CN101581779B - Method for generating three-dimensional imaging original echoed signals of chromatography synthetic aperture radars - Google Patents

Abstract

The invention relates to a method for generating three-dimensional imaging original echoed signals of chromatography synthetic aperture radars, which comprises the following steps: taking a three-dimensional image containing backward plural scattering coefficients of imaging area targets in a rectangular coordinate system OXYZ as the input, carrying out three dimensional fourier transform on the three-dimensional image and converting an image signal to a rectangular coordinate system wave-number domain; converting signals in Kx, Ky and Kz domains to be signals in Kw, Ku and Kv domains according to the method of converting the rectangular coordinate system to a spherical coordinate system; introducing imaging geometrical relationships among same imaging area of chromatography synthetic aperture radars by multiplying three dimensional filter function H2 (Kw, Ku and Kv); introducing a transmission signal form by the multiplication of a two-dimensional inverse Fourier transform function and a reference phase function; and at last, by W direction process and other operations, obtaining the three-dimensional imaging original echoed signals of chromatography synthetic aperture radars, which contains a carrier frequency. The method can be used for generating three-dimensional imaging original echoed signals of side-looking, downward-looking, forward-looking, backward-looking and downward side-looking chromatography synthetic aperture radars, and has high echo generating efficiency and easy realization of modularization.

Description

A kind of method for generating three-dimensional imaging original echoed signals of chromatography synthetic aperture radars

Technical field

The information of the present invention relates to is obtained and processing technology field, particularly a kind of method for generating three-dimensional imaging original echoed signals of chromatography synthetic aperture radars.

Background technology

The chromatography synthetic aperture radar imaging technique is a kind of novel synthetic aperture radar three-dimensional imaging technology; By people such as A.Reigber and A.Moreira (A.Reigber andA.Moreira. " First demonstration of airborne SAR tomography usingmultibaseline L-band data " was proposed 20 end of the centurys; Processing of IGARSS 1999; Hamburg, Germany, 1:44-46).As shown in Figure 1, the chromatography synthetic aperture radar sensor emission has the signal of certain bandwidth, and has formed first synthetic aperture through the motion of chromatography synthetic aperture radar sensor place platform in the motion of Y direction; Pass through again along on the Z direction differing heights; Same imaging region is carried out various visual angles observation along the Z direction, on the Z direction, formed second synthetic aperture that differs from Y direction synthetic aperture: Z direction synthetic aperture, thus formed the chromatography synthetic aperture radar two dimension synthetic aperture plane that is positioned on the OYZ plane; Realization is to the three-dimensional resolution imaging of imaging region; Wherein, the direction that chromatography synthetic aperture radar two dimension synthetic aperture plane does not transmit with chromatography synthetic aperture radar is parallel or overlap, and OXYZ is the three-dimensional orthogonal rectangular coordinate system at chromatography synthetic aperture radar and imaging region place; O is the initial point of quadrature rectangular coordinate system, (x _n, y _n, z _n) be target P _n(x _n, y _n, z _n) at the three dimensional space coordinate of imaging region, X ₀, Y ₀And Z ₀Be expressed as width, length and the height of picture zone (imaging region), X along X, Y and Z direction _cFor the two-dimentional synthetic aperture plane of chromatography synthetic aperture radar among the rectangular coordinate system OXYZ with the vertical range between the imaging region center O.

In the process of development chromatography synthetic aperture radar system; This system can realize through repeatedly flight, aerial array or the formation flight of chromatography synthetic aperture radar; Before the chromatography synthetic aperture radar original echoed signals that obtains the actual imaging zone; Need at first carry out system design, system emulation and the Study on Processing Methods relevant with actual chromatography synthetic aperture radar; Therefore; Press for to imaging region on a large scale or complex target and carry out the emulation of three-dimensional imaging original echoed signals of chromatography synthetic aperture radars, also promptly need generate the three-dimensional imaging original echoed signals of chromatography synthetic aperture radars of required imaging region through method of computer simulation.

At present; Carried out some researchs with regard to chromatography synthetic aperture radar three-dimensional imaging treatment theory and method both at home and abroad, the most representative scholar is A.Reigber (A.Reigber and A.Moreira. " First demonstration of airborne SAR tomography using multibaselineL-band data ", IEEE Trans.on Geoscience and Remote Sensing; Vol.38; No.5, pp:2142-2152, Sep.2000).Aspect three-dimensional imaging original echoed signals of chromatography synthetic aperture radars obtains; People such as A.Reigber utilize E-SAR to carry out experimental data acquisition; But the experimental data of being obtained is very limited; Be difficult to carry out repeated experiment simultaneously, of paramount importance when being to test the level of hardware of desired chromatography synthetic aperture radar system higher, therefore; It is uncontrollable, not reproducible to adopt the mode of practical large-scale flight experiment data acquisition to carry out the checking of correlation process method, is unfavorable for the expansion of three-dimensional imaging disposal route previous research work.

At present; In the synthetic-aperture radar two-dimensional imaging, emerge to the existing relevant hardware equipment of complicated appearance target computer simulation system on a large scale, and aspect the chromatography synthetic aperture radar three-dimensional imaging; Mainly be emulation to a single point target or a small amount of single-point target; According to Born approximation, the generating mode that the time domain coherence stack can be directly adopted in the generation of three-dimensional imaging original echoed signals of chromatography synthetic aperture radars promptly passes through

$s(t,u,v)=\underset{n}{\mathrm{\Σ}}{\mathrm{\σ}}_{n}p(t-\frac{2R_n}{C})$

$=\underset{n}{\mathrm{\Σ}}{\mathrm{\σ}}_{n}p(t-\frac{2}{C}\sqrt{{(x-x_n)}^2+{(y-y_n)}^2+{(z-z_n)}^2})$ (1)

Wherein, (t, u v) represent chromatography synthetic aperture radar three-dimensional imaging echoed signal to s, and t representes the sampling time of radar line of sight direction, and u representes the orientation to sampling, and v representes elevation to sampling, σ _nThe expression target P _n(x _n, y _n, z _n) backscattering coefficient, $R_n=\sqrt{{(x-x_n)}^2+{(y-y_n)}^2+{(z-z_n)}^2}$ The expression target P _n(x _n, y _n, z _n) to the distance of chromatography synthetic aperture radar, C representes velocity of electromagnetic wave, p (t) transmits for chromatography synthetic aperture radar,

The relevant summation of n point target of expression imaging region.Can find out by formula (1), to each point target P _n(x _n, y _n, z _n), chromatography synthetic aperture radar need calculate each target P _n(x _n, y _n, z _n) to distance between the chromatography synthetic aperture radar, then generate echoed signal and and target P _n(x _n, y _n, z _n) scattering coefficient σ _nMultiply each other, suppose that chromatography synthetic aperture radar forms about point target P along OYZ flight _n(x _n, y _n, z _n) two-dimentional synthetic aperture plane be respectively n along counting of Y direction and Z direction _yAnd n _zThen need repeat said process to each point target in the imaging region, therefore, this method only is fit to carry out the echo generation of a small amount of point target; And for a large amount of observed objects or scene in complex target or the large space scope; Because the point target number that comprises is excessive, its echo generates very consuming time, also is unfavorable for the modular implementation of hardware devices such as computing machine simultaneously.

2007, Meng Xiangxin, Xue Minghua and Wang Zhenrong carried out point target echoed signal (data) generation method research (Meng Xiangxin, the Xue Minghua relevant with the ISAR three-dimensional imaging; Wang Zhenrong, " microwave three-dimensional imaging discrete point target echo digital simulation ", electronic measurement technique; The 30th the 8th phase of volume; In August, 2007), in this ISAR three-dimensional imaging echoed signal generation method, having supposed transmits is " tightening the plane wave that send the field "; " target is around a point of fixity rotation "; Do not consider " influence that ISAR and observed object centre distance generate echo ", essence remains based on " reflection wave vector superposed " in the generative process of its echo, also promptly adopts the generating mode of time domain coherence stack; Need to calculate " position angle and the angle of pitch " of each point target with respect to ISAR; Along with the increase of point target quantity or the increase of ISAR data acquisition amount, straight line rises the calculated amount in its echo generative process along with the increase of point target quantity, for a large amount of observed objects or the scene in complex target or the large space scope; Because the point target number that comprises is excessive, its echo generative process will be more consuming time; This method only is applicable to that the ISAR three-dimensional imaging echoed signal of a small amount of point target generates among a small circle; Along with the increase of imaging region scope and the raising of systemic resolution; Transmit and no longer set up for the hypothesis of plane wave, thereby introduced than mistake in the ISAR three-dimensional imaging echoed signal that generates.This method is not suitable for for the chromatography synthetic aperture radar three-dimensional imaging echoed signal of a large amount of observed objects in complex target or the large space scope or scene.

At present, domestic aspect method for generating three-dimensional imaging original echoed signals of chromatography synthetic aperture radars, the development as yet furtherd investigate, and document or the patent relevant with the chromatography synthetic aperture radar echo generation method are not arranged as yet yet.Along with the development of chromatography synthetic aperture radar three-dimensional imaging technology, adopt fast, generation method efficient and that be easy to the three-dimensional imaging original echoed signals of chromatography synthetic aperture radars of modular implementation carries out system emulation and seem very necessary.

