CN104597444A - Microwave gaze high resolution imaging method based on intensity association - Google Patents

Abstract

The invention discloses a microwave gaze high resolution imaging method based on intensity association. The method includes the step of separating coupled information from each other by through the second-order intensity association of a microwave radiation field jointed with received scattering echoes to reconstruct a high resolution objective image in a gaze situation. Compared with first-order distribution of a random radiation field, the time change rate of second-order intensity distribution of different positions of observation space is reduced greatly, so that the imaging method can effectively solve the phase sensitive problem of the radiation field of microwave first-order association imaging, greatly reduces requirements on hardware system synchronization errors of association imaging and provides a feasible way for practical engineering application of microwave gaze association high resolution imaging radars.

Description

A kind of microwave based on intensity correlation stares high-resolution imaging method

Technical field

The present invention relates to Radar Technology, remote sensing observations and precision Guidance Technique field, particularly relate to a kind of microwave based on intensity correlation and stare high-resolution imaging method.

Background technology

Traditional radar imaging technology, as synthetic-aperture radar (SAR), inverse synthetic aperture radar (ISAR) (ISAR), under its high-resolution imaging all exists relative motion situation between observation platform and target, by improving signal bandwidth and utilizing doppler information to obtain.Utilize doppler information to need the regular hour to accumulate, real-time is very poor, and in addition, the relative motion state of target and radar usually has uncertainty, and comparatively difficulty in the motion compensation Project Realization solving target well.Real aperture radar imaging technology has real time imagery, does not need to carry out target the advantage of motion compensation, therefore, can solve the problem of staring imaging.But due to the impact of antenna beam effect, the angular resolution of real aperture radar imaging to fixed observer target is subject to the restriction of antenna beamwidth, obtain high azimuth resolution, need to increase the horizontal aperture of aerial array, cause that array scale is excessive, cost is too expensive.

Classical microwave radar imaging mode, from the electromagnetic field of classics, utilizes Maxwell equation, Electric and magnetic fields as position and time can measurement functions, do not relate to the concept of the relevant, incoherent of field or partial coherence.Optically, " imaging of optics ghost " make use of the space-time statistic fluctuation characteristic of incoherent light field strength, is carried out the high-resolution imaging of target, breach traditional diffraction limit by the second order spatial association of optical strength.The light of association inputs different linear optical systems respectively, be called sampling system and frame of reference, object to be imaged is placed in sampling system, and by sampling and the coincidence measurement of frame of reference, the space distribution of object is reproduced in frame of reference with non-localized form.

In statistical optics, light and electromagnetic field have similar character, therefore, optic intensity correlation imaging is introduced in microwave imaging, during leggy center, the random electromagnetic signal of empty random radiation source radiation, formed time, the empty random radiation field (amplitude of electromagnetic field, phase place, frequency) there is change and fluctuation over time and space, utilize the statistical property of electromagnetic field, single order association process is carried out to radiation field and scattered field, can microwave staring imaging be realized.

Existing microwave single order radiation field stares in relevance imaging process the phase information needing to use single order radiation field, time, empty random microwave radiation field has higher time statistics variations rate, single order radiation field sample is difficult to precise synchronization with the direct correlation of not scattered field echo in the same time; Further, when microwave high-frequency, phase information to the transmitting-receiving synchronous error of imaging system and the steric configuration error of aerial array very responsive, very large technical matters can be run into when Project Realization.

Summary of the invention

The object of this invention is to provide a kind of microwave based on intensity correlation and stare high-resolution imaging method, phase sensitive can be eliminated, and greatly reducing relevance imaging to the requirement of hardware system synchronous error, the practical engineering application of staring association high-resolution imaging radar for microwave provides a feasible approach.

The object of the invention is to be achieved through the following technical solutions:

Microwave based on intensity correlation stares a high-resolution imaging method, it is characterized in that, the method comprises:

By structure time, empty random radiation source be placed in target observation region formed time, empty random radiation field;

When calculating and store described, the field intensity information of empty random radiation field, and receive the field intensity information of scattered field echo;

By time, the field intensity information of empty random radiation field and the field intensity information of scattered field echo carry out field strength association process, the decoupling zero of realize target intensity scattered information; Thus in the situation of staring, reconstruct target image.

Further, described structure time, empty random radiation source is the radar antenna array be made up of many array element, leggy center radiation;

Radar antenna array spatially meets non-homogeneous, irregular stochastic distribution, and the signal of radiation is uncorrelated random signal;

Same radar antenna is being not mutually orthogonal between transmitting in the same time, and different radar antenna synchronization is also mutually completely orthogonal between transmitting; Launch orthogonal signal related function to meet:

$\∫S({{\stackrel{\→}{r}}_i}^T,t)S^{*}({{\stackrel{\→}{r}}_j}^T,t-\mathrm{\τ})\mathrm{dt}=\mathrm{\δ}(i-j,\mathrm{\τ});$

Wherein, be respectively i-th and the random signal waveform launched at moment t of a jth radar antenna, S* represents the complex conjugate of art of mathematics, be respectively the spatial position vector of i-th and a jth radar antenna, τ is signal arbitrary time delay, and δ (i-j, τ) is impulse Response Function.

Further, described calculating and store described install beforehand time, empty random radiation field field intensity information, and the field intensity information receiving scattered field echo comprises:

Time described, empty random radiation source when being formed in target observation region, empty random radiation field, during all different resolution element instantaneous radiation field strength distribution formations one, empty two-dimensional matrix, utilize imaging system to carry out preset, calculation and storage by radiation field computational model to the two-dimensional matrix vector that radiation field intensity distribute;

Time described, empty random radiation field and observed object interact and form scattered field echo, and the different sampling instant scattered field intensity utilizing receiver to receive form one dimension matrix-vectors.

