CN115877318A - Radiation source positioning method based on multi-aperture cross positioning - Google Patents
Radiation source positioning method based on multi-aperture cross positioning Download PDFInfo
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Abstract
The invention discloses a radiation source positioning method based on multi-aperture cross positioning. The positioning method comprises the following steps: based on a back projection algorithm, obtaining azimuth angle estimated values of targets under a plurality of sub-apertures at different positions in the multi-aperture search model through rough search and fine search; and solving a linear equation set by a least square method to obtain the distance and the azimuth distance of the target based on the obtained azimuth estimation value so as to realize target positioning. Compared with a positioning method with two apertures, the multi-aperture cross positioning method increases the positioning accuracy.
Description
Technical Field
The invention relates to a radiation source positioning technology, in particular to a multi-aperture-based cross positioning method.
Background
Compared with a radiation source positioning technology based on a plurality of position information, the positioning method based on the passive synthetic aperture has obvious advantages in sensitivity and resolution due to coherent accumulation characteristics. In the synthetic aperture positioning method, the azimuth angle of the target under the sub-aperture can be obtained based on the back projection algorithm, and the position of the target can be obtained by utilizing the azimuth angle information of the target under the two apertures. However, the backward projection algorithm-based two-aperture target positioning result has large fluctuation and poor target positioning precision.
Disclosure of Invention
Aiming at the defects of the prior art, the invention aims to provide a novel multi-aperture cross positioning-based radiation source positioning method, which can solve the problem of poor positioning precision in the positioning of a back projection algorithm based on double apertures in the prior art and improve the positioning accuracy of the whole target.
The technical scheme of the invention is as follows:
a multi-aperture cross-localization based radiation source localization method, comprising:
step 101: performing down-conversion and demodulation processing on a radiation source target signal, namely a received signal, received by a receiver to obtain a Doppler received signal of a radiation source target;
step 102: sampling the de-modulated Doppler received signal according to a signal sampling model, intercepting and searching the obtained sampled signal based on a search model with multiple synthetic apertures, obtaining azimuth angle estimated values of targets under multiple sub-apertures with different central aperture positions through a back projection algorithm in the search, and constructing the search model based on a search strategy which is sequentially carried out by coarse search and fine search;
step 103: according to the obtained azimuth angle estimated values of the targets under the sub-apertures with different central aperture positions, the distance and the azimuth distance of the radiation source target are obtained through a least square method;
wherein the search model is constructed as follows:
the sub-apertures participating in the search include sub-apertures 1,2, 8230, I, 8230, I and I, and the central time positions of the corresponding sub-apertures are T ci I =1,2, \ 8230;, I, the central spatial positions of the corresponding sub-apertures are L i ＝vT ci And v is the moving speed of the platform, and the coarse search and the fine search aiming at the target are sequentially carried out under the aperture arrays of the plurality of sub-apertures to obtain the azimuth angle phi between any ith sub-aperture and the target i Wherein the aperture search duration of the coarse search is T short Fine search aperture search duration of T long ，T long ＞T short And the search center of the fine search is the preliminary location position of the target obtained by the coarse search.
According to some embodiments of the invention, the signal sampling model is set as follows:
rd(l)＝r 2 (lT s ),l＝0,1,…,L-1
wherein rd () denotes a discretized signal sequence obtained after sampling, which is a complex matrix of dimensions 1 xl, i.e. rd ∈ C 1 ×L (ii) a L represents a one-dimensional vector L sampling point signal, and L represents the number of signal sampling points;
represents a signal sampling time interval, wherein s Representing the sampling frequency, corresponding to a signal sampling time range of t = lT s ,l＝0,1,…,L-1。/>
According to some embodiments of the present invention, the obtaining of the doppler receiving signal of the radiation source target in step 101 includes:
(1) Setting relevant parameters of a radiation source, specifically comprising: setting the radiation source signal modulation mode as binary phase shift keying BPSK, the carrier frequency is f c The radiation source signal is s (t) = g (t) exp (j 2 pi f) c t), t represents time, g (t) is a baseband code element signal of the radiation source signal;
(2) Setting parameters of a scene and a platform receiver, specifically comprising: under a rectangular coordinate system, the platform is in a uniform straight line with a speed vThe motion locus is [ x (t), y (t), z (t)]Velocity vector is [ v ] x ,v y ,v z ]. The target of the radiation source radiates electromagnetic signals to the periphery on the ground surface, and the corresponding coordinate is [ x ] 0 ,y 0 ,0]；
(3) According to the settings of (1) and (2), the radiation source target signal received by the onboard receiver, namely the received signal r (t), is obtained as follows:
where a represents the strength of the received signal, w (t) is zero mean, and the variance is σ 2 White gaussian noise, c denotes the speed of light,
representing the instantaneous distance of the radiation source target from the receiver;
(4) Performing down-conversion processing on the received signal r (t) according to the signal carrier frequency to obtain a down-conversion processed signal r 1 (t), as follows:
wherein w 1 (t)＝w(t)exp(-j2πf c t) represents the down-converted interferer,
to represent
A baseband code element signal of the radiation source signal at the moment;
(5) For down-conversion processed signal r 1 (t) square demodulation is carried out to obtain a Doppler received signal r of a radiation source target 2 (t)：
Wherein C is a normal complex number,
representing the de-modulated interfering signal.
According to some embodiments of the invention, the step 102 comprises:
sampling the Doppler received signal according to the signal sampling model to obtain a discretized sampled received signal;
search aperture duration T based on the coarse search short Intercepting and sampling the discretized sampling receiving signal to obtain a target Doppler signal under a short synthetic aperture;
carrying out first gridding subdivision on a search area for target search according to an azimuth angle and a distance in the azimuth angle direction, namely carrying out coarse gridding subdivision;
taking the grid point obtained by coarse meshing as a first target point, and obtaining a unmodulated Doppler signal of the first target point, namely a unmodulated Doppler signal under short synthesis duration;
performing correlation processing on the Doppler signal of the target under the short synthetic aperture and the de-modulated Doppler signal under the short synthetic duration within a short synthetic aperture range to obtain a positioning result of the first target point;
searching the peak position of the positioning result under coarse gridding subdivision according to the positioning result of the first target point, and obtaining the positioning position of the first target point under coarse searching according to the first azimuth index and the distance index in the first azimuth direction, which are correspondingly obtained, and the positioning position comprises the coarse first azimuth and the distance in the first azimuth direction;
calculating according to the first azimuth and the distance in the direction of the first azimuth to obtain the frequency and the modulation frequency corresponding to the target;
performing down-conversion processing on the discretized sampled received signal according to the frequency corresponding to the target to obtain a down-converted sampled received signal;
according to the frequency modulation frequency, low-pass filtering processing is carried out on the sampling signal after the down-conversion processing, and a filtered sampling receiving signal is obtained;
performing up-conversion processing on the filtered sampled received signal according to the frequency corresponding to the target to obtain an up-converted sampled signal;
according to the search aperture duration T of the fine search long Intercepting and sampling the sampling signal after the up-conversion to obtain a target Doppler signal under a long synthetic aperture;
taking the positioning position of the first target point under the rough search as a center, and carrying out second gridding subdivision on a search area for carrying out target search according to an azimuth angle and the distance in the azimuth angle direction, namely fine gridding subdivision;
taking the grid point obtained by the fine gridding subdivision as a second target point, and obtaining a Doppler signal after the demodulation of the second target point, namely a demodulation Doppler signal under a long synthesis duration;
performing correlation processing on the Doppler signal of the target under the long synthetic aperture and the de-modulated Doppler signal under the long synthetic duration within a long synthetic aperture range to obtain a positioning result of the second target point;
searching the peak position of the positioning result divided by the fine grid according to the positioning result of the second target point, and obtaining the azimuth angle of the second target point under the fine search, namely the azimuth angle estimation value according to the second azimuth angle index correspondingly obtained and the distance index in the second azimuth angle direction;
wherein the distance in the azimuth direction is the distance between the center of the sub-aperture and the target.
