CN104597444B - Microwave gaze high resolution imaging method based on intensity association - Google Patents
Microwave gaze high resolution imaging method based on intensity association Download PDFInfo
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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
Technical field
The present invention relates to Radar Technology, remote sensing observations and precision Guidance Technique field, more particularly to one kind is based on intensity pass
The microwave of connection stares high-resolution imaging method.
Background technology
Traditional radar imaging technology, such as synthetic aperture radar (SAR), ISAR (ISAR), its high-resolution
Rate imaging exists in the case of relative motion all between observation platform and target, by improving signal bandwidth and being believed using Doppler
Cease to obtain.The regular hour is needed to accumulate using doppler information, real-time is very poor, additionally, the relative fortune of target and radar
Dynamic state usually has uncertainty, and solves well more difficult in the motion compensation Project Realization of target.Real aperture thunder
There is realtime imaging, motion compensation need not be carried out to target up to imaging technique, therefore, it can solve staring imaging
Problem.But due to the impact of antenna beam effect, real aperture radar imaging is subject to day to the angular resolution of fixed observer target
The restriction of line beam angle, will obtain high azimuth resolution, need the horizontal aperture for increasing aerial array, cause array to be advised
Mould is excessive, cost is prohibitively expensive.
Classical microwave radar imaging mode from classical electromagnetic field, using Maxwell equation, electric field and magnetic field
As position and the measurable function of time, relevant, incoherent or partially coherent the concept of field is not related to.Optically,
" optics ghost imaging " make use of the space-time statistic fluctuation characteristic of incoherent light field intensity, be associated by the second order spatial of optical strength
The high-resolution imaging of target is carried out, traditional diffraction limit is breached.The light of association is input into respectively different linear optical systems,
Referred to as sampler and reference system, object to be imaged is placed in sampler, and by sampling and reference system survey is met
Amount, the spatial distribution of object is reproduced in reference system in non-localized form.
In statistical optics, light has similar property with electromagnetic field, therefore, the imaging of optic intensity correlation is introduced
In microwave imaging, during leggy center, the random electromagnetic signal of empty random radiation source radiation, formed when, empty random radiation
Field (amplitude of electromagnetic field, phase place, frequency) has over time and space change and fluctuation, using the statistical property of electromagnetic field,
Single order association process is carried out to radiation field and scattered field, it is possible to achieve microwave staring imaging.
Existing microwave single order radiation field is stared during relevance imaging is processed and needs to use the phase information of single order radiation field,
When, empty random microwave radiation field there is higher time statistics variations rate, single order radiation field sample and scattered field not in the same time
The direct correlation of echo is difficult to precise synchronization；Also, in the case of microwave high-frequency, transmitting-receiving of the phase information to imaging system is same
The steric configuration error of step error and aerial array is very sensitive, and very big technical problem can be run in Project Realization.
The content of the invention
It is an object of the invention to provide a kind of microwave based on intensity correlation stares high-resolution imaging method, phase can be eliminated
Position is sensitive, and greatly reduces requirement of the relevance imaging to hardware system synchronous error, be microwave stare association high-resolution into
As the practical engineering application of radar provides a feasible approach.
The purpose of the present invention is achieved through the following technical solutions：
A kind of microwave based on intensity correlation stares high-resolution imaging method, it is characterised in that the method includes：
By structure when, empty random radiation source be placed in when being formed in target observation region, empty random radiation field；
When calculating and storing described, the field intensity information of empty random radiation field, and the field intensity information for receiving scattered field echo；
By when, empty random radiation field field intensity information carry out field strength with the field intensity information of scattered field echo and associate place
Reason, realizes the decoupling of target strength scattered information；So as in the case of staring, reconstruct target image.
Further, the structure when, empty random radiation source be the radar being made up of many array elements, the radiation of leggy center
Aerial array；
Radar antenna array spatially meets non-homogeneous, irregular random distribution, and the signal for radiating is irrelevant
Stochastic signal；
Same radar antenna is mutually orthogonal between transmission signal not in the same time, and different radar antennas are with for the moment
It is also mutually completely orthogonal for carving between transmission signal；Transmitting orthogonal signalling correlation function meets：
Wherein,The stochastic signal ripple that respectively ith and jth radar antenna is launched in moment t
Shape, S* represents the complex conjugate of art of mathematics,The respectively spatial position vector of ith and jth radar antenna, τ is
Signal arbitrary time delay, δ (i-j, τ) is impulse Response Function.