Further, described observed object region is turned to N number of target resolution element by discrete, wherein N=P × Q, P are the horizontal resolution element number of target area, and Q is the longitudinal resolution unit number of target area, and observed object backscattering coefficient vector matrix is wherein, be the n-th target resolution element position vector, n=1,2 ..., N, for target resolution element place's backscattering coefficient; Time then above-mentioned, the random radiation field that formed in t target observation space, empty random radiation source is expressed as:

$E^{\mathrm{rad}}(t,{\stackrel{\→}{r}}_n)=\underset{k=1}{\overset{K}{\mathrm{\Σ}}}\frac{S({{\stackrel{\→}{r}}_k}^T,t-|{\stackrel{\→}{r}}_n-{{\stackrel{\→}{r}}_k}^T|/c)F_k({\stackrel{\→}{r}}_n-{{\stackrel{\→}{r}}_k}^T)}{4\mathrm{\π}|{\stackrel{\→}{r}}_n-{{\stackrel{\→}{r}}_k}^T|};$

Wherein, k=1,2 ... K, K are the radar antenna array antenna sum of described radiation source, for the spatial position vector of a kth radar antenna, represent amplitude, the phase pattern steric factor of a kth radar antenna, c is the light velocity;

The instantaneous strength distribution of object space random radiation field is defined as:

$I^{\mathrm{rad}}(t,{\stackrel{\→}{r}}_n)=E^{\mathrm{rad}}(t,{\stackrel{\→}{r}}_n)\·E^{\mathrm{rad}*}(t,{\stackrel{\→}{r}}_n);$

Wherein, represent random radiation field complex conjugate;

Total imaging observation time T is divided into M observed samples moment, then in target observation region the distribution of random radiation field strength form time, empty two-dimensional matrix vector is:

$I^{\mathrm{rad}}=\left[\begin{array}{cccc}{I}^{\mathrm{rad}}(t_1,r_1)& I^{\mathrm{rad}}(t_1,r_2)& ...& I^{\mathrm{rad}}(t_1,r_N)\\ I^{\mathrm{rad}}(t_2,r_1)& I^{\mathrm{rad}}(t_2,r_2)& & I^{\mathrm{rad}}(t_2,r_N)\\ ...& & & ...\\ I^{\mathrm{rad}}(t_M,r_1)& I^{\mathrm{rad}}(t_M,r_2)& ...& I^{\mathrm{rad}}(t_M,r_N)\end{array}\right];$

Wherein, m capable n-th arranges I ^rad(t _m, r _n) represent m sampling instant t _mtarget resolution element the instantaneous radiation field strength distribution at place, m=1,2 ..., M;

Receiver location vector the target echo scattered field distribution at place is expressed as:

$E^{\mathrm{sca}}(t,{{\stackrel{\→}{r}}_s}^R)=\underset{k=1}{\overset{K}{\mathrm{\Σ}}}\underset{n=1}{\overset{N}{\mathrm{\Σ}}}\frac{\mathrm{\σ}\left({\stackrel{\→}{r}}_n\right)F_k({\stackrel{\→}{r}}_n-{{\stackrel{\→}{r}}_k}^T)}{{\left(4\mathrm{\π}\right)}^2\·|{\stackrel{\→}{r}}_n-{{\stackrel{\→}{r}}_k}^T|\·|{{\stackrel{\→}{r}}_k}^T-{{\stackrel{\→}{r}}_s}^R|}S({{\stackrel{\→}{r}}_k}^T,t-\frac{|{\stackrel{\→}{r}}_n-{{\stackrel{\→}{r}}_k}^T|+|{{\stackrel{\→}{r}}_k}^T-{{\stackrel{\→}{r}}_s}^R|}{c});$

The scattered field echo instantaneous strength then received is defined as:

$I^{\mathrm{sca}}(t,{{\stackrel{\→}{r}}_s}^R)=E^{\mathrm{sca}}(t,{{\stackrel{\→}{r}}_s}^R)\·E^{\mathrm{sca}*}(t,{{\stackrel{\→}{r}}_s}^R);$

Wherein, represent receiver location vector the target echo scattered field at place complex conjugate;

Obtain the one dimension matrix-vector that corresponding M discrete observation moment scattered field echo strength form thus to be expressed as:

$\begin{array}{c}{I}^{\mathrm{sca}}=[I^{\mathrm{sca}}(t_1,{{\stackrel{\→}{r}}_s}^R),I^{\mathrm{sca}}(t_2,{{\stackrel{\→}{r}}_s}^R),...,I^{\mathrm{sca}}(t_M,{{\stackrel{\→}{r}}_s}^R){]}^T\\ ={[I^{\mathrm{sca}}\left(t_1\right),I^{\mathrm{sca}}\left(t_2\right),...,I^{\mathrm{sca}}\left(t_M\right)]}^T\end{array}.$

Further, described by time, the field intensity information of empty random radiation field and the field intensity information of scattered field echo carry out field strength association process, the decoupling zero of realize target intensity scattered information; Thus in the situation of staring, reconstruct target image comprises:

According to time, empty random radiation field propagation equation, the second order dispersion field echo strength the Representation Equation of reception is discretize matrix form:

Wherein, be the n-th target resolution element position vector, n=1,2 ..., N; represent observed object backscattering coefficient vector matrix, for target resolution element place's backscattering coefficient; represent m sampling instant t _m, the random radiation field at place with the random radiation field at place real part computing is got after doing the multiplication of complex numbers;

In above formula, scattered field echo strength is made up of two parts contribution, and Part I represents the linear superposition of incident radiation field strength, and Part II cross term represents the impact of the single order correlativity of incident radiation field;

At that time, the random statistical characteristic of empty bidimensional random radiation field was when meeting an order ideal or nearly desirable random character, then, after the enough number of times of accumulation, the impact of Part II goes to zero, and is expressed as:

$\left[\begin{array}{c}{I}^{\mathrm{sca}}\left(t_1\right)\\ I^{\mathrm{sca}}\left(t_2\right)\\ .\\ .\\ .\\ I^{\mathrm{sca}}\left(t_M\right)\end{array}\right]=\left[\begin{array}{cccc}{I}^{\mathrm{rad}}(t_1,r_1)& I^{\mathrm{rad}}(t_1,r_2)& ...& I^{\mathrm{rad}}(t_1,r_N)\\ I^{\mathrm{rad}}(t_2,r_1)& I^{\mathrm{rad}}(t_2,r_2)& & I^{\mathrm{rad}}(t_2,r_N)\\ ...& & & ...\\ I^{\mathrm{rad}}(t_M,r_1)& I^{\mathrm{rad}}(t_M,r_2)& ...& I^{\mathrm{rad}}(t_M,r_N)\end{array}\right]\left[\begin{array}{c}{\mathrm{\σ}}_1^2\\ {\mathrm{\σ}}_2^2\\ .\\ .\\ .\\ {\mathrm{\σ}}_N^2\end{array}\right];$

Pair time, the field intensity information of empty random radiation field and the field intensity information of scattered field echo carry out field strength association process, when the association of strength information reflects second order between the two, empty statistical property, by association scattered field echo signal intensity and time, empty random radiation field strength information carries out decoupling zero process, thus the target information be originally coupled is separated, thus in the situation of staring, reconstruct target image, its formula is:

In above formula, to intensity scattered information after the observed object that expression recovers, represent restructing algorithm.

Further, under sending and receiving split mode, receiver is single-point detector; Under mode is put in sending and receiving altogether, receiver is single channel or multichannel receiver.

As seen from the above technical solution provided by the invention, receive the second order intensity correlation of scatter echo by United microwave radiation field and institute, the target information that script is coupled is separated, thus reconstructs high resolution target picture in the situation of staring; Compared with distributing with random radiation field single order, the time rate of change of its observation space diverse location second order intensity distributions significantly reduces, therefore this formation method effectively can eliminate the radiation field phase sensitive problem in microwave single order relevance imaging, and greatly reducing relevance imaging to the requirement of hardware system synchronous error, the practical engineering application of staring association high-resolution imaging radar for microwave provides a feasible approach.

Accompanying drawing explanation

In order to be illustrated more clearly in the technical scheme of the embodiment of the present invention, below the accompanying drawing used required in describing embodiment is briefly described, apparently, accompanying drawing in the following describes is only some embodiments of the present invention, for those of ordinary skill in the art, under the prerequisite not paying creative work, other accompanying drawings can also be obtained according to these accompanying drawings.

Fig. 1 stares the process flow diagram of high-resolution imaging method for a kind of microwave based on intensity correlation that the embodiment of the present invention provides;

Fig. 2 is the imaging scene schematic diagram that the microwave based on intensity correlation that the embodiment of the present invention provides stares high-resolution imaging method;

The structural representation of the standard horn antenna that Fig. 3 embodiment of the present invention provides;

Fig. 4 be the embodiment of the present invention provide time, empty random radiation source radar antenna array steric configuration stochastic distribution schematic diagram;

Fig. 5 is the time domain waveform schematic diagram of the ideal Gaussian white noise of the different radar antenna array element radiation that the embodiment of the present invention provides;

Fig. 6 is the directional beam radiation field schematic diagram of the real aperture antenna of tradition that embodiment provides;

Fig. 7 be embodiment provide time, empty bidimensional random radiation field schematic diagram;

The microwave based on intensity correlation that Fig. 8 embodiment of the present invention provides stares the observed object realistic model schematic diagram of high-resolution imaging method;

Fig. 9 is that the microwave based on intensity correlation that the embodiment of the present invention provides stares the imaging results schematic diagram adopting lower 1000 intensity correlations of band-limited noise random frequency modulation signal conditioning in high-resolution imaging method;

Figure 10 is that the microwave based on intensity correlation that the embodiment of the present invention provides stares the imaging results schematic diagram adopting lower 5000 intensity correlations of band-limited noise random frequency modulation signal conditioning in high-resolution imaging method.

Embodiment

Below in conjunction with the accompanying drawing in the embodiment of the present invention, be clearly and completely described the technical scheme in the embodiment of the present invention, obviously, described embodiment is only the present invention's part embodiment, instead of whole embodiments.Based on embodiments of the invention, those of ordinary skill in the art, not making the every other embodiment obtained under creative work prerequisite, belong to protection scope of the present invention.

Embodiment

Fig. 1 stares the process flow diagram of high-resolution imaging method for a kind of microwave based on intensity correlation that the embodiment of the present invention provides.As shown in Figure 1, the method mainly comprises the steps:

Step 11, by structure time, empty random radiation source be placed in target observation region formed time, empty random radiation field.

Step 12, when calculating and store described, the field intensity information of empty random radiation field, and receive the field intensity information of scattered field echo.

Step 13, by time, the field intensity information of empty random radiation field and the field intensity information of scattered field echo carry out field strength association process, the decoupling zero of realize target intensity scattered information; Thus in the situation of staring, reconstruct target image.