Summary of the invention

The technical matters that solves:

The objective of the invention is to a large amount of observed objects or scene in complex target or the large space scope; Give full play to the effect of FFT in the synthetic aperture radar three-dimensional imaging original echoed signals generates; Adopt the three-dimensional wave number field to generate the mode of echo, shorten program runtime, for this reason; The present invention provide a kind of fast, efficient and be easy to modular implementation, and be applicable to the method that the three-dimensional imaging original echoed signals of chromatography synthetic aperture radars of multiple imaging geometry generates.

The technical scheme of the technical matters that solves:

In order to realize said purpose, a kind of method for generating three-dimensional imaging original echoed signals of chromatography synthetic aperture radars of the present invention comprises that step is following:

Step S1: with the 3-D view s that comprises among the quadrature rectangular coordinate system OXYZ behind the imaging region to multiple scattering coefficient _3D(x-x _n, y-y _n, z-z _n) send into the three dimensional fourier transform unit, generate the 1st signal and be: S ₁(K _x, K _y, K _z), wherein, x _n, y _nAnd z _nBe expressed as the coordinate of target in OXYZ in the picture zone, x, y and z represent the coordinate of 3-D view, K respectively _x, K _yAnd K _zBe respectively directions X wave number, Y direction wave number and Z direction wave number;

Step S2: the 1st signal is sent to the coordinate Mapping unit,, will be in the three-dimensional wave number field signal S in the quadrature rectangular coordinate system according to the imaging geometry of chromatography synthetic aperture radar ₁(K _x, K _y, K _z) be mapped as spherical coordinate system O ₂The 2nd signal S among the UVW ₂(K _w, K _u, K _v), wherein, K _w, K _uAnd K _vBe respectively the wave number of W direction, U direction and V direction;

Step S3: the 2nd signal is sent to chromatography synthetic aperture radar antenna radiation pattern processing unit, carries out chromatography synthetic aperture radar antenna radiation pattern function H ₁(K _w, K _u, K _v) multiply each other, generate the 3rd signal S ₃(K _w, K _u, K _v);

Step S4: the 3rd signal is sent to three-dimensional wave number field filter unit, the 3rd signal and three-dimensional filtering function H ₂(K _w, K _u, K _v) multiply each other, generate the 4th signal S ₄(K _w, K _u, K _v), from the 4th signal, obtain chromatography synthetic aperture radar with the imaging geometry between the imaging region;

Step S5: the 4th signal is sent to two-dimentional inverse Fourier transform unit, carries out inverse Fourier transform respectively, generate the 5th signal S along the U direction and the V direction of the 4th signal ₅(K _w, u, v), wherein, K _w, u and v represent W direction wave number, U direction time and V direction time respectively;

Step S6: the 5th signal is sent into W trend pass filtering unit, the 5th signal with comprise reference distance R _cFixed phase function interior multiplies each other, and generates the 6th signal S ₆(K _w, u, v), the form that obtains transmitting;

Step S7: the 6th signal is along W direction condition judgment and processing: if transmitting of adopting is the frequency modulation on pulse signal, then carry out inverse Fourier transform along the W direction of the 6th signal, and multiply by and comprise chromatography synthetic aperture radar system carrier frequency at interior reference function H ₇(f _c, t, u v), generates initial three-dimensional imaging original echoed signals of chromatography synthetic aperture radars the 7th signal: ss ₇(v), wherein, t representes the W direction sampling time for t, u, and this signal is in W direction time domain, U direction time domain and the V direction time domain, continues execution in step S8 then; If transmitting of adopting is stepping frequency continuous wave signal or other bandwidth signal, this moment, the 7th signal equaled the 6th signal, then directly forwarded step S8 to;

Step S8: the 7th signal is sent into signal intercepting and resampling unit, the 7th signal is carried out intercepting or rises sampling or sampling, or rise sampling and sampling; Or liter sampling and intercepting; The three-dimensional imaging original echoed signals of chromatography synthetic aperture radars ss of acquisition imaging region (w, u, v).

According to embodiments of the invention, in the imaging geometry of said chromatography synthetic aperture radar, form chromatography synthetic aperture radar two dimension synthetic aperture plane through repeatedly flight or aerial array or formation flight, thereby realize three-dimensional imaging same imaging region.

According to embodiments of the invention, the concrete steps of said coordinate Mapping unit are:

Step S21: through directions X wave number thresholding K in the quadrature rectangular coordinate system _x, Y direction wave number field value K _yWith Z direction wave number field value K _zCalculate W direction wave number field value K in the corresponding spherical coordinate system _w, U direction wave number field value K _uWith V direction wave number field value K _vFor:

$\left\{\begin{array}{c}{K}_w(K_x,K_y,K_z)=\frac{1}{2}\sqrt{K_x^2+K_y^2+K_z^2}\\ K_u(K_x,K_y,K_z)=K_y\\ K_v(K_x,K_y,K_z)=K_z\end{array}\right.$

Wherein, K _w(K _x, K _y, K _z), K _u(K _x, K _y, K _z) and K _v(K _x, K _y, K _z) be respectively and shine upon back W direction wave numerical value, U direction wave numerical value and V direction wave numerical value;

Step S22: according to each coordinate figure (K _x, K _y, K _z) on corresponding the 1st signal S of institute ₁(K _x, K _y, K _z) generate each coordinate figure (K in the spherical coordinate system through interpolation method _w, K _u, K _v) pairing the 2nd signal S ₂(K _w, K _u, K _v).

According to embodiments of the invention, said three-dimensional filtering function H ₂(K _w, K _u, K _v) and the chromatography synthetic aperture radar imaging geometry between relation table be shown:

$H_2(K_w,K_u,K_v)=\exp [-j{K}_u{Y}_c-j{K}_v{Z}_c+j2K_w{R}_c]$

$\×\exp [-j{X}_c\sqrt{4K_w^2-K_u^2-K_v^2}]$

Wherein, K _wThe corresponding wave number of expression radar emission signal frequency, K _uBe the corresponding wave number of U direction, K _vBe the corresponding wave number of V direction.When chromatography synthetic aperture radar two dimension synthetic aperture plane is positioned at O ₂On the UV plane, and chromatography synthetic aperture radar is when the U direction is moved, X _cBe spherical coordinate system O ₂The two-dimentional synthetic aperture plane O of chromatography synthetic aperture radar among the UVW ₂UV is with the vertical range between the imaging region center O, Y _cFor chromatography synthetic aperture radar beam center on the Y direction passes through constantly and the difference pairing distance of zero Doppler between the moment, Z _cBe synthetic aperture center O on the Z direction ₂To the vertical range between the imaging region center O, R _cBe the reference distance of radar to the imaging region center.

According to embodiments of the invention, said chromatography synthetic aperture radar dimensional antenna pattern function H ₂(K _w, K _u, K _v) be amplitude pattern that antenna measurement is obtained or desirable rectangular window function.

According to embodiments of the invention, said chromatography synthetic aperture radar two dimension synthetic aperture plane is parallel to a plane in OXY plane, OXZ plane, the OYZ plane; Or be arranged on the tapered plane of OXYZ coordinate system.

According to embodiments of the invention, said chromatography synthetic aperture radar two dimension synthetic aperture plane, along on X, Y or the Z direction be centered close to chromatography synthetic aperture radar imaging region center one side or directly over.

Beneficial effect of the present invention: the present invention provides a kind of method for generating three-dimensional imaging original echoed signals of chromatography synthetic aperture radars; Make full use of the FFT instrument, avoided pointwise calculating computed tomography synthetic aperture radar three-dimensional imaging original echoed signals then to carry out the process of coherence stack.

The present invention carries out the mapping of the signal in the spherical coordinate system of signal in the quadrature rectangular coordinate system, thus in three-dimensional imaging original echoed signals of chromatography synthetic aperture radars, introduce between target and the chromatography synthetic aperture radar apart from coupling phenomenon.

The present invention has carried out the mapping of the signal in the spherical coordinate system of signal in the accurate quadrature rectangular coordinate system, and therefore, chromatography synthetic aperture radar transmits and is plane wave or spherical wave signal, need not suppose to transmit only to be the plane.

The present invention introduces three-dimensional filtering function H ₂(K _w, K _u, K _v), thereby introduced the imaging geometry between imaging region and the chromatography synthetic aperture radar, when chromatography synthetic aperture radar two dimension synthetic aperture plane parallel in the OXY plane, and Y _c=0, X _c, can be used for looking down the generation of three-dimensional imaging original echoed signals of chromatography synthetic aperture radars at=0 o'clock; When chromatography synthetic aperture radar two dimension synthetic aperture plane parallel in the OXY plane, and Y _c=0, | X _c|, can be used for the generation of side-looking three-dimensional imaging original echoed signals of chromatography synthetic aperture radars down at＞0 o'clock; When chromatography synthetic aperture radar two dimension synthetic aperture plane parallel in the OXY plane, and X _c, work as Y at=0 o'clock _c＞0 can be used for the generation of forward sight three-dimensional imaging original echoed signals of chromatography synthetic aperture radars, works as Y _c＜0 can be used for the generation of backsight three-dimensional imaging original echoed signals of chromatography synthetic aperture radars; When chromatography synthetic aperture radar two dimension synthetic aperture plane parallel during, can be used for the generation of side-looking chromatography synthetic aperture radar three-dimensional imaging original echoed signals in OYZ plane or OXZ.Also promptly through selecting two-dimentional synthetic aperture plane and use to comprise X _c, Y _c, Z _cAnd R _cCan realize that at interior three-dimensional wave number field filter function the three-dimensional imaging original echoed signals of chromatography synthetic aperture radars under the different imaging geometries generates.