Further, the calculating and store it is described can be preset when, the field intensity information of empty random radiation field, and receive
The field intensity information of scattered field echo includes：
When described, empty random radiation source when being formed in target observation region, empty random radiation field, it is all different to differentiate lists
First instantaneous radiation field intensity is distributed when constituting one, empty two-dimensional matrix, using imaging system by radiation field computational model to spoke
Penetrating the two-dimensional matrix vector of field intensity distribution carries out preset, calculation and stores；
When described, empty random radiation field and observed object interact to form scattered field echo, received using receiver
Different sampling instants scattering field intensity constitute one-dimensional matrix-vector.
Further, the observed object region is discretized as N number of target resolution cell, wherein N=P × Q, P are
The horizontal resolution cell number of target area, Q is the longitudinal resolution unit number of target area, and observed object backscattering coefficient is vectorial
Matrix isWherein,For n-th target resolution cell position vector, n=1,2 ...,
N,For target resolution cellPlace's backscattering coefficient；When then above-mentioned, empty random radiation source it is empty in t target observation
Between formed random radiation field be expressed as：
Wherein, k=1,2 ... K, K are the radar antenna array antenna sum of the radiation source,For k-th radar day
The spatial position vector of line,Amplitude, the phase pattern steric factor of k-th radar antenna are represented, c is the light velocity；
The instantaneous strength distribution of object space random radiation field is defined as：
Wherein,Represent random radiation fieldComplex conjugate；
Total imaging observation time T is divided into into M observed samples moment, then random radiation field intensity in target observation region
Degree distribution constitute when, empty two-dimensional matrix vector be：
Wherein, the row of m rows n-th Irad(tm,rn) represent m-th sampling instant tmTarget resolution cellThe instantaneous radiation at place
Field intensity is distributed, m=1, and 2 ..., M；
Receiver location vectorThe target echo scattered field distribution at place is expressed as：
The scattered field echo instantaneous strength for then receiving is defined as：
Wherein,Represent receiver location vectorThe target echo scattered field at placeIt is multiple altogether
Yoke；
Thus obtain the one-dimensional matrix-vector that M discrete observation moment scattered field echo strength of correspondence constituted to be expressed as：
Further, it is described by when, the empty field intensity information of random radiation field and the field intensity information of scattered field echo carry out field
Strong intensity correlation is processed, and realizes the decoupling of target strength scattered information；So as in the case of staring, reconstruct target image includes：
According to when, empty random radiation field propagation equation, the second order dispersion field echo strength equation of reception is expressed as discrete
Change matrix form：
Wherein,For n-th target resolution cell position vector, n=1,2 ..., N；
Observed object backscattering coefficient vector matrix is represented,For target resolution cellPlace's backscattering coefficient；Represent m-th sampling instant tm,The random radiation field at placeWithPlace
Random radiation fieldDo treating excess syndrome portion computing after the multiplication of complex numbers；
In above formula, scattered field echo strength is made up of two parts contribution, and Part I represents the line of incident radiation field intensity
Property superposition, Part II cross term represents the impact of the single order dependency of incident radiation field；
At that time, when the random statistical characteristic of empty bidimensional random radiation field meets an order ideal or nearly ideal stochastic behaviour, then
After enough number of times are accumulated, the impact of Part II goes to zero, and is expressed as：
Pair when, the field intensity information of empty random radiation field carries out field strength and associates place with the field intensity information of scattered field echo
Reason, when the association of strength information reflects second order between the two, empty statistical property, by association scattered field echo signal intensity
With when, empty random radiation field intensity information carry out decoupling process so that the target information being coupled originally is separated
Come, so as in the case of staring, reconstruct target image, its formula is：
In above formula,Represent after the observed object recovered to intensity scattered information,Represent restructing algorithm.
Further, in the case where sending and receiving split mode, receiver is single point detector；Put altogether under mode in sending and receiving, receive
Machine is single channel or multichannel receiver.
As seen from the above technical solution provided by the invention, by United microwave radiation field with receive scatter echo
Second order intensity correlation so that the target information being coupled originally is separated, so as to reconstruct high score in the case of staring
Distinguish target picture；Compared with random radiation field single order is distributed, the time rate of change of its observation space diverse location second order intensity distributions
Significantly reduce, therefore the imaging method can effectively eliminate the radiation field phase sensitive problem in microwave single order relevance imaging, and pole
The earth reduces requirement of the relevance imaging to hardware system synchronous error, is the reality that microwave stares association high-resolution imaging radar
Engineer applied provides a feasible approach.
