CN108776342A - A kind of high speed platform SAR moving-target detection and speed estimation method at a slow speed - Google Patents

A kind of high speed platform SAR moving-target detection and speed estimation method at a slow speed Download PDF

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CN108776342A
CN108776342A CN201810767255.9A CN201810767255A CN108776342A CN 108776342 A CN108776342 A CN 108776342A CN 201810767255 A CN201810767255 A CN 201810767255A CN 108776342 A CN108776342 A CN 108776342A
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moving
target
radar
orientation
imaging
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CN108776342B (en
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张晓玲
唐欣欣
马德娇
贾淑培
张星月
师君
韦顺军
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University of Electronic Science and Technology of China
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
    • G01S13/88—Radar or analogous systems specially adapted for specific applications
    • G01S13/89—Radar or analogous systems specially adapted for specific applications for mapping or imaging
    • G01S13/90—Radar or analogous systems specially adapted for specific applications for mapping or imaging using synthetic aperture techniques, e.g. synthetic aperture radar [SAR] techniques
    • G01S13/9021—SAR image post-processing techniques
    • G01S13/9029—SAR image post-processing techniques specially adapted for moving target detection within a single SAR image or within multiple SAR images taken at the same time
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
    • G01S13/88—Radar or analogous systems specially adapted for specific applications
    • G01S13/89—Radar or analogous systems specially adapted for specific applications for mapping or imaging
    • G01S13/90—Radar or analogous systems specially adapted for specific applications for mapping or imaging using synthetic aperture techniques, e.g. synthetic aperture radar [SAR] techniques
    • G01S13/9004—SAR image acquisition techniques
    • G01S13/9017—SAR image acquisition techniques with time domain processing of the SAR signals in azimuth
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
    • G01S13/88—Radar or analogous systems specially adapted for specific applications
    • G01S13/89—Radar or analogous systems specially adapted for specific applications for mapping or imaging
    • G01S13/90—Radar or analogous systems specially adapted for specific applications for mapping or imaging using synthetic aperture techniques, e.g. synthetic aperture radar [SAR] techniques
    • G01S13/904—SAR modes
    • G01S13/9058—Bistatic or multistatic SAR

Abstract

The invention discloses a kind of high speed platform SAR, moving-target detects the method with velocity estimation at a slow speed, it is to use two-way SAR imaging patterns first while obtaining two width SAR image of front-and rear-view, then microinching target is detected in the azimuth deviation of two width SAR image of front-and rear-view by the moving-target caused by front and back wave beam time delay and imaging mismatch, and by the orientation pixel-shift amount rough estimate moving-target orientation speed of moving-target, the method for iteration refocusing is finally used to further increase the precision of azimuthal velocity estimation.Detections and velocity estimation of the high speed platform SAR to moving-target at a slow speed not only may be implemented in the present invention, can also carry out refocusing to moving-target, and good data basis is provided for the identification of subsequent moving-target.With traditional single channel moving target detection method, the present invention can detect the microinching target that frequency spectrum is submerged in clutter spectrum.Improve the detection probability of moving-target at a slow speed.

Description

A kind of high speed platform SAR moving-target detection and speed estimation method at a slow speed
Technical field
The invention belongs to Radar Signal Processing Technology field, more particularly to a kind of high speed platform synthetic aperture radar moves mesh The side of mark instruction (Synthetic Aperture Radar-Ground Moving Target Indication, SAR-GMTI) Method.
Background technology
Synthetic aperture radar ground moving object instruction (SAR-GMTI) technology can detect ground moving target and to its into Row parameter Estimation and positioning.High speed platform SAR is high due to platform movement velocity so that it, which has, is not easy disturbed and quickly reaches The advantage of area-of-interest is research hotspot in recent years.However the technique study of high speed platform SAR imagings is obtained not at present It is few, refer to document " Wang Y, Cao Y, Peng Z, et al.Clutter suppression and moving target imaging approach for multichannel hypersonic vehicle borne radar.Digital Signal Processing,2017,68:81-92. ", but research to high speed platform SAR-GMTI methods and few, therefore There is an urgent need for research is unfolded to the SAR-GMTI methods under high speed platform.
Traditional single-channel SAR-GMTI mainly detects moving-target using the method for filtering, but it is only able to detect frequency spectrum The all or part of moving target fallen except clutter spectrum, is submerged in frequency spectrum the inspection of the slow motion target within clutter spectrum completely It surveys, traditional single channel method is generally difficult to detect, and referring to document, " Tian Bin, Zhu Daiyin, Wu Di wait one kind being based on multistage wiener The multichannel SAR moving-targets detection algorithm electronics of filtering and information journal, 2011,33 (10):2420-2426.".
Dual-Channel SAR-GMTI methods mainly have displaced phase center antenna (Displacement Phase Center Antenna, DPCA) technology and along course made good interference handle (Along-Track Interferometry, ATI) technology.It is based on The moving target detection method of DPCA mainly makes system exist by increasing spatial information (si) using antenna phase center compensation principle Different time domain, different spatial domains obtain identical clutter information, to which clutter spectrum widening caused by due to platform moves is fallen in compensation, retain Moving-target information realizes moving-target detection, refers to document " Mu Huilin, the research of multichannel SAR moving target detection methods, Harbin Polytechnical university's Master's thesis, 2016 ".However DPCA technologies needs meet some requirements, these conditions are difficult under high speed platform It is satisfied, therefore the performance of clutter cancellation can be influenced so that moving-target is difficult to be detected at a slow speed.Moreover, in velocity estimation Aspect, binary channels DPCA methods mostly use estimation moving-target Doppler frequency modulation slope and the method estimation of doppler centroid is dynamic The kinematic parameter of target refers to document " Li Y, Wang T, Liu B, et al.Ground Moving Target Imaging and Motion Parameter Estimation With Airborne Dual-Channel CSSAR.IEEE Transactions on Geoscience&Remote Sensing,2017,PP(99):1-12. ", however depend Doppler's tune alone Frequency slope and doppler centroid can not complete testing the speed and positioning to moving-target, it is desirable to complete testing the speed and positioning for task The echo data for needing three channels refers to " Sun Huadong, multichannel SAR Ground moving target detections and parameter Estimation research, Kazakhstan That shore polytechnical university doctoral thesis, 2009 ", overhead will be greatly increased.
ATI measuring devices and DPCA devices have almost the same system structure, and only backend information process flow is different, Refer to document " noble quality etc., interference synthetic aperture radar moving object detection and velocity estimation, Science Press, 2017 ".Though ATI It so needs to meet harsh DPCA conditions unlike DPCA, but baseline is needed to be always maintained at along course made good, otherwise will introduce Elevation phase drastically reduces the detection performance of moving-target, refers to document " Yang Lei, multichannel SAR-GMTI technique studies, Xi'an electricity Scarabaeidae skill University Ph.D. dissertation, 2009 ".However high speed platform SAR is difficult to ensure baseline always along course made good, therefore ATI is answered It uses the detection of high speed platform SAR moving-targets and also brings along certain difficulty.And ATI can only generally estimate the radial speed of moving-target Degree, is unable to estimate the azimuthal velocity of moving-target.
Other than above-mentioned reason, the size limitation of high speed platform, which can also become, influences DPCA and ATI moving-target inspections at a slow speed A factor with velocity estimation is surveyed, " Wang Y, Cao Y, Peng Z, et al.Clutter suppression and are referred to GMTI for hypersonic vehicle borne SAR system with MIMO antenna.Iet Signal Processing,2017,11(8):909-915".Therefore, moving-target detection and velocity estimation are currently one to high speed platform at a slow speed A difficult point, there is an urgent need for the research to high speed platform moving target detection method at a slow speed is unfolded.
Invention content
The method that the present invention proposes a kind of high speed platform SAR moving-target detection and velocity estimation at a slow speed, this method use Two-way SAR imaging patterns (Bi-Directional SAR imaging mode, BiDi), while obtaining two width SAR figures of front-and rear-view Picture.By as front and back wave beam time delay and imaging mismatch caused by moving-target two width SAR image of front-and rear-view azimuth deviation Detect microinching target, and by the orientation pixel-shift amount rough estimate moving-target orientation speed of moving-target, then The precision of azimuthal velocity estimation is further increased using the method for iteration refocusing.In this way, high speed not only may be implemented Detections and velocity estimation of the platform SAR to moving-target at a slow speed can also carry out refocusing to moving-target, know for subsequent moving-target Indescribably supply good data basis.
In order to facilitate description present disclosure, make following term definition first：
Define 1, two-way synthetic aperture radar (Bi-Directional SAR, BiDi SAR) imaging pattern
BiDi SAR imaging patterns refer to single antenna from orientation while emitting two wave beams being pointed in different directions, and The echo data for receiving two wave beams simultaneously, respectively obtains two width SAR image of forward sight and backsight, refers to document " Mittermayer J,Wollstadt S,Prats-Iraola P,et al.Bidirectional SAR Imaging Mode.IEEE Transactions on Geoscience&Remote Sensing,2013,51(1):601-614.”。
2, BiDi SAR are defined along flight path time interval
BiDi SAR along flight path time interval refer to preceding wave beam and rear wave beam is irradiated to the time needed for same observation area Interval, refers to document " Mittermayer, Josef, and S.Wollstadt. " Simultaneous Bi-directional SAR Acquisition with TerraSAR-X."Synthetic Aperture Radar(EUSAR),2010 8th European Conference on VDE,2010:1-4.”。
Define the 3, Fourier transformation method of standard and Fourier inversion method
Fourier transformation is a kind of method of the signal Analysis of classics, can be expressed as some signal for meeting certain condition Trigonometric function (sinusoidal and/or cosine function) or the linear combination that they are integrated.Fourier inversion is Fourier transformation Inverse process refers to document " digital signal processing theory, algorithm and realization ", and Hu Guangshu writes, publishing house of Tsinghua University.
Define 4, standard synthetic aperture radar rear orientation projection imaging algorithm
Standard synthetic aperture radar rear orientation projection imaging algorithm is the synthetic aperture radar image-forming based on matched filtering principle Algorithm, mainly by the calculating of SAR scene resolution cell oblique distances, range cell search, original echo Doppler phase compensation, return Wave number realizes the focal imaging of synthetic aperture radar raw radar data according to coherent accumulation etc..Detailed content can refer to：It is " bistatic SAR is studied with linear array SAR principles and imaging technique ", Shi Jun, University of Electronic Science and Technology's doctoral thesis.