The mode that the present invention adopts the wavenumber domain echo data to generate; Promptly considered to exist in the reality influence of antenna radiation pattern; Considered serious in the chromatography synthetic aperture radar three-dimensional imaging again, thereby can generate three-dimensional imaging original echoed signals of chromatography synthetic aperture radars accurately apart from coupling phenomenon.

Step of the present invention is clear succinct, and modularization is strong, and characteristics such as implementation procedure is simple effective, helps computing machine or other specialized equipment and realizes.

Description of drawings

Fig. 1 is the chromatography synthetic aperture radar three-dimensional imaging geometric representation of prior art.

Fig. 2 is the chromatography synthetic aperture radar three-dimensional imaging geometric representation that the present invention adopts.

Fig. 3 looks chromatography synthetic aperture radar three-dimensional imaging geometric representation under of the present invention.

Fig. 4 is a side-looking chromatography synthetic aperture radar three-dimensional imaging geometric representation down of the present invention.

Fig. 5 be of the present invention before/backsight chromatography synthetic aperture radar three-dimensional imaging geometric representation.

Fig. 6 is that chromatography synthetic aperture radar original echoed signals of the present invention generates method flow diagram.

Fig. 7 is a coordinate Mapping cell processing process flow diagram of the present invention.

Fig. 8 is computing machine of the present invention or specialized equipment processing flow chart.

Embodiment

Specify each related detailed problem in the technical scheme of the present invention below in conjunction with accompanying drawing.Be to be noted that described embodiment only is intended to be convenient to understanding of the present invention, and it is not played any qualification effect.

To the three-dimensional imaging geometric representation of the chromatography synthetic aperture radar of prior art shown in Figure 1, do not consider the two-dimentional synthetic aperture planar central of chromatography synthetic aperture radar and the relation between the imaging region as yet.The present invention has provided the three-dimensional imaging geometric representation of the chromatography synthetic aperture radar that comprises multiple imaging geometry, has comprised two coordinate system OXYZ and O in this imaging geometry synoptic diagram ₂UVW, OXYZ represent that needs generate the 3-D view space of the three-dimensional imaging original echoed signals of chromatography synthetic aperture radars of imaging region, O ₂UVW representes chromatography synthetic aperture radar image-forming geometric space, and is as shown in Figure 2:

In the imaging region (image space) of quadrature rectangular coordinate system OXYZ, (x _n, y _n, z _n) be target P _n(x _n, y _n, z _n) three dimensional space coordinate, O is the initial point (central point of image) of quadrature rectangular coordinate system, X ₀, Y ₀And Z ₀Be expressed as width, length and the height of picture zone (imaging region) along X, Y and Z direction;

O ₂UVW is the coordinate system of chromatography synthetic aperture radar, because follow-up generation echo need transform to wavenumber domain space, K _w, K _uAnd K _vBe respectively corresponding wavenumber domain space, K in the wavenumber domain space _u, K _vAnd K _wShared space is spherical in shape, therefore, and O ₂UVW is called spherical coordinate system O again ₂UVW, wherein, the U coordinate axis is parallel to the Y coordinate axis, and the V coordinate axis is parallel to the Z coordinate axis, and the W coordinate axis is by synthetic aperture planar central O ₂Point to the 3-D view regional center O that promptly forms images, the W direction is the average direction of visual lines of chromatography synthetic aperture radar along the V direction observation.The flying platform at chromatography synthetic aperture radar place moves repeatedly to fly or carry the two-dimentional synthetic aperture plane that aerial array or formation flight form along the U direction and is positioned at O ₂On the UV plane, O ₂UV is parallel to plane OYZ, X _cBe spherical coordinate system O ₂The two-dimentional synthetic aperture plane O of chromatography synthetic aperture radar among the UVW ₂UV is with the vertical range between the imaging region center O, Y _cFor chromatography synthetic aperture radar beam center on the Y direction passes through constantly and the difference pairing distance of zero Doppler between the moment, Z _cBe synthetic aperture center O on the Z direction ₂To the vertical range between the imaging region center O.

The three-dimensional dreamboat function definition of spatial domain is:

$s_{3D}(x-x_n,y-y_n,z-z_n)=\underset{n}{\mathrm{\Σ}}{\mathrm{\σ}}_n\mathrm{\δ}(x-x_n,y-y_n,{z-z}_n)$ (2)

Wherein, x _n, y _nAnd z _nBe expressed as the coordinate of target in OXYZ in the picture zone, x, y and z represent the coordinate of 3-D view respectively, | x _n|≤0.5X ₀, | y _n|≤0.5Y ₀, and | z _n|≤0.5Z ₀3-D view s _3D(x-x _n, y-y _n, z-z _n) be respectively Δ x, Δ y and Δ z along the interval between the pixel on directions X, Y direction and the Z direction.Then entire image is M along counting on directions X, Y direction and the Z direction _X, M _YAnd M _Z,

$\left\{\begin{array}{c}{M}_X=\frac{X_0}{\mathrm{\Δx}}\\ M_Y=\frac{Y_0}{\mathrm{\Δy}}\\ M_Z=\frac{Z_0}{\mathrm{\Δz}}\end{array}\right.$ (3)

The three-dimensional dreamboat function definition of spatial domain is the generation for three-dimensional imaging original echoed signals of chromatography synthetic aperture radars; Its step such as Fig. 5 and shown in Figure 8; Wherein, comprise behind the imaging region 3-D view s in the input quadrature rectangular coordinate system to multiple scattering coefficient _3D(x-x _n, y-y _n, z-z _n).

Before generating the chromatography synthetic aperture radar original echoed signals; Need to confirm earlier chromatography synthetic aperture radar transmit form and bandwidth B thereof, the chromatography synthetic aperture radar beam center passes through constantly and the difference pairing distance Y of zero Doppler between constantly on the Y direction _c, synthetic aperture center O on the Z direction ₂To the vertical range Z between the imaging region center O _c, the chromatography synthetic aperture radar system is along the dimensional resolution ρ of U direction, Y direction and W direction _U, ρ _VAnd ρ _W, wherein, dimensional resolution ρ _U, ρ _VAnd ρ _W" Δ x＞ρ need satisfy condition between pixel interval delta x, Δ y and the Δ z with image _WΔ y＞ρ _UΔ z＞ρ _V", if do not satisfy this condition, then need after comprising imaging region, sample to the 3-D view of multiple scattering coefficient, make " Δ x＞ρ _WΔ y＞ρ _UΔ z＞ρ _V" set up, obtain 3-D view s to be imported _3D(x-x _n, y-y _n, z-z _n).Can obtain the three-dimensional imaging original echoed signals of chromatography synthetic aperture radars of observation area through chromatography synthetic aperture radar original echoed signals generation method, implementation step is as shown in Figure 6, and the practical implementation process is following:

Step S1: with the 3-D view s that comprises among the quadrature rectangular coordinate system OXYZ behind the imaging region to multiple scattering coefficient _3D(x-x _n, y-y _n, z-z _n) send into the three dimensional fourier transform unit, generate the 1st signal and be: S ₁(K _x, K _y, K _z), wherein, x _n, y _nAnd z _nBe expressed as the coordinate of target in OXYZ in the picture zone, x, y and z represent the coordinate of 3-D view, K respectively _z, K _yAnd K _zBe respectively directions X wave number, Y direction wave number and Z direction wave number, implementation process is:

With the 3-D view s that comprises among the quadrature rectangular coordinate system OXYZ behind the imaging region to multiple scattering coefficient _3D(x-x _n, y-y _n, z-z _n) send into the three dimensional fourier transform unit, along 3-D view s _3D(x-x _n, y-y _n, z-z _n) directions X, Y direction and Z direction carry out Fourier transform respectively, generate the 1st signal S ₁(K _x, K _y, K _z) be:

$S_1(K_x,K_y,K_z)=F{T}_{x,y,x}\left\{s_{3D}(x-x_n,y-y_n,z-z_n)\right\}$

$=\underset{n}{\mathrm{\Σ}}{\mathrm{\σ}}_n\exp (-j{K}_x{x}_n-j{K}_y{y}_n-K_z{z}_n)$ (4)

Wherein, | x _n|≤0.5X ₀, | y _n|≤0.5Y ₀, and | z _n|≤0.5Z ₀, FT _{X, y, z}Expression is carried out Fourier transform, σ respectively along directions X, Y direction and Z direction _nBe target P _n(x _n, y _n, z _n) back to multiple scattering coefficient, K _x, K _yAnd K _zBe respectively directions X wave number, Y direction wave number and Z direction wave number, Δ K _x, Δ K _yWith Δ K _zBe respectively K behind the Fourier transform _x, K _yAnd K _zSI

$\left\{\begin{array}{c}\mathrm{\Δ}{K}_x=\frac{2\mathrm{\π}}{X_0}\\ \mathrm{\Δ}{K}_y=\frac{2\mathrm{\π}}{Y_0}\\ \mathrm{\Δ}{K}_z=\frac{2\mathrm{\π}}{Z_0}\end{array}\right.$ (5)

Through behind the three dimensional fourier transform, the 1st signal is in the three-dimensional wave number field of directions X wavenumber domain under the quadrature rectangular coordinate system, Y direction wave number field and Z direction wave number field, and the 1st signal that obtain this moment is in the wavenumber domain space of image;