Description of the drawings
In order to be illustrated more clearly that the technical scheme of the embodiment of the present invention, below will be to use needed for embodiment description
Accompanying drawing be briefly described, it should be apparent that, drawings in the following description are only some embodiments of the present invention, for this
For the those of ordinary skill in field, on the premise of not paying creative work, can be obtaining other according to these accompanying drawings
Accompanying drawing.
Fig. 1 is the flow process that a kind of microwave based on intensity correlation provided in an embodiment of the present invention stares high-resolution imaging method
Figure；
Fig. 2 is the image scene that the microwave based on intensity correlation provided in an embodiment of the present invention stares high-resolution imaging method
Schematic diagram；
The structural representation of Fig. 3 standard horn antennas provided in an embodiment of the present invention；
When Fig. 4 is provided in an embodiment of the present invention, empty random radiation source radar antenna array steric configuration random distribution shows
It is intended to；
Fig. 5 is the time domain waveform of the ideal Gaussian white noise of different radar antenna array element radiation provided in an embodiment of the present invention
Schematic diagram；
Fig. 6 is the directional beam radiation field schematic diagram of the tradition reality aperture antenna that embodiment is provided；
When Fig. 7 is that embodiment is provided, empty bidimensional random radiation field schematic diagram；
Fig. 8 microwaves based on intensity correlation provided in an embodiment of the present invention are stared the observed object of high-resolution imaging method and are imitated
True mode schematic diagram；
Fig. 9 is that the microwave based on intensity correlation provided in an embodiment of the present invention is stared in high-resolution imaging method using band limit
The imaging results schematic diagram of lower 1000 intensity correlations of noise random frequency modulation signal conditioning；
Figure 10 is that the microwave based on intensity correlation provided in an embodiment of the present invention is stared in high-resolution imaging method using band
The imaging results schematic diagram of lower 5000 intensity correlations of limit noise random frequency modulation signal conditioning.
Specific embodiment
With reference to the accompanying drawing in the embodiment of the present invention, the technical scheme in the embodiment of the present invention is carried out clear, complete
Ground description, it is clear that described embodiment is only a part of embodiment of the invention, rather than the embodiment of whole.Based on this
Inventive embodiment, the every other enforcement that those of ordinary skill in the art are obtained under the premise of creative work is not made
Example, belongs to protection scope of the present invention.
Embodiment
Fig. 1 is the flow process that a kind of microwave based on intensity correlation provided in an embodiment of the present invention stares high-resolution imaging method
Figure.As shown in figure 1, the method mainly comprises the steps：
Step 11, by structure when, empty random radiation source be placed in when being formed in target observation region, empty random radiation field.
Step 12, when calculating and storing described, the field intensity information of empty random radiation field, and the field for receiving scattered field echo
Strong information.
Step 13, by when, the empty field intensity information of random radiation field and the field intensity information of scattered field echo carry out field strength
Association process, realizes the decoupling of target strength scattered information；So as in the case of staring, reconstruct target image.
As shown in Fig. 2 the present invention implements the imaging that high-resolution imaging method is stared based on the microwave of intensity correlation for providing
Schematic diagram of a scenario.In Fig. 2, when, empty random radiation source be the radar antenna array being made up of many array elements, the radiation of leggy center；
Radar antenna can adopt standard horn antenna (as shown in Figure 3), set up as zero with the physical centre of radiant source plane and sat
Mark system O (x, y, z), the spatial position vector of k-th array element electromagnetic horn isK=1,2 ... K, K are the radar antenna
The radar antenna sum of array, the locus of a receiver areObserved object plane S ' (x ', y ', z0) it is flat with x-y
Face is parallel, distance is Z0Plane, turn to N number of target resolution cell, wherein N=P × Q, P by the observed object plane is discrete
For the horizontal resolution cell number of target area, Q for target area longitudinal resolution unit number, observed object backscattering coefficient to
Moment matrix isWherein,For n-th target resolution cell position vector, n=1,2 ...,
N,For target resolution cellPlace's backscattering coefficient；
Using it is described based on high-altitude static platform when, empty random radiation source irradiation target observation region, using random spoke
Penetrate random radiation field intensity two-dimensional matrix distribution of the computational model of field to irradiation area to be calculated and stored；Through random spoke
The scattering process of field and observation area target is penetrated, by the receiver reception, sampling scattered field echo information that split.By what is obtained
Scattering field intensity echo samples sample carries out intensity correlation process with the random radiation field intensity information of pre-stored, by target weight
Structure algorithm is finally inversed by target picture.