Define 5, standard synthetic aperture distance by radar compression method
Standard synthetic aperture distance by radar compression method refers to the transmission signal parameters using polarization sensitive synthetic aperture radar system, raw At Range compress reference signal, and the mistake that the distance of synthetic aperture radar is filtered to signal using matched filtering technique Journey.Refer to document " radar imaging technology ", protect it is polished etc. write, Electronic Industry Press publishes.
Define 6, frequency resolution
Frequency resolution refers to that used algorithm can be by two spectral peaks in close proximity are held apart in signal ability.In detail See document " digital signal processing theory, algorithm and realization ", Hu Guangshu writes, and publishing house of Tsinghua University publishes.
Define 7, synthetic aperture radar slow moment and fast moment
The synthetic aperture radar slow time refers to that radar platform flies over a synthetic aperture required time.Radar system with Certain repetition period transmitting receives pulse, therefore when the slow time can be expressed as one using the repetition period as the discretization of step-length Between variable, wherein each discrete-time variable value be a slow moment.
The synthetic aperture radar fast time refers to the time for a cycle that radar emission receives pulse.Since radar is received back Wave is sampled with sample rate, then the fast moment can be expressed as the time variable of a discretization, each discrete variable value For a fast moment.Refer to document " synthetic aperture radar image-forming principle ", skin, which also rings, etc. writes, and publishing house of University of Electronic Science and Technology goes out Version.
Define 8, the slow moment frequency of synthetic aperture radar
The slow moment frequency of synthetic aperture radar refers to the discretization frequency being fourier transformed into the radar slow time corresponding to frequency domain Rate variable, wherein each discrete frequency variate-value are a slow moment frequency.Referring to document, " synthetic aperture radar image-forming is former Reason ", skin, which also rings, etc. writes, and publishing house of University of Electronic Science and Technology publishes.
Define 9, synthetic aperture radar image-forming scene reference point
Synthetic aperture radar image-forming scene reference point refers to some scattering point in synthetic aperture radar projection imaging space, Reference as other resolution cells in data of synthetic aperture radar processing and scene.In general, the centre of selection image scene Point is used as synthetic aperture radar image-forming scene reference point.
Define 10, synthetic aperture radar projection imaging space
Synthetic aperture radar projection imaging space refers to the imaging space chosen when data of synthetic aperture radar is imaged, and is closed It needs echo data projecting to the imaging space at aperture radar imaging and is focused processing.In general, synthetic aperture radar Projection imaging space is selected as oblique distance plane coordinate system or level ground coordinate system.
It defines 11, high speed platform SAR radar systems and refers to oblique distance
High speed platform SAR radar systems with reference to oblique distance refer in SAR radar systems antenna in length of synthetic aperture interposition The distance of imaging space reference point is set, SAR radar systems are denoted as R with reference to oblique distance in the present invention0。
Define 12, standard synthetic aperture radar original echo emulation mode
Standard synthetic aperture radar original echo emulation mode refer to given radar system parameters, platform trajectory parameters and It observes under the Parameter Conditions needed for scenario parameters etc., obtains believing with SAR echoes based on synthetic aperture radar image-forming principles simulation The method of the original echoed signals of number characteristic, detailed content can refer to document：" interference SAR echo-signal is ground with system emulation Study carefully ", Zhang Jianqi, Harbin Institute of Technology's Master's thesis.
Define the big value method CFAR detection method of 13, choosing
The detection of radar signal constant false alarm rate is exactly that false-alarm probability is required to keep constant, can be using Neyman-Pearson criterion Under conditions of the false-alarm probability kept constant, the probability correctly detected is made to reach maximum value.The big value method CFAR detection method of choosing It is to reduce the influence of clutter edge in the constant false alarm processing method of numerous Rayleigh envelope clutter environments and propose, refer to text Offer " multichannel SAR Ground moving target detections and parameter Estimation research ", Sun Huadong, Harbin Institute of Technology's doctoral thesis.
Define 2 norms of 14, vector
2 norms of vector | | | |2The quadratic sum sqrt again for indicating each element of vector, referring to document, " matrix is managed By ", Huang Ting, which wishes etc., to be write, Higher Education Publishing House.
Moving-target detects the method with velocity estimation to a kind of high speed platform SAR provided by the invention at a slow speed, it includes following Several steps：
Step 1：Initialize the systematic parameter of two-way synthetic aperture imaging radar BiDi SAR：
The systematic parameter of two-way synthetic aperture imaging radar BiDi SAR is initialized, including：Radar carrier wavelength, is denoted as λ, Radar antenna transmitted signal bandwidth, is denoted as B, and radar transmitted pulse time width is denoted as Tr, radar sampling frequency is denoted as Fs, radar enters Firing angle is denoted as φ, and radar pulse repetition frequency is denoted as PRF, and radar system distance is denoted as N to sampling numberr, radar system side Position is denoted as N to sampling numbera, radar system orientation frequency resolution is denoted as Δ fa=PRF/Na, radar system antenna is initial Position, is denoted as P (0), and radar antenna emits the orientation angle of squint of forward looking beam, is denoted as θ1, radar antenna transmitting backsight wave beam Orientation angle of squint, is denoted as θ2, radar platform movement velocity vector is denoted as Vp=[Vpx, 0,0], wherein VpxIndicate radar platform side Position to movement velocity, in the sampling time of radar system orientation, be denoted asJ is Natural number, j=0,1,2 ..., (Na-1)；In above-mentioned parameter, radar carrier wavelength lambda, radar antenna transmitted signal bandwidth B, radar Emit pulse time width Tr, radar sampling frequency Fs, radar incidence angle φ, radar pulse repetition rate PRF, radar antenna emit forward sight The orientation angle of squint θ of wave beam1, the orientation angle of squint θ of radar antenna transmitting backsight wave beam2, during radar system design It determines；Radar platform movement velocity vector Vp, radar system distance is to sampling number Nr, radar system orientation sampling number Na、 The sampling time t of radar system orientationm, radar system orientation frequency resolution Δ fa, radar system antenna initial position P (0), radar platform movement velocity vector Vp, had determined in the design of radar imagery observation program.
Step 2, the parameter for initializing moving-target
Initialization moving-target parameter include：The velocity vector of moving-target, is denoted as Vm=[vx,vy, 0], moving-target it is initial Position is denoted as Pm(0), wherein vxIndicate the speed of moving-target orientation, vyIndicate moving-target distance to speed.
Step 3, the raw radar data for obtaining two-way synthetic aperture imaging radar BiDi SAR systems：
Two-way synthetic aperture imaging radar BiDi SAR systems antenna is slow to k-th of t-th fast moment orientation in distance The raw radar data at moment is denoted as E (t, k), t=1,2 ..., Nr, k=1,2 ..., Na, wherein t and k are natural number, and t is indicated Distance indicates k-th of slow moment of orientation, N to t-th of fast moment, krFor the step 1 obtained radar system distance of initialization to Sampling number, NaObtained radar system orientation sampling number is initialized for step 1；High speed platform BiDi SAR it is practical at As in, two-way synthetic aperture imaging radar BiDi SAR systems antenna is in distance to k-th of slow moment of t-th of fast moment orientation Raw radar data E (t, k), t=1,2 ..., Nr, k=1,2 ..., Na, by two-way synthetic aperture imaging radar BiDi SAR System data receiver provides.
Step 4, to the raw radar datas of two-way synthetic aperture imaging radar BiDi SAR system antennas into row distance pressure Contracting：
Using traditional standard synthetic aperture radar Range compress method to the two-way synthetic aperture imaging thunder that is obtained in step 3 Up to BiDi SAR systems antenna in distance to the raw radar data E (t, k), t at k-th of slow moment of t-th of fast moment orientation =1,2 ..., Nr, k=1,2 ..., Na, Range compress is carried out, two-way synthetic aperture imaging radar BiDi SAR system antennas are obtained In distance to the echo data after t-th of fast moment orientation, k-th of slow moment Range compress, it is denoted as S (t, k), t=1, 2,…,Nr, k=1,2 ..., Na。
Step 5 carries out orientation to the raw radar data of two-way synthetic aperture imaging radar BiDi SAR system antennas Fourier transformation：
The two-way synthetic aperture imaging thunder obtained in orientation is to step 4 using the Fourier transformation method of traditional standard Up to BiDiSAR system antennas distance to after t-th of fast moment orientation, k-th of slow moment Range compress echo data S (t, K) make Fourier transformation, obtain number of echoes of the radar system in distance to t-th of fast moment orientation, f-th of slow moment frequency According to being denoted as SFFT(t, f), t=1,2 ..., Nr, f=1,2 ..., Na, f is natural number, indicates f-th of slow moment frequency of orientation.
