CN105445698A - High precision time delay estimation method between double straight line arrays - Google Patents

Abstract

The invention discloses a high precision time delay estimation method between double straight line arrays, comprising steps of dividing each straight line array in the double-straight-line array into a plurality of superposed sub-arrays, pointing all sub-arrays at the angle of a target to obtain a plurality of wave beam outputs after obtaining the measurement angle result through the double-straight-line array, performing processing on the wave beam to construct a new covariance matrix and a time scanning vector, obtaining output along time dimension, and searching a peak value respond to estimate the time delay between the double straight line arrays. The high precision time delay estimation method between double straight line arrays, eliminates the azimuth ambiguity.

Description

High-accuracy time delay estimation method between a kind of bilinear battle array

Technical field

The invention belongs to Array Signal Processing field, relate to high-accuracy time delay estimation method between a kind of bilinear battle array.

Background technology

Shortcoming (the VanTreesHL.Optimumarrayprocessing:part4ofdetection of azimuth ambiguity is there is in single line array when carrying out angle measurement, estimation, andmodulationtheory.Hoboken:JohnWiley & SonsInc., 2002.).Use bilinear battle array can overcome this shortcoming of single line array, by the time delay estimating between bilinear battle array can judge target azimuth (Li Qihu. the initial analysis of left-right ambiguity resolution performance for twin-line array. acoustic journal, 2006; 31 (5): 385-388. Li Qi tigers. time-delay estimation method and the realization thereof of port and starboard target is distinguished with two wires control system. acoustic journal, 2006; 31 (6): 485-487.).But, during the azimuth ambiguity of existing method when utilizing bilinear battle array to overcome angle measurement, use interpolation method estimate time delay between bilinear battle array (Li Qihu. distinguish time-delay estimation method and the realization thereof of port and starboard target with two wires control system. acoustic journal, 2006; 31 (6): 485-487.).Interpolation method carries out numerical value interpolation to the correlation output sequences that single line array beam in twin-line array exports, and estimate bilinear battle array time delay value according to correlation output sequences peak value after interpolation, its precision is unsatisfactory, is not very desirable to elimination azimuth ambiguity.

Summary of the invention

The technical issues that need to address of the present invention are: in order to improve the measuring accuracy of time delay between bilinear battle array, and the present invention proposes a kind of method utilizing submatrix process to carry out high-precision time-delay estimation.Every bar line array in bilinear battle array is divided into multiple overlapped submatrix by the method.After utilizing bilinear battle array to obtain multiobject angle measurement result, all submatrixs are pointed to certain target place angle and obtain the output of multiple wave beam.Export these wave beams and carry out the process new covariance matrix of structure and time scan vector, obtain the output along time dimension, the time delay between bilinear battle array is estimated in search peak response.

Technical scheme of the present invention is: high-accuracy time delay estimation method between a kind of bilinear battle array, comprises the following steps:

Step one: carry out angle measurement to target by bilinear battle array, carries out Wave beam forming, obtains wave beam output quantity, comprises following sub-step:

Sub-step one: bilinear battle array is made up of line array 1 and line array 2.The M unit uniform straight line array of line array 1 and line array 2 to be all array element distance be d, both are parallel to each other and distance is d ₀; Bilinear battle array receives P (P=1,2,3 ...) signal launched of individual target, and in bilinear battle array angulation; This bilinear battle array carries out multiple goal angle measurement, and obtain multiobject angle measurement result and spatial spectrum b (θ), wherein θ is scanning angle, and span is-180 ° to 180 °; The peak response angle θ that p target is corresponding on spatial spectrum _p(p=1,2,3 ... P), now due to the impact of azimuth ambiguity, be difficult to directly judge that target is from larboard or starboard from angle measurement result;

Sub-step two: line array 1 and line array 2 are divided into N number of overlapped submatrix respectively, namely two line arraies have 2N submatrix; The array element of each submatrix is M ₀(M ₀≤ M); In each M unit line array, the array number N that adjacent submatrix overlaps ₀, can be expressed as:

Wherein, represent and get the smallest positive integral being more than or equal to wherein numerical value, f is the centre frequency of handled signal subband, f _dfor the Array Design frequency corresponding with array element distance d, be expressed as f _d=c/ (2d), wherein c is signal velocity;