The embodiment of the present invention is by United microwave radiation field and the second order intensity correlation for receiving scatter echo so that originally
The target information being coupled is separated, so as to reconstruct high resolution target picture in the case of staring；With random radiation field one
Rank distribution is compared, and the time rate of change of its observation space diverse location second order intensity distributions significantly reduces, therefore the imaging method
The radiation field phase sensitive problem in microwave single order relevance imaging can be effectively eliminated, and greatly reduces relevance imaging to hardware system
The requirement of system synchronous error, the practical engineering application for staring association high-resolution imaging radar for microwave provide one it is feasible
Approach.
In order to make it easy to understand, below in conjunction with the accompanying drawings 4-10 the present invention is described further.
When the 1st, empty random radiation source.
In the embodiment of the present invention, structure when, empty random radiation source be the thunder being made up of many array elements, the radiation of leggy center
Up to aerial array；As shown in figure 4, radar antenna array spatially meets non-homogeneous, irregular random distribution, and radiate
Signal is uncorrelated stochastic signal.
The aerial array steric configuration random arrangement and Stochastic Modulation signal construction it is effective when, empty random radiation source will
Good room and time uncorrelated nature is produced, i.e., same radar antenna is mutually just between transmission signal not in the same time
Hand over, and be also mutual completely orthogonal, the random radiation being consequently formed between different radar antenna synchronization transmission signals
Field is when also possessing, the random distribution of empty bidimensional.
Transmitting orthogonal signalling correlation function meets：
Wherein,The stochastic signal ripple that respectively ith and jth radar antenna is launched in moment t
Shape, S* represents the complex conjugate of art of mathematics,The respectively spatial position vector of ith and jth radar antenna, τ is letter
Number arbitrary time delay, δ (i-j, τ) is impulse Response Function.
Preferably white Gaussian noise complies fully with above-mentioned requirements；In practical application, because white Gaussian noise is not only difficult to obtain
, and it is actual uncontrollable, therefore, it can be replaced with band-limited noise signal, pseudo-random signal or chaotic signal etc..Thus, this
In 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., in effectively constructing many array elements, leggy
The space-time random radiation source of heart radiation；Accompanying drawing 5 has shown the time domain waveform of the preferable white Gaussian noise of different array element radiation.
In the present embodiment, the stochastic signal of k-th radar antenna radiation is expressed as：
Wherein fcFor carrier frequency, KfFor chirp rate, modulated signal x of kth array elementkT () is zero-mean, steady
, the Gaussian sequence with a width of B,For its variance.
Random noise frequency modulated signal normalized autocorrelation functions are：
Its envelope is Rs(τ)=exp { -2 π2Kf 2σk 2τ2, auto-correlation function is in square exponential damping, and rate of decay is by height
The variance of this noise sequenceWith chirp rate KfTogether decide on.In carrier frequency fcOn the premise of certain, KfσkIt is bigger, decay
Faster, the main lobe of auto-correlation function is narrower, and system has more preferable resolving power.With the increase of bandwidth, the master of auto-correlation function
Lobe narrows, sidelobe level step-down, and the interior flatness of the band of power spectral density can be more preferable, and the randomness of signal also can be with improving.
On the other hand, directional beam radiation field distribution not time to time change (as shown in Figure 6) of tradition reality 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 institute
The radiation field of formation is spatially presented violent diversity in synchronization in different target, meets space random distribution, and
And guarantee that is, composition meets the time in the same time the radiation field distribution of object space does not show as irrelevant, omnidirectional distribution feature
Peacekeeping space dimension random distribution when, empty bidimensional random radiation field, as shown in Figure 7.Its space time correlation function is defined as：
μ(r1,r2；t1,t2)=<E(r1,t1)E*(r2,t2)>；
Wherein E (r1,t1)、E(r2,t2) for objective plane difference resolution cell, random radiation field distribution not in the same time,
<.>Represent ensemble average.Form preferable space-time bidimensional random radiation field correlation properties to meet：
μ(r1,r2)=G0δ(r1-r2)
μ(r；t1,t2)=K0δ(t1-t2)
Wherein, G0、K0For a normaliztion constant more than zero.