As shown in Figure 2, the microwave based on intensity correlation that the invention process provides stares the imaging scene schematic diagram of high-resolution imaging method.In Fig. 2, time, empty random radiation source is the radar antenna array be made up of many array element, leggy center radiation; Radar antenna can adopt standard horn antenna (as shown in Figure 3), and with the physical centre of radiant source plane for true origin sets up coordinate system O (x, y, z), the spatial position vector of a kth array element electromagnetic horn is k=1,2 ... K, K are the radar antenna sum of described radar antenna array, and the locus of a receiver is observed object planar S ' (x ', y ', z ₀) be that, distance parallel with x-y plane is for Z ₀plane, turn to N number of target resolution element by discrete for described observed object plane, wherein N=P × Q, P are the horizontal resolution element number of target area, and Q is the longitudinal resolution unit number of target area, and observed object backscattering coefficient vector matrix is wherein, be the n-th target resolution element position vector, n=1,2 ..., N, for target resolution element place's backscattering coefficient;

Utilize described based on high-altitude static platform time, empty random radiation source irradiates target observation region, utilizes the random radiation field strength two-dimensional matrix distribution of the computational model of random radiation field to irradiation area to calculate and store; Through the scattering process of random radiation field and observation area target, to be received by the receiver split, sampling scattered field echo information.The random radiation field strength information of obtained scattered field intensity echo samples sample and pre-stored is carried out intensity correlation process, is finally inversed by target picture by object reconstruction algorithm.

The embodiment of the present invention receives the second order intensity correlation of scatter echo by United microwave radiation field and institute, and the target information that script is coupled is separated, thus reconstructs high resolution target picture in the situation of staring; Compared with distributing with random radiation field single order, the time rate of change of its observation space diverse location second order intensity distributions significantly reduces, therefore this formation method effectively can eliminate the radiation field phase sensitive problem in microwave single order relevance imaging, and greatly reducing relevance imaging to the requirement of hardware system synchronous error, the practical engineering application of staring association high-resolution imaging radar for microwave provides a feasible approach.

For the ease of understanding, below in conjunction with accompanying drawing 4-10, the present invention is described further.

1, time, empty random radiation source.

In the embodiment of the present invention, structure time, empty random radiation source is the radar antenna array be made up of many array element, leggy center radiation; As shown in Figure 4, radar antenna array spatially meets non-homogeneous, irregular stochastic distribution, and the signal of radiation is uncorrelated random signal.

During described aerial array steric configuration random arrangement and Stochastic Modulation signal configuration effective, empty random radiation source will produce good room and time uncorrelated nature, namely same radar antenna is being not mutually orthogonal between transmitting in the same time, and different radar antenna synchronization is also mutually completely orthogonal between transmitting, when the random radiation field formed thus also possesses, the stochastic distribution of empty bidimensional.

Launch orthogonal signal related function to meet:

$\∫S({{\stackrel{\→}{r}}_i}^T,t)S^{*}({{\stackrel{\→}{r}}_j}^T,t-\mathrm{\τ})\mathrm{dt}=\mathrm{\δ}(i-j,\mathrm{\τ});$

Wherein, be respectively i-th and the random signal waveform launched at moment t of a jth radar antenna, S* represents the complex conjugate of art of mathematics, be respectively the spatial position vector of i-th and a jth radar antenna, τ is signal arbitrary time delay, and δ (i-j, τ) is impulse Response Function.

Desirable white Gaussian noise meets above-mentioned requirements completely; In practical application, because white Gaussian noise is not only difficult to obtain, and actual uncontrollable, therefore, can the replacements such as band-limited noise signal, pseudo random signal or chaotic signal be used.Thus, in the present embodiment, the signal of each radar antenna radiation can be band this white noise signal of limit for height or pseudorandom modulation pulse signal (random amplitude modulation, phase modulation, frequency hopping etc.), by the appropriate design of bandwidth, modulation system etc., the effectively space-time random radiation source of the many array element of structure, leggy center radiation; Accompanying drawing 5 has shown the time domain waveform of the desirable white Gaussian noise of different array element radiation.

At the present embodiment, the random signal of a kth radar antenna radiation is expressed as:

$S({{\stackrel{\→}{r}}_k}^T,t)=A\cos \left\{\right[2\mathrm{\π}{f}_c+2\mathrm{\π}{K}_f\underset{0}{\overset{t}{\∫}}{x}_k\left(\mathrm{\τ}\right)\mathrm{d\τ}\left]t\right\};$

Wherein f _cfor carrier frequency, K _ffor chirp rate, the modulation signal x of kth array element _kt () is a zero-mean, stably, bandwidth is the Gaussian sequence of B, for its variance.

Random noise frequency modulated signal normalized autocorrelation functions is:

$R_s\left(\mathrm{\τ}\right)=\exp \left(j2\mathrm{\π}{f}_c\mathrm{\τ}\right)\exp \{-2{\mathrm{\π}}^2{K_f}^2{{\mathrm{\σ}}_k}^2{\mathrm{\τ}}^2\};$

Its envelope is R _s(τ)=exp{-2 π ²k _f ²σ _k ²τ ², autocorrelation function is in square exponential damping, and rate of decay is by the variance of Gaussian noise sequence with chirp rate K _fcommon decision.At carrier frequency f _cunder certain prerequisite, K _fσ _klarger, decay faster, the main lobe of autocorrelation function is narrower, and system has better resolving power.Along with the increase of bandwidth, the main lobe of autocorrelation function narrows, sidelobe level step-down, and in the band of power spectrum density, flatness can be better, and the randomness of signal also can along with improving.

On the other hand, the directional beam radiation field distribution not time to time change (as shown in Figure 6) of traditional real aperture antenna, thus containing less quantity of information.

And when described, under the irradiation in empty random radiation source, in wave cover observed object region, not only ensure that formed radiation field spatially presents violent otherness at synchronization at different target, meeting spatial random distribution, and guarantee not in the same time the radiation field distribution of object space show as irrelevant, omnidirectional distribution feature, namely form meet time dimension and space dimension stochastic distribution time, empty bidimensional random radiation field, as shown in Figure 7.Its spacetime correlation function is defined as:

μ(r ₁,r ₂；t ₁,t ₂)＝<E(r ₁,t ₁)E ^*(r ₂,t ₂)>；

Wherein E (r ₁, t ₁), E (r ₂, t ₂) be the different resolution element of objective plane, not random radiation field distribution in the same time, <.> represents ensemble average.Formed desirable space-time bidimensional random radiation field correlation properties meet:

μ(r ₁,r ₂)＝G ₀δ(r ₁-r ₂)

μ(r；t ₁,t ₂)＝K ₀δ(t ₁-t ₂)

Wherein, G ₀, K ₀it is a normaliztion constant being greater than zero.