Step S2: the 1st signal is sent to the coordinate Mapping unit,, will be in the three-dimensional wave number field signal S in the quadrature rectangular coordinate system according to the imaging geometry of chromatography synthetic aperture radar ₁(K _x, K _y, K _z) be mapped as spherical coordinate system O ₂The 2nd signal S among the UVW ₂(K _w, K _u, K _v), wherein, K _w, K _uAnd K _vBe respectively the wave number of W direction, U direction and V direction, as shown in Figure 7, the practical implementation step is:

Step S21: through directions X wave number thresholding K in the quadrature rectangular coordinate system _x, Y direction wave number field value K _yWith Z direction wave number field value K _zCalculate W direction wave number field value K in the corresponding spherical coordinate system _w, U direction wave number field value K _uWith V direction wave number field value K _vFor:

$\left\{\begin{array}{c}{K}_w(K_x,K_y,K_z)=\frac{1}{2}\sqrt{K_x^2+K_y^2+K_z^2}\\ K_u(K_x,K_y,K_z)=K_y\\ K_v(K_x,K_y,K_z)=K_z\end{array}\right.$ (6)

Wherein, K _w(K _x, K _y, K _z), K _u(K _x, K _y, K _z) and K _v(K _x, K _y, K _z) be respectively and shine upon back W direction wave numerical value, U direction wave numerical value and V direction wave numerical value; Formula (6) is in fact carried out the mapping of coordinate wave number value; The coordinate figure that through type (6) calculates not is equally distributed; Therefore this is mapped as Nonlinear Mapping, for the ease of Fourier analysis and processing, then need obtain to be evenly distributed on K _w, K _uAnd K _vThe 2nd signal on the direction for this reason, need carry out the processing of following step S22;

Step S22: according to each coordinate figure (K _x, K _y, K _z) on corresponding the 1st signal S of institute ₁(K _x, K _y, K _z) generate each coordinate figure (K in the spherical coordinate system through interpolation method _w, K _u, K _v) pairing the 2nd signal S ₂(K _w, K _u, K _v).Specifically through being evenly distributed on (K _x, K _y, K _z) on the 1st signal obtain because formula through interpolation

$S_2(K_w,K_u,K_v)\⇐S_1(K_x,K_y,K_z)---\left(7\right)$

Wherein,

representes interpolation, and its interpolation method is one dimension sinc function, once two-dimentional sinc function or polynomial interpolation method.

Particularly, let K _uAnd K _vThe wave number value even variation of direction, the SI is made as Δ K _yWith Δ K _z, owing to adopted in the formula (6) in the coordinate Mapping

Calculate, so K _wDemonstrate nonlinearities change, then need obtain along K through interpolation method _wEqually distributed the 2nd signal S of direction ₂(K _w, K _u, K _v).During three-dimensional imaging original echoed signals of chromatography synthetic aperture radars generates, will be along K _uAnd K _vDirectional interpolation interval delta K _uWith Δ K _vBe made as Δ K respectively _yWith Δ K _z, then along K _xDirection can obtain corresponding to K through sinc function interpolation _wEqually distributed the 2nd signal S of direction ₂(K _w, K _u, K _v) do

$S_2(K_w,K_u,K_v)\≈\underset{|K_x-\mathrm{n\Δ}{K}_w|\≤N_W\mathrm{\Δ}{K}_w}{\mathrm{\Σ}}{S}_1(\mathrm{n\Δ}{K}_w,K_y,K_z)\sin c\left(\frac{K_z-\mathrm{n\Δ}{K}_w}{\mathrm{\Δ}{K}_w}\right)$ (8)

Wherein, Δ K _wFor after the interpolation along the wavenumber domain SI of W direction, need satisfy following condition

$\mathrm{\Δ}{K}_w\≤\frac{2\mathrm{\π}}{\sqrt{X_0^2+Z_0^2}}$ (9)

This condition can guarantee that the echoed signal that generates the range ambiguity phenomenon can not occur, and formula (9) has provided required satisfied pacing items when avoiding range ambiguity in the three-dimensional imaging original echoed signals generation.Correspond to emission signal frequency and in the SI, have suc as formula the relation shown in (10) to exist:

$\frac{2\mathrm{\π\Δf}}{C}\≤\frac{2\mathrm{\π}}{\sqrt{X_0^2+Z_0^2}}$ (10)

C representes velocity of electromagnetic wave, and Δ f representes that needs generate the wavenumber domain SI of three-dimensional imaging original echoed signals of chromatography synthetic aperture radars along the W direction, and the W coordinate axis is by synthetic aperture planar central O ₂Point to the 3-D view regional center O that promptly forms images, the W direction is the average direction of visual lines of chromatography synthetic aperture radar along the V direction observation, sinc (x)=sin (π x)/(π x), and n is a sequence number, N _WDuring for interpolation required along directions X with a S ₁(K _x, K _y, K _z) for getting counting of the 1st signal right ends in the center, used the 1st signal S in the whole Interpolation Process ₁(K _x, K _y, K _z) count and be (2N _W+ 1), generally speaking, N _WBe taken as 8 and can have satisfied the requirement that high precision focuses on.

Said method is along K _uAnd K _vDirectional interpolation interval delta K _uWith Δ K _vBe made as Δ K respectively _yWith Δ K _zThe time Interpolation Process, when along K _uDirectional interpolation interval delta K _uLess than Δ K _yOr along K _vDirectional interpolation interval delta K _uLess than Δ K _zThe time, then need carry out two-dimentional sinc function interpolation, then the 1st signal becomes the 2nd signal S through after the interpolation ₂(K _w, K _u, K _v), formula (11-12) and formula (13-14) have provided the Interpolation Process under this situation respectively:

$S_2(K_w,K_u,K_v)\≈\underset{\begin{array}{c}|K_x-\mathrm{n\Δ}{K}_w|\≤N_W\mathrm{\Δ}{K}_w\\ |K_v-\mathrm{l\Δ}{K}_u|\≤N_U\mathrm{\Δ}{K}_u\end{array}}{\mathrm{\Σ}}{S}_1(\mathrm{n\Δ}{K}_w,\mathrm{\Δ}{K}_u,K_z)\sin c_2(K_x,K_y,K_z)$ (11)

$\sin c_2(K_x,K_y,K_z)=\sin c\left(\frac{K_x-\mathrm{n\Δ}{K}_w}{\mathrm{\Δ}{K}_w}\right)\sin c\left(\frac{K_y-\mathrm{l\Δ}{K}_u}{\mathrm{\Δ}{K}_u}\right)$ (12)

Or

$S_2(K_w,K_u,K_v)\≈\underset{\begin{array}{c}|K_x-\mathrm{n\Δ}{K}_w|\≤N_W\mathrm{\Δ}{K}_w\\ |K_z-\mathrm{l\Δ}{K}_v|\≤N_V\mathrm{\Δ}{K}_v\end{array}}{\mathrm{\Σ}}{S}_1(\mathrm{n\Δ}{K}_w,\mathrm{\Δ}{K}_y,K_v)\sin c_2(K_x,K_y,K_z)$ (13)

$\sin c_2(K_x,K_y,K_z)=\sin c\left(\frac{K_x-\mathrm{n\Δ}{K}_w}{\mathrm{\Δ}{K}_w}\right)\sin c\left(\frac{K_y-\mathrm{l\Δ}{K}_v}{\mathrm{\Δ}{K}_v}\right)$ (14)

L, m and n are sequence number, N _WDuring for interpolation required along directions X with a S ₁(K _x, K _y, K _z) for getting counting of the 1st signal right ends in the center, used the 1st signal S in the whole Interpolation Process ₁(K _x, K _y, K _z) count and be (2N _W+ 1), generally speaking, N _WBe taken as 8 and can have satisfied the requirement that high precision focuses on; N _UDuring for interpolation required along the Y direction with a S ₁(K _x, K _y, K _z) for getting counting of the 1st signal right ends in the center, used the 1st signal S in the whole Interpolation Process ₁(K _x, K _y, K _z) count and be (2N _U+ 1), generally speaking, N _WBe taken as 8 and can have satisfied the requirement that high precision focuses on; N _VDuring for interpolation required along the Z direction with a S ₁(K _x, K _y, K _z) for getting counting of the 1st signal right ends in the center, used the 1st signal S in the whole Interpolation Process ₁(K _x, K _y, K _z) count and be (2N _V+ 1), generally speaking, N _VBe taken as 8 and can have satisfied the requirement that high precision focuses on.

When along K _uDirectional interpolation interval delta K _uLess than Δ K _yWith along K _vDirectional interpolation interval delta K _uLess than Δ K _zThe time, then need carry out three-dimensional sinc function interpolation, then the 1st signal becomes the 2nd signal S through after the interpolation ₂(K _w, K _u, K _v),

$S_2(K_w,K_u,K_v)$

$\≈\underset{\begin{array}{c}|K_y-\mathrm{l\Δ}{K}_u|\≤N_U\mathrm{\Δ}{K}_u\\ |K_y-\mathrm{m\Δ}{K}_v|\≤N_V\mathrm{\Δ}{K}_v\\ |K_z-\mathrm{n\Δ}{K}_w|\≤N_W\mathrm{\Δ}{K}_w\end{array}}{\mathrm{\Σ}}{S}_1(\mathrm{n\Δ}{K}_w,\mathrm{l\Δ}{K}_u,\mathrm{m\Δ}{K}_v)\sin c_3(K_x,K_y,K_z)$ (15)

$\sin c_3(K_x,K_y,K_z)$

$=\sin c\left(\frac{K_x-\mathrm{n\Δ}{K}_w}{\mathrm{\Δ}{K}_w}\right)\sin c\left(\frac{K_y-\mathrm{l\Δ}{K}_u}{\mathrm{\Δ}{K}_u}\right)\sin c\left(\frac{K_z-\mathrm{m\Δ}{K}_v}{\mathrm{\Δ}{K}_v}\right)$ (16)

Because imaging region is along width, the length of X, Y and Z direction and highly be respectively X ₀, Y ₀And Z ₀, therefore, along K _uDirectional interpolation interval delta K _uCan not be greater than Δ K _y, along K _vDirectional interpolation interval delta K _uCan not be greater than Δ K _z

Above-mentioned for passing through the Interpolation Process of one dimension sinc function, two-dimentional sinc function and three-dimensional sinc function, also can obtain the 2nd corresponding signal S through the polynomial interpolation method ₂(K _w, K _u, K _v).

