISAR image for calculating the second residual signal by using the following equation:

here

Is the residual signal vector for the i th scattering point of the n th distance bin,

Is the residual signal vector for the i + 1th scattering point of the nth distance bin. The method of claim 13,
The cost function (C ₁ ) is,
Auto focus and vertical distance scaling device of ISAR image calculated using the following equation:

Δ is the preset threshold.

Images