2N submatrix is pointed to P target peak response angle θ corresponding on spatial spectrum _p(p=1,2,3 ...) carry out Wave beam forming, obtain 2N wave beam output vector; In line array 1, the wave beam output vector of the n-th submatrix is in line array 2, the wave beam output vector of the n-th submatrix is

Step 3: comprise following sub-step:

Sub-step one: according to the wave beam output vector in step 2, ask N number of cross-spectrum of two line arraies to export, formula is

Wherein R _n(θ _p) the n-th cross-spectrum of obtaining for line array 1 and line array 2;

Wherein [] ^hconjugate transpose is asked in representative, and L is expressed as the fast umber of beats that wave beam exports; represent by k before in N number of cross-spectrum (k=1,2 ..., N) and individual quadrature.

Sub-step two: obtained N number of cross-spectrum is exported and builds covariance matrix R (θ _p)

Sub-step three: design the weighing vector in time dimension change, a (Δ t):

Wherein, Δ t is time delay, and its span is Δ t ∈ [-d ₀/ c, d ₀/ c]; F is the centre frequency of handled signal subband.

Step 4: by the R (θ obtained in step 3 _p), a (Δ t) substitutes in time delay estimation formulas, obtain p target and (on spatial spectrum, correspond to θ _p) corresponding bilinear battle array time delay, judge that target is from larboard or starboard according to this time delay, elimination azimuth ambiguity.

Invention effect

Technique effect of the present invention is: ultimate principle of the present invention and embodiment have passed through the checking of Computerized Numerical Simulation, its result shows: the method for division submatrix process proposed by the invention accurately can estimate the time delay between bilinear battle array, can eliminate the azimuth ambiguity of line array when angle measurement.

Accompanying drawing explanation

The coordinate system figure of Fig. 1 bilinear battle array when carrying out angle measurement;

The process flow diagram of key step in Fig. 2 the present invention;

Bilinear battle array division submatrix is utilized to carry out the process flow diagram of time delay estimation in Fig. 3 the present invention;

The multiple goal angle measurement result figure of bilinear battle array in Fig. 4 embodiment;

The time delay estimated result figure utilizing the inventive method to obtain in Fig. 5 embodiment.

Embodiment

Below in conjunction with concrete embodiment, technical solution of the present invention is further illustrated.

Adopt bilinear battle array (be made up of line array 1 and line array 2, both are all M unit's uniform straight line array and are parallel to each other) to carry out multiple goal angle measurement, every bar line array is divided into N number of overlapped submatrix, and 2 line arraies can obtain 2 groups of 2N submatrixs altogether.Utilize bilinear battle array to obtain multiobject angle measurement result, these 2 groups common 2N submatrixs are pointed to the angle measurement result corresponding to certain target, obtains 2N wave beam output vector.To the n-th (n=1 in line array 1,2 ..., N) and individual sub-array beam output vector asks conjugate transpose, utilize the n-th submatrix wave beam output vector in line array 2 to be multiplied with this conjugate transpose result simultaneously, obtain a n-th cross-spectrum 2N submatrix and obtain N number of cross-spectrum altogether.

By k before in N number of cross-spectrum (k=1,2 ..., N) and individual quadrature, by the conjugation of result of product divided by the 1st cross-spectrum, obtain N number of output so altogether.Utilize this N number of output to build covariance matrix, design the weighing vector in time dimension change simultaneously, obtain the output response in different delay value.Time delay value corresponding to search peak response, namely obtains the time delay value between bilinear battle array.

Given the angle measurement result using method in the present invention by Computerized Numerical Simulation, demonstrate with this bilinear battle array time delay estimation result that institute of the present invention extracting method can obtain degree of precision.

The present invention solves the technical scheme that Problems Existing adopts can be divided into following step:

Adopt bilinear battle array (be made up of line array 1 and line array 2, both are all M unit's uniform straight line array and are parallel to each other) to carry out multiple goal angle measurement, utilize bilinear battle array to obtain multiobject angle measurement result, in now angle measurement result, there is port and starboard ambiguity.Every bar line array is divided into N number of overlapped submatrix, and 2 line arraies can obtain 2 groups of 2N submatrixs altogether.When elimination azimuth ambiguity is carried out to certain target, these 2 groups of submatrixs are pointed to this target place angle and carries out Wave beam forming, obtain 2N wave beam altogether and export.