Through above-mentioned interpolation method, the 2nd signal S of acquisition ₂(K _w, K _u, K _v) do

$S_2(K_w,K_u,K_v)~\underset{n}{\mathrm{\Σ}}{\mathrm{\σ}}_n\exp (-j\sqrt{4K_w^2-K_u^2-K_v^2}{x}_n-j{K}_u{y}_n-K_v{z}_n)$ (17)

Through the 2nd signal S that generates after the coordinate Mapping ₂(K _w, K _u, K _v) be in spherical coordinate system O ₂In the W direction of UVW, U direction and the V direction three-dimensional wave number field; Also promptly be transformed in the chromatography synthetic aperture radar coordinate system; At this moment; No longer keep mutually orthogonal relation between all directions of signal, but introduced between target and the chromatography synthetic aperture radar apart from coupling phenomenon, thereby demonstrate non-orthogonal relation.

In this step, can realize coordinate Mapping accurately, unqualified to the form that transmits among the later step S6, so chromatography synthetic aperture radar transmits and is plane wave or spherical wave signal, need not suppose to transmit only is the plane;

Step S3: the 2nd signal is sent to chromatography synthetic aperture radar antenna radiation pattern processing unit, carries out chromatography synthetic aperture radar antenna radiation pattern function H ₁(K _w, K _u, K _v) multiply each other, generate the 3rd signal S ₃(K _w, K _u, K _v), the practical implementation process is:

Be in spherical coordinate system O with what obtain ₂The 2nd signal in the UVW three-dimensional wave number field is sent to chromatography synthetic aperture radar antenna radiation pattern processing unit, carries out chromatography synthetic aperture radar dimensional antenna pattern function H ₁(K _w, K _u, K _v) multiply each other, introduce chromatography synthetic aperture radar dimensional antenna directional diagram, generate the 3rd signal: S ₃(K _w, K _u, K _v), the 3rd signal of introducing antenna radiation pattern is in spherical coordinate system W direction, U direction and the V direction three-dimensional wave number field.Particularly, need to confirm the chromatography synthetic aperture radar dimensional antenna directional diagram H of introducing earlier ₁(K _w, K _u, K _v):

H ₁(K _w，K _u，K _v)＝A _T(K _w，K _u，K _v)A _R(K _w，K _u，K _v) (18)

Wherein, A _T(K _w, K _u, K _v) and A _R(K _w, K _u, K _v) difference chromatography synthetic aperture radar emitting antenna amplitude pattern and receiving antenna amplitude pattern, both equate or do not wait.As required, H ₁(K _w, K _u, K _v) get the three-dimensional amplitude pattern of actual antennas or desirable rectangular window function.If A _T(K _w, K _u, K _v) and A _R(K _w, K _u, K _v) get the three-dimensional amplitude pattern of actual antennas, then need be to the influence of considering antenna radiation pattern in the processing of three-dimensional imaging original echoed signals of chromatography synthetic aperture radars; Then need be if get desirable rectangular window function in influence to consideration antenna radiation pattern in the processing of three-dimensional imaging original echoed signals of chromatography synthetic aperture radars.

Therefore, chromatography synthetic aperture radar dimensional antenna pattern function H ₁(K _w, K _u, K _v) be amplitude pattern that antenna measurement is obtained or desirable rectangular window function;

Through the 3rd signal S behind the antenna radiation pattern processing unit ₃(K _w, K _u, K _v) be:

S ₃(K _w，K _u，K _v)＝S ₂(K _w，K _u，K _v)H ₁(K _w，K _u，K _v) (19)

Can get the 3rd signal S according to formula (17) ₃(K _w, K _u, K _v) be:

$S_3(K_w,K_u,K_v)~\underset{n}{\mathrm{\Σ}}{\mathrm{\σ}}_n{A}_T(K_w,K_u,K_v)A_R(K_w,K_u,K_v)$

$\×\exp (-j\sqrt{4K_w^2-K_u^2-K_v^2}{x}_n-j{K}_u{y}_n-K_v{z}_n)$ (20)

This signal is in spherical coordinate system W direction, U direction and the V direction three-dimensional wave number field;

Step S4: the 3rd signal is sent to three-dimensional wave number field filter unit, the 3rd signal and three-dimensional filtering function H ₂(K _w, K _u, K _v) multiply each other, generate the 4th signal S ₄(K _w, K _u, K _v), from the 4th signal, obtaining chromatography synthetic aperture radar with the imaging geometry between the imaging region, the practical implementation process is:

Be in spherical coordinate system O with what obtain ₂The 3rd signal in the W direction of UVW, U direction and the V direction three-dimensional wave number field is sent to three-dimensional wave number field filter unit, carries out three-dimensional filtering function H ₂(K _w, K _u, K _v) multiply each other, introduce chromatography synthetic aperture radar with the imaging geometry between the imaging region, generate the 4th signal and be: S ₄(K _w, K _u, K _v), this signal is in spherical coordinate system O ₂In the three-dimensional wave number field of the W direction of UVW, U direction and V direction.

Three-dimensional filtering function H ₂(K _w, K _u, K _v) and the chromatography synthetic aperture radar imaging geometry between relation table be shown:

$H_2(K_w,K_u,K_v)=\exp [-j{K}_u{Y}_c-j{K}_v{Z}_c+j2K_w{R}_c]$

$\×\exp [-j{X}_c\sqrt{4K_w^2-K_u^2-K_v^2}]$ (21)

Wherein, K _wThe corresponding wave number of expression radar emission signal frequency, K _uBe the corresponding wave number of U direction, K _vBe the corresponding wave number of V direction.When chromatography synthetic aperture radar two dimension synthetic aperture plane is positioned at O ₂On the UV plane, and chromatography synthetic aperture radar is when the U direction is moved, X _cBe spherical coordinate system O ₂The two-dimentional synthetic aperture plane O of chromatography synthetic aperture radar among the UVW ₂UV is with the vertical range between the imaging region center O, Y _cFor chromatography synthetic aperture radar beam center on the Y direction passes through constantly and the difference pairing distance of zero Doppler between the moment, Z _cBe synthetic aperture center O on the Z direction ₂To the vertical range between the imaging region center O, R _cBe the reference distance of radar to the imaging region center.

When chromatography synthetic aperture radar two dimension synthetic aperture plane parallel during, can be used for the generation of side-looking chromatography synthetic aperture radar three-dimensional imaging original echoed signals in OYZ plane or OXZ.Adopt three-dimensional filtering function H ₂(K _w, K _u, K _v) in different X _c, Y _c, Z _cAnd R _cCan realize that at interior variable the three-dimensional imaging original echoed signals of chromatography synthetic aperture radars under the different imaging geometries generates.

Fig. 3, Fig. 4 and Fig. 5 have provided how much of several kinds of special chromatography synthetic aperture radar three-dimensional imagings respectively:

As shown in Figure 3, in the imaging region (image space) of quadrature rectangular coordinate system OXYZ, (x _n, y _n, z _n) be target P _n(x _n, y _n, z _n) three dimensional space coordinate, O is the initial point (central point of image) of quadrature rectangular coordinate system, X ₀, Y ₀And Z ₀Be expressed as width, length and the height of picture zone (imaging region), O along X, Y and Z direction ₂UVW is the coordinate system of chromatography synthetic aperture radar, and the U coordinate axis is parallel to the Y coordinate axis, and the V coordinate axis is parallel to the X coordinate axis, and the W coordinate axis is by synthetic aperture planar central O ₂Point to the 3-D view regional center O that promptly forms images, the W direction is the average direction of visual lines of chromatography synthetic aperture radar along the V direction observation, also be chromatography synthetic aperture radar along the flight of Y direction, and multi-angle observation, Z are carried out in the observation area along the V direction ₀Be O ₂The two-dimentional synthetic aperture plane O of chromatography synthetic aperture radar among the UVW ₂UV is with the vertical range between the imaging region center O, Y _cFor chromatography synthetic aperture radar beam center on the Y direction passes through constantly and the difference pairing distance of zero Doppler between the moment, X _vBe synthetic aperture center O on the Z direction ₂To the vertical range between the imaging region center O, as chromatography synthetic aperture radar two dimension synthetic aperture plane O ₂UV is parallel to the OXY plane, and Y _c=0, X _c=0 o'clock; For under look chromatography synthetic aperture radar three-dimensional imaging how much, this method can be used for looking down the generation of three-dimensional imaging original echoed signals of chromatography synthetic aperture radars, particularly; In echo generates; Need carry out transforming to along the Z direction along the execution in step of directions X among the embodiment, transform to along directions X along the execution in step of Z direction and carry out, the change of variable of corresponding directions X is the variable of Z direction; The change of variable of corresponding Z direction is the variable of directions X, and other execution in step and variable along all directions remains unchanged.