According to some embodiments of the present invention, the step 102 specifically comprises:
based on the search model, the sub-aperture center time position T is used ci Is a center, T short In order to intercept the length, the discretized signal rd obtained by sampling the signal sampling model is intercepted to obtain a Doppler signal of a target under a short synthetic aperture, as follows:
rd short (l；T ci )＝rd(l)，l＝N s1 ,N s1 +1,…,N s2
therein, rd short The Doppler signal of the target at the short synthetic aperture representing the ith sub-aperture is 1 (N) sk2 -N sk1 + 1) dimensional complex matrices, i.e.
N s1 ＝round(T si1 f s ) Initial sampling point, N, of the intercepted signal rd representing the ith sub-aperture at the time of short synthetic aperture interception s2 ＝round(T si2 f s ) Represents the termination sampling point of the interception signal rd of the ith sub-aperture under the interception of the short synthetic aperture, round (·) represents the rounding and the combination of the adjacent sub-apertures>
Represents the time of the intercepted signal, and>
indicating the time end of the intercepted signal, i.e. the Doppler signal interception time range t of the ith sub-aperture under short synthetic aperture interception si (l；T ci ,T short )＝t(lT s ),l＝N s1 ,N s1 +1,…,N s2 ；
(2) Setting the coordinate of the center position of the search area as X 0 ,Y 0 ,0]In combination with the synthetic aperture center position coordinate [ x ] ci ,y ci ,z ci ]And velocity vector [ v x ,v y ,v z ]Calculating the squint angle theta corresponding to the center position of the search area ci And the pitch R ci The following are:
(3) At an oblique angle of view theta ci And the pitch R ci For the center, the coarse mesh division of the azimuth angle and the distance in the azimuth angle direction, namely the azimuth angle distance, is carried out on the search area,
wherein, the coarse mesh subdivision of the azimuth angle is as follows:
wherein,
the azimuth grid point obtained by coarse gridding subdivision under the ith sub-aperture is represented, and is M s X 1-dimensional real number matrix; theta si Subdividing the range for the azimuth angle; m s Is the number of grid cells in the total azimuth angle, θ si ＝M s dθ si ，dθ si Subdividing the interval for the azimuth angle; m denotes an mth azimuth grid cell.
The coarse meshing subdivision of the azimuth angle distance is as follows:
wherein,
the distance grid points of azimuth angles obtained by coarse gridding subdivision under the ith sub-aperture are represented and are N s X 1-dimensional real number matrix; r si Dividing the range for the distance of the azimuth angle; n is a radical of hydrogen s Number of grid cells, R, of distances of total azimuth si ＝N s dR si ，dR si Subdividing intervals for the distance of azimuth angles; n represents the nth range grid cell in azimuth;
(4) In azimuth angle theta smi ,m＝1,…,M s Azimuth angle distance of R sni ,n＝1,…,N s The grid point of (1) is taken as a target point, namely a first target point, and the de-modulation is considered by combining the motion track of the platformDoppler signal r at short synthesis duration of ith sub-aperture of effect short (l；m,n,T ci ) The following are:
wherein R (l; m, n, T) ci ,T short ) For a short synthetic aperture representing the ith sub-aperture, the sampling interval is T s Azimuth angle theta smi (m) azimuthal distance R sni (n) instantaneous distance of the target from the satellite trajectory, and
(5) Doppler signal rd of target under short synthetic aperture of ith sub-aperture short (l；T ci ) Doppler signal r at short synthesis time with the ith sub-aperture short (l；m,n,T ci ) And performing correlation processing within a short synthetic aperture range to obtain a positioning result of the first target point, wherein the positioning result comprises the following steps:
wherein, I short (m,n；T ci ) And under the short synthetic aperture representing the ith sub-aperture, obtaining a target grid point positioning result obtained by rough search, wherein the target grid point positioning result is M s ×N s Dimensional real number matrix, i.e.
Representing a correlation calculation, | representing a module value, | based on>
Doppler of target under short synthetic aperture representing ith sub-apertureLe signal rd short (l；T ci ) Complex conjugation of (a);
(6) Searching I according to the positioning result of the first target point short (m,n；T ci ) By the azimuth index m of the grid point of that position si And an azimuthal distance index n si Correspondingly obtaining a coarse positioning azimuth angle theta of the first target point smi (m si ) And azimuth distance R sni (n si )；
(7) According to the obtained azimuth angle theta smi (m si ) And azimuth distance R sni (n si ) Calculating the frequency and the tuning frequency corresponding to the target positioned at the first target point as follows:
wherein v represents the platform operating speed and λ represents the signal carrier wavelength;
(8) According to the frequency corresponding to the target, performing down-conversion processing on the discretization signal sequence rd sampled by the signal sampling model to obtain a down-converted sampling receiving signal rd1, which comprises the following steps:
rd 1 ＝rd·exp(-j2πf d t)；
(9) According to the frequency modulation rate corresponding to the obtained target, performing low-pass filtering processing on the sampling received signal rd1 after the down-conversion processing to obtain a filtered sampling received signal rd2, as follows:
rd 2 ＝ifft(fft(filter,length(rd 1 ))·fft(rd 1 ))
wherein fft (-) is fourier transform, ifft (-) is inverse fourier transform, | - | represents a module value, length (-) represents a signal length, and filter represents a filter time domain representation as follows:
filter＝cfirpm(N o ,[-1 -F 2 -F 1 F 1 F 2 1],@lowpass)；
wherein cfirpm is a function of a filter time domain expression used to generate a corresponding frequency band range；F 1 ＝2|K a |T long /f s ，F 2 ＝3|K a |T long /f s ；N o Represents order, and @ lowpass represents a low pass filter call function;
(10) According to the frequency corresponding to the obtained target, the filtered sampling signal rd is processed 2 Performing up-conversion processing to obtain a sampling signal rd3 after up-conversion, which is as follows:
rd 3 ＝rd 2 ·exp(j2πf d t)；
(11) By T ci Is a center, T long In order to intercept the length, down is a down-sampling multiple of a positive integer, and the sampling signal rd3 after up-conversion is intercepted and sampled to obtain a Doppler signal of a target under a long synthetic aperture as follows:
rd long (l；T ci ,down)＝rd 3 (l·down)，l＝N l1 ,N l1 +1,…,N l2
therein, rd long (l；T ci Down) represents a target doppler signal obtained by down-sampling the long synthetic aperture of the i-th sub-aperture, which is 1 × (N) l2 -N l1 + 1) dimensional complex matrices, i.e.
N l1 ＝round(T li1 f s /down) denotes the starting sample point of the down-sampled signal intercepted by the ith sub-aperture, N, at a long synthetic aperture l2 ＝round(T li2 f s /down) represents the ending sampling point of the down-times down-sampled signal intercepted by the ith sub-aperture under the long synthetic aperture, round (·) represents rounding nearby, and/or is/are greater than or equal to>
Represents the time start of an intercepted down-sampled signal, is>
The time end point of the intercepted down-sampled signal is shown, and the ith sub-aperture is formed under the long synthetic apertureThe interception time range of the doppler signal of the lower target is: t is t li (l；T ci ,T long ,down)＝t(l·T s ·down),l＝N l1 ,N l1 +1,…,N l2 ；
(12) Azimuth theta of first target point obtained by coarse search smi (m si ) And an azimuthal distance R sni (n si ) For a search center of fine search, carrying out fine gridding subdivision based on azimuth angles and azimuth angle distances on a search area near the center, and as follows:
the azimuth angle is divided into:
wherein, theta lmi (M) represents the azimuth grid point obtained by fine grid subdivision under the ith sub-aperture, which is M l X 1 dimensional real matrix, i.e.