To n-th in line array 1 (n=1,2 ..., N) and individual sub-array beam output vector asks conjugate transpose, utilizes the n-th submatrix wave beam output vector in line array 2 to be multiplied with this conjugate transpose simultaneously, and obtain the n-th cross-spectrum and export.2N submatrix obtains N number of cross-spectrum altogether and exports.By k before in N number of cross-spectrum (k=1,2 ..., N) and individual quadrature, by the conjugation of result of product divided by the 1st cross-spectrum, obtain N number of phase differential factor so altogether.Utilize this N number of phase differential factor to build covariance matrix, design the weighing vector along with the change of bilinear battle array time delay value simultaneously.

Utilize step 2) in covariance matrix and weighing vector, the response obtained in different delay value exports.The time delay value at search peak response place, namely obtains the delay inequality of certain echo signal between bilinear battle array.Judge that certain target is from larboard or starboard according to this delay inequality, reach the object eliminating azimuth ambiguity.

Below each step of the present invention is elaborated:

Step 1) correlation theory and particular content as follows:

Bilinear battle array is utilized to carry out angle measurement.If the distance between bilinear battle array is d ₀, M unit's uniform straight line array (ULA:uniformlineararray) of every bar line array to be array element distance be d, as shown in Figure 1.Bilinear battle array receives the signal with certain bandwidth of a far field P target emanation, and adopts the sampled signal in the method process bilinear battle array of molecular band process.For simplifying the analysis, hereafter for the sampled signal in certain subband, provide concrete treatment step.On other subband, the processing mode of signal can with reference to the treatment step of this subband.

Be located in this subband, spatial spectrum that angle measurement obtains is b (θ) to utilize double-H groove weld LA to carry out, and wherein θ is scanning angle, and span is-180 ° to 180 °.As shown in Figure 1, with θ _pwhen corresponding direction vector and y-axis positive dirction overlap, θ is 0 °; When the direction vector corresponding with θ p and y-axis negative direction overlap, θ is 180 ° and-180 °; When the direction vector corresponding with θ p and x-axis positive dirction overlap, θ is 90 °, and when the direction vector corresponding with θ p and x-axis negative direction overlap, θ is-90 °.In spatial spectrum b (θ), with p (p=1,2 ..., P) and peak response corresponding to individual target be at θ=θ _pplace.Owing to there is port and starboard ambiguity, directly cannot judge that this target is positioned at θ according to spatial spectrum result _pin angle.

Carry out Subarray partition respectively to two M unit ULA, each ULA is all divided into N number of overlapped sub-ULA, and the element number of array of every sub-ULA is M ₀(M ₀≤ M).In each M unit ULA, the array number that adjacent sub-ULA overlaps, N0, can be expressed as:

Wherein, represent and get the smallest positive integral being more than or equal to wherein numerical value, f is the centre frequency of handled signal subband, f _d=c/ (2d) is the Array Design frequency corresponding with array element distance d, and c is signal velocity.

Article two, M unit ULA marks off 2N sub-ULA altogether.This 2N sub-ULA is pointed to P target peak response angle θ corresponding on spatial spectrum _p(p=1,2 ..., P) and carry out Wave beam forming, then 2N sub-ULA obtains 2N wave beam output vector altogether.For the 1st ULA, therebetween n-th (n=1,2 ..., N) individual sub-ULA wave beam export complex vector be when using discretize to express, it is that 1 × L ties up plural row vector, and wherein L represents the fast umber of beats that wave beam exports.Correspondingly, in the 2nd ULA, the wave beam output complex vector of the n-th sub-ULA is it is also that 1 × L ties up plural row vector.

Step 2) correlation theory and particular content as follows:

To in the 1st ULA n-th (n=1,2 ..., N) and individual sub-array beam output vector ask conjugate transpose, obtain wherein [] ^hconjugate transpose is asked in representative.Use the wave beam output vector of the n-th sub-ULA in the 2nd ULA with be multiplied, obtain the n-th cross-spectrum, R _n(θ _p), its expression formula is:

2N wave beam on 2N sub-ULA is exported and processes according to formula (2), obtain N number of cross-spectrum altogether.To k before in N number of cross-spectrum (k=1,2 ..., N) and individual quadrature, by the conjugation [R of result of product divided by the 1st cross-spectrum ₁(θ _p)] ^*(wherein [] ^*conjugation is asked in representative) obtain a kth value, X _k(θ _p), its expression formula is:

Wherein, a front k value is multiplied by representative, || representative takes absolute value.Process N number of cross-spectrum according to formula (3), obtain N number of output altogether.