The quantity of information that space-time bidimensional random radiation field comprises is much larger than the directional beam radiation field of the real aperture antenna of tradition, this uncorrelated nature distributed at space dimension and time dimension constitutes the condition precedent realizing microwave intensity and associate, intensity correlation in this and optics is similar, but it has unique intrinsic advantage.In optics, no matter be thermal light source, or counterfeit thermal light source is all unknowable, uncontrollable, therefore need increase reference path, utilize special exploring block to carry out measuring and record, during microwave, empty random radiation source is then controlled, known, therefore, preset, pre-stored can be carried out to radiation field distribution, not need special reference arm, save system cost.

2, calculate time, empty random radiation field field intensity information.

By time aforementioned, empty random radiation source formed in target observation region time, empty random radiation field, during all different resolution element instantaneous radiation field strength distribution formations one, empty two-dimensional matrix; Be known, controlled due to random radiation field distribution and can survey, therefore, imaging system just can be utilized to carry out theory calculate by radiation field computational model to radiation field, and by experiment error calibration and correction are carried out to it, thus to space-time random radiation field strength distribution two-dimensional matrix vector carry out preset, calculation and store, as the reference function of intensity correlation imaging.Detailed process comprises:

Described observed object region is turned to N number of target resolution element by discrete, and wherein N=P × Q, P are the horizontal resolution element number of target area, and Q is the longitudinal resolution unit number of target area, and observed object backscattering coefficient vector matrix is wherein, be the n-th target resolution element position vector, n=1,2 ..., N, for target resolution element place's backscattering coefficient; Time then above-mentioned, the random radiation field that formed in t target observation space, empty random radiation source is expressed as:

$E^{\mathrm{rad}}(t,{\stackrel{\&RightArrow;}{r}}_n)=\underset{k=1}{\overset{K}{\mathrm{\&Sigma;}}}\frac{S({{\stackrel{\&RightArrow;}{r}}_k}^T,t-|{\stackrel{\&RightArrow;}{r}}_n-{{\stackrel{\&RightArrow;}{r}}_k}^T|/c)F_k({\stackrel{\&RightArrow;}{r}}_n-{{\stackrel{\&RightArrow;}{r}}_k}^T)}{4\mathrm{\&pi;}|{\stackrel{\&RightArrow;}{r}}_n-{{\stackrel{\&RightArrow;}{r}}_k}^T|};$

Wherein, k=1,2 ... K, K are the radar antenna array antenna sum of described radiation source, for the spatial position vector of a kth radar antenna, represent amplitude, the phase pattern steric factor of a kth radar antenna, c is the light velocity;

The instantaneous strength distribution of object space random radiation field is defined as:

$I^{\mathrm{rad}}(t,{\stackrel{\&RightArrow;}{r}}_n)=E^{\mathrm{rad}}(t,{\stackrel{\&RightArrow;}{r}}_n)\&CenterDot;E^{\mathrm{rad}*}(t,{\stackrel{\&RightArrow;}{r}}_n);$

Wherein, represent random radiation field complex conjugate;

Total imaging observation time T is divided into M observed samples moment t={t ₀, t ₁..., t _m, then in target observation region the distribution of random radiation field strength form time, empty two-dimensional matrix vector is:

$I^{\mathrm{rad}}=\left[\begin{array}{cccc}{I}^{\mathrm{rad}}(t_1,r_1)& I^{\mathrm{rad}}(t_1,r_2)& ...& I^{\mathrm{rad}}(t_1,r_N)\\ I^{\mathrm{rad}}(t_2,r_1)& I^{\mathrm{rad}}(t_2,r_2)& & I^{\mathrm{rad}}(t_2,r_N)\\ ...& & & ...\\ I^{\mathrm{rad}}(t_M,r_1)& I^{\mathrm{rad}}(t_M,r_2)& ...& I^{\mathrm{rad}}(t_M,r_N)\end{array}\right];$

Wherein, m capable n-th arranges I ^rad(t _m, r _n) represent m sampling instant t _mtarget resolution element the instantaneous radiation field strength distribution at place, m=1,2 ..., M;

3, the reception of scattered field echo field intensity information and sampling.

Time described, empty random radiation field and observed object interact and form scattered field echo, and after free-space propagation, received machine receives.Time, empty random radiation field transient response determine scattered field echo and need ultra-high speed sampling and vast capacity to store, the Method compare received is flexible, can be that point probe receives, also can receive by hyperchannel, can be receive and dispatch to put altogether, also can bistatic, single-point or single channel receive greatly to simplify and receive configuration, handled easily.