θ li Subdividing the range for the azimuth; m is a group of l Is the number of grid cells in the total azimuth angle, θ li ＝M l dθ li ，dθ li Subdividing the interval for the azimuth angle;
the azimuthal distance is subdivided as follows:
wherein R is lni (N) distance grid points of azimuth direction obtained by fine-grid subdivision under the ith sub-aperture are represented, and are N l X 1 dimensional real number matrix, i.e.
R li Dividing the range for the distance of the azimuth angle; n is a radical of l Number of grid cells, R, of distances of total azimuth li ＝N l dR li ，dR li For azimuthal distance profileDividing into intervals;
(13) In azimuth angle theta lmi Azimuth distance R lni The grid point of (2) is used as a target point, namely a second target point, and a Doppler signal r of the grid target point in a long synthesis time and considering the demodulation effect is obtained by combining the platform track long I.e. de-modulated Doppler signals r at long synthesis durations long (l；m,n,T ci Down), as follows:
wherein R (l; m, n, T) ci ,T long Down) denotes the sampling interval of down.T at the long resultant aperture of the ith sub-aperture s Has an azimuth angle of theta lmi (m) azimuthal distance R lni (n) an instantaneous distance of the target from the satellite trajectory, and:
wherein, t li (l；T ci ,T long Down) represents the interception time range of the Doppler received signal of the ith sub-aperture under the long synthetic aperture;
(14) Intercepting Doppler signal rd under the long synthetic aperture long (l；T ci Down) with the unmodulated doppler signal r for the long synthesis duration long (l；m,n,T ci Down) to perform correlation processing within a long synthetic aperture range to obtain a positioning result of the second target point, as follows:
wherein,
indicating second mesh target point location junction under ith sub-aperture under long synthetic apertureFruit of which is M l ×N l Dimension and real number matrix, < >>
Represents a correlation calculation, |, represents a modulus value, | is greater than>
Indicating the Doppler signal rd representing the target under the long synthetic aperture representing the ith sub-aperture long (l；T ci Down) complex conjugation;
(15) Searching I according to the positioning result of the second target point long (m,n；T ci Down) peak position, the azimuth index m of the grid point passing through that position li To obtain the azimuth angle phi of the target under the ith sub-aperture i I =1,2, \ 8230;, I estimate phi i The following are:
φ i ＝θ lmi (m li )。
according to some embodiments of the invention, the step 103 comprises:
based on the obtained azimuth angle estimated values of the targets under the sub-apertures with different central aperture positions, according to the geometric relationship between different distances and azimuth angles, a distance R and an azimuth distance A are established z R1, R2, \8230;, ri, \8230;, RI, the position of the radiation source target solving a system of equations R as follows:
wherein the sub-aperture center distance L i ＝v·L ci ，R i I =1,2, \ 8230;, I, φ, is the distance between the center of the sub-aperture and the target, i.e. the azimuthal direction, the upward distance i I =1,2, \8230;, I denotes the target azimuth;
solving the equation set by a least square method to obtain the distance R and the azimuth distance A of the target s 。
According to some embodiments of the inventionThe distance of the target is R and the azimuth distance A s The solution is as follows:
A z = x (1), R = x (2), x (1), x (2) representing the first and second row elements of a solution matrix x of the following system of equations:
x＝(A * A)\(A * b) Wherein:
A * representing the conjugate transpose of matrix a.
Compared with a two-aperture target positioning method of a back projection algorithm, the method has the advantages that the stability of the positioning result and the positioning precision are remarkably improved, the number and the position of the sub-apertures can be flexibly designed according to actual engineering requirements, the use is flexible, and the real-time performance is good.
Drawings
Fig. 1 is a schematic flow chart of the positioning of the radiation source in the embodiment of the invention.
Fig. 2 is a schematic diagram of the azimuth search according to the embodiment of the present invention.
Fig. 3 is a schematic diagram illustrating the solution of the target position of the radiation source according to the embodiment of the present invention.
Fig. 4 is a schematic diagram of a simulation positioning scenario in embodiment 1 of the present invention.
Fig. 5 is a schematic diagram of the 2-aperture azimuth positioning error result in embodiment 1 of the present invention.
Fig. 6 is a schematic diagram of a 2-aperture distance positioning error result in embodiment 1 of the present invention.
Fig. 7 is a schematic diagram of the results of the 21-aperture azimuth positioning error in embodiment 1 of the present invention.
Fig. 8 is a schematic diagram of a 21-aperture distance positioning error result in embodiment 1 of the present invention.
Detailed Description
The present invention is described in detail below with reference to the following embodiments and the attached drawings, but it should be understood that the embodiments and the attached drawings are only used for the illustrative description of the present invention and do not limit the protection scope of the present invention in any way. All reasonable variations and combinations that fall within the spirit of the invention are intended to be within the scope of the invention.
Referring to fig. 1, an embodiment of a multi-aperture based radiation source cross-location method according to the present invention comprises the following steps:
step 101: the receiver receives the target signal of the radiation source, and the received target signal of the radiation source, namely the received signal, is subjected to down-conversion and de-modulation processing to obtain a Doppler received signal of the target of the radiation source.
In some embodiments, the radiation source target signal received by the receiver may be obtained for instrument reading and/or generated by simulation.
Further, in some embodiments, step 101 includes:
(1) Setting relevant parameters of a radiation source, specifically comprising: setting the radiation source signal modulation mode as binary phase shift keying BPSK, the carrier frequency is f c The radiation source signal is s (t) = g (t) exp (j 2 pi f) c t), t represents time, g (t) is the baseband symbol signal of the radiation source signal.
(2) Setting parameters of a scene and a platform receiver, specifically comprising: under a rectangular coordinate system, the platform moves linearly at a constant speed v with the motion trail [ x (t), y (t), z (t)]Velocity vector of
The target of the radiation source radiates electromagnetic signals towards the periphery on the ground surface, and the corresponding coordinate is [ x ] 0 ,y 0 ,0]。/>
(3) According to the settings of (1) and (2), the radiation source target signal received by the onboard receiver, namely the received signal r (t), is obtained as follows:
where a represents the strength of the received signal, w (t) is zero mean, and the variance is σ 2 White gaussian noise, c denotes the speed of light,
representing the instantaneous distance of the radiation source target from the receiver.
In the above steps, in an actual scene, r (t) is a radiation source signal received by an actual receiver instrument, in a simulation scene, r (t) is a received signal generated according to actual scene simulation, and is a scene reproduction of the actual scene, and the subsequent positioning modes of the two are the same.
(4) Carrying out down-conversion processing on the received signal r (t) according to the signal carrier frequency to obtain a down-conversion processed signal r 1 (t), as follows:
wherein, w 1 (t)＝w(t)exp(-j2πf c t) represents the down-converted interferer,
to represent
The baseband symbol signal of the radiation source signal at a time instant.
(5) For down-conversion processed signal r 1 (t) square demodulation is carried out to obtain Doppler received signal r of the radiation source target 2 (t)：
Wherein C is a normal complex number,
representing the de-modulated interfering signal.
Step 102: sampling the de-modulated Doppler received signal according to a signal sampling model, intercepting and searching the obtained sampled signal based on a search model with multiple synthetic apertures, obtaining azimuth angle estimated values of targets under multiple sub-apertures with different central aperture positions through a back projection algorithm in the search, and constructing the search model based on a search strategy which is sequentially carried out by coarse search and fine search.