The N number of output utilizing formula (3) to obtain builds covariance matrix, R (θ _p):

Design the weighing vector in time dimension change, a (Δ t):

Wherein, Δ t is time delay, and its span is Δ t ∈ [-d ₀/ c, d ₀/ c].

Step 3) correlation theory and particular content as follows:

Utilize step 2) in the covariance matrix that builds and weighing vector obtain estimated result under different delay.Estimate the time delay between bilinear battle array according to conventional method, then the output on time dimension, b (Δ t), can be expressed as:

b(Δt)＝[a(Δt)] ^HR(θ _p)a(Δt)(6)

Estimate the time delay between bilinear battle array according to Capon beam-forming schemes, then the output on time dimension, b (Δ t), can be expressed as:

Wherein, [] ^-1representative is to matrix inversion.

Estimating the time delay between bilinear battle array according to MUSIC method, owing to mainly comprising the component of signal of p target in the output of this wave beam, can hypothetical target number be directly therefore 1, then the output on time dimension, and b (Δ t), can be expressed as:

Wherein, U _noise(θ _p) be to R (θ _p) decompose after the eigenmatrix that forms of the little eigenwert characteristic of correspondence vector of N-1, it is as follows that characteristic of correspondence decomposes expression formula:

R(θ _p)＝U(θ _p)Γ(θ _p)U ^H(θ _p)(9)

Wherein U (θ _p) and Γ (θ _p) be respectively R (θ _p) eigenvectors matrix and eigenvalue matrix.

According to formula (6), formula (7) and formula (8), the bilinear battle array time delay corresponding with p target (corresponding to θ p on spatial spectrum) all can be obtained.Can judge that certain target is from larboard or starboard according to this time delay, finally reach the object eliminating azimuth ambiguity.

Key step flow process of the present invention as shown in Figure 2, utilizes submatrix to carry out the flow process of bilinear battle array time delay estimation as shown in Figure 3.

For typical submarine target angle measurement, provide embodiment of the present invention.

If the line array in bilinear battle array is 36 yuan of ULA, array element distance is d=1.5 rice, and the spacing between bilinear battle array is d0=1.5 rice.2 targets lay respectively on-60 ° and 150 °, the broadband signal of equal radiation 200Hz to 800Hz.Molecular band carries out angle measurement, and extraction centre frequency is that the subband (bandwidth is 10Hz) of 500Hz carries out time delay estimation.In 500Hz subband, if the PSNR power signal-to-noise ratio in each reception array element is set to 10dB.Each 36 yuan of ULA are marked off 8 sub-ULA, and submatrix is 29 yuan of ULA.

Utilize the angle measurement result of bilinear battle array as shown in Figure 4, although can see peak response-60 ° and 30 ° respectively, due to the existence of ambiguity of space angle, target is also likely respectively from-120 ° and 150 °.

According to the flow process of Fig. 2 and Fig. 3, institute of the present invention extracting method is utilized to carry out the result of time delay estimation as shown in Figure 4.When group array beam points to-60 °, the result that corresponding time delay is estimated as shown in Figure 4, the time delay estimated result that now conventional Time Delay Estimation Method, Capon Time Delay Estimation Method and the MUSIC experiment estimation technique obtains is 0.4986 millisecond, close to 0.5 millisecond of actual value.Because the time delay value estimated is positive number, can judge that signal first arrives line array 1, rear arrival line array 2, this target known is positioned at-60 °.When group array beam points to 30 °, the result that corresponding time delay is estimated as shown in Figure 4.The time delay estimated result that now conventional Time Delay Estimation Method, Capon Time Delay Estimation Method and the MUSIC experiment estimation technique obtains is-0.8679 millisecond, close to-0.8660 millisecond of actual value.Because the time delay value estimated is negative, can judge that signal first arrives line array 2, rear arrival line array 1, this target known is positioned at 150 °.

According to embodiment, what the present invention proposed carries out Subarray partition to bilinear battle array and the time delay estimated result that the method for estimation time delay can obtain and actual value is more close, and azimuth ambiguity when can eliminate angle measurement according to this time delay estimated result.