The quantity of information that space-time bidimensional random radiation field includes is much larger than the directional beam radiation field of tradition reality aperture antenna, this
The uncorrelated nature kind being distributed with time dimension in space dimension constitutes the prerequisite for realizing that microwave intensity is associated, during this is with optics
Intensity correlation be similar to, but its have uniqueness intrinsic advantage.In optics, either thermal light source, or counterfeit thermal light source is not
Understand, it is uncontrollable, it is therefore desirable to increase a reference path, measure and record using special exploring block, and micro-
During ripple, empty random radiation source be then controllable, knowable, therefore, it can carry out preset, pre-stored to radiation field distribution, it is not necessary to
Special reference arm, saves system cost.
When the 2nd, calculating, the field intensity information of empty random radiation field.
By it is aforementioned when, empty random radiation source is formed in target observation region when, empty random radiation field, all different resolutions
Unit instantaneous radiation field intensity is distributed when constituting one, empty two-dimensional matrix；Due to random radiation field distribution be understand, it is controllable and can
Survey, accordingly, it is possible to Theoretical Calculation is carried out to radiation field by radiation field computational model using imaging system, and it is right by testing
It carries out error calibration and amendment, so as to carry out preset, calculation to the two-dimensional matrix vector that space-time random radiation field intensity is distributed
And storage, as the reference function of intensity correlation imaging.Detailed process includes：
The observed object region is discretized as N number of target resolution cell, wherein N=P × Q, P is target area
Horizontal resolution cell number, Q is the longitudinal resolution unit number of target area, and observed object backscattering coefficient vector matrix isWherein,For n-th target resolution cell position vector, n=1,2 ..., N,
For target resolution cellPlace's backscattering coefficient；When then above-mentioned, empty random radiation source formed in t target observation space
Random radiation field is expressed as：
Wherein, k=1,2 ... K, K are the radar antenna array antenna sum of the radiation source,For k-th radar day
The spatial position vector of line,Amplitude, the phase pattern steric factor of k-th radar antenna are represented, c is the light velocity；
The instantaneous strength distribution of object space random radiation field is defined as：
Wherein,Represent random radiation fieldComplex conjugate；
Total imaging observation time T is divided into into M observed samples moment t={ t0,t1,...,tM, then target observation area
In domain the distribution of random radiation field intensity constitute when, empty two-dimensional matrix vector be：
Wherein, the row of m rows n-th Irad(tm,rn) represent m-th sampling instant tmTarget resolution cellThe instantaneous radiation at place
Field intensity is distributed, m=1, and 2 ..., M；
3rd, the reception of scattered field echo field intensity information and sampling.
When described, empty random radiation field and observed object interact to form scattered field echo, Jing after free-space propagation
Received by receiver.When, the transient response of empty random radiation field determine that scattered field echo needs ultra-high speed sampling with super large appearance
Amount is stored, and the mode of reception is more flexible, can be that point probe is received, it is also possible to which multichannel is received, and can be transmitting-receiving
Put altogether, it is also possible to bistatic, single-point or single channel are received and can greatly simplify reception configuration, convenient operation.
Receiver location vectorThe target echo scattered field distribution at place is expressed as：
The scattered field echo instantaneous strength for then receiving is defined as：
Wherein,Represent receiver location vectorThe target echo scattered field at placeIt is multiple altogether
Yoke；
Thus M discrete observation moment t={ t of correspondence is obtained0,t1,...,tM, scattered field echo strength constituted one
Dimension matrix-vector is expressed as：
4th, intensity correlation imaging processing.