In some embodiments, the signal sampling model is as follows:
for Doppler signal r 2 (t) truncating and sampling to obtain discrete signals:
rd(l)＝r 2 (lT s ),l＝0,1,…,L-1
wherein rd () represents a discretized signal sequence obtained after sampling, which is a complex matrix of dimension 1 xl, i.e. rd ∈ C 1 ×L (ii) a L represents a one-dimensional vector ith sampling point signal, and L represents the number of signal sampling points;
represents a signal sampling time interval, wherein s Representing the sampling frequency, corresponding to a signal sampling time range of t = lT s ,l＝0,1,…,L-1。
In some embodiments, referring to fig. 2, the search model is constructed as follows:
the sub-apertures participating in the search include sub-apertures 1,2, 8230, I, 8230, I and I, and the central time positions of the corresponding sub-apertures are T ci I =1,2, \ 8230;, I, the central spatial positions of the corresponding sub-apertures are L i ＝vT ci And sequentially carrying out coarse search and fine search aiming at the target under the aperture arrays of the plurality of sub-apertures to obtain the azimuth angle phi of any ith sub-aperture and the target i Wherein the aperture search duration of the coarse search is T short Fine search aperture search duration of T long ，T long ＞T short 。
Wherein, in some embodiments, the intercepting and searching comprises:
(1) Based on the search model, the sub-aperture central moment position T is firstly used ci Is a center, T short For intercepting the length, intercepting the discretization signal sequence sampled by the signal sampling model to obtain the Doppler signal of the target under the short synthetic aperture as follows:
rd short (l；T ci )＝rd(l)，l＝N s1 ,N s1 +1,…,N s2
therein, rd short The Doppler signal of the target at the short synthetic aperture representing the ith sub-aperture is 1 (N) sk2 -N sk1 + 1) dimensional complex matrices, i.e.
N s1 ＝round(T si1 f s ) Initial sampling point, N, of the intercepted signal rd representing the ith sub-aperture at the time of short synthetic aperture interception s2 ＝round(T si2 f s ) Represents the ending sampling point of the interception signal rd of the ith sub-aperture under the interception of the short synthetic aperture, round (·) represents the rounding nearby, and the length of the sampling point is greater than the length of the sampling point>
Represents the time of the intercepted signal, and>
indicating the time end of the intercepted signal, i.e. the Doppler signal interception time range t of the ith sub-aperture under short synthetic aperture interception si (l；T ci ,T short )＝t(lT s ),l＝N s1 ,N s1 +1,…,N s2 。
(2) Setting the coordinate of the center position of the search area as X 0 ,Y 0 ,0]In combination with the synthetic aperture center position coordinate [ x ] ci ,y ci ,z ci ]And velocity vector
Calculating the squint angle theta corresponding to the center position of the search area ci And the pitch R ci The following are:
(3) At an oblique angle of view theta ci And the pitch R ci For the center, coarse gridding division is carried out on the azimuth angle and the azimuth angle distance (namely the distance between the center of the sub-aperture and the target) of the search area.
The coarse meshing subdivision of the azimuth angle is as follows:
wherein,
the azimuth grid point obtained by coarse gridding subdivision under the ith sub-aperture is represented and is M s X 1-dimensional real number matrix; theta si Subdividing the range for the azimuth; m s Is the number of grid cells in the total azimuth angle, θ si ＝M s dθ si ，dθ si Subdividing the interval for the azimuth angle; m denotes an mth azimuth grid cell.
The azimuthal distance is subdivided as follows:
wherein,
the distance grid points of azimuth angles obtained by coarse gridding subdivision under the ith sub-aperture are represented and are N s X 1-dimensional real number matrix; r si Distance subdivision for azimuth anglesA range; n is a radical of s Number of grid cells, R, of distances of total azimuth si ＝N s dR si ，dR si Partitioning intervals for the distance of azimuth angles; n denotes the nth range grid cell in azimuth.
(4) In azimuth angle theta smi ,m＝1,…,M s Azimuth distance R sni ,n＝1,…,N s The grid point of (1) is used as a target point, namely a first grid target point, the Doppler signal r under the short synthesis duration of the ith sub-aperture considering the demodulation effect is obtained by referring to the received signal acquisition process in the step 101 and combining the motion track of the platform short (l；m,n,T ci ) The following are:
wherein R (l; m, n, T) ci ,T short ) At a short synthetic aperture representing the ith sub-aperture, the sampling interval is T s Azimuth angle theta smi (m) azimuthal distance R sni (n) instantaneous distance of the target from the satellite trajectory, and
(5) Doppler signal rd of target under short synthetic aperture of ith sub-aperture short (l；T ci ) Doppler signal r at short synthesis time with the ith sub-aperture short (l；m,n,T ci )r short (l；m,n,T ci ) And performing related processing within a short synthetic aperture range to obtain a positioning result of the first grid target point:
wherein, I short (m,n；T ci ) Under the short synthetic aperture of the ith sub-aperture, the target grid point obtained by rough searchPositioning result, which is M s ×N s Dimensional real number matrix, i.e.
Represents a correlation calculation, |, represents a modulus value, | is greater than>
Doppler signal rd of the target at short synthetic aperture representing the ith sub-aperture short (l；T ci ) Complex conjugation of (a).
(6) Searching I according to the positioning result of the first grid target point short (m,n；T ci ) By the azimuth index m of the grid point of that position si And an azimuthal distance index n si Correspondingly obtaining a coarse positioning azimuth angle theta of the first grid target point smi (m si ) And azimuth distance R sni (n si )。
(7) According to the obtained azimuth angle theta smi (m si ) And azimuth distance R sni (n si ) Calculating the frequency and the tuning frequency corresponding to the target positioned at the target point of the first grid as follows:
where v denotes the platform speed of operation and λ denotes the signal carrier wavelength.
(8) According to the frequency corresponding to the target, performing down-conversion treatment on the discretization signal sequence rd sampled by the signal sampling model to obtain a sampling receiving signal rd subjected to down-conversion treatment 1 The following are:
rd 1 ＝rd·exp(-j2πf d t)。
(9) According to the frequency modulation rate corresponding to the obtained target, the sampling receiving signal rd after the down-conversion treatment is carried out 1 Low-pass filtering to obtain filterPost-sampling received signal rd 2 The following are:
rd 2 ＝ifft(fft(filter,length(rd 1 ))·fft(rd 1 ))
wherein fft (-) is fourier transform, ifft (-) is inverse fourier transform, | - | represents a module value, length (-) represents a signal length, and filter represents a filter time domain representation as follows:
filter＝cfirpm(N o ,[-1 -F 2 -F 1 F 1 F 2 1],@lowpass)；
the filter time domain expression generating method comprises the following steps of obtaining a cfirpm function of matlab, wherein the cfirpm is a self-contained cfirpm function of matlab and is used for generating a filter time domain expression corresponding to a frequency band range; f 1 ＝2|K a |T long /f s ，F 2 ＝3|K a |T long /f s ；N o Denotes the order, and @ lowpass denotes the low pass filter call function.
(10) According to the frequency corresponding to the obtained target, the filtered sampling signal rd is processed 2 Carrying out up-conversion treatment to obtain a sampling signal rd after up-conversion 3 The following are:
rd 3 ＝rd 2 ·exp(j2πf d t)。
(11) By T ci Is a center, T long In order to intercept the length, down is the down-sampling multiple of a positive integer, and the up-converted sampling signal rd is sampled 3 Intercepting and sampling are carried out to obtain a Doppler signal of a target under a long synthetic aperture as follows:
rd long (l；T ci ,down)＝rd 3 (l·down)，l＝N l1 ,N l1 +1,…,N l2
wherein rd is long (l；T ci Down) represents the Doppler signal of the target under the long synthetic aperture of the i-th sub-aperture, which is 1 × (N) l2 -N l1 + 1) dimensional complex matrices, i.e.