The raw radar data of step 6, the two-way synthetic aperture imaging radar BiDi SAR system antennas of separation：
Using formulaTwo-way synthetic aperture imaging radar BiDi SAR systems are calculated in distance To t-th of fast moment orientation, f-th of slow moment frequency echo data SFFTThe orientation frequency of (t, f), is denoted as Fa；F is step The natural number obtained in 5 indicates f-th of slow moment frequency of orientation, Δ faObtained radar system orientation is initialized for step 1 To frequency resolution, NaObtained radar system orientation sampling number, S are initialized for step 1FFT(t, f) is that step 5 obtains Radar system in distance to the echo data of t-th of fast moment orientation, f-th of slow moment frequency；
By distance to the echo data S of t-th of fast moment orientation, f-th of slow moment frequencyFFT(t, f), t=1,2 ..., Nr, f=1,2 ..., Na, with distance to the echo data S of t-th of fast moment orientation, f-th of slow moment Frequency pointFFT(t, f), t =1,2 ..., Nr, f=1,2 ..., Na, orientation frequency FaCentered on=0, it is divided into Fa> 0 and Fa0 two parts of <；
By distance to t-th of fast moment orientation, f-th of slow moment frequency echo data SFFT(t, f), t=1,2 ..., Nr, f=1,2 ..., Na, middle orientation frequency FaThe echo zero setting of 0 parts < obtains forward sight apart from time domain-orientation frequency domain echo Data are denoted as SFFFT(t, f), t=1,2 ..., Nr, f=1,2 ..., Na；
By distance to t-th of fast moment orientation, f-th of slow moment frequency echo data SFFT(t, f), t=1,2 ..., Nr, f=1,2 ..., Na, middle orientation frequency FaThe echo zero setting of 0 parts > obtains backsight apart from time domain-orientation frequency domain echo Data are denoted as SBFFT(t, f), t=1,2 ..., Nr, f=1,2 ..., Na；
Using the Fourier inversion method of standard to forward sight apart from time domain-orientation frequency domain echo data SFFFT(t, f), t =1,2 ..., Nr, f=1,2 ..., Na, make Fourier inversion in orientation, obtain radar system antenna in distance to t-th Echo data after fast moment k-th of slow moment forward sight Range compress of orientation, is denoted as SF (t, k), t=1,2 ..., Nr, k= 1,2,…,Na；
Using the Fourier inversion method of standard to backsight apart from time domain-orientation frequency domain echo data SBFFT(t, f), t =1,2 ..., Nr, f=1,2 ..., Na, make Fourier inversion in orientation, obtain high speed platform BiDi SAR radar systems day Line, to the echo data after t-th of fast moment orientation, k-th of slow moment backsight Range compress, is denoted as SB (t, k), t in distance =1,2 ..., Nr, k=1,2 ..., Na。
Step 7, the parameter for initializing two-way synthetic aperture imaging radar BiDi SAR projection imagings space：
It is ground level coordinate system, the coordinate system to initialize two-way synthetic aperture imaging radar BiDi SAR projection imagings space Horizontal cross shaft is denoted as X-axis, which is denoted as Y-axis, the centre coordinate of radar projections imaging space be located at [2040, 110000], the X axis resolution cell number of radar projections imaging space, is denoted as Nx, the Y-axis resolution of radar projections imaging space Unit number is denoted as Ny, the X axis areas imaging of radar projections imaging space is denoted as Wx, the Y-axis of radar projections imaging space at As range, it is denoted as Wy, the X axis cell resolution of radar projections imaging space is denoted as ρx, the Y-axis of radar projections imaging space Cell resolution is denoted as ρy, the reference oblique distance of radar system to projection imaging space is denoted as R0；By radar projections imaging space into Row is evenly dividing, and is obtained the two-dimentional resolution cell in projection imaging space, is denoted as PT(a, r)=[x (a, r), y (a, r)], a= 1,…,Nx, r=1 ..., Ny, wherein a and r are natural number, and a indicates a-th of resolution cell of X axis in projection imaging space, R indicates r-th of resolution cell of Y-axis in projection imaging space, and x (a, r) and y (a, r) indicate projection imaging space two respectively Tie up X axis position, the Y-axis position of resolution cell.
Step 8 carries out projection imaging processing using standard synthetic aperture radar rear orientation projection's imaging algorithm to resolution cell
Enable all resolution cells in two-way synthetic aperture imaging radar BiDi SAR system projection imagings space that step 7 obtains PT(a, r), a=1 ..., Nx, r=1 ..., Ny, highly to coordinate be 0, using standard synthetic aperture radar rear orientation projection be imaged Algorithm is to radar system antenna in distance to the number of echoes after t-th of fast moment orientation, k-th of slow moment forward sight Range compress According to SF (t, k), t=1,2 ..., Nr, k=1,2 ..., Na, carry out imaging, obtain radar system antenna forword-looking imaging as a result, It is denoted as If(a, r), a=1 ..., Nx, r=1 ..., Ny, wherein SF (t, k), t=1,2 ..., Nr, k=1,2 ..., Na, it is step 6 Obtained radar system antenna is in distance to the number of echoes after t-th of fast moment orientation, k-th of slow moment forward sight Range compress According to.
Enable all resolution cells in two-way synthetic aperture imaging radar BiDi SAR system projection imagings space that step 7 obtains PT(a, r), a=1 ..., Nx, r=1 ..., Ny, highly to coordinate be 0, using standard synthetic aperture radar rear orientation projection be imaged Algorithm is to radar system antenna in distance to the number of echoes after t-th of fast moment orientation, k-th of slow moment backsight Range compress According to SB (t, k), t=1,2 ..., Nr, k=1,2 ..., Na, imaging is carried out, radar system antenna backsight imaging results are obtained, It is denoted as Ib(a, r), a=1 ..., Nx, r=1 ..., Ny, wherein SB (t, k), t=1,2 ..., Nr, k=1,2 ..., Na, it is step 6 Obtained radar system antenna is in distance to the number of echoes after t-th of fast moment orientation, k-th of slow moment backsight Range compress According to.
Step 9 inhibits Clutter using the method for amplitude subtraction
The radar system antenna forword-looking imaging result I that step 8 is obtainedf(a, r) is tied with the imaging of radar system antenna backsight Fruit Ib(a, r), using formula Iresult(a, r)=| If(a,r)|-|Ib(a, r) |, the letter after Clutter inhibits is calculated Number, it is denoted as Iresult(a, r), a=1 ..., Nx, r=1 ..., Ny, wherein | | indicate signed magnitude arithmetic(al) symbol.
Step 10, detection moving-target and the position range for determining moving-target
After being inhibited to the Clutter that step 9 obtains using the big value method CFAR detection method of the choosing for defining 13 traditional standards Signal Iresult(a, r), a=1 ..., Nx, r=1 ..., Ny, CFAR detection is carried out, is detected respectively：
(1) radar system antenna forword-looking imaging result I is detectedfMoving-target in (a, r), is denoted asA=1 ..., Nx, R=1 ..., Ny；
(2) radar system antenna backsight imaging results I is detectedbMoving-target in (a, r), is denoted asA=1 ..., Nx, R=1 ..., Ny；
(3) detect moving-target in radar system antenna forword-looking imaging result IfPosition range in (a, r), is denoted as Wherein,Indicate moving-target In radar system antenna forword-looking imaging result IfThe position coordinates of orientation in (a, r),Indicate moving-target in radar system day Line forword-looking imaging result IfThe position coordinates of (a, r) middle-range descriscent,Indicate moving-target in radar system antenna forword-looking imaging knot Fruit IfThe coordinate of orientation central point in (a, r),Indicate moving-target in radar system antenna forword-looking imaging result IfIn (a, r) Coordinate from distance to central point,Indicate moving-target in radar system antenna forword-looking imaging result IfThe position of orientation in (a, r) Length is set,Indicate moving-target in radar system antenna forword-looking imaging result If(a, r), a=1 ..., Nx, r=1 ..., Ny；
(4) detect moving-target in radar system antenna backsight imaging results IfPosition range in (a, r), is denoted as Wherein,Indicate moving-target In radar system antenna backsight imaging results IbThe position coordinates of orientation in (a, r),Indicate moving-target in radar system day Line backsight imaging results IbThe position coordinates of (a, r) middle-range descriscent,It indicates that moving-target is imaged in radar system antenna backsight to tie Fruit IfThe coordinate of orientation central point in (a, r),Indicate moving-target in radar system antenna backsight imaging results If(a, r), a =1 ..., Nx, r=1 ..., Ny, the coordinate of middle-range descriscent central point,Indicate that moving-target is imaged in radar system antenna backsight As a result IfThe position length of orientation in (a, r),Indicate moving-target in radar system antenna backsight imaging results IbIn (a, r) Distance to position length, wherein a=1 ..., Nx, r=1 ..., Ny；
The speed of step 11, the moving-target orientation of the low precision of acquisition
By the moving-target obtained in step 10 in radar system antenna forword-looking imaging result IfOrientation central point in (a, r) CoordinateAs position coordinates of the moving-target in radar system antenna forword-looking imaging result, it is denoted asA= 1,…,Nx, r=1 ..., Ny；By the moving-target obtained in step 10 in radar system antenna backsight imaging results IbSide in (a, r) Coordinate of the position to central pointAs moving-target in radar system antenna backsight imaging results IbPosition coordinates in (a, r), note ForA=1 ..., Nx, r=1 ..., Ny；
Using formulaBe calculated moving-target initial orientation to speed,At the beginning of indicating moving-target The speed of beginning orientation, Δ t=(R0tanθ1-R0tanθ2)/VpxIndicate two-way synthetic aperture imaging radar BiDi SAR along flight path Time interval, VpxFor the movement velocity of the radar platform orientation initialized in step 1, R0It is arrived for the radar system in step 7 The reference oblique distance in projection imaging space, θ1And θ2The orientation of the radar antenna transmitting forward looking beam respectively initialized in step 1 is oblique The orientation angle of squint at visual angle and radar antenna transmitting backsight wave beam.
Parameter needed for step 12, initialization moving-target iteration imaging
The parameter needed for the imaging of moving-target iteration is initialized, including：The maximum times of algorithm iteration, are denoted as MI, and algorithm changes For threshold value, it is denoted as ε；The speed of the moving-target residue orientation estimated during ith iteration, is denoted asIth iteration The azimuthal velocity of the moving-target estimated, is denoted asI=1 ..., MI during ith iteration, wherein i are natural number, are indicated The ith iteration of imaging algorithm,For moving-target initial orientation to speed.
Step 13, the parameter in initialization moving-target iteration projection space：
By moving-target iteration projection space, it is denoted as Ω；The X axis of moving-target iteration projection space Ω is imaged model It encloses, is denoted as W 'x；The Y-axis areas imaging of moving-target iteration projection space Ω, is denoted as W 'y；Moving-target iteration projection The X axis centre coordinate of space Ω, is denoted as W 'xc；The Y-axis centre coordinate of moving-target iteration projection space Ω, is denoted as W′yc；Wherein, the X axis areas imaging of moving-target iteration projection space ΩMoving-target changes For the Y-axis areas imaging W ' of projection space Ωy=W 'x；The X axis center of moving-target iteration projection space Ω is sat MarkThe Y-axis centre coordinate of moving-target iteration projection space ΩIts In,It is the moving-target that is obtained in step 10 in radar system antenna forword-looking imaging result If(a, r), a=1 ..., Nx, r= 1,…,Ny, the position length of middle orientation,The moving-target obtained for step 10 is in radar system antenna backsight imaging results Ib (a, r), a=1 ..., Nx, r=1 ..., Ny, the position length of middle orientation,It is the moving-target that is obtained in step 10 in radar System antenna forword-looking imaging result If(a, r), a=1 ..., Nx, r=1 ..., Ny, the coordinate of middle orientation central point,For step Rapid 10 obtained moving-targets are in radar system antenna backsight imaging results Ib(a, r), a=1 ..., Nx, r=1 ..., Ny, middle orientation To the coordinate of central point
The X axis cell resolution of moving-target iteration projection space Ω, is set as ρlx；Moving-target iteration projection is empty Between Ω Y-axis cell resolution, be set as ρly；The X axis resolution cell number of moving-target iteration projection space Ω, is denoted as N′x；The Y-axis resolution cell number of moving-target iteration projection space Ω, is denoted as N 'y；Moving-target iteration projection space Ω Reference oblique distance, be denoted as R0；
Moving-target iteration projection space Ω is evenly dividing, obtains moving-target iteration projection space Ω's Two-dimentional resolution cell, is denoted as PΩ(m, n)=[x (m, n), y (m, n)], m=1 ..., N 'x, n=1 ..., N 'y, wherein m and n are Natural number, m indicate m-th of resolution cell of X axis in moving-target iteration projection space Ω, n indicate moving-target iteration at As n-th of resolution cell of Y-axis in projector space Ω, x (m, n) and y (m, n) indicate respectively moving-target iteration projection at X axis position, the Y-axis position of image space Ω two dimension resolution cells.