Intensity correlation using the decoupling that the second-order statisticses of electromagnetic field are that strength information realizes target scattering information, not only
Make use of pre-stored when, empty random radiation field intensity distributed intelligence, and also introduce received scattered field echo strength
Sampling, both is joined together to carry out constantly intensity correlation process, so that it may so as to be coupled in the target of scattered field echo originally
Information is little by little separated and extracted, and completes the decoupling of target information, and this is the core objective information decoupling used by the present invention
Method.Detailed process is as follows：
According to when, empty random radiation field propagation equation, the second order dispersion field echo strength equation of reception is expressed as discrete
Change matrix form：
Wherein,For n-th target resolution cell position vector, n=1,2 ..., N；
Observed object backscattering coefficient vector matrix is represented,For target resolution cellPlace's backscattering coefficient；Represent m-th sampling instant tm,The random radiation field at placeWith
The random radiation field at placeDo treating excess syndrome portion computing after the multiplication of complex numbers；
In above formula, scattered field echo strength is made up of two parts contribution, and Part I represents the line of incident radiation field intensity
Property superposition, Part II cross term represents the impact of the single order dependency of incident radiation field；
At that time, when the random statistical characteristic of empty bidimensional random radiation field meets an order ideal or nearly ideal stochastic behaviour, then
After enough number of times are accumulated, the impact of Part II goes to zero, and is expressed as：
Pair when, the field intensity information of empty random radiation field carries out field strength and associates place with the field intensity information of scattered field echo
Reason, when the association of strength information reflects second order between the two, empty statistical property, by association scattered field echo signal intensity
With when, empty random radiation field intensity information carry out decoupling process so that the target information being coupled originally is separated
Come, so as in the case of staring, reconstruct target image, its formula is：
In above formula,Represent after the observed object recovered to intensity scattered information,Represent restructing algorithm.It is described heavy
Structure algorithm can including but not limited to be based on direct correlation restructing algorithm, the pseudo- inverse operator based on singular value decomposition of Orthogonal Decomposition
Method, based on the object reconstruction algorithm of regularization method, sparse restructing algorithm (BP, OMP, FOCUSS, SBL) etc..
It is exemplary, if when, empty random radiation field intensity matrix IradWhen possessing ideal, empty uncorrelated nature, weight
Structure algorithm can directly using the Pseudoinverse algorithm inverting target picture based on singular value decomposition：
Wherein [Irad]-1For IradPseudoinverse.It is enough to obtain by increasing observation integration time and sampling number
When, empty random radiation field and scattered field echo samples, select possess preferable uncorrelated nature when, empty random radiation field
Intensity distributions sample and the scattering field intensity echo-signal at corresponding moment, it becomes possible to which the method solved by pseudoinverse is accurately obtained this
Inverting target picture under grid cell division.
Further, it is described further with reference to experiment simulation and description of the drawings.
It is exemplary, in image scene as shown in Figure 2, observed object plane apart from Z0=-500m, is divided into
40 × 40 resolution cell, its coordinate range is (0m, 0m)～(Dobj=80m, Dobj=80m), when, the day in empty random radiation source
Linear array adopts 16 standard horn antennas, and Aperture distribution scope is 2m × 2m；The center of random noise frequency modulated signal carries
Wave frequency fc=10GHz, bandwidth B=1GHz, frequency modulation index (FM index) KkFor 0.2GHz/V, white Gaussian noise power is modulated for 2dBW, its side
DifferenceIt is 62.
Accompanying drawing 8 is the object module used in emulation, and accompanying drawing 9, Figure 10 respectively illustrates band-limited noise random frequency tune
Signal processed irradiates the imaging results of lower 1000 times, 5000 times intensity correlations；Imaging results demonstrate put forward intensity correlation method
Correctness.
The above, the only present invention preferably specific embodiment, but protection scope of the present invention is not limited thereto,
Any those familiar with the art in the technical scope of present disclosure, the change or replacement that can be readily occurred in,
All should be included within the scope of the present invention.Therefore, protection scope of the present invention should be with the protection model of claims
Enclose and be defined.