N l1 ＝round(T li1 f s /down) denotes the extraction of the ith sub-aperture at long synthetic apertureInitial sampling point of sample signal, N l2 ＝round(T li2 f s /down) represents the end sample point of the intercepted sample signal at the ith sub-aperture under the long synthetic aperture, round (·) represents rounding nearby, and/or is/are>
Represents the start of the time at which the sample signal is intercepted, and>
and representing the time end point of intercepting the sampling signal, and under a long synthetic aperture, the interception time range of the Doppler signal of the target under the ith sub-aperture is as follows:
t li (l；T ci ,T long ,down)＝t(l·T s ·down),l＝N l1 ,N l1 +1,…,N l2 。
(12) Azimuth theta of first mesh target point obtained by coarse search smi (m si ) And an azimuthal distance R sni (n si ) For the search center of the fine search, a fine gridding subdivision based on azimuth and azimuth distance (i.e. the distance between the sub-aperture center and the target) is performed on the search area near the center, as follows:
the azimuth angle is divided into:
wherein, theta lmi (M) represents the azimuth grid point obtained by fine grid subdivision under the ith sub-aperture, which is M l X 1 dimensional real matrix, i.e.
θ li Subdividing the range for the azimuth angle; m l Is the number of grid cells in the total azimuth angle, θ li ＝M l dθ li ，dθ li The interval is subdivided for the azimuth.
The subdivision based on the distance of the azimuth angle is as follows:
wherein R is lni (N) azimuthal distance grid points obtained by fine-grid subdivision under the ith sub-aperture, which are N l X 1 dimensional real number matrix, i.e.
R li Dividing the range for the distance of the azimuth angle; n is a radical of l Number of grid cells, R, of distance of total azimuth li ＝N l dR li ，dR li And (5) dividing intervals for the distance of azimuth angles.
(13) In azimuth of theta lmi Azimuth angle distance of R lni The grid point of (1) is used as a target point, namely a second grid target point, the Doppler receiving signal acquisition process in the step 101 is referred to, and a Doppler signal r which considers the de-modulation effect of the grid target point in a long synthesis duration is obtained by combining the platform track long I.e. de-modulated Doppler signals r at long synthesis durations long (l；m,n,T ci Down), as follows:
wherein R (l; m, n, T) ci ,T long Down) denotes the sampling interval of down.T at the long resultant aperture of the ith sub-aperture s Has an azimuth angle of theta lmi (m) azimuthal distance R lni (n) an instantaneous distance of the target from the satellite trajectory, and:
wherein, t li (l；T ci ,T long Down) denotes the range of the doppler reception signal interception time of the i-th sub-aperture under the long synthetic aperture.
(14) Intercepting Doppler signal rd under the long synthetic aperture long (l；T ci Down) with the unmodulated doppler signal r for the long synthesis duration long (l；m,n,T ci Down) to perform correlation processing within the long synthetic aperture range to obtain a positioning result of the second mesh target point, as follows:
wherein,
the positioning result of the second grid target point under the ith sub-aperture under the long synthetic aperture is expressed and is M l ×N l Dimension and real number matrix, < >>
Represents a correlation calculation, |, represents a modulus value, | is greater than>
Indicating the Doppler signal rd representing the target under the long synthetic aperture representing the ith sub-aperture long (l；T ci Down).
(15) Searching I according to the positioning result of the second grid target point long (m,n；T ci Down) peak position, the azimuth index m of the grid point passing through that position li (its azimuthal distance index is n) li ) To obtain the azimuth angle phi of the target under the ith sub-aperture i I =1,2, \ 8230;, I estimate phi i The following are:
φ i ＝θ lmi (m li )
step 103: and obtaining the distance and the azimuth distance of the radiation source target by a least square method according to the obtained azimuth angle estimated values of the target under the plurality of sub-apertures with different central aperture positions.
Further, in some embodiments, step 103 comprises:
referring to fig. 3, based on the obtained azimuth angle estimated values of the target under the sub-apertures with different central aperture positions, according to the geometric relationship between different distances and azimuth angles, a range-wise distance R and an azimuth-wise distance a are established z Azimuth distance R 1 、R 2 、…、R i 、…、R I The position of the radiation source target of (2) solves the system of equations R as follows:
wherein the sub-aperture center distance L i ＝v·L ci ，R i I =1,2, \ 8230, i.e. the distance between the subaperture center and the target, i.e. the azimuthal distance, I, phi i I =1,2, \ 8230;, I denotes the target azimuth.
The above equation set can be expressed as:
Ax＝b
wherein
Solving the equation system by a least square method can obtain:
x＝(A * A)\(A * b)
wherein A is * The conjugate transpose of the matrix A is represented, and the range-wise distance R and the azimuth-wise distance A of the target are obtained s The positioning position of (2): a. The z = x (1), R = x (2), wherein x (1) represents a first element of a solution vector x of the system of equations and x (2) represents a second element of the solution vector x of the system of equations.
The positioning effect of the present invention is further shown below with reference to specific embodiments.
Example 1
Fig. 4 is a schematic diagram of a simulation positioning scene according to an embodiment of the present invention, where simulation parameters set in the embodiment include:
the platform data is generated by MATLAB, P is the central position of a scene, T is the target position, the platform has the height of 371km at A point, the included angle between AP and a yoz plane is 70 degrees, the AP distance is 1200km, the platform has the height of 357km at B point, the included angle between BP and the yoz plane is 68 degrees, the platform flies at a constant speed of 3000m/s from A to B, the time is from 0 to 42.92s, and the target T coordinate position of a radiation source is as follows: r =303636.02m z ＝1146263.59m。
Echo signals are generated in MATLAB using platform data, signal carrier frequency: 7.2445GHz; code rate: 200bound/s; signal-to-noise ratio: 5dB; the sampling rate is 2KHz.
In the positioning process:
the coarse search synthesis time is 0.1s, the azimuth search range is 5 degrees, and the azimuth search interval is 2e-3 degrees; the distance search range is 100km, and the interval is 25km.
The fine search synthesis time is 1s, the azimuth search range is 2e-2 degrees, and the azimuth search interval is 1e-6 degrees; the distance search range is 100km, and the interval is 25km.
Examples include two sets of comparative experiments with different pore sizes, including:
(1) Group A: aperture number 2, center time T c1 ＝5，T c1 ＝10；
(2) Group B: aperture number 21, center time T ci ＝5+(i-1)/4，i＝1,2,…,21。
Fig. 5 is a schematic diagram of the results of the positioning errors of the group a, fig. 6 is a schematic diagram of the results of the positioning errors of the group a, fig. 7 is a schematic diagram of the results of the positioning errors of the group B, and fig. 8 is a schematic diagram of the results of the positioning errors of the group B. The calculation can yield: under 2 sub-apertures, the azimuth positioning deviation is 118.8m, the standard deviation is 516.1m, the distance deviation is 31.9m, the standard deviation is 139.4m, and the average error is 442m; under 21 sub-apertures, the azimuth positioning deviation is 85.9m, the standard deviation is 228.9m, the distance deviation is 22.9m, the standard deviation is 61.8m, and the average error is 204m.
The above examples are merely preferred embodiments of the present invention, and the scope of the present invention is not limited to the above examples. All technical schemes belonging to the idea of the invention belong to the protection scope of the invention. It should be noted that modifications and embellishments within the scope of the invention may be made by those skilled in the art without departing from the principle of the invention, and such modifications and embellishments should also be considered as within the scope of the invention.
Claims (7)
1. A radiation source positioning method based on multi-aperture cross positioning is characterized by comprising the following steps:
step 101: performing down-conversion and demodulation processing on a radiation source target signal, namely a received signal, received by a receiver to obtain a Doppler received signal of a radiation source target;
step 102: sampling the de-modulated Doppler received signal according to a signal sampling model, intercepting and searching the obtained sampling signal based on a multi-synthetic aperture searching model, obtaining azimuth angle estimated values of targets under a plurality of sub-apertures with different central aperture positions through a back projection algorithm in the searching process, and constructing the searching model based on a searching strategy which is sequentially carried out by coarse searching and fine searching;
step 103: according to the obtained azimuth angle estimated values of the targets under the sub-apertures with different central aperture positions, the distance and the azimuth distance of the radiation source target are obtained through a least square method;
wherein the search model is constructed as follows:
the sub-apertures participating in the search comprise 1 st, 2 nd, 8230, I th, 8230, I th sub-apertures, and the central time positions of the corresponding sub-apertures are T ci I =1,2, \8230, I, the corresponding sub-aperture central space positions are respectively L i ＝vT ci Wherein v is the moving speed of the platform, and the coarse search and the fine search aiming at the target are sequentially carried out under the aperture arrays of the plurality of sub-apertures to obtain the azimuth angle phi between any ith sub-aperture and the target i Wherein the aperture search duration of the coarse search is T short Fine search aperture search duration of T long ，T long ＞T short And the search center of the fine search is the preliminary target positioning position obtained through the coarse search.