Step 14 carries out projection imaging processing to moving-target
Speed when moving-target ith iteration is imaged is denoted asI=1 ..., MI indicate imaging The ith iteration of algorithm, MI are the maximum iteration of algorithm；Enable the moving-target iteration projection space Ω that step 13 obtains All resolution cell PΩ(m, n) highly to coordinate be 0, m=1 ..., N 'x, n=1 ..., N 'y, using formulaRadar platform is calculated in orientation time tmMoment is to moving-target iteration All resolution cell P of projection space ΩΩThe oblique distance of (m, n), m=1 ..., N 'x, n=1 ..., N 'y, it is denoted as R (PΩ, tm).Wherein, tmFor the time for the orientation that step 1 initializes, P (0) is the radar system antenna initial position that step 1 is mentioned, VpFor the platform movement velocity vector that step 1 is mentioned, VmFor the velocity to moving target vector that step 1 is mentioned, | | | |2Indicate vector 2 norm operations.
Construct penalty functionWherein λ is the radar carrier wavelength that step 1 is mentioned,Indicate empty Number unit, e=2.71828183 is constant.
By radar system antenna distance to after t-th of fast moment orientation, k-th of slow moment forward sight Range compress return Wave number is according to SF (t, k), t=1,2 ..., Nr, k=1,2 ..., NaAnd penalty functionUsing the backward throwing of standard Shadow imaging algorithm is iterated imaging, obtains the iterative projection imaging results of forward sight echo data, is denoted asM= 1,…,N′x, n=1 ..., N 'y；I=1 ..., MI indicate that the ith iteration of imaging algorithm, SF (t, k) are the thunder that step 6 obtains Up to system antenna in distance to the echo data after t-th of fast moment orientation, k-th of slow moment forward sight Range compress, t=1, 2,…,Nr, k=1,2 ..., Na；
By radar system antenna distance to after t-th of fast moment orientation, k-th of slow moment backsight Range compress return Wave number is according to SB (t, k), t=1,2 ..., Nr, k=1,2 ..., NaAnd penalty functionUsing the backward throwing of standard Shadow imaging algorithm is iterated imaging, obtains the iterative projection imaging results of backsight echo data, is denoted asM= 1,…,N′x, n=1 ..., N 'y；I=1 ..., MI indicate that the ith iteration of imaging algorithm, SB (t, k) are the thunder that step 6 obtains Up to system antenna in distance to the echo data after t-th of fast moment orientation, k-th of slow moment backsight Range compress, t=1, 2,…,Nr, k=1,2 ..., Na。
Step 15, the speed for iterating to calculate moving-target orientation
Using the peak value of moving-target as the position of pre-filter method, then moving-target forward sight echo data iterative projection at As resultM=1 ..., N 'x, n=1 ..., N 'y, in position be denoted asI=1 ..., MI indicates imaging algorithm Ith iteration, the iterative projection imaging results of moving-target backsight echo dataM=1 ..., N 'x, n=1 ..., N 'y, In position be denoted asI=1 ..., MI indicates the ith iteration of imaging algorithm；
Using formulaThe speed of the remaining orientation of moving-target, i=1 ..., MI is calculated Indicate the ith iteration of imaging algorithm；Wherein, MI is that initialization obtains the maximum times of algorithm iteration in step 12, and Δ t is step High speed platform BiDi SAR in rapid 11 along flight path time interval,Indicate remaining orientation speed.
Using formulaBy the remaining azimuthal velocity of calculated moving-target during ith iteration Compensate the orientation speed of the moving-target gone out to (i-1)-th iterative estimateIt obtains calculated dynamic during ith iteration The azimuthal velocity of target, is denoted asWherein, i=1 ..., MI indicate that the ith iteration of imaging algorithm, MI are initial in step 12 Change obtains the maximum times of algorithm iteration, and the repeatedly initial value of moving-target azimuthal velocity is the side of calculated moving-target in step 11 Bit rate
Step 16, the condition of decision algorithm iteration and obtain final azimuthal velocity estimated result
IfAnd i≤MI, add 1 to obtain i ← i+1 imaging algorithm iterations i；Repeat step 13, step Rapid 14, step 15；
IfOr i >=MI, iterative step is terminated, is obtainedThe as final estimation of moving-target orientation Speed；Wherein i=1 ..., MI indicate that the ith iteration of imaging algorithm, MI are that initialization obtains algorithm iteration most in step 12 Big number, ε are the algorithm iteration threshold value initialized in step 12,It is dynamic for what is estimated during algorithm ith iteration The azimuthal velocity of target,Azimuthal velocity for the moving-target estimated in (i-1)-th iterative process of algorithm.
The innovative point of the present invention
Propose the detection of moving-target at a slow speed and speed estimation method of a kind of high speed platform SAR under BiDi patterns.The party Method is examined using moving-target caused by front and back wave beam time delay and imaging mismatch in the azimuth deviation of two width SAR image of front-and rear-view Survey microinching target, and by moving-target two width SAR image of front-and rear-view position of orientation offset rough estimate moving-target The speed of orientation, and the precision that azimuthal velocity is estimated is further increased using the method for moving-target iteration imaging.In single channel Under conditions of complete the detection to moving-target at a slow speed and azimuthal velocity and estimate.
Advantages of the present invention
First compared to traditional single channel moving target detection method, institute's extracting method can detect that frequency spectrum is submerged in clutter Microinching target in spectrum.Secondly because the method for using the imaging of moving-target iteration, if static target is using moving-target Adaptation function imaging, it will occur imaging mismatch phenomenon, in turn result in static target focus energy decline, opposite moving-target Since imaging matches, the energy focused can then enhance, and according to this feature, can reject false-alarm targets to a certain extent, Improve the detection probability of moving-target at a slow speed so that institute's extracting method can complete the inspection to moving-target at a slow speed under the conditions of single pass It surveys and velocity estimation, the method compared to multichannel saves overhead, moving-target at a slow speed can be effectively detected in this method And estimate its kinematic parameter.
Description of the drawings
Fig. 1 for invention institute providing method schematic process flow diagram
Fig. 2 is system emulation parameter value
Specific implementation mode
The present invention mainly uses the method for emulation experiment to verify, and all steps, conclusion are all soft in MATLABR2017b It is verified on part correct.Specific implementation step is as follows：
Step 1：Initialize the systematic parameter of two-way synthetic aperture imaging radar BiDi SAR：
The systematic parameter of high speed platform BiDi SAR imaging radars is initialized, including：Radar carrier wavelength lambda=0.03m, thunder Up to antenna transmitted signal bandwidth B=1.5 × 108Hz, radar transmitted pulse time width Tr=1 × 10-6S, radar sampling frequency Fs= 2.1×108Hz, radar incidence angle φ=79.7 °, radar pulse repetition frequency PRF=8000Hz, radar system distance is to sampling Points Nr=2048, radar system orientation sampling number Na=16384, radar system orientation frequency resolution is denoted as Δ fa =8000/16384, radar system antenna initial position P (0)=[0,0,20000] m, radar antenna emit the side of forward looking beam Position angle of squint θ1=1 °, radar antenna emits the orientation angle of squint θ of backsight wave beam2=-1 °, radar platform movement velocity vector Vp =[2040,0,0] m/s, wherein Vpx=2040m/s indicates the movement velocity of radar platform orientation, radar system orientation Sampling time tm=-1.024, -1.0239, -1.0238 ... 1.0238,1.0239.
Step 2, the parameter for initializing moving-target
Initialization moving-target parameter include：The velocity vector of moving-target, is denoted as Vm=[- 9.22,0,0], moving-target Initial position Pm(0)=[2342,109859,0] m.
Step 3, the raw radar data for obtaining two-way synthetic aperture imaging radar BiDi SAR systems：
High speed platform BiDi SAR radar systems antennas are in distance to the original at t-th of fast k-th of slow moment of moment orientation Beginning echo data is denoted as E (t, k), t=1,2 ..., Nr, k=1,2 ..., Na, wherein t and k are natural number, and t indicates distance to the T fast moment, k indicate k-th of slow moment of orientation, NrObtained radar system distance is initialized to sampling number N for step 1r =2048, NaObtained radar system orientation sampling number N is initialized for step 1a=16384；In high speed platform BiDiSAR In actual imaging, high speed platform BiDi SAR radar systems antennas are in distance to t-th fast moment orientation, k-th slow moment Raw radar data E (t, k), t=1,2 ..., Nr, k=1,2 ..., Na, Nr=2048, Na=16384, by high speed platform BiDi SAR radar system data receivers provide.
Step 4, to the raw radar datas of two-way synthetic aperture imaging radar BiDi SAR system antennas into row distance pressure Contracting：
Using standard synthetic aperture distance by radar compression method to the high speed platform BiDi SAR radars system that is obtained in step 3 Unite antenna in distance to raw radar data E (t, k), the t=1 at k-th of slow moment of t-th of fast moment orientation, 2 ..., Nr, k =1,2 ..., Na, Nr=2048, Na=16384, Range compress is carried out, high speed platform BiDi SAR radar system antennas is obtained and exists Distance is to echo data S (t, k), t=1 after t-th of fast moment orientation, k-th of slow moment Range compress, 2 ..., Nr, k= 1,2,…,Na, Nr=2048, Na=16384.
Step 5 carries out orientation to the raw radar data of two-way synthetic aperture imaging radar BiDi SAR system antennas Fourier transformation：
The high speed platform BiDi SAR radars system obtained in orientation is to step 4 using the Fourier transformation method of standard Unite antenna in distance to echo data S (t, k) t=1 after t-th of fast moment orientation, k-th of slow moment Range compress, 2,…,Nr, k=1,2 ..., Na, Nr=2048, Na=16384, make Fourier transformation, obtains radar system in distance to t-th The echo data S of fast moment f-th of slow moment frequency of orientationFFT(t, f), t=1,2 ..., Nr, f=1,2 ..., Na, Nr= 2048, Na=16384, f are natural number, indicate f-th of slow moment frequency of orientation.