Receiver location vector the target echo scattered field distribution at place is expressed as:

$E^{\mathrm{sca}}(t,{{\stackrel{\&RightArrow;}{r}}_s}^R)=\underset{k=1}{\overset{K}{\mathrm{\&Sigma;}}}\underset{n=1}{\overset{N}{\mathrm{\&Sigma;}}}\frac{\mathrm{\&sigma;}\left({\stackrel{\&RightArrow;}{r}}_n\right)F_k({\stackrel{\&RightArrow;}{r}}_n-{{\stackrel{\&RightArrow;}{r}}_k}^T)}{{\left(4\mathrm{\&pi;}\right)}^2\&CenterDot;|{\stackrel{\&RightArrow;}{r}}_n-{{\stackrel{\&RightArrow;}{r}}_k}^T|\&CenterDot;|{{\stackrel{\&RightArrow;}{r}}_k}^T-{{\stackrel{\&RightArrow;}{r}}_s}^R|}S({{\stackrel{\&RightArrow;}{r}}_k}^T,t-\frac{|{\stackrel{\&RightArrow;}{r}}_n-{{\stackrel{\&RightArrow;}{r}}_k}^T|+|{{\stackrel{\&RightArrow;}{r}}_k}^T-{{\stackrel{\&RightArrow;}{r}}_s}^R|}{c});$

The scattered field echo instantaneous strength then received is defined as:

$I^{\mathrm{sca}}(t,{{\stackrel{\&RightArrow;}{r}}_s}^R)=E^{\mathrm{sca}}(t,{{\stackrel{\&RightArrow;}{r}}_s}^R)\&CenterDot;E^{\mathrm{sca}*}(t,{{\stackrel{\&RightArrow;}{r}}_s}^R);$

Wherein, represent receiver location vector the target echo scattered field at place complex conjugate;

Obtain corresponding M discrete observation moment t={t thus ₀, t ₁..., t _m, the one dimension matrix-vector that scattered field echo strength is formed is expressed as:

$\begin{array}{c}{I}^{\mathrm{sca}}=[I^{\mathrm{sca}}(t_1,{{\stackrel{\&RightArrow;}{r}}_s}^R),I^{\mathrm{sca}}(t_2,{{\stackrel{\&RightArrow;}{r}}_s}^R),...,I^{\mathrm{sca}}(t_M,{{\stackrel{\&RightArrow;}{r}}_s}^R){]}^T\\ ={[I^{\mathrm{sca}}\left(t_1\right),I^{\mathrm{sca}}\left(t_2\right),...,I^{\mathrm{sca}}\left(t_M\right)]}^T\end{array}.$

4, intensity correlation imaging processing.

Intensity correlation utilizes the second-order statistics of electromagnetic field and the decoupling zero of strength information realize target scattered information, not only make use of pre-stored time, the distributed intelligence of empty random radiation field strength, but also introduce received scattered field echo strength sampling, both are joined together carry out constantly intensity correlation process, little by little separation and extraction is out for the target information that just can make originally to be coupled in scattered field echo, complete the decoupling zero of target information, this is the present invention's core objective information decoupling method used.Detailed process is as follows:

According to time, empty random radiation field propagation equation, the second order dispersion field echo strength the Representation Equation of reception is discretize matrix form:

Wherein, be the n-th target resolution element position vector, n=1,2 ..., N; represent observed object backscattering coefficient vector matrix, for target resolution element place's backscattering coefficient; represent m sampling instant t _m, the random radiation field at place with the random radiation field at place real part computing is got after doing the multiplication of complex numbers;

In above formula, scattered field echo strength is made up of two parts contribution, and Part I represents the linear superposition of incident radiation field strength, and Part II cross term represents the impact of the single order correlativity of incident radiation field;

At that time, the random statistical characteristic of empty bidimensional random radiation field was when meeting an order ideal or nearly desirable random character, then, after the enough number of times of accumulation, the impact of Part II goes to zero, and is expressed as:

$\left[\begin{array}{c}{I}^{\mathrm{sca}}\left(t_1\right)\\ I^{\mathrm{sca}}\left(t_2\right)\\ .\\ .\\ .\\ I^{\mathrm{sca}}\left(t_M\right)\end{array}\right]=\left[\begin{array}{cccc}{I}^{\mathrm{rad}}(t_1,r_1)& I^{\mathrm{rad}}(t_1,r_2)& ...& I^{\mathrm{rad}}(t_1,r_N)\\ I^{\mathrm{rad}}(t_2,r_1)& I^{\mathrm{rad}}(t_2,r_2)& & I^{\mathrm{rad}}(t_2,r_N)\\ ...& & & ...\\ I^{\mathrm{rad}}(t_M,r_1)& I^{\mathrm{rad}}(t_M,r_2)& ...& I^{\mathrm{rad}}(t_M,r_N)\end{array}\right]\left[\begin{array}{c}{\mathrm{\&sigma;}}_1^2\\ {\mathrm{\&sigma;}}_2^2\\ .\\ .\\ .\\ {\mathrm{\&sigma;}}_N^2\end{array}\right];$

Pair time, the field intensity information of empty random radiation field and the field intensity information of scattered field echo carry out field strength association process, when the association of strength information reflects second order between the two, empty statistical property, by association scattered field echo signal intensity and time, empty random radiation field strength information carries out decoupling zero process, thus the target information be originally coupled is separated, thus in the situation of staring, reconstruct target image, its formula is:

In above formula, to intensity scattered information after the observed object that expression recovers, represent restructing algorithm.Described restructing algorithm can include but not limited to based on the direct correlation restructing algorithm of Orthogonal Decomposition, the Pseudoinverse algorithm based on svd, the object reconstruction algorithm based on regularization method, sparse restructing algorithm (BP, OMP, FOCUSS, SBL) etc.

Exemplary, if time, empty random radiation field strength matrix I ^radwhen possessing ideal, empty uncorrelated nature, restructing algorithm directly can adopt the Pseudoinverse algorithm inverting target picture based on svd:

$\widehat{{\mathrm{\&sigma;}}^2}={\left[I^{\mathrm{rad}}\right]}^{-1}\&CenterDot;\left[I^{\mathrm{sca}}\right];$

Wherein [I ^rad] ^-1for I ^radpseudoinverse.By increasing observation integration time and sampling number, time abundant to obtain, empty random radiation field and scattered field echo samples, select possess desirable uncorrelated nature time, empty random radiation field strength distribution sample and the scattered field intensity echoed signal in corresponding moment, the method that just can be solved by pseudoinverse accurately obtains the inverting target picture under the division of this grid cell.

Further, be described further below in conjunction with experiment simulation and accompanying drawing explanation.