2. The radiation source positioning method of claim 1, wherein the signal sampling model is set as follows:
rd(l)＝r 2 (lT s ),l＝0,1,…,L-1
wherein rd () denotes a discretized signal sequence obtained after sampling, which is a complex matrix of dimensions 1 xl, i.e. rd ∈ C 1×L (ii) a L represents a one-dimensional vector ith sampling point signal, and L represents the number of signal sampling points;
represents a signal sampling time interval, wherein s Representing the sampling frequency, corresponding to a signal sampling time range of t = lT s ,l＝0,1,…,L-1。
3. The method according to claim 1, wherein the step 101 of obtaining the doppler receiving signal of the target of the radiation source comprises:
(1) Setting relevant parameters of a radiation source, specifically comprising: setting the modulation mode of radiation source signal as binary phase shift keying BPSK, the carrier frequency is f c The radiation source signal is s (t) = g (t) exp (j 2 pi f) c t), t represents time, g (t) is a baseband code element signal of the radiation source signal;
(2) Setting parameters of a scene and a platform receiver, specifically comprising: under a rectangular coordinate system, the platform moves linearly at a constant speed v, and the motion trail is [ x (t), y (t), z (t)]Velocity vector of
The target of the radiation source radiates electromagnetic signals towards the periphery on the ground surface, and the corresponding coordinate is [ x ] 0 ,y 0 ,0]；
(3) According to the settings of (1) and (2), the radiation source target signal received by the onboard receiver, namely the received signal r (t), is obtained as follows:
where a represents the strength of the received signal, w (t) is zero mean, and the variance is σ 2 White gaussian noise, c denotes the speed of light,
representing the instantaneous distance of the radiation source target from the receiver;
(4) Performing down-conversion processing on the received signal r (t) according to the signal carrier frequency to obtain a down-conversion processed signal r 1 (t), as follows:
wherein, w 1 (t)＝w(t)exp(-j2πf c t) represents the down-converted interferer,
represents->
A baseband code element signal of the radiation source signal of the moment;
(5) For down-conversion processed signal r 1 (t) square demodulation is carried out to obtain a Doppler received signal r of a radiation source target 2 (t)：
Wherein C is a normal complex number,
representing the de-modulated interfering signal.
4. The radiation source positioning method of claim 1, wherein the step 102 comprises:
sampling the Doppler received signal according to the signal sampling model to obtain a discretized sampled received signal;
search aperture duration T based on the coarse search short Intercepting and sampling the discretized sampling receiving signal to obtain a target Doppler signal under a short synthetic aperture;
carrying out first gridding subdivision on a search area for carrying out target search according to an azimuth angle and a distance in the direction of the azimuth angle, namely carrying out coarse gridding subdivision;
taking the grid points obtained by the coarse meshing as first target points, and obtaining the unmodulated Doppler signals of the first target points, namely the unmodulated Doppler signals under the short synthesis time;
performing correlation processing on the Doppler signal of the target under the short synthetic aperture and the de-modulated Doppler signal under the short synthetic duration within a short synthetic aperture range to obtain a positioning result of the first target point;
searching the peak position of the positioning result under coarse gridding subdivision according to the positioning result of the first target point, and obtaining the positioning position of the first target point under coarse searching according to the first azimuth index and the distance index in the first azimuth direction, which are correspondingly obtained, and the positioning position comprises the coarse first azimuth and the distance in the first azimuth direction;
calculating according to the first azimuth and the distance in the direction of the first azimuth to obtain the frequency and the modulation frequency corresponding to the target;
performing down-conversion processing on the discretized sampled received signal according to the frequency corresponding to the target to obtain a down-converted sampled received signal;
according to the frequency modulation frequency, low-pass filtering processing is carried out on the sampling signal after the down-conversion processing, and a filtered sampling receiving signal is obtained;
performing up-conversion processing on the filtered sampled received signal according to the frequency corresponding to the target to obtain an up-converted sampled signal;
search aperture duration based on the fine searchT long Intercepting and sampling the up-converted sampling signal to obtain a target Doppler signal under a long synthetic aperture;
taking the positioning position of the first target point under the rough search as a center, and carrying out second gridding subdivision on the search area for carrying out target search according to the azimuth angle and the distance in the azimuth angle direction, namely fine gridding subdivision;
taking the grid point obtained by the fine gridding subdivision as a second target point, and obtaining a Doppler signal after the demodulation of the second target point, namely a demodulation Doppler signal under a long synthesis duration;
performing correlation processing on the Doppler signal of the target under the long synthetic aperture and the de-modulated Doppler signal under the long synthetic aperture within the range of the long synthetic aperture to obtain a positioning result of the second target point;
searching the peak position of the positioning result divided by the fine grid according to the positioning result of the second target point, and obtaining the azimuth angle of the second target point under the fine search, namely the azimuth angle estimation value according to the second azimuth angle index correspondingly obtained and the distance index in the second azimuth angle direction;
wherein the distance in the azimuth direction is the distance between the center of the sub-aperture and the target.
5. The multi-aperture based cross-referencing method according to claim 4, wherein said step 102 comprises:
(1) Based on the search model, the sub-aperture center time position T is used ci Is a center, T short For intercepting the length, intercepting the discretized signal rd sampled by the signal sampling model to obtain the Doppler signal of the target under the short synthetic aperture as follows:
rd short (l；T ci )＝rd(l)，l＝N s1 ,N s1 +1,…,N s2
therein, rd short Doppler signal of a target under a short synthetic aperture representing the ith sub-aperture, which is 1 × (N) sk2 -N sk1 + 1) dimensional complex numberMatrices, i.e.
N s1 ＝round(T si1 f s ) Initial sampling point, N, of the intercepted signal rd representing the ith sub-aperture at the time of short synthetic aperture interception s2 ＝round(T si2 f s ) Represents the ending sampling point of the interception signal rd of the ith sub-aperture under the interception of the short synthetic aperture, round (·) represents the rounding nearby, and the length of the sampling point is greater than the length of the sampling point>
Represents the time origin of an intercepted signal>
Indicating the time end of the intercepted signal, i.e. the Doppler signal interception time range t of the ith sub-aperture under short synthetic aperture interception si (l；T ci ,T short )＝t(lT s ),l＝N s1 ,N s1 +1,…,N s2 ；
(2) Setting the coordinate of the center position of the search area as X 0 ,Y 0 ,0]In combination with the synthetic aperture center position coordinate [ x ] ci ,y ci ,z ci ]And velocity vector [ v x ,v y ,v z ]Calculating the squint angle theta corresponding to the center position of the search area ci And the pitch R ci The following are:
(3) At an oblique angle of view theta ci And the pitch R ci For the center, the coarse mesh division of the azimuth angle and the distance in the azimuth angle direction, namely the azimuth angle distance, is carried out on the search area,
wherein, the coarse mesh subdivision of the azimuth angle is as follows:
wherein,
the azimuth grid point obtained by coarse gridding subdivision under the ith sub-aperture is represented, and is M s X 1-dimensional real number matrix; theta si Subdividing the range for the azimuth; m s Is the number of grid cells in the total azimuth angle, θ si ＝M s dθ si ，dθ si Subdividing the interval for the azimuth; m represents an mth azimuth grid cell;
the coarse meshing subdivision of the azimuth angle distance is as follows:
wherein,
the distance grid points of azimuth angles obtained by coarse gridding subdivision under the ith sub-aperture are represented and are N s X 1-dimensional real number matrix; r si Dividing the range for the distance of the azimuth angle; n is a radical of s For the total number of distance grid cells, R, for azimuth si ＝N s dR si ，dR si Partitioning intervals for the distance of azimuth angles; n represents the nth range grid cell in azimuth;
(4) In azimuth angle theta smi ,m＝1,…,M s Azimuth distance R sni ,n＝1,…,N s The grid point of (1) is used as a target point, namely a first target point, and a Doppler signal r under the short synthesis duration of the ith sub-aperture considering the modulation removing effect is obtained by combining the motion track of the platform short (l；m,n,T ci ) The following are:
wherein R (l; m, n, T) ci ,T short ) For a short synthetic aperture representing the ith sub-aperture, the sampling interval is T s Has an azimuth angle theta of smi (m) azimuthal distance R sni (n) instantaneous distance of the target from the satellite trajectory, and
(5) Doppler signal rd of target under short synthetic aperture of ith sub-aperture short (l；T ci ) Doppler signal r at short synthesis time with the ith sub-aperture short (l；m,n,T ci ) And performing correlation processing within a short synthetic aperture range to obtain a positioning result of the first target point, wherein the positioning result comprises the following steps:
wherein, I short (m,n；T ci ) And under the short synthetic aperture representing the ith sub-aperture, obtaining a target grid point positioning result obtained by rough search, wherein the target grid point positioning result is M s ×N s Dimensional real number matrix, i.e.