As shown in Figure 4, in the imaging region (image space) of quadrature rectangular coordinate system OXYZ, (x _n, y _n, z _n) be target P _n(x _n, y _n, z _n) three dimensional space coordinate, O is the initial point (central point of image) of quadrature rectangular coordinate system, X ₀, Y ₀And Z ₀Be expressed as width, length and the height of picture zone (imaging region), O along X, Y and Z direction ₂UVW is the coordinate system of chromatography synthetic aperture radar, and the U coordinate axis is parallel to the Y coordinate axis, and the V coordinate axis is parallel to the X coordinate axis, and the W coordinate axis is by synthetic aperture planar central O ₂Point to the 3-D view regional center O that promptly forms images, the W direction is the average direction of visual lines of chromatography synthetic aperture radar along the V direction observation, also be chromatography synthetic aperture radar along the flight of Y direction, and multi-angle observation, Z are carried out in the observation area along the V direction ₀Be O ₂The two-dimentional synthetic aperture plane O of chromatography synthetic aperture radar among the UVW ₂UV is with the vertical range between the imaging region center O, Y _cFor chromatography synthetic aperture radar beam center on the Y direction passes through constantly and the difference pairing distance of zero Doppler between the moment, X _cBe synthetic aperture center O on the Z direction ₂To the vertical range between the imaging region center O, as chromatography synthetic aperture radar two dimension synthetic aperture plane O ₂UV is parallel to the OXY plane, and Y _c=0, | X _c|＞0 o'clock; Be side-looking chromatography synthetic aperture radar three-dimensional imaging how much down, this method can be used for the generation of side-looking three-dimensional imaging original echoed signals of chromatography synthetic aperture radars down, particularly; In echo generates; Need carry out transforming to along the Z direction along the execution in step of directions X among the embodiment, transform to along directions X along the execution in step of Z direction and carry out, the change of variable of corresponding directions X is the variable of Z direction; The change of variable of corresponding Z direction is the variable of directions X, and other execution in step and variable along all directions remains unchanged.

As shown in Figure 5, in the imaging region (image space) of quadrature rectangular coordinate system OXYZ, (x _n, y _n, z _n) be target P _n(x _n, y _n, z _n) three dimensional space coordinate, O is the initial point (central point of image) of quadrature rectangular coordinate system, X ₀, Y ₀And Z ₀Be expressed as width, length and the height of picture zone (imaging region), O along X, Y and Z direction ₂UVW is the coordinate system of chromatography synthetic aperture radar, and the U coordinate axis is parallel to the Y coordinate axis, and the V coordinate axis is parallel to the X coordinate axis, and the W coordinate axis is by synthetic aperture planar central O ₂Point to the 3-D view regional center O that promptly forms images, the W direction is the average direction of visual lines of chromatography synthetic aperture radar along the U direction observation, also be chromatography synthetic aperture radar along the flight of Y direction, and multi-angle observation, Z are carried out in the observation area along the V direction ₀Be O ₂The two-dimentional synthetic aperture plane O of chromatography synthetic aperture radar among the UVW ₂UV is with the vertical range between the imaging region center O, Y ₀For chromatography synthetic aperture radar beam center on the Y direction passes through constantly and the difference pairing distance of zero Doppler between the moment, X _cBe synthetic aperture center O on the Z direction ₂To the vertical range between the imaging region center O, as chromatography synthetic aperture radar two dimension synthetic aperture plane O ₂UV is parallel to the OXY plane, and X _c, work as Y at=0 o'clock _c＞0 o'clock is the generation of forward sight three-dimensional imaging original echoed signals of chromatography synthetic aperture radars, works as Y _c＜0 o'clock is the generation of backsight three-dimensional imaging original echoed signals of chromatography synthetic aperture radars, and this method can be used for the generation of preceding/backsight three-dimensional imaging original echoed signals of chromatography synthetic aperture radars, particularly; In echo generates; Need carry out transforming to along the Y direction along the execution in step of directions X among the embodiment, transform to along the Z direction along the execution in step of Y direction and carry out, transform to along the Z direction along the execution in step of Z direction and carry out; The change of variable of corresponding directions X is the variable of Y direction; The change of variable of corresponding Y direction is the variable of Z direction, and the change of variable of corresponding Z direction is the variable of directions X, and other execution in step and variable along all directions remains unchanged.

Therefore, through selecting two-dimentional synthetic aperture plane and using three-dimensional filtering function H ₂(K _w, K _u, K _v) in different X _c, Y _c, Z _cAnd R _cAt interior variable, can introduce chromatography synthetic aperture radar with the imaging geometry between the imaging region, realize that the three-dimensional imaging original echoed signals of chromatography synthetic aperture radars under the different imaging geometries generates.

The 4th signal that multiplies each other after generating through the three-dimensional filtering function is:

S ₄(K _w，K _u，K _v)＝S ₃(K _w，K _u，K _v)H ₂(K _w，K _u，K _v) (22)

Can get according to formula (20) and formula (22)

$S_4(K_w,K_u,K_v)~\underset{n}{\mathrm{\Σ}}{\mathrm{\σ}}_n{A}_T(K_w,K_u,K_v)A_R(K_w,K_u,K_v)$

$\×\exp \{-j{K}_u(Y_c+y_n)-K_v(Z_c+z_n)+j2K_w{R}_c\}$

$\×\exp \{-j(X_c+x_n)\sqrt{4K_w^2-K_u^2-K_v^2}\}$ (23)

Thereby introduce the imaging geometry between imaging region and the chromatography synthetic aperture radar, generation comprises the wavenumber domain signal of imaging geometry information in interior spherical coordinates territory, and promptly this signal is in the three-dimensional wave number field of W direction in the spherical coordinates territory, U direction and V direction;

Step S5: the 4th signal is sent to two-dimentional inverse Fourier transform unit, carries out inverse Fourier transform respectively, generate the 5th signal S along the U direction and the V direction of the 4th signal ₅(K _w, u, v), wherein, K _w, u and v represent W direction wave number, U direction time and V direction time respectively, the practical implementation process is:

Be in spherical coordinate system O with what obtain ₂The 4th signal in the three-dimensional wave number field of the W direction of UVW, U direction and V direction is sent to two-dimentional inverse Fourier transform unit, carry out inverse Fourier transform respectively along U direction and V direction after, generate the 5th signal and be:

$S_5(K_w,u,v)=F{T}_{(K_u,K_v)}^{-1}\left\{S_4(K_w,K_u,K_v)\right\}$ (24)

Can get according to formula (23), because A _T(K _w, K _u, K _v) A _R(K _w, K _u, K _v) be the chromatography synthetic aperture radar antenna radiation pattern, be tempolabile function, can from formula (23), separate, therefore

$S_5(K_w,u,v)$

$~\underset{n}{\mathrm{\Σ}}{\mathrm{\σ}}_{n}F{T}_{K_{u,}{K}_v}^{-1}\left\{A_T(K_w,K_u,K_v)A_R(K_w,K_u,K_v)\right\}$

$\×\exp \left\{j2K_w{R}_c\right\}$

$\×\exp \{-j4\mathrm{\π}{K}_w\sqrt{{(X_c+x_n)}^2+{[u-(Y_c+y_n)]}^2+{[v-(Z_c+z_n)]}^2}\}$ (25)

Wherein, F _{(Ku, Kv)} ^-1Expression is along K _uAnd K _vDirection is carried out two-dimentional inverse Fourier transform, for the U direction and the V direction time domain directional diagram a of chromatography synthetic aperture radar _T(K _w, u, v) a _R(K _w, u v) is FT _{Ku, Kv} ^-1{ A _T(K _w, K _u, K _v) A _R(K _w, K _u, K _v);

Step S6: the 5th signal is sent into W trend pass filtering unit, the 5th signal with comprise reference distance R _cFixed phase function interior multiplies each other, and generates the 6th signal S ₆(K _w, u, v), the form that obtains transmitting, the practical implementation process is:

If adopt transmit to the frequency modulation on pulse signal time, fixed phase function H ₄(K _w, u v) does

$H_4(K_w,u,v)=F{T}_t\left\{p(t-\frac{2R_c}{C})\right\}=\exp (-j2K_w{R}_c-j\frac{K_w^2}{2\mathrm{\β}})$ (26)

Wherein, FT _tExpression pulse signals p (t) carries out Fourier transform along the time variable t on the W direction, and β is a pulse signal frequency modulation rate, β=2 π B/T, and B is a transmitted signal bandwidth, T is the transmit signal pulse time width.Then, generating the 6th signal is:

S ₆(K _w，u，v)＝S ₅(K _w，u，v)H ₄(K _w，u，v) (27)

According to formula (25), then

$S_6(K_w,u,v)$

$~\underset{n}{\mathrm{\Σ}}{\mathrm{\σ}}_{n}F{T}_{K_{u,}{K}_v}^{-1}\left\{A_T(K_w,K_u,K_v)A_R(K_w,K_u,K_v)\right\}$

$\×\exp \{-j\frac{K_w^2}{2\mathrm{\β}}\}$

$\×\exp \{-j4\mathrm{\π}{K}_w\sqrt{{(X_c+x_n)}^2+{[u-(Y_c+y_n)]}^2+{[v-(Z_c+z_n)]}^2}\}$ (28)