Exemplary, in imaging scene as shown in Figure 2, the distance Z of observed object plane ₀=-500m, is divided into the resolution element of 40 × 40, and its coordinate range is (0m, 0m) ~ (D _obj=80m, D _obj=80m), time, empty random radiation source aerial array adopt 16 standard horn antennas, Aperture distribution scope is 2m × 2m; The center carrier frequencies f of random noise frequency modulated signal _c=10GHz, bandwidth B=1GHz, frequency-modulation index K _kfor 0.2GHz/V, modulation white Gaussian noise power is 2dBW, its variance 62.

Accompanying drawing 8 is the object modules used in emulation, and accompanying drawing 9, Figure 10 respectively illustrate the imaging results that band-limited noise random frequency modulation signal irradiates lower 1000 times, 5000 times intensity correlations; Imaging results demonstrates the correctness of put forward intensity correlation method.

The above; be only the present invention's preferably embodiment, but protection scope of the present invention is not limited thereto, is anyly familiar with those skilled in the art in the technical scope that the present invention discloses; the change that can expect easily or replacement, all should be encompassed within protection scope of the present invention.Therefore, protection scope of the present invention should be as the criterion with the protection domain of claims.

Claims (6)

1. the microwave based on intensity correlation stares a high-resolution imaging method, and it is characterized in that, the method comprises:

By structure time, empty random radiation source be placed in target observation region formed time, empty random radiation field;

When calculating and store described, the field intensity information of empty random radiation field, and receive the field intensity information of scattered field echo;

By time, the field intensity information of empty random radiation field and the field intensity information of scattered field echo carry out field strength association process, the decoupling zero of realize target intensity scattered information; Thus in the situation of staring, reconstruct target image.

2. method according to claim 1, is characterized in that, described structure time, empty random radiation source is the radar antenna array be made up of many array element, leggy center radiation;

Radar antenna array spatially meets non-homogeneous, irregular stochastic distribution, and the signal of radiation is uncorrelated random signal;

Same radar antenna is being not mutually orthogonal between transmitting in the same time, and different radar antenna synchronization is also mutually completely orthogonal between transmitting; Launch orthogonal signal related function to meet:

$\&Integral;S({\stackrel{\&RightArrow;}{r}}_i^T,t)S^{*}({\stackrel{\&RightArrow;}{r}}_j^T,t-\mathrm{\&tau;})\mathrm{dt}=\mathrm{\&delta;}(i-j,\mathrm{\&tau;});$

Wherein, be respectively i-th and the random signal waveform launched at moment t of a jth radar antenna, S* represents the complex conjugate of art of mathematics, be respectively the spatial position vector of i-th and a jth radar antenna, τ is signal arbitrary time delay, and δ (i-j, τ) is impulse Response Function.

3. method according to claim 1 and 2, is characterized in that, described calculating and store described install beforehand time, empty random radiation field field intensity information, and the field intensity information receiving scattered field echo comprises:

Time described, empty random radiation source when being formed in target observation region, empty random radiation field, during all different resolution element instantaneous radiation field strength distribution formations one, empty two-dimensional matrix, utilize imaging system to carry out preset, calculation and storage by radiation field computational model to the two-dimensional matrix vector that radiation field intensity distribute;

Time described, empty random radiation field and observed object interact and form scattered field echo, and the different sampling instant scattered field intensity utilizing receiver to receive form one dimension matrix-vectors.

4. method according to claim 3, is characterized in that,

Described observed object region is turned to N number of target resolution element by discrete, and wherein N=P × Q, P are the horizontal resolution element number of target area, and Q is the longitudinal resolution unit number of target area, and observed object backscattering coefficient vector matrix is wherein, be the n-th target resolution element position vector, n=1,2 ..., N, for target resolution element place's backscattering coefficient; Time then above-mentioned, the random radiation field that formed in t target observation space, empty random radiation source is expressed as:

$E^{\mathrm{rad}}(t,{\stackrel{\&RightArrow;}{r}}_n)=\underset{k=1}{\overset{K}{\mathrm{\&Sigma;}}}\frac{S({\stackrel{\&RightArrow;}{r}}_k^T,t-|{\stackrel{\&RightArrow;}{r}}_n-{\stackrel{\&RightArrow;}{r}}_k^T|/c)F_k({\stackrel{\&RightArrow;}{r}}_n-{\stackrel{\&RightArrow;}{r}}_k^T)}{4\mathrm{\&pi;}|{\stackrel{\&RightArrow;}{r}}_n-{\stackrel{\&RightArrow;}{r}}_k^T|},$

Wherein, k=1,2 ... K, K are the radar antenna array antenna sum of described radiation source, for the spatial position vector of a kth radar antenna, represent amplitude, the phase pattern steric factor of a kth radar antenna, c is the light velocity;

The instantaneous strength distribution of object space random radiation field is defined as:

$I^{\mathrm{rad}}(t,{\stackrel{\&RightArrow;}{r}}_n)=E^{\mathrm{rad}}(t,{\stackrel{\&RightArrow;}{r}}_n)\&CenterDot;E^{\mathrm{rad}*}(t,{\stackrel{\&RightArrow;}{r}}_n);$

Wherein, represent random radiation field complex conjugate;

Total imaging observation time T is divided into M observed samples moment, then in target observation region the distribution of random radiation field strength form time, empty two-dimensional matrix vector is:

$I^{\mathrm{rad}}=\left[\begin{array}{cccc}{I}^{\mathrm{rad}}(t_1,r_1)& I^{\mathrm{rad}}(t_1,r_2)& ...& I^{\mathrm{rad}}(t_1,r_N)\\ I^{\mathrm{rad}}(t_2,r_1)& I^{\mathrm{rad}}(t_2,r_2)& & I^{\mathrm{rad}}(t_2,r_N)\\ ...& & & ...\\ I^{\mathrm{rad}}(t_M,r_1)& I^{\mathrm{rad}}(t_M,r_2)& ...& I^{\mathrm{rad}}(t_M,r_N)\end{array}\right],$