The raw radar data of step 6, the two-way synthetic aperture imaging radar BiDi SAR system antennas of separation：
Using formulaRadar system is calculated in distance to f-th of t-th fast moment orientation Slow moment frequency echo data SFFTThe orientation frequency F of (t, f)a；F is the natural number obtained in step 5, f=1,2 ..., Na, Na=16384, indicate f-th of slow moment frequency of orientation, Δ faObtained radar system orientation frequency is initialized for step 1 Resolution ratio, Δ fa=800016384, NaObtained radar system orientation sampling number N is initialized for step 1a=16384, SFFT(t, f) t=1,2 ..., Nr, f=1,2 ..., Na, Nr=2048, Na=16384, the radar system obtained for step 5 away from The echo data of descriscent t-th of fast moment orientation, f-th of slow moment frequency；
By distance to the echo data S of t-th of fast moment orientation, f-th of slow moment frequencyFFT(t, f), t=1,2 ..., Nr, f=1,2 ..., Na, Nr=2048, Na=16384, with distance to t-th of fast moment orientation, f-th of slow moment Frequency point Echo data SFFT(t, f) t=1,2 ..., Nr, f=1,2 ..., Na, Nr=2048, Na=16384, orientation frequency Fa= Centered on 0, it is divided into Fa> 0 and Fa0 two parts of <.
By distance to t-th of fast moment orientation, f-th of slow moment frequency echo data SFFT(t, f) t=1,2 ..., Nr, F=1,2 ..., Na, Nr=2048, Na=16384, middle orientation frequency FaThe echo zero setting of 0 parts <, obtain forward sight apart from when Domain-orientation frequency domain echo data SFFFT(t, f), t=1,2 ..., Nr, f=1,2 ..., Na, Nr=2048, Na=16384；It will be away from T-th of the descriscent slow moment frequency echo data S of f-th of fast moment orientationFFT(t, f), t=1,2 ..., Nr, f=1,2 ..., Na, Nr=2048, Na=16384, middle orientation frequency FaThe echo zero setting of 0 parts > obtains backsight apart from time domain-orientation frequency Domain echo data SBFFT(t, f), t=1,2 ..., Nr, f=1,2 ..., Na, Nr=2048, Na=16384；
Using the Fourier inversion method of standard to forward sight apart from time domain-orientation frequency domain echo data SFFFT(t, f), t =1,2 ..., Nr, f=1,2 ..., Na, Nr=2048, Na=16384, make Fourier inversion in orientation, obtains radar system Unite antenna in distance to the echo data SF (t, k), t=after t-th of fast moment orientation, k-th of slow moment forward sight Range compress 1,2,…,Nr, k=1,2 ..., Na, Nr=2048, Na=16384；Using the Fourier inversion method of standard to backsight distance Time domain-orientation frequency domain echo data SBFFT(t, f), t=1,2 ..., Nr, k=1,2 ..., Na, Nr=2048, Na=16384, Orientation makees Fourier inversion, obtains high speed platform BiDi SAR radar systems antennas in distance to t-th of fast moment orientation Echo data SB (t, k), t=1 to after k-th of slow moment backsight Range compress, 2 ..., Nr, k=1,2 ..., Na, Nr= 2048, Na=16384.
Step 7, the parameter for initializing two-way synthetic aperture imaging radar BiDi SAR projection imagings space：
It is ground level coordinate system to initialize high speed platform BiDi SAR projection imagings space, which is denoted as X-axis, the coordinate system horizontal longitudinal axis are denoted as Y-axis, and the centre coordinate of radar projections imaging space is located at [2040,110000], radar The X axis resolution cell number N in projection imaging spacex=200, the Y-axis resolution cell number N of radar projections imaging spacey=200, The X axis areas imaging W of radar projections imaging spacex=200m, the Y-axis areas imaging W of radar projections imaging spacey= 200m, the X axis cell resolution ρ of radar projections imaging spacexThe Y-axis unit of=1m, radar projections imaging space are differentiated Rate ρy=1m, the reference oblique distance R of radar system to projection imaging space0=111820m；Radar projections imaging space is carried out equal Even division obtains the two-dimentional resolution cell P in projection imaging spaceT(a, r)=[x (a, r), y (a, r)], a=1 ..., Nx, r= 1,…,Ny, Nx=200, Ny=200, wherein a and r are natural number, and a indicates a-th of resolution of X axis in projection imaging space Unit, r indicate that r-th of resolution cell of Y-axis in projection imaging space, x (a, r) and y (a, r) indicate projection imaging sky respectively Between two-dimentional resolution cell X axis position, Y-axis position.
Step 8 carries out projection imaging processing using standard synthetic aperture radar rear orientation projection's imaging algorithm to resolution cell
Enable the high speed platform BiDi SAR radar system projection imagings all resolution cell P in space that step 7 obtainsT(a, r), A=1 ..., Nx, r=1 ..., Ny, Nx=200, Ny=200, highly to coordinate be 0, it is backward using standard synthetic aperture radar Projection imaging algorithm is to radar system antenna in distance to after t-th of fast moment orientation, k-th of slow moment forward sight Range compress Echo data SF (t, k), t=1,2 ..., Nr, k=1,2 ..., Na, Nr=2048, Na=16384, imaging is carried out, is obtained To radar system antenna forword-looking imaging result If(a, r), a=1 ..., Nx, r=1 ..., Ny, Nx=200, Ny=200, wherein SF (t, k), t=1,2 ..., Nr, k=1,2 ..., Na, Nr=2048, Na=16384, the radar system antenna obtained for step 6 exists Distance is to the echo data after t-th of fast moment orientation, k-th of slow moment forward sight Range compress.
Enable the high speed platform BiDi SAR radar system projection imagings all resolution cell P in space that step 7 obtainsT(a, r), A=1 ..., Nx, r=1 ..., Ny, Nx=200, Ny=200, highly to coordinate be 0, it is backward using standard synthetic aperture radar Projection imaging algorithm is to radar system antenna in distance to after t-th of fast moment orientation, k-th of slow moment backsight Range compress Echo data SB (t, k), t=1,2 ..., Nr, k=1,2 ..., Na, Nr=2048, Na=16384, imaging is carried out, is obtained To radar system antenna backsight imaging results Ib(a, r), a=1 ..., Nx, r=1 ..., Ny, Nx=200, Ny=200, wherein SB (t, k), t=1,2 ..., Nr, k=1,2 ..., Na, Nr=2048, Na=16384, the radar system antenna obtained for step 6 exists Distance is to the echo data after t-th of fast moment orientation, k-th of slow moment backsight Range compress.
Step 9 inhibits Clutter using the method for amplitude subtraction
The radar system antenna forword-looking imaging result I that step 8 is obtainedf(a, r), a=1 ..., Nx, r=1 ..., Ny, Nx =200, Ny=200, with radar system antenna backsight imaging results Ib(a, r), a=1 ..., Nx, r=1 ..., Ny, Nx=200, Ny=200, using formula Iresult(a, r)=| If(a,r)|-|Ib(a, r) | inhibit Clutter, after obtaining Clutter inhibition Signal Iresult(a, r), a=1 ..., Nx, r=1 ..., Ny, Nx=200, Ny=200, wherein | | indicate signed magnitude arithmetic(al) Symbol.
Step 10, detection moving-target and the position range for determining moving-target
After being inhibited to the Clutter that step 9 obtains using the big value method CFAR detection method of the choosing for defining 13 traditional standards Signal Iresult(a, r), a=1 ..., Nx, r=1 ..., Ny, Nx=200, Ny=200, CFAR detection is carried out, is detected respectively It arrives：
(1) radar system antenna forword-looking imaging result I is detectedf(a, r), a=1 ..., Nx, r=1 ..., Ny, Nx= 200, Ny=200, in moving-target
(2) radar system antenna backsight imaging results I is detectedb(a, r), a=1 ..., Nx, r=1 ..., Ny, Nx= 200, Ny=200, in moving-target
(3) detect moving-target in radar system antenna forword-looking imaging result If(a, r), a=1 ..., Nx, r=1 ..., Ny, Nx=200, Ny=200, in position range Wherein,Indicate moving-target in radar system antenna forword-looking imaging result If(a, r), A=1 ..., Nx, r=1 ..., Ny, Nx=200, Ny=200, the position coordinates of middle orientation,Indicate moving-target in radar system Antenna forword-looking imaging result of uniting If(a, r), a=1 ..., Nx, r=1 ..., Ny, Nx=200, Ny=200, the position of middle-range descriscent Coordinate,Indicate moving-target in radar system antenna forword-looking imaging result If(a, r), a=1 ..., Nx, r=1 ..., Ny, Nx= 200, Ny=200, the coordinate of middle orientation central point,Indicate moving-target radar system antenna forward sight at As result If(a, r), a=1 ..., Nx, r=1 ..., Ny, Nx=200, Ny=200, the coordinate of middle-range descriscent central point,Indicate moving-target in radar system antenna forword-looking imaging result If(a, r), a=1 ..., Nx, r= 1,…,Ny, Nx=200, Ny=200, the position length of middle orientation,Indicate moving-target in radar system day Line forword-looking imaging result If(a, r), a=1 ..., Nx, r=1 ..., Ny, Nx=200, Ny=200, the position length of middle-range descriscent,
(4) detect moving-target in radar system antenna backsight imaging results If(a, r), a=1 ..., Nx, r=1 ..., Ny, Nx=200, Ny=200, in position range Wherein,Indicate moving-target in radar system antenna backsight imaging results Ib(a, r), a =1 ..., Nx, r=1 ..., Ny, Nx=200, Ny=200, the position coordinates of middle orientation,Indicate moving-target in radar system Antenna backsight imaging results Ib(a, r), a=1 ..., Nx, r=1 ..., Ny, Nx=200, Ny=200, the position of middle-range descriscent is sat Mark,Indicate moving-target in radar system antenna backsight imaging results If(a, r), a=1 ..., Nx, r=1 ..., Ny, Nx= 200, Ny=200, the coordinate of middle orientation central point,Indicate moving-target in radar system antenna backsight Imaging results If(a, r), a=1 ..., Nx, r=1 ..., Ny, Nx=200, Ny=200, the coordinate of middle-range descriscent central point,Indicate moving-target in radar system antenna backsight imaging results If(a, r), a=1 ..., Nx, r= 1,…,Ny, Nx=200, Ny=200, the position length of middle orientation,Indicate moving-target in radar system day Line backsight imaging results Ib(a, r), a=1 ..., Nx, r=1 ..., Ny, Nx=200, Ny=200, the position length of middle-range descriscent,
The speed of step 11, the moving-target orientation of the low precision of acquisition
By the moving-target obtained in step 10 in radar system antenna forword-looking imaging result If(a, r), a=1 ..., Nx, r= 1,…,Ny, Nx=200, Ny=200, the coordinate of middle orientation central pointAs moving-target in radar system antenna Forword-looking imaging result If(a, r), a=1 ..., Nx, r=1 ..., Ny, Nx=200, Ny=200, in position coordinatesBy the moving-target obtained in step 10 in radar system antenna backsight imaging results Ib(a, r), a= 1,…,Nx, r=1 ..., Ny, Nx=200, Ny=200, the coordinate of middle orientation central pointAs moving-target in thunder Up to system antenna backsight imaging results Ib(a, r), a=1 ..., Nx, r=1 ..., Ny, Nx=200, Ny=200, in position sit Mark
Using formulaCalculate moving-target initial orientation to speed,Indicate moving-target initially side Position to speed,Δ t indicates high speed platform BiDi SAR along flight path time interval, Δ t=2s；VpxFor step The movement velocity of the radar platform orientation initialized in rapid 1, Vpx=2040m/s；R0For the radar system in step 7 to projection The reference oblique distance of imaging space, R0=111820m；θ1And θ2The radar antenna transmitting forward looking beam respectively initialized in step 1 Orientation angle of squint and radar antenna transmitting backsight wave beam orientation angle of squint, θ1=1 °, θ2=-1 °.