Claims (1)

1. a high-accuracy time delay estimation method between bilinear battle array, is characterized in that, comprise the following steps:

Step one: carry out angle measurement to target by bilinear battle array, carries out Wave beam forming, obtains wave beam output quantity, comprises following sub-step:

Sub-step one: bilinear battle array is made up of line array 1 and line array 2.The M unit uniform straight line array of line array 1 and line array 2 to be all array element distance be d, both are parallel to each other and distance is d ₀; Bilinear battle array receives P (P=1,2,3 ...) signal launched of individual target, and in bilinear battle array angulation; This bilinear battle array carries out multiple goal angle measurement, and obtain multiobject angle measurement result and spatial spectrum b (θ), wherein θ is scanning angle, and span is-180 ° to 180 °; The peak response angle θ that p target is corresponding on spatial spectrum _p(p=1,2,3 ... P), now due to the impact of azimuth ambiguity, be difficult to directly judge that target is from larboard or starboard from angle measurement result;

Sub-step two: line array 1 and line array 2 are divided into N number of overlapped submatrix respectively, namely two line arraies have 2N submatrix; The array element of each submatrix is M ₀(M ₀≤ M); In each M unit line array, the array number N that adjacent submatrix overlaps ₀, can be expressed as:

Wherein, represent and get the smallest positive integral being more than or equal to wherein numerical value, f is the centre frequency of handled signal subband, f _dfor the Array Design frequency corresponding with array element distance d, be expressed as f _d=c/ (2d), wherein c is signal velocity;

2N submatrix is pointed to P target peak response angle θ corresponding on spatial spectrum _p(p=1,2,3 ...) carry out Wave beam forming, obtain 2N wave beam output vector; In line array 1, the wave beam output vector of the n-th submatrix is in line array 2, the wave beam output vector of the n-th submatrix is

Step 3: comprise following sub-step:

Sub-step one: according to the wave beam output vector in step 2, ask N number of cross-spectrum of two line arraies to export, formula is

$X_k\left({\mathrm{\θ}}_p\right)=\frac{\[\underset{n=1}{\overset{k}{\Π}}{R}_n\left({\mathrm{\θ}}_p\right)\]/{\[R_1\left({\mathrm{\θ}}_p\right)\]}^{*}}{\[\underset{n=1}{\overset{k}{\Π}}\left|R_n\left({\mathrm{\θ}}_p\right)\right|\]/\left|R_1\left({\mathrm{\θ}}_p\right)\right|}$

Wherein R _n(θ _p) the n-th cross-spectrum of obtaining for line array 1 and line array 2;

$R_n\left({\mathrm{\θ}}_p\right)=b_n^2\left({\mathrm{\θ}}_p\right){\[b_n^1\left({\mathrm{\θ}}_p\right)\]}^H/L$

Wherein [] ^hconjugate transpose is asked in representative, and L is expressed as the fast umber of beats that wave beam exports; represent by k before in N number of cross-spectrum (k=1,2 ..., N) and individual quadrature.

Sub-step two: obtained N number of cross-spectrum is exported and builds covariance matrix R (θ _p)

$R\left({\mathrm{\θ}}_p\right)=\left[\begin{array}{c}{X}_1\left({\mathrm{\θ}}_p\right)\\ .\\ .\\ .\\ X_k\left({\mathrm{\θ}}_p\right)\\ .\\ .\\ .\\ X_N\left({\mathrm{\θ}}_p\right)\end{array}\right]{\left[\begin{array}{c}{X}_1\left({\mathrm{\θ}}_p\right)\\ .\\ .\\ .\\ X_k\left({\mathrm{\θ}}_p\right)\\ .\\ .\\ .\\ X_N\left({\mathrm{\θ}}_p\right)\end{array}\right]}^H$

Sub-step three: design the weighing vector in time dimension change, a (Δ t):

$a\left(\mathrm{\Δ}t\right)=\exp (-j2\mathrm{\π}f\left[\begin{array}{c}0\\ 1\\ .\\ .\\ .\\ N-1\end{array}\right]\mathrm{\Δ}t)$

Wherein, Δ t is time delay, and its span is Δ t ∈ [-d ₀/ c, d ₀/ c]; F is the centre frequency of handled signal subband.

Step 4: by the R (θ obtained in step 3 _p), a (Δ t) substitutes in time delay estimation formulas, obtain p target and (on spatial spectrum, correspond to θ _p) corresponding bilinear battle array time delay, judge that target is from larboard or starboard according to this time delay, elimination azimuth ambiguity.