If transmitting of adopting is stepping frequently during continuous wave signal, fixed phase function H ₅(K _w, u v) does

H ₅(K _w，u，v)＝exp(-j2K _wR _c) (29)

Then, generating the 6th signal is:

S ₆(K _w，u，v)＝S ₅(K _w，u，v)H ₅(K _w，u，v) (30)

The same, according to formula (25), then

$S_6(K_w,u,v)$

$~\underset{n}{\mathrm{\Σ}}{\mathrm{\σ}}_{n}F{T}_{K_{u,}{K}_v}^{-1}\left\{A_T(K_w,K_u,K_v)A_R(K_w,K_u,K_v)\right\}$

$\×\exp \{-j4\mathrm{\π}{K}_w\sqrt{{(X_c+x_n)}^2+{[u-(Y_c+y_n)]}^2+{[v-(Z_c+z_n)]}^2}\}$ (31)

Step S7: the 6th signal is along W direction condition judgment and processing: if transmitting of adopting is the frequency modulation on pulse signal, then carry out inverse Fourier transform along the W direction of the 6th signal, and multiply by and comprise chromatography synthetic aperture radar system carrier frequency at interior reference function H ₇(f _c, t, u v), generates initial three-dimensional imaging original echoed signals of chromatography synthetic aperture radars the 7th signal: ss ₇(v), wherein, t representes the W direction sampling time for t, u, and this signal is in W direction time domain, U direction time domain and the V direction time domain, continues execution in step S8 then; If transmitting of adopting is stepping frequency continuous wave signal or other bandwidth signal, this moment, the 7th signal equaled the 6th signal, then directly forwarded step S8 to, and the practical implementation process is:

If transmit and be the frequency modulation on pulse signal, the signal that then carries out behind the W direction inverse Fourier transform does

${\mathrm{ss}}_7(t,u,v)=F{T}_{K_w}^{-1}\left\{S_6\right[K_w,u,v\left]\right\}$

$=\underset{n}{\mathrm{\Σ}}{\mathrm{\σ}}_n\exp \{j2K_c{R}_n(w,u,v)-\mathrm{j\β}{(t-\frac{2R_n(w,u,v)}{C})}^2\}$ (32)

Wherein, $R_n(w,u,v)=\sqrt{{(X_c+x_n)}^2+{[u-(Y_c+y_n)]}^2+{[v-(Z_c+z_n)]}^2}$ For chromatography synthetic aperture radar arrives target P _n(x _n, y _n, z _n) distance, β is a pulse signal frequency modulation rate, $|t-\frac{2R_n}{C}|\≤\frac{T}{2},$ (t, u v) are O ₂The coordinate of echo in the UVW coordinate system then multiply by and comprises radar carrier frequency f _cIn the interior factor

H ₂(f _c，t，u，v)＝exp(j2πf _ct) (33)

Then

ss ₇(t，u，v)＝ss ₇(t，u，v)H ₇(f _c，t，u，v) (34)

expression imaging region n point target is carried out coherence stack.

In this step, transmitting of chromatography synthetic aperture radar is plane wave or spherical wave signal;

If needing transmitting of employing is stepping continuous wave signal or other bandwidth signal frequently, this moment, the 7th signal equaled the 6th signal,

ss ₇(t，u，v)←S ₆(K _w，u，v) (35)

Directly forward step S8 to;

Step S8: the 7th signal is sent into signal intercepting and resampling unit; The 7th signal is carried out intercepting or rises sampling or sampling, or rise sampling and sampling, or rise sampling and intercepting; Obtain the three-dimensional imaging original echoed signals of chromatography synthetic aperture radars ss (w of imaging region; U, v), the practical implementation process is:

During actual three-dimensional imaging original echoed signals of chromatography synthetic aperture radars generates; For the validity of verifying each disposal route and to U, V and the dependence in W direction SI in how much of the chromatography synthetic aperture radar three-dimensional imagings; In order to realize that echo rapidly and efficiently generates; In the present invention; Adopt the three-dimensional imaging original echoed signals of chromatography synthetic aperture radars of unified mode to generate; Because initial original echoed signals the 7th signal that obtains all satisfies how to lose this special sampling thheorem in W, U and three directions of V; Therefore, if in the three-dimensional imaging original echoed signals of chromatography synthetic aperture radars that need to generate along U, V and W direction SI greater than the three-dimensional imaging original echoed signals of chromatography synthetic aperture radars that generates along U, V and W direction SI, then need to the echoed signal that the inventive method generates carry out a liter sampling, sampling generations need three-dimensional imaging original echoed signals of chromatography synthetic aperture radars;

If in the three-dimensional imaging original echoed signals of chromatography synthetic aperture radars that need to generate along U, V and W direction SI less than the three-dimensional imaging original echoed signals of chromatography synthetic aperture radars that generates along U, V and W direction SI, then need to the echoed signal that the inventive method generates carry out liter sampling generations need a three-dimensional imaging original echoed signals of chromatography synthetic aperture radars;

If in the three-dimensional imaging original echoed signals of chromatography synthetic aperture radars that need to generate along the effective length of U, V or W direction less than the effective length of the three-dimensional imaging original echoed signals of chromatography synthetic aperture radars that generates along U, V and W direction, then need to the echoed signal that the inventive method generates carry out intercepting generations need three-dimensional imaging original echoed signals of chromatography synthetic aperture radars;

If the three-dimensional imaging original echoed signals of chromatography synthetic aperture radars that need to generate exists the effective length of other sampling and signal indication inconsistent with the echoed signal of generation, can to the various combination formula that the echoed signal of the inventive method generation carries out rising sampling, sampling and intercepting operate obtain need three-dimensional imaging original echoed signals of chromatography synthetic aperture radars.

The movement locus that the inventive method can not generate chromatography synthetic aperture radar is not in conplane three-dimensional imaging original echoed signals of chromatography synthetic aperture radars.

The present invention provides a kind of method for generating three-dimensional imaging original echoed signals of chromatography synthetic aperture radars; Make full use of the FFT instrument, avoided pointwise calculating computed tomography synthetic aperture radar three-dimensional imaging original echoed signals then to carry out the process of coherence stack.

The present invention carries out the mapping of the signal in the spherical coordinate system of signal in the quadrature rectangular coordinate system, thus in three-dimensional imaging original echoed signals of chromatography synthetic aperture radars, introduce between target and the chromatography synthetic aperture radar apart from coupling phenomenon.

The present invention has carried out the mapping of the signal in the spherical coordinate system of signal in the accurate quadrature rectangular coordinate system, and therefore, chromatography synthetic aperture radar transmits and is plane wave or spherical wave signal, need not suppose to transmit only to be the plane.

The present invention introduces three-dimensional filtering function H ₂(K _w, K _u, K _v), thereby introduced the imaging geometry between imaging region and the chromatography synthetic aperture radar, when chromatography synthetic aperture radar two dimension synthetic aperture plane parallel in the OXY plane, and Y _c=0, X _c, can be used for looking down the generation of three-dimensional imaging original echoed signals of chromatography synthetic aperture radars at=0 o'clock; When chromatography synthetic aperture radar two dimension synthetic aperture plane parallel in the OXY plane, and Y _c=0, | X _c|, can be used for the generation of side-looking three-dimensional imaging original echoed signals of chromatography synthetic aperture radars down at＞0 o'clock; When chromatography synthetic aperture radar two dimension synthetic aperture plane parallel in the OXY plane, and X _c, work as Y at=0 o'clock _c＞0 can be used for the generation of forward sight three-dimensional imaging original echoed signals of chromatography synthetic aperture radars, works as Y _c＜0 can be used for the generation of backsight three-dimensional imaging original echoed signals of chromatography synthetic aperture radars; When chromatography synthetic aperture radar two dimension synthetic aperture plane parallel during, can be used for the generation of side-looking chromatography synthetic aperture radar three-dimensional imaging original echoed signals in OYZ plane or OXZ.Therefore through selecting two-dimentional synthetic aperture plane and use to comprise X _c, Y _c, Z _cAnd R _cCan realize that at interior three-dimensional wave number field filter function the three-dimensional imaging original echoed signals of chromatography synthetic aperture radars under the different imaging geometries generates.

The mode that the present invention adopts the wavenumber domain echo data to generate; Promptly considered to exist in the reality influence of antenna radiation pattern; Considered serious in the chromatography synthetic aperture radar three-dimensional imaging again, thereby can generate three-dimensional imaging original echoed signals of chromatography synthetic aperture radars accurately apart from coupling phenomenon.

Step of the present invention is clear succinct, and modularization is strong, and characteristics such as implementation procedure is simple effective, helps computing machine or other specialized equipment and realizes.

The above-mentioned method of the present invention mainly realizes through 7 program elements on computing machine or specialized equipment; As shown in Figure 8, three dimensional fourier transform processing unit, coordinate Mapping unit, chromatography synthetic aperture radar antenna radiation pattern processing module, three-dimensional wave number field filter processing unit, two-dimentional inverse Fourier transform unit, W trend pass filtering unit, W direction condition judgment and processing unit, signal intercepting and resampling unit be the function of completing steps S1, step S2, step S3, step S4, step S5, step S6, step S7 and step S8 respectively.