Claims (5)
1. a kind of microwave based on intensity correlation stares high-resolution imaging method, it is characterised in that the method includes：
By structure when, empty random radiation source be placed in when being formed in target observation region, empty random radiation field；
When calculating and storing described, the field intensity information of empty random radiation field, and the field intensity information for receiving scattered field echo；
By when, the empty field intensity information of random radiation field carry out field strength association process with the field intensity information of scattered field echo, reality
The decoupling of existing target strength scattered information；So as in the case of staring, reconstruct target image；Its step is as follows：
According to when, empty random radiation field propagation equation, the second order dispersion field echo strength equation of reception is expressed as discretization square
Formation formula：
Wherein,For n-th target resolution cell position vector, n=1,2 ..., N；
Observed object backscattering coefficient vector matrix is represented,For target resolution cellPlace's backscattering coefficient；Represent m-th sampling instant tm,The random radiation field at placeWithThe random spoke at place
Penetrate fieldDo treating excess syndrome portion computing after the multiplication of complex numbers；
For random radiation field intensity distribution in target observation region constitute when, empty two-dimensional matrix vector, m rows n-th arrange
Represent m-th sampling instant tmTarget resolution cellThe instantaneous radiation field intensity distribution at place, m=1,2 ..., M；
In above formula, scattered field echo strength is made up of two parts contribution, and Part I represents the linear folded of incident radiation field intensity
Plus, Part II cross term represents the impact of the single order dependency of incident radiation field；
At that time, when the random statistical characteristic of empty bidimensional random radiation field meets an order ideal or nearly ideal stochastic behaviour, then accumulating
After tiring out enough number of times, the impact of Part II goes to zero, and is expressed as：
Pair when, the empty field intensity information of random radiation field and the field intensity information of scattered field echo carry out field strength association process, by force
When the association of degree information reflects second order between the two, empty statistical property, by associate scattered field echo signal intensity with when,
Empty random radiation field intensity information carries out decoupling process, so that the target information being coupled originally is separated, from
And in the case of staring, target image being reconstructed, its formula is：
In above formula,Represent after the observed object recovered to intensity scattered information, IscaRepresent M discrete observation moment scattered field
The one-dimensional matrix-vector that echo strength is constituted,Represent restructing algorithm.
2. method according to claim 1, it is characterised in that the structure when, empty random radiation source be by many array elements,
The radar antenna array that the radiation of leggy center is constituted；
Radar antenna array spatially meets non-homogeneous, irregular random distribution, and the signal for radiating be it is uncorrelated with
Machine signal；
Same radar antenna is mutually orthogonal between transmission signal not in the same time, and different radar antenna synchronizations are sent out
It is also mutually completely orthogonal to penetrate between signal；Transmitting orthogonal signalling correlation function meets：
Wherein,The stochastic signal waveform that respectively ith and jth radar antenna is launched in moment t, S*Table
Show the complex conjugate of art of mathematics,The respectively spatial position vector of ith and jth radar antenna, τ is that signal is any
Time delay, δ (i-j, τ) be impulse Response Function.
3. method according to claim 2, it is characterised in that calculate and store can be preset when, empty random radiation field
Field intensity information, and receive scattered field echo field intensity information include：
When described, empty random radiation source when being formed in target observation region, sky random radiation field, all different resolution cell winks
When radiation field intensity distribution when constituting, empty two-dimensional matrix, using imaging system by radiation field computational model to radiation field
The two-dimensional matrix vector of intensity distributions carries out preset, calculation and stores；
When described, empty random radiation field and observed object interact to form scattered field echo, received not using receiver
One-dimensional matrix-vector is constituted with sampling instant scattering field intensity.
4. method according to claim 3, it is characterised in that
The observed object discrete region is turned to into N number of target resolution cell, wherein N=P × Q, P divide for the horizontal of target area
Unit number is distinguished, Q is the longitudinal resolution unit number of target area, and observed object backscattering coefficient vector matrix isWherein,For n-th target resolution cell position vector, n=1,2 ..., N,For
Target resolution cellPlace's backscattering coefficient；When then above-mentioned, empty random radiation source t target observation space formed with
Machine radiation field is expressed as：
Wherein, k=1,2 ... K, K are the radar antenna array antenna sum of the radiation source,For k-th radar antenna
Spatial position vector,Amplitude, the phase pattern steric factor of k-th radar antenna are represented, c is the light velocity；
The instantaneous strength distribution of object space random radiation field is defined as：
Wherein,Represent random radiation fieldComplex conjugate；
Total imaging observation time T is divided into into M observed samples moment, then random radiation field intensity point in target observation region
Cloth constitute when, empty two-dimensional matrix vector be：
Wherein, m rows n-th are arrangedRepresent m-th sampling instant tmTarget resolution cellThe instantaneous radiation field intensity at place
Degree distribution, m=1,2 ..., M；
Receiver location vectorThe target echo scattered field distribution at place is expressed as：
The scattered field echo instantaneous strength for then receiving is defined as：
Wherein,Represent receiver location vectorThe target echo scattered field at placeComplex conjugate；
Thus obtain the one-dimensional matrix-vector that M discrete observation moment scattered field echo strength of correspondence constituted to be expressed as：
5. method according to claim 3, it is characterised in that
In the case where sending and receiving split mode, receiver is single point detector；Put altogether under mode in sending and receiving, receiver is single channel or many
Channel receiver.
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