Represents a correlation calculation, |, represents a modulus value, | is greater than>
Doppler signal rd of the target at short synthetic aperture representing the ith sub-aperture short (l；T ci ) Complex conjugation of (a);
(6) Searching I according to the positioning result of the first target point short (m,n；T ci ) By the azimuth index m of the grid point of that position si And an azimuthal distance index n si Correspondingly obtaining a coarse positioning azimuth angle theta of the first target point smi (m si ) And an azimuthal distance R sni (n si )；
(7) According to the obtained azimuth angle theta smi (m si ) And an azimuthal distance R sni (n si ) Calculating the frequency and the tuning frequency corresponding to the target positioned at the first target point as follows:
wherein v represents the platform running speed, and λ represents the signal carrier wavelength;
(8) According to the frequency corresponding to the target, performing down-conversion treatment on the discretization signal sequence rd sampled by the signal sampling model to obtain a down-converted sampling receiving signal rd 1 The following are:
rd 1 ＝rd·exp(-j2πf d t)；
(9) According to the frequency modulation rate corresponding to the obtained target, the sampling receiving signal rd after the down-conversion treatment is carried out 1 Low-pass filtering to obtain filtered sampled received signal rd 2 The following are:
rd 2 ＝ifft(fft(filter,length(rd 1 ))·fft(rd 1 ))
wherein fft (-) is fourier transform, ifft (-) is inverse fourier transform, | - | represents a module value, length (-) represents a signal length, and filter represents a filter time domain representation as follows:
filter＝cfirpm(N o ,[-1 -F 2 -F 1 F 1 F 2 1],@lowpass)；
wherein cfirpm is a function of a filter time domain expression used for generating a corresponding frequency band range; f 1 ＝2|K a |T long /f s ，F 2 ＝3|K a |T long /f s ；N o Represents order, and @ lowpass represents a low pass filter call function;
(10) According to the frequency corresponding to the obtained target, the filtered sampling signal rd is processed 2 Carrying out up-conversion treatment to obtain a sampling signal rd after up-conversion 3 The following are:
rd 3 ＝rd 2 ·exp(j2πf d t)；
(11) By T ci Is a center, T long In order to intercept the length, down is the down-sampling multiple of a positive integer, and the up-converted sampling signal rd is 3 Intercepting and sampling are carried out to obtain a Doppler signal of a target under a long synthetic aperture as follows:
rd long (l；T ci ,down)＝rd 3 (l·down)，l＝N l1 ,N l1 +1,…,N l2
wherein rd is long (l；T ci Down) represents a target doppler signal obtained by down-sampling the long synthetic aperture of the i-th sub-aperture, which is 1 × (N) l2 -N l1 + 1) dimensional complex matrices, i.e.
N l1 ＝round(T li1 f s /down) denotes the starting sample point of the down-sampled signal intercepted by the ith sub-aperture, N, at a long synthetic aperture l2 ＝round(T li2 f s /down) represents the ending sampling point of the down-times down-sampled signal intercepted by the ith sub-aperture under the long synthetic aperture, round (·) represents rounding nearby, and/or is/are greater than or equal to>
Represents the time start of an intercepted down-sampled signal, is>
The time end point of the intercepted down-sampled signal is shown, and the ith sub-aperture is formed under the long synthetic apertureThe interception time range of the doppler signal of the lower target is: t is t li (l；T ci ,T long ,down)＝t(l·T s ·down),l＝N l1 ,N l1 +1,…,N l2 ；
(12) Azimuth theta of first target point obtained by coarse search smi (m si ) And an azimuthal distance R sni (n si ) For a search center of fine search, carrying out fine gridding subdivision based on an azimuth angle and an azimuth angle distance on a search area near the center, and the following steps:
the azimuth angle is divided into:
wherein, theta lmi (M) represents the azimuth grid point obtained by fine grid subdivision under the ith sub-aperture, which is M l X 1 dimensional real number matrix, i.e.
θ li Subdividing the range for the azimuth; m l The number of grid cells in the total azimuth angle, θ li ＝M l dθ li ，dθ li Subdividing the interval for the azimuth angle;
the distance of azimuth is subdivided as follows:
wherein R is lni (N) distance grid points of azimuth direction obtained by fine-grid subdivision under the ith sub-aperture are represented, and are N l X 1 dimensional real number matrix, i.e.
R li Dividing the range for the distance of the azimuth angle; n is a radical of l Number of grid cells, R, of distances of total azimuth li ＝N l dR li ，dR li Subdividing intervals for the distance of azimuth angles;
(13) In azimuth angle theta lmi Azimuth angle distance of R lni The grid point of (2) is used as a target point, namely a second target point, and a Doppler signal r of the grid target point in a long synthesis duration and considering the demodulation effect is obtained by combining the platform track long I.e. de-modulated Doppler signals r at long synthesis durations long (l；m,n,T ci Down), as follows:
wherein R (l; m, n, T) ci ,T long Down) denotes the sampling interval of down.T at the long resultant aperture of the ith sub-aperture s Has an azimuth angle of theta lmi (m) azimuthal distance R lni (n) an instantaneous distance of the target from the satellite trajectory, and:
wherein, t li (l；T ci ,T long Down) represents the interception time range of the Doppler received signal of the ith sub-aperture under the long synthetic aperture;
(14) Intercepting Doppler signal rd under the long synthetic aperture long (l；T ci Down) with the unmodulated doppler signal r for the long synthesis duration long (l；m,n,T ci Down) to perform correlation processing within a long synthetic aperture range to obtain a positioning result of the second target point, as follows:
wherein,
the positioning result of the second grid target point under the ith sub-aperture under the long synthetic aperture is expressed and is M l ×N l Dimension and real number matrix, < >>
Representing correlation calculations, |, representing the modulus value,
indicating the Doppler signal rd representing the target under the long synthetic aperture representing the ith sub-aperture long (l；T ci Down) complex conjugation;
(15) Searching I according to the positioning result of the second target point long (m,n；T ci Down) peak position, the azimuth index m of the grid point passing through that position li Obtaining the azimuth angle phi of the target under the ith sub-aperture i I =1,2, \ 8230;, I estimate phi i The following:
φ i ＝θ lmi (m li )。
6. a multi-aperture based cross-referencing method according to claim 1, wherein said step 103 comprises:
based on the obtained azimuth angle estimated values of the targets under the sub-apertures with different central aperture positions, according to the geometric relations between different distances and azimuth angles, a range-wise distance R and an azimuth-wise distance A are established z At a distance R in the azimuthal direction 1 、R 2 、…、R i 、…、R I The position of the radiation source target of (2) solves the system of equations R as follows:
wherein the sub-aperture center distance L i ＝v·L ci ，R i I =1,2, which is the distance between the center of the sub-aperture and the target, i.e. the distance in the azimuthal direction, i =1,2,…,I，φ i I =1,2, \ 8230;, I denotes the target azimuth;
solving the equation set by a least square method to obtain the distance R and the azimuth distance A of the target s 。
7. The multi-aperture-based cross-positioning method of claim 6, wherein the range-wise distance of the target is R and the azimuth-wise distance is A s The solution is as follows:
A z = x (1), R = x (2), x (1), x (2) representing the first and second row elements of a solution matrix x of the following system of equations:
x＝(A * A)\(A * b) Wherein:
A * representing the conjugate transpose of matrix a.