Parameter needed for step 12, initialization moving-target iteration imaging
The parameter needed for the imaging of moving-target iteration is initialized, including：The maximum times MI=10 of algorithm iteration, algorithm iteration Threshold epsilon=0.025, the speed for the moving-target residue orientation that ith iteration estimates in the process, is denoted asIth iteration The azimuthal velocity of calculated moving-target, is denoted asI=1 ..., MI during ith iteration, wherein i are natural number, are indicated The ith iteration of imaging algorithm,For moving-target initial orientation to speed,
Step 13, the parameter in initialization moving-target iteration projection space：
By moving-target iteration projection space, it is denoted as Ω.The X axis of moving-target iteration projection space Ω is imaged model Enclose W 'x=75m, the Y-axis areas imaging W ' of moving-target iteration projection space Ωy=75m.Moving-target iteration projection The X axis centre coordinate W ' of space Ωxc=2047.5, the Y-axis centre coordinate W ' of moving-target iteration projection space Ωyc =109864.Wherein, the X axis areas imaging W ' of moving-target iteration projection space Ωx=75m, the imaging of moving-target iteration The Y-axis areas imaging W ' of projector space Ωy=75m；The X axis centre coordinate W ' of moving-target iteration projection space Ωxc =2047.5, the Y-axis centre coordinate W ' of moving-target iteration projection space Ωyc=109864.Wherein,For step 10 In obtained moving-target in radar system antenna forword-looking imaging result If(a, r), a=1 ..., Nx, r=1 ..., Ny, Nx=200, Ny=200, the position length of middle orientation,The moving-target obtained for step 10 is in radar system antenna Backsight imaging results Ib(a, r), a=1 ..., Nx, r=1 ..., Ny, Nx=200, Ny=200, the position length of middle orientation,It is the moving-target that is obtained in step 10 in radar system antenna forword-looking imaging result If(a, r), a=1 ..., Nx, r =1 ..., Ny, Nx=200, Ny=200, the coordinate of middle orientation central point,The moving-target obtained for step 10 In radar system antenna backsight imaging results Ib(a, r), a=1 ..., Nx, r=1 ..., Ny, Nx=200, Ny=200, middle orientation To the coordinate of central point
The X axis cell resolution ρ of moving-target iteration projection space Ωlx=0.04m, moving-target iteration projection The Y-axis cell resolution ρ of space ΩlyThe X axis resolution cell number N ' of=0.04m, moving-target iteration projection space Ωx The Y-axis resolution cell number N ' of=1875, moving-target iteration projection space Ωy=1875.Moving-target iteration projection The reference oblique distance R of space Ω0Moving-target iteration projection space Ω is evenly dividing, obtains moving-target by=111820m The two-dimentional resolution cell P of iteration projection space ΩΩ(m, n)=[x (m, n), y (m, n)], m=1 ..., N 'x, n=1 ..., N′y, N 'x=1875, N 'y=1875, wherein m and n are natural number, and m indicates X-axis in moving-target iteration projection space Ω To m-th of resolution cell, n indicates n-th of resolution cell of Y-axis in moving-target iteration projection space Ω, x (m, n) Indicate X axis position, the Y-axis position of moving-target iteration projection imaging space Ω two dimension resolution cells respectively with y (m, n) It sets.
Step 14 carries out projection imaging processing to moving-target
Speed when moving-target ith iteration is imaged is denoted asI=1 ..., MI indicates that imaging is calculated The ith iteration of method, MI=10 are the maximum iteration of algorithm；Enable the moving-target iteration projection space that step 13 obtains All resolution cell P of ΩΩ(m, n) highly to coordinate be 0, m=1 ..., N 'x, n=1 ..., N 'y, N 'x=1875, N 'y= 1875, using formulaRadar platform is calculated in orientation time tmMoment To all resolution cell P of moving-target iteration projection space ΩΩThe oblique distance of (m, n), m=1 ..., N 'x, n=1 ..., N 'y, It is denoted as R (PΩ,tm).Wherein, tmFor the time for the orientation that step 1 initializes, P (0)=[0,0,20000] m is that step 1 is mentioned Radar system antenna initial position, Vp=[2040,0,0] m/s is the platform movement velocity vector that step 1 is mentioned, Vm=[- 9.22,0,0] m/s is the velocity to moving target vector that step 1 is mentioned, | | | |2Indicate 2 norm operations of vector.
Construct penalty functionWherein λ is the radar carrier wavelength that step 1 is mentioned,Indicate empty Number unit, e=2.71828183 is constant.
By radar system antenna distance to after t-th of fast moment orientation, k-th of slow moment forward sight Range compress return Wave number is according to SF (t, k), t=1,2 ..., Nr, k=1,2 ..., Na, Nr=2048, Na=16384 and penalty functionImaging is iterated using rear orientation projection's imaging algorithm of standard, obtains changing for forward sight echo data For projection imaging as a result, being denoted asM=1 ..., N 'x, n=1 ..., N 'y, N 'x=1875, N 'y=1875；I= 1 ..., MI, MI=10, indicate the ith iteration of imaging algorithm, and SF (t, k) is the obtained radar system antenna of step 6 in distance Echo data to after t-th of fast moment orientation, k-th of slow moment forward sight Range compress, t=1,2 ..., Nr, k=1, 2,…,Na, Nr=2048, Na=16384；
By radar system antenna distance to after t-th of fast moment orientation, k-th of slow moment backsight Range compress return Wave number is according to SB (t, k), t=1,2 ..., Nr, k=1,2 ..., Na, Nr=2048, Na=16384 and penalty functionImaging is iterated using rear orientation projection's imaging algorithm of standard, obtains changing for backsight echo data For projection imaging as a result, being denoted asM=1 ..., N 'x, n=1 ..., N 'y, N 'x=1875, N 'y=1875, i= 1 ..., MI, MI=10 indicate that the ith iteration of imaging algorithm, SB (t, k) are the obtained radar system antenna of step 6 in distance Echo data to after t-th of fast moment orientation, k-th of slow moment backsight Range compress, t=1,2 ..., Nr, k=1, 2,…,Na, Nr=2048, Na=16384.
Step 15, the speed for iterating to calculate moving-target orientation
Using the peak value of moving-target as the position of pre-filter method, then moving-target forward sight echo data iterative projection at As resultM=1 ..., N 'x, n=1 ..., N 'y, in position be denoted asI=1 ..., MI indicates imaging algorithm Ith iteration, the iterative projection imaging results of moving-target backsight echo dataM=1 ..., N 'x, n=1 ..., N ′y, N 'x=1875, N 'y=1875, in position be denoted asI=1 ..., MI indicate the ith iteration of imaging algorithm, MI=10 For the maximum iteration of algorithm；
Using formulaThe speed of the remaining orientation of moving-target is calculated, i=1 ..., MI are expressed as As the ith iteration of algorithm, MI=10 is the maximum iteration of algorithm；Wherein, Δ t=2s is the high speed platform in step 11 BiDi SAR along flight path time interval,Indicate remaining orientation speed.
Using formulaBy the remaining azimuthal velocity of calculated moving-target during ith iteration Compensate the orientation speed of the moving-target gone out to (i-1)-th iterative estimateIt obtains calculated dynamic during ith iteration The azimuthal velocity of target, is denoted asI=1 ..., MI indicate that the ith iteration of imaging algorithm, MI=10 are that the maximum of algorithm changes Generation number, the repeatedly initial value of moving-target azimuthal velocity are the azimuthal velocity of calculated moving-target in step 11
Step 16, the condition of decision algorithm iteration and obtain final azimuthal velocity estimated result
IfAnd i≤MI, add 1 to obtain i ← i+1 imaging algorithm iterations i；Repeat step 13, step Rapid 14, step 15；IfOr i >=MI, iterative step is terminated, is obtainedAs moving-target orientation is final Estimating speed,Wherein i=1 ..., MI indicate that the ith iteration of imaging algorithm, MI are initial in step 12 Change obtains the maximum times of algorithm iteration, and MI=10, ε are the algorithm iteration threshold value initialized in step 12, ε=0.025,Azimuthal velocity for the moving-target estimated during algorithm ith iteration,To estimate in (i-1)-th iterative process of algorithm The azimuthal velocity for the moving-target counted out.