Wherein, m capable n-th arranges I ^rad(t _m, r _n) represent m sampling instant t _mtarget resolution element the instantaneous radiation field strength distribution at place, m=1,2 ..., M;

Receiver location vector the target echo scattered field distribution at place is expressed as:

$E^{\mathrm{sca}}(t,{\stackrel{\&RightArrow;}{r}}_s^R)=\underset{k=1}{\overset{k}{\mathrm{\&Sigma;}}}\underset{n=1}{\overset{N}{\mathrm{\&Sigma;}}}\frac{\mathrm{\&sigma;}\left({\stackrel{\&RightArrow;}{r}}_n\right)F_k({\stackrel{\&RightArrow;}{r}}_n-{\stackrel{\&RightArrow;}{r}}_k^T)}{{\left(4\mathrm{\&pi;}\right)}^2\&CenterDot;|{\stackrel{\&RightArrow;}{r}}_n-{\stackrel{\&RightArrow;}{r}}_k^T|\&CenterDot;|{\stackrel{\&RightArrow;}{r}}_k^T-{\stackrel{\&RightArrow;}{r}}_s^R|}S({\stackrel{\&RightArrow;}{r}}_k^T,t-\frac{|{\stackrel{\&RightArrow;}{r}}_n-{\stackrel{\&RightArrow;}{r}}_k^T|+|{\stackrel{\&RightArrow;}{r}}_k^T-{\stackrel{\&RightArrow;}{r}}_s^R}{c});$

The scattered field echo instantaneous strength then received is defined as:

$I^{\mathrm{sca}}(t,{\stackrel{\&RightArrow;}{r}}_s^R)=E^{\mathrm{sca}}(t,{\stackrel{\&RightArrow;}{r}}_s^R)\&CenterDot;E^{\mathrm{sc}{a}^{*}}(t,{\stackrel{\&RightArrow;}{r}}_s^R);$

Wherein, represent receiver location vector the target echo scattered field at place complex conjugate;

Obtain the one dimension matrix-vector that corresponding M discrete observation moment scattered field echo strength form thus to be expressed as:

$\begin{array}{c}{I}^{\mathrm{sca}}={[I^{\mathrm{sca}}(t_1,{\stackrel{\&RightArrow;}{r}}_s^R),I^{\mathrm{sca}}(t_2,{\stackrel{\&RightArrow;}{r}}_s^R),...,I^{\mathrm{sca}}(t_M,{\stackrel{\&RightArrow;}{r}}_s^R)]}^T\\ ={[I^{\mathrm{sca}}\left(t_1\right),I^{\mathrm{sca}}\left(t_2\right),...,I^{\mathrm{sca}}\left(t_M\right)]}^T\end{array}.$

5. the method according to claim 1 or 4, is characterized in that, described by time, the field intensity information of empty random radiation field and the field intensity information of scattered field echo carry out field strength association process, the decoupling zero of realize target intensity scattered information; Thus in the situation of staring, reconstruct target image comprises:

According to time, empty random radiation field propagation equation, the second order dispersion field echo strength the Representation Equation of reception is discretize matrix form:

Wherein, be the n-th target resolution element position vector, n=1,2 ..., N; represent observed object backscattering coefficient vector matrix, for target resolution element place's backscattering coefficient; represent m sampling instant t _m, the random radiation field at place with the random radiation field at place real part computing is got after doing the multiplication of complex numbers;

In above formula, scattered field echo strength is made up of two parts contribution, and Part I represents the linear superposition of incident radiation field strength, and Part II cross term represents the impact of the single order correlativity of incident radiation field;

At that time, the random statistical characteristic of empty bidimensional random radiation field was when meeting an order ideal or nearly desirable random character, then, after the enough number of times of accumulation, the impact of Part II goes to zero, and is expressed as:

$\left[\begin{array}{c}{I}^{\mathrm{sca}}\left(t_1\right)\\ I^{\mathrm{sca}}\left(t_a\right)\\ .\\ .\\ .\\ I^{\mathrm{sca}}\left(t_M\right)\end{array}\right]=\left[\begin{array}{cccc}{I}^{\mathrm{rad}}(t_1,r_1)& I^{\mathrm{rad}}(t_1,r_2)& ...& I^{\mathrm{rad}}(t_1,r_N)\\ I^{\mathrm{rad}}(t_2,r_1)& I^{\mathrm{rad}}(t_2,r_2)& & I^{\mathrm{rad}}(t_2,r_N)\\ ...& & & ...\\ I^{\mathrm{rad}}(t_M,r_1)& I^{\mathrm{rad}}(t_M,r_2)& ...& I^{\mathrm{rad}}(t_M,r_N)\end{array}\right]\left[\begin{array}{c}{\mathrm{\&sigma;}}_1^2\\ {\mathrm{\&sigma;}}_2^2\\ .\\ .\\ .\\ {\mathrm{\&sigma;}}_N^2\end{array}\right];$

Pair time, the field intensity information of empty random radiation field and the field intensity information of scattered field echo carry out field strength association process, when the association of strength information reflects second order between the two, empty statistical property, by association scattered field echo signal intensity and time, empty random radiation field strength information carries out decoupling zero process, thus the target information be originally coupled is separated, thus in the situation of staring, reconstruct target image, its formula is:

In above formula, to intensity scattered information after the observed object that expression recovers, represent restructing algorithm.

6. method according to claim 3, is characterized in that,

Under sending and receiving split mode, receiver is single-point detector; Under mode is put in sending and receiving altogether, receiver is single channel or multichannel receiver.