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
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Citations (13)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20100164785A1 (en) * | 2007-08-30 | 2010-07-01 | DEUTSCHES ZENTRUM FüR LUFT-UND RAUMFAHRT E.V. | Synthetic aperture radar process |
| US20100207808A1 (en) * | 2007-07-04 | 2010-08-19 | Deutsches Zentrum für Luft- und Raumfahrt e.V. | Method for processing TOPS (Terrain Observation by Progressive Scan)-SAR (Synthetic Aperture Radar)-Raw Data |
| US8227735B1 (en) * | 2007-07-24 | 2012-07-24 | Lockheed Martin Coherent Technologies, Inc. | Combined active and passive imaging system with radiation source unit and detector |
| EP2743727A2 (en) * | 2014-01-16 | 2014-06-18 | Institute of Electronics, Chinese Academy of Sciences | Method for implementing high-resolution wide-swath spaceborne SAR system |
| CN109814100A (en) * | 2019-01-31 | 2019-05-28 | 西安电子科技大学 | SAR Ground moving target imaging method based on sub-aperture parameter Estimation |
| CN110673143A (en) * | 2019-09-30 | 2020-01-10 | 西安电子科技大学 | Two-step processing method for sub-aperture large squint SAR (synthetic aperture radar) diving imaging |
| CN111352067A (en) * | 2020-04-01 | 2020-06-30 | 北京理工大学 | Passive positioning method for multi-target passive synthetic aperture |
| CN112560295A (en) * | 2021-02-20 | 2021-03-26 | 北京理工大学 | Satellite equivalent velocity calculation method for passive synthetic aperture positioning |
| CN112596056A (en) * | 2021-02-26 | 2021-04-02 | 北京理工大学 | Passive synthetic aperture radiation source positioning method based on multi-view processing |
| CN114114267A (en) * | 2022-01-24 | 2022-03-01 | 中国人民解放军32035部队 | Target attitude estimation method based on projection matching of spin space target model |
| CN114460539A (en) * | 2022-02-14 | 2022-05-10 | 北京航天齐宇科技有限公司 | Passive synthetic aperture radiation source positioning method based on phase difference interference processing |
| CN115267775A (en) * | 2022-06-24 | 2022-11-01 | 中国人民解放军国防科技大学 | Non-uniform missing aperture imaging method of distributed in-orbit formation SAR system |
| CN115267777A (en) * | 2022-08-10 | 2022-11-01 | 北京理工大学 | Single-star strabismus positioning method based on passive synthetic aperture |
-
2022
- 2022-12-07 CN CN202211567244.9A patent/CN115877318B/en active Active
Patent Citations (13)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20100207808A1 (en) * | 2007-07-04 | 2010-08-19 | Deutsches Zentrum für Luft- und Raumfahrt e.V. | Method for processing TOPS (Terrain Observation by Progressive Scan)-SAR (Synthetic Aperture Radar)-Raw Data |
| US8227735B1 (en) * | 2007-07-24 | 2012-07-24 | Lockheed Martin Coherent Technologies, Inc. | Combined active and passive imaging system with radiation source unit and detector |
| US20100164785A1 (en) * | 2007-08-30 | 2010-07-01 | DEUTSCHES ZENTRUM FüR LUFT-UND RAUMFAHRT E.V. | Synthetic aperture radar process |
| EP2743727A2 (en) * | 2014-01-16 | 2014-06-18 | Institute of Electronics, Chinese Academy of Sciences | Method for implementing high-resolution wide-swath spaceborne SAR system |
| CN109814100A (en) * | 2019-01-31 | 2019-05-28 | 西安电子科技大学 | SAR Ground moving target imaging method based on sub-aperture parameter Estimation |
| CN110673143A (en) * | 2019-09-30 | 2020-01-10 | 西安电子科技大学 | Two-step processing method for sub-aperture large squint SAR (synthetic aperture radar) diving imaging |
| CN111352067A (en) * | 2020-04-01 | 2020-06-30 | 北京理工大学 | Passive positioning method for multi-target passive synthetic aperture |
| CN112560295A (en) * | 2021-02-20 | 2021-03-26 | 北京理工大学 | Satellite equivalent velocity calculation method for passive synthetic aperture positioning |
| CN112596056A (en) * | 2021-02-26 | 2021-04-02 | 北京理工大学 | Passive synthetic aperture radiation source positioning method based on multi-view processing |
| CN114114267A (en) * | 2022-01-24 | 2022-03-01 | 中国人民解放军32035部队 | Target attitude estimation method based on projection matching of spin space target model |
| CN114460539A (en) * | 2022-02-14 | 2022-05-10 | 北京航天齐宇科技有限公司 | Passive synthetic aperture radiation source positioning method based on phase difference interference processing |
| CN115267775A (en) * | 2022-06-24 | 2022-11-01 | 中国人民解放军国防科技大学 | Non-uniform missing aperture imaging method of distributed in-orbit formation SAR system |
| CN115267777A (en) * | 2022-08-10 | 2022-11-01 | 北京理工大学 | Single-star strabismus positioning method based on passive synthetic aperture |
Non-Patent Citations (7)
| Title |
|---|
| LITING ZHANG ET AL.: "Emitter Localization Algorithm Based on Passive Synthetic Aperture", IEEE TRANSACTIONS ON AEROSPACE AND ELECTRONIC SYSTEMS, 21 December 2021 (2021-12-21) * |
| LIU HAITAO ET AL.: "Study on the Localization Method of Multi-Aperture Acoustic Array Based on TDOA", IEEE SENSORS JOURNAL, 30 June 2021 (2021-06-30) * |
| 夏孟;王俊;: "无源雷达成像的平动补偿", 电子科技, no. 12, 28 December 2006 (2006-12-28) * |
| 张莉婷 等: "基于被动合成孔径的单星无源高精度定位方法", 航天电子对抗, vol. 36, no. 6, 31 December 2020 (2020-12-31) * |
| 李兵 等: "环形子孔径拼接检测的中心偏移误差补偿", 光子学报, vol. 45, no. 9, 31 August 2016 (2016-08-31) * |
| 王裕旗;孙光才;杨军;邢孟道;杨小牛;保铮;: "基于长合成孔径的辐射源成像定位算法", 雷达学报, vol. 9, no. 01, 29 February 2020 (2020-02-29) * |
| 艾未华;严卫;赵现斌;刘文俊;马烁;: "C波段机载合成孔径雷达海面风场反演新方法", 物理学报, no. 06, 23 March 2013 (2013-03-23) * |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116827458A (en) * | 2023-08-24 | 2023-09-29 | 北京理工大学 | Multi-angle-based frequency offset estimation and interference source positioning method |
| CN116827458B (en) * | 2023-08-24 | 2023-12-05 | 北京理工大学 | Multi-angle-based frequency offset estimation and interference source positioning method |
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