Claims (1)

1. moving-target detects the method with velocity estimation to a kind of high speed platform SAR at a slow speed, it is characterized in that it includes following step Suddenly：
Step 1：Initialize the systematic parameter of two-way synthetic aperture imaging radar BiDi SAR：
The systematic parameter of two-way synthetic aperture imaging radar BiDi SAR is initialized, including：Radar carrier wavelength is denoted as λ, radar Antenna transmitted signal bandwidth, is denoted as B, and radar transmitted pulse time width is denoted as Tr, radar sampling frequency is denoted as Fs, radar incidence angle, It is denoted as φ, radar pulse repetition frequency is denoted as PRF, and radar system distance is denoted as N to sampling numberr, radar system orientation Sampling number is denoted as Na, radar system orientation frequency resolution is denoted as Δ fa=PRF/Na, radar system antenna initial bit It sets, is denoted as P (0), radar antenna emits the orientation angle of squint of forward looking beam, is denoted as θ1, the side of radar antenna transmitting backsight wave beam Position angle of squint, is denoted as θ2, radar platform movement velocity vector is denoted as Vp=[Vpx, 0,0], wherein VpxIndicate radar platform orientation To movement velocity, in the sampling time of radar system orientation, be denoted asJ is Natural number, j=0,1,2 ..., (Na-1)；In above-mentioned parameter, radar carrier wavelength lambda, radar antenna transmitted signal bandwidth B, radar Emit pulse time width Tr, radar sampling frequency Fs, radar incidence angle φ, radar pulse repetition rate PRF, radar antenna emit forward sight The orientation angle of squint θ of wave beam1, the orientation angle of squint θ of radar antenna transmitting backsight wave beam2, during radar system design It determines；Radar platform movement velocity vector Vp, radar system distance is to sampling number Nr, radar system orientation sampling number Na、 The sampling time t of radar system orientationm, radar system orientation frequency resolution Δ fa, radar system antenna initial position P (0), radar platform movement velocity vector Vp, had determined in the design of radar imagery observation program；
Step 2, the parameter for initializing moving-target
Initialization moving-target parameter include：The velocity vector of moving-target, is denoted as Vm=[vx,vy, 0], the initial bit of moving-target It sets, is denoted as Pm(0), wherein vxIndicate the speed of moving-target orientation, vyIndicate moving-target distance to speed；
Step 3, the raw radar data for obtaining two-way synthetic aperture imaging radar BiDi SAR systems：
Two-way synthetic aperture imaging radar BiDi SAR systems antenna is in distance to k-th of slow moment of t-th of fast moment orientation Raw radar data, be denoted as E (t, k), t=1,2 ..., Nr, k=1,2 ..., Na, wherein t and k are natural number, and t indicates distance To t-th of fast moment, k indicates k-th of slow moment of orientation, NrObtained radar system distance is initialized to sampling for step 1 Points, NaObtained radar system orientation sampling number is initialized for step 1；In high speed platform BiDi SAR actual imagings In, two-way synthetic aperture imaging radar BiDi SAR systems antenna is in distance to t-th fast moment orientation, k-th slow moment Raw radar data E (t, k), t=1,2 ..., Nr, k=1,2 ..., Na, by two-way synthetic aperture imaging radar BiDi SAR systems Data receiver of uniting provides；
Step 4 carries out Range compress to the raw radar data of two-way synthetic aperture imaging radar BiDi SAR system antennas：
Using traditional standard synthetic aperture radar Range compress method to the two-way synthetic aperture imaging radar that is obtained in step 3 BiDi SAR systems antenna is in distance to the raw radar data E (t, k), t=at k-th of slow moment of t-th of fast moment orientation 1,2,…,Nr, k=1,2 ..., Na, Range compress is carried out, two-way synthetic aperture imaging radar BiDi SAR system antennas is obtained and exists Distance is denoted as S (t, k), t=1,2 ... to the echo data after t-th of fast moment orientation, k-th of slow moment Range compress, Nr, k=1,2 ..., Na；
Step 5 carries out in orientation Fu the raw radar data of two-way synthetic aperture imaging radar BiDi SAR system antennas Leaf transformation：
The two-way synthetic aperture imaging radar obtained in orientation is to step 4 using the Fourier transformation method of traditional standard BiDi SAR systems antenna distance to after t-th of fast moment orientation, k-th of slow moment Range compress echo data S (t, K) make Fourier transformation, obtain number of echoes of the radar system in distance to t-th of fast moment orientation, f-th of slow moment frequency According to being denoted as SFFT(t, f), t=1,2 ..., Nr, f=1,2 ..., Na, f is natural number, indicates f-th of slow moment frequency of orientation；
The raw radar data of step 6, the two-way synthetic aperture imaging radar BiDi SAR system antennas of separation：
Using formulaTwo-way synthetic aperture imaging radar BiDi SAR systems are calculated in distance to T fast moment f-th of slow moment frequency echo data S of orientationFFTThe orientation frequency of (t, f), is denoted as Fa；F is in step 5 Obtained natural number indicates f-th of slow moment frequency of orientation, Δ faObtained radar system orientation is initialized for step 1 Frequency resolution, NaObtained radar system orientation sampling number, S are initialized for step 1FFT(t, f) is what step 5 obtained Radar system is in distance to the echo data of t-th of fast moment orientation, f-th of slow moment frequency；
By distance to the echo data S of t-th of fast moment orientation, f-th of slow moment frequencyFFT(t, f), t=1,2 ..., Nr, f =1,2 ..., Na, with distance to the echo data S of t-th of fast moment orientation, f-th of slow moment Frequency pointFFT(t, f), t= 1,2,…,Nr, f=1,2 ..., Na, orientation frequency FaCentered on=0, it is divided into Fa> 0 and Fa0 two parts of <；
By distance to t-th of fast moment orientation, f-th of slow moment frequency echo data SFFT(t, f), t=1,2 ..., Nr, f= 1,2,…,Na, middle orientation frequency FaThe echo zero setting of 0 parts < obtains forward sight apart from time domain-orientation frequency domain echo data, note For SFFFT(t, f), t=1,2 ..., Nr, f=1,2 ..., Na；
By distance to t-th of fast moment orientation, f-th of slow moment frequency echo data SFFT(t, f), t=1,2 ..., Nr, f= 1,2,…,Na, middle orientation frequency FaThe echo zero setting of 0 parts > obtains backsight apart from time domain-orientation frequency domain echo data, note For SBFFT(t, f), t=1,2 ..., Nr, f=1,2 ..., Na；
Using the Fourier inversion method of standard to forward sight apart from time domain-orientation frequency domain echo data SFFFT(t, f), t=1, 2,…,Nr, f=1,2 ..., Na, make Fourier inversion in orientation, obtain radar system antenna when distance is fast to t-th The echo data after k-th of slow moment forward sight Range compress of orientation is carved, SF (t, k), t=1,2 ..., N are denoted asr, k=1, 2,…,Na；
Using the Fourier inversion method of standard to backsight apart from time domain-orientation frequency domain echo data SBFFT(t, f), t=1, 2,…,Nr, f=1,2 ..., Na, make Fourier inversion in orientation, obtain high speed platform BiDi SAR radar system antennas and exist Distance is denoted as SB (t, k), t=1 to the echo data after t-th of fast moment orientation, k-th of slow moment backsight Range compress, 2,…,Nr, k=1,2 ..., Na；
Step 7, the parameter for initializing two-way synthetic aperture imaging radar BiDi SAR projection imagings space：
It is ground level coordinate system to initialize two-way synthetic aperture imaging radar BiDi SAR projection imagings space, and the coordinate system is horizontal Horizontal axis is denoted as X-axis, which is denoted as Y-axis, the centre coordinate of radar projections imaging space be located at [2040, 110000], the X axis resolution cell number of radar projections imaging space, is denoted as Nx, the Y-axis resolution of radar projections imaging space Unit number is denoted as Ny, the X axis areas imaging of radar projections imaging space is denoted as Wx, the Y-axis of radar projections imaging space at As range, it is denoted as Wy, the X axis cell resolution of radar projections imaging space is denoted as ρx, the Y-axis of radar projections imaging space Cell resolution is denoted as ρy, the reference oblique distance of radar system to projection imaging space is denoted as R0；By radar projections imaging space into Row is evenly dividing, and is obtained the two-dimentional resolution cell in projection imaging space, is denoted as PT(a, r)=[x (a, r), y (a, r)], a= 1,…,Nx, r=1 ..., Ny, wherein a and r are natural number, and a indicates a-th of resolution cell of X axis in projection imaging space, R indicates r-th of resolution cell of Y-axis in projection imaging space, and x (a, r) and y (a, r) indicate projection imaging space two respectively Tie up X axis position, the Y-axis position of resolution cell；
Step 8 carries out projection imaging processing using standard synthetic aperture radar rear orientation projection's imaging algorithm to resolution cell
Enable all resolution cell P in two-way synthetic aperture imaging radar BiDi SAR system projection imagings space that step 7 obtainsT(a, R), a=1 ..., Nx, r=1 ..., Ny, highly to coordinate be 0, using standard synthetic aperture radar rear orientation projection imaging algorithm To radar system antenna in distance to the echo data SF after t-th of fast moment orientation, k-th of slow moment forward sight Range compress (t, k), t=1,2 ..., Nr, k=1,2 ..., Na, imaging is carried out, obtains radar system antenna forword-looking imaging as a result, being denoted as If(a, r), a=1 ..., Nx, r=1 ..., Ny, wherein SF (t, k), t=1,2 ..., Nr, k=1,2 ..., Na, obtained for step 6 Radar system antenna in distance to the echo data after t-th of fast moment orientation, k-th of slow moment forward sight Range compress；
Enable all resolution cell P in two-way synthetic aperture imaging radar BiDi SAR system projection imagings space that step 7 obtainsT(a, R), a=1 ..., Nx, r=1 ..., Ny, highly to coordinate be 0, using standard synthetic aperture radar rear orientation projection imaging algorithm To radar system antenna in distance to the echo data SB after t-th of fast moment orientation, k-th of slow moment backsight Range compress (t, k), t=1,2 ..., Nr, k=1,2 ..., Na, imaging is carried out, radar system antenna backsight imaging results is obtained, is denoted as Ib(a, r), a=1 ..., Nx, r=1 ..., Ny, wherein SB (t, k), t=1,2 ..., Nr, k=1,2 ..., Na, obtained for step 6 Radar system antenna in distance to the echo data after t-th of fast moment orientation, k-th of slow moment backsight Range compress；
Step 9 inhibits Clutter using the method for amplitude subtraction
The radar system antenna forword-looking imaging result I that step 8 is obtainedf(a, r) and radar system antenna backsight imaging results Ib (a, r), using formula Iresult(a, r)=| If(a,r)|-|Ib(a, r) |, the signal after Clutter inhibits, note is calculated For Iresult(a, r), a=1 ..., Nx, r=1 ..., Ny, wherein | | indicate signed magnitude arithmetic(al) symbol；
Step 10, detection moving-target and the position range for determining moving-target
Signal after being inhibited to the Clutter that step 9 obtains using the big value method CFAR detection method of the choosing of traditional standard Iresult(a, r), a=1 ..., Nx, r=1 ..., Ny, CFAR detection is carried out, is detected respectively：