The three dimensional fourier transform processing unit is input as and comprises among the quadrature rectangular coordinate system OXYZ behind the imaging region to the 3-D view of multiple scattering coefficient, is output as the 1st signal that is in directions X wavenumber domain, Y direction wave number field and Z direction wave number field;

The coordinate Mapping processing module is input as the 1st signal, is output as to be in W direction, U direction and V direction wave number field, i.e. spherical coordinate system O ₂The 2nd signal in the UVW wavenumber domain;

Chromatography synthetic aperture radar antenna radiation pattern processing unit is input as the 2nd signal, is output as the 3rd signal after process chromatography synthetic aperture radar antenna radiation pattern function multiplies each other;

Three-dimensional wave number field filter processing unit is input as the 3rd signal, is output as to comprise 4th signal of chromatography synthetic aperture radar with the imaging geometry between the imaging region;

Two dimension inverse Fourier transform processing unit is input as the 4th signal, is output as along the U direction of the 4th signal and V direction to carry out the 5th signal behind the inverse Fourier transform respectively;

W trend pass filtering unit is input as the 5th signal, is output as the 6th signal that multiplies each other through the fixed phase function;

W direction condition judgment and processing unit are input as the 6th signal, are output as the 8th signal;

Signal intercepting and resampling processing unit are input as the 7th signal, and be output as through intercepting or rise to sample or sampling, or rise sampling and sampling, or the three-dimensional imaging original echoed signals of chromatography synthetic aperture radars after liter sampling and the intercepting;

The method that the present invention is above-mentioned has obtained checking, and the three-dimensional imaging original echoed signals of chromatography synthetic aperture radars of generation has been used for the checking of chromatography synthetic aperture radar system emulation and data processing method, and the validity of the inventive method has obtained checking.

The above; Be merely the embodiment among the present invention, but protection scope of the present invention is not limited thereto, anyly is familiar with this technological people in the technical scope that the present invention disclosed; Can understand conversion or the replacement expected; All should be encompassed in of the present invention comprising within the scope, therefore, protection scope of the present invention should be as the criterion with the protection domain of claims.

Claims (6)

1. a method for generating three-dimensional imaging original echoed signals of chromatography synthetic aperture radars is characterized in that, comprises that step is following:

Step S1: with the 3-D view s that comprises among the quadrature rectangular coordinate system OXYZ behind the imaging region to multiple scattering coefficient _3D(x-x _n, y-y _n, z-z _n) send into the three dimensional fourier transform unit, generate the 1st signal and be: S ₁(K _x, K _y, K _z), wherein, x _n, y _nAnd z _nBe expressed as the coordinate of target in OXYZ in the picture zone, x, y and z represent the coordinate of 3-D view, K respectively _x, K _yAnd K _zBe respectively directions X wave number, Y direction wave number and Z direction wave number;

Step S2: the 1st signal is sent to the coordinate Mapping unit,, will be in the three-dimensional wave number field signal S in the quadrature rectangular coordinate system according to the imaging geometry of chromatography synthetic aperture radar ₁(K _x, K _y, K _z) be mapped as spherical coordinate system O ₂The 2nd signal S among the UVW ₂(K _w, K _u, K _v), wherein, K _w, K _uAnd K _vBe respectively the wave number of W direction, U direction and V direction;

Step S3: the 2nd signal is sent to chromatography synthetic aperture radar antenna radiation pattern processing unit, with chromatography synthetic aperture radar antenna radiation pattern function H ₁(K _w, K _u, K _v)=A _T(K _w, K _u, K _v) A _R(K _w, K _u, K _v) multiply each other, generate the 3rd signal S ₃(K _w, K _u, K _v); In the formula, A _T(K _w, K _u, K _v) and A _R(K _w, K _u, K _v) difference chromatography synthetic aperture radar emitting antenna amplitude pattern and receiving antenna amplitude pattern, both equate or do not wait;

Step S4: the 3rd signal is sent to three-dimensional wave number field filter unit, the 3rd signal and three-dimensional filtering function H ₂(K _w, K _u, K _v) multiply each other, generate the 4th signal S ₄(K _w, K _u, K _v), from the 4th signal, obtain chromatography synthetic aperture radar with the imaging geometry between the imaging region; Said three-dimensional filtering function H ₂(K _w, K _u, K _v) and the chromatography synthetic aperture radar imaging geometry between relation table be shown:

In the formula, K _wThe corresponding wave number of expression radar emission signal frequency, K _uBe the corresponding wave number of U direction, K _vBe the corresponding wave number of V direction; When chromatography synthetic aperture radar two dimension synthetic aperture plane is positioned at O ₂On the UV plane, and chromatography synthetic aperture radar is when the U direction is moved, X _cBe spherical coordinate system O ₂The two-dimentional synthetic aperture plane O of chromatography synthetic aperture radar among the UVW ₂UV is with the vertical range between the imaging region center O, Y _cFor chromatography synthetic aperture radar beam center on the Y direction passes through constantly and the difference pairing distance of zero Doppler between the moment, Z _cBe synthetic aperture center O on the Z direction ₂To the vertical range between the imaging region center O, R _cBe the reference distance of radar to the imaging region center;

Step S5: the 4th signal is sent to two-dimentional inverse Fourier transform unit, carries out inverse Fourier transform respectively, generate the 5th signal S along the U direction and the V direction of the 4th signal ₅(K _w, u, v), wherein, K _w, u and v represent W direction wave number, U direction time and V direction time respectively;

Step S6: the 5th signal is sent into W trend pass filtering unit, the 5th signal with comprise reference distance R _cFixed phase function interior multiplies each other, and generates the 6th signal S ₆(K _w, u, v), the form that obtains transmitting; If adopt transmit to the frequency modulation on pulse signal time, said fixed phase function is: Wherein, FT _tExpression pulse signals p (t) carries out Fourier transform along the time variable t on the W direction, and β is a pulse signal frequency modulation rate, β=2 π B/T, and B is a transmitted signal bandwidth, T is the transmit signal pulse time width; If transmitting of adopting is stepping frequently during continuous wave signal, said fixed phase function is: H ₅(K _w, u, v)=exp (j2K _wR _c);

Step S7: the 6th signal is along W direction condition judgment and processing: if transmitting of adopting is the frequency modulation on pulse signal, then carry out inverse Fourier transform along the W direction of the 6th signal, and multiply by and comprise chromatography synthetic aperture radar system carrier frequency at interior reference function H ₇(f _c, t, u, v)=exp (j2 π f _cT), generate initial three-dimensional imaging original echoed signals of chromatography synthetic aperture radars the 7th signal: ss ₇(v), wherein, t representes the W direction sampling time for t, u, and this signal is in W direction time domain, U direction time domain and the V direction time domain, f _cBe the radar carrier frequency, continue execution in step S8 then; If transmitting of adopting is stepping frequency continuous wave signal or other bandwidth signal, this moment, the 7th signal equaled the 6th signal, then directly forwarded step S8 to;

Step S8: the 7th signal is sent into signal intercepting and resampling unit, the 7th signal is carried out intercepting or rises sampling or sampling, or rise sampling and sampling; Or liter sampling and intercepting; The three-dimensional imaging original echoed signals of chromatography synthetic aperture radars ss of acquisition imaging region (w, u, v).

2. a kind of method for generating three-dimensional imaging original echoed signals of chromatography synthetic aperture radars according to claim 1; It is characterized in that; In the imaging geometry of said chromatography synthetic aperture radar; Form chromatography synthetic aperture radar two dimension synthetic aperture plane through repeatedly flight or aerial array or formation flight, thereby realize three-dimensional imaging same imaging region.

3. a kind of method for generating three-dimensional imaging original echoed signals of chromatography synthetic aperture radars according to claim 1 is characterized in that, the concrete steps of said coordinate Mapping unit are:

Step S21: through directions X wave number thresholding K in the quadrature rectangular coordinate system _x, Y direction wave number field value K _yWith Z direction wave number field value K _zCalculate W direction wave number field value K in the corresponding spherical coordinate system _w, U direction wave number field value K _uWith V direction wave number field value K _vFor:

Wherein, K _w(K _x, K _y, K _z), K _u(K _x, K _y, K _z) and K _v(K _x, K _y, K _z) be respectively and shine upon back W direction wave numerical value, U direction wave numerical value and V direction wave numerical value;

Step S22: according to each coordinate figure (K _x, K _y, K _z) on corresponding the 1st signal S of institute ₁(K _x, K _y, K _z) generate each coordinate figure (K in the spherical coordinate system through interpolation method _w, K _u, K _v) pairing the 2nd signal S ₂(K _w, K _u, K _v).

4. a kind of method for generating three-dimensional imaging original echoed signals of chromatography synthetic aperture radars according to claim 1 is characterized in that, said chromatography synthetic aperture radar dimensional antenna pattern function H ₁(K _w, K _u, K _v) be amplitude pattern that antenna measurement is obtained or desirable rectangular window function.

5. a kind of method for generating three-dimensional imaging original echoed signals of chromatography synthetic aperture radars according to claim 2; It is characterized in that; Said chromatography synthetic aperture radar two dimension synthetic aperture plane is parallel to a plane in OXY plane, OXZ plane, the OYZ plane; Or be arranged on the tapered plane of OXYZ coordinate system.

6. a kind of method for generating three-dimensional imaging original echoed signals of chromatography synthetic aperture radars according to claim 2; It is characterized in that; Said chromatography synthetic aperture radar two dimension synthetic aperture plane, along on X, Y or the Z direction be centered close to chromatography synthetic aperture radar imaging region center one side or directly over.

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