(1) radar system antenna forword-looking imaging result I is detectedfMoving-target in (a, r), is denoted as
(2) radar system antenna backsight imaging results I is detectedbMoving-target in (a, r), is denoted as
(3) detect moving-target in radar system antenna forword-looking imaging result IfPosition range in (a, r), is denoted as Wherein,Indicate moving-target in radar system Antenna forword-looking imaging result of uniting IfThe position coordinates of orientation in (a, r),Indicate moving-target radar system antenna forward sight at As result IfThe position coordinates of (a, r) middle-range descriscent,Indicate moving-target in radar system antenna forword-looking imaging result If(a,r) The coordinate of middle orientation central point,Indicate moving-target in radar system antenna forword-looking imaging result IfIn (a, r) middle-range descriscent The coordinate of heart point,Indicate moving-target in radar system antenna forword-looking imaging result IfThe position length of orientation in (a, r), Indicate moving-target in radar system antenna forword-looking imaging result If(a, r), a=1 ..., Nx, r=1 ..., Ny；
(4) detect moving-target in radar system antenna backsight imaging results IfPosition range in (a, r), is denoted as Wherein,Indicate moving-target in radar system Antenna backsight imaging results of uniting IbThe position coordinates of orientation in (a, r),Indicate moving-target radar system antenna backsight at As result IbThe position coordinates of (a, r) middle-range descriscent,Indicate moving-target in radar system antenna backsight imaging results If(a,r) The coordinate of middle orientation central point,Indicate moving-target in radar system antenna backsight imaging results If(a, r), a=1 ..., Nx, r=1 ..., Ny, the coordinate of middle-range descriscent central point,Indicate moving-target in radar system antenna backsight imaging results If The position length of orientation in (a, r),Indicate moving-target in radar system antenna backsight imaging results Ib(a, r) middle-range descriscent Position length, wherein a=1 ..., Nx, r=1 ..., Ny；
The speed of step 11, the moving-target orientation of the low precision of acquisition
By the moving-target obtained in step 10 in radar system antenna forword-looking imaging result IfThe seat of orientation central point in (a, r) MarkAs position coordinates of the moving-target in radar system antenna forword-looking imaging result, it is denoted as By the moving-target obtained in step 10 in radar system antenna backsight imaging results IbOrientation center in (a, r) The coordinate of pointAs moving-target in radar system antenna backsight imaging results IbPosition coordinates in (a, r), are denoted as
Using formulaBe calculated moving-target initial orientation to speed,Indicate moving-target initially side Position to speed, Δ t=(R0tanθ1-R0tanθ2)/VpxIndicate two-way synthetic aperture imaging radar BiDi SAR along the flight path time Interval, VpxFor the movement velocity of the radar platform orientation initialized in step 1, R0For the radar system in step 7 to projection The reference oblique distance of imaging space, θ1And θ2The orientation angle of squint of the radar antenna transmitting forward looking beam respectively initialized in step 1 Emit the orientation angle of squint of backsight wave beam with radar antenna；
Parameter needed for step 12, initialization moving-target iteration imaging
The parameter needed for the imaging of moving-target iteration is initialized, including：The maximum times of algorithm iteration are denoted as MI, algorithm iteration threshold Value, is denoted as ε；The speed of the moving-target residue orientation estimated during ith iteration, is denoted asIth iteration is estimated The azimuthal velocity of the moving-target gone out, is denoted asI=1 ..., MI during ith iteration, wherein i are natural number, indicate imaging The ith iteration of algorithm,For moving-target initial orientation to speed；
Step 13, the parameter in initialization moving-target iteration projection space：
By moving-target iteration projection space, it is denoted as Ω；The X axis areas imaging of moving-target iteration projection space Ω, It is denoted as W 'x；The Y-axis areas imaging of moving-target iteration projection space Ω, is denoted as W 'y；Moving-target iteration projection space The X axis centre coordinate of Ω, is denoted as W 'xc；The Y-axis centre coordinate of moving-target iteration projection space Ω, is denoted as W 'yc；Its In, the X axis areas imaging of moving-target iteration projection space ΩMoving-target iteration is imaged The Y-axis areas imaging W ' of projector space Ωy=W 'x；The X axis centre coordinate of moving-target iteration projection space ΩThe Y-axis centre coordinate of moving-target iteration projection space ΩWherein,It is the moving-target that is obtained in step 10 in radar system antenna forword-looking imaging result If(a, r), a=1 ..., Nx, r=1 ..., Ny, the position length of middle orientation,The moving-target obtained for step 10 is in radar system antenna backsight imaging results Ib(a, R), a=1 ..., Nx, r=1 ..., Ny, the position length of middle orientation,It is the moving-target that is obtained in step 10 in radar system Antenna forword-looking imaging result of uniting If(a, r), a=1 ..., Nx, r=1 ..., Ny, the coordinate of middle orientation central point,For step 10 obtained moving-targets are in radar system antenna backsight imaging results Ib(a, r), a=1 ..., Nx, r=1 ..., Ny, middle orientation The coordinate of central point
The X axis cell resolution of moving-target iteration projection space Ω, is set as ρlx；Moving-target iteration projection space Ω Y-axis cell resolution, be set as ρly；The X axis resolution cell number of moving-target iteration projection space Ω, is denoted as N 'x；It is dynamic The Y-axis resolution cell number of target iteration projection space Ω, is denoted as N 'y；The ginseng of moving-target iteration projection space Ω Oblique distance is examined, R is denoted as0；
Moving-target iteration projection space Ω is evenly dividing, the two dimension of moving-target iteration projection space Ω is obtained Resolution cell is denoted as PΩ(m, n)=[x (m, n), y (m, n)], m=1 ..., N 'x, n=1 ..., N 'y, wherein m and n are nature Number, m indicate that m-th of resolution cell of X axis in moving-target iteration projection space Ω, n indicate that the imaging of moving-target iteration is thrown N-th of resolution cell of Y-axis in the Ω of shadow space, x (m, n) and y (m, n) indicate that the imaging of moving-target iteration projection is empty respectively Between Ω two dimension resolution cells X axis position, Y-axis position；
Step 14 carries out projection imaging processing to moving-target
Speed when moving-target ith iteration is imaged is denoted asIndicate imaging algorithm Ith iteration, MI be algorithm maximum iteration；Enable the institute for the moving-target iteration projection space Ω that step 13 obtains There is resolution cell PΩ(m, n) highly to coordinate be 0, m=1 ..., N 'x, n=1 ..., N 'y, using formulaRadar platform is calculated in orientation time tmMoment is to moving-target iteration All resolution cell P of projection space ΩΩThe oblique distance of (m, n), m=1 ..., N 'x, n=1 ..., N 'y, it is denoted as R (PΩ, tm)；Wherein, tmFor the time for the orientation that step 1 initializes, P (0) is the radar system antenna initial position that step 1 is mentioned, VpFor the platform movement velocity vector that step 1 is mentioned, VmFor the velocity to moving target vector that step 1 is mentioned, | | | |2Indicate vector 2 norm operations；
Construct penalty functionWherein λ is the radar carrier wavelength that step 1 is mentioned,Indicate imaginary number list Position, e=2.71828183 is constant；
By radar system antenna in distance to the number of echoes after t-th of fast moment orientation, k-th of slow moment forward sight Range compress According to SF (t, k), t=1,2 ..., Nr, k=1,2 ..., NaAnd penalty functionIt is imaged using the rear orientation projection of standard Algorithm is iterated imaging, obtains the iterative projection imaging results of forward sight echo data, is denoted as N=1 ..., N 'y；I=1 ..., MI indicate that the ith iteration of imaging algorithm, SF (t, k) are the radar system day that step 6 obtains Line is in distance to the echo data after t-th of fast moment orientation, k-th of slow moment forward sight Range compress, t=1,2 ..., Nr, k =1,2 ..., Na；
By radar system antenna in distance to the number of echoes after t-th of fast moment orientation, k-th of slow moment backsight Range compress According to SB (t, k), t=1,2 ..., Nr, k=1,2 ..., NaAnd penalty functionUsing standard rear orientation projection at As algorithm is iterated imaging, the iterative projection imaging results of backsight echo data are obtained, are denoted as N=1 ..., N 'y；I=1 ..., MI indicate that the ith iteration of imaging algorithm, SB (t, k) are the radar system day that step 6 obtains Line is in distance to the echo data after t-th of fast moment orientation, k-th of slow moment backsight Range compress, t=1,2 ..., Nr, k =1,2 ..., Na；
Step 15, the speed for iterating to calculate moving-target orientation
Using the peak value of moving-target as the position of pre-filter method, then moving-target is imaged knot in the iterative projection of forward sight echo data FruitIn position be denoted asIndicate the i-th of imaging algorithm Secondary iteration, the iterative projection imaging results of moving-target backsight echo dataIn Position be denoted asIndicate the ith iteration of imaging algorithm；
Using formulaThe speed of the remaining orientation of moving-target is calculated, i=1 ..., MI are expressed as As the ith iteration of algorithm；Wherein, MI is that initialization obtains the maximum times of algorithm iteration in step 12, and Δ t is in step 11 High speed platform BiDi SAR along flight path time interval,Indicate remaining orientation speed；
Using formulaBy the remaining azimuthal velocity of calculated moving-target during ith iterationCompensation The orientation speed of the moving-target gone out to (i-1)-th iterative estimateObtain calculated moving-target during ith iteration Azimuthal velocity, be denoted asWherein, i=1 ..., MI indicate that the ith iteration of imaging algorithm, MI are to be initialized in step 12 Repeatedly initial value to the maximum times of algorithm iteration, moving-target azimuthal velocity is the orientation speed of calculated moving-target in step 11 Degree
Step 16, the condition of decision algorithm iteration and obtain final azimuthal velocity estimated result
IfAnd i≤MI, add 1 to obtain i ← i+1 imaging algorithm iterations i；Repeat step 13, step 14, step 15；
IfOr i >=MI, iterative step is terminated, is obtainedThe as final estimating speed of moving-target orientation； Wherein i=1 ..., MI indicate that the ith iteration of imaging algorithm, MI are that initialization obtains the maximum time of algorithm iteration in step 12 Number, ε are the algorithm iteration threshold value initialized in step 12,For the moving-target estimated during algorithm ith iteration Azimuthal velocity,Azimuthal velocity for the moving-target estimated in (i-1)-th iterative process of algorithm.
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