CN106990386A - A kind of single dipole polarization sensitive rotation array DOA and polarization parameter combined estimation method - Google Patents

Abstract

The purpose of the present invention is to provide a single dipole polarization-sensitive rotating array DOA and polarization parameter joint estimation method. First, the array receiving signal of the polarization-sensitive rotating array is mathematically modeled. The expression of the steering vector in the function is modified, so that the MUSIC algorithm is used to realize the joint estimation of the DOA of the incident signal and the polarization parameters. The rotating array of the present invention can not only be constructed by using a single dipole to construct a polarization-sensitive rotating array, but also can be constructed by using any polarization-sensitive antenna unit or combination, and has strong portability. The array can effectively reduce the number of channels of the system, greatly reducing the cost of the system, and the less number of array elements effectively avoids the problem of channel inconsistency caused by a large number of array elements.

Description

Joint Estimation of DOA and Polarization Parameters of a Single Dipole Polarization Sensitive Rotating Array method

technical field

The invention relates to an array signal processing method, in particular to a polarization-sensitive array signal processing method.

Background technique

The joint estimation of DOA and polarization parameters based on polarization-sensitive arrays is an important research direction of array signal processing, and its main task is to estimate the incident direction and polarization state of signals received by polarization-sensitive arrays. Compared with the scalar-based array, the polarization-sensitive array can be sensitive to the DOA and polarization information of the incident signal at the same time, which increases the amount of available information and can effectively improve system performance. Therefore, how to use the polarization-sensitive array to estimate the DOA and polarization parameters of the incident signal is the basis for applying the polarization-sensitive array to the actual direction-finding system.

The choice of the array structure directly affects the estimation performance of the MUSIC algorithm. The uniform circular array can estimate the two-dimensional DOA information of the incident signal at the same time, and has a beam width independent of the azimuth angle. It is one of the typical arrays commonly used in practical engineering. The direction-finding performance of the MUSIC algorithm based on the uniform circular array is related to the radius of the array and the number of array elements. In theory, the larger the radius of the uniform circular array and the more the number of array elements, the higher the estimation accuracy of the algorithm. However, in practical engineering applications, the increase in the number of array elements will also bring about the problem of increased channel inconsistency. Moreover, the increase in the number of array elements means the increase in the number of channels in the system, as well as the increase in the scale of the receiving system and the signal processing system, which greatly increases the cost of the system.

Contents of the invention

The purpose of the present invention is to provide a single dipole polarization-sensitive rotating array DOA and polarization parameter joint estimation method for estimating the DOA and polarization parameters of the incident signal with a small number of array elements.

The purpose of the present invention is achieved like this:

A single dipole polarization-sensitive rotating array DOA and polarization parameter joint estimation method of the present invention is characterized in that it includes an antenna dish and a single dipole antenna array element 1 conforming to the edge of the antenna dish and a single dipole Antenna element 2, the antenna disk rotates at a constant speed of R; the antenna disk is located in the xoy plane, and the single dipole antenna element 1 and the single dipole antenna element 2 are respectively placed on the positive half axis and the negative half axis of the x axis axis, the distance from the origin of the coordinates is d; during the rotation of the antenna dish, the plane where the antenna dish is located is always perpendicular to the rotation axis;

(1) During the half cycle rotation of each single dipole antenna, 2M arrays are selected to output data according to the equal time interval Δτ, and the received data vector X=[ X ₁ ,X ₂ ] ^T ＝ΦAS+N, S is K×1-dimensional incident signal vector, K is the number of incident signal sources, N=[N ₁ ,N ₂ ] ^T is 2M×1-dimensional array receiving noise vector, N ₁ and N ₂ are respectively M×1-dimensional array element 1 and array element 2 receiving noise vectors;

(2) Calculate the covariance matrix R _x =E{XX ^H } according to the received data vector, and E{ } represents expectation;

(3) Decompose the eigenvalues of the covariance matrix R _x to obtain 2M eigenvalues and corresponding eigenvectors;

(4) arrange the 2M eigenvalues of R _x in descending order, and use the last 2M-K small eigenvalues of the covariance matrix R _x to correspond to the eigenvectors to form a noise subspace U _N ;

(5) Utilization formula Construct the spectral function of the joint estimation of two-dimensional DOA and polarization parameters;

(6) Change the values of θ, φ, γ and η in the spectral function, search the spectral peaks of the constructed spectral function, and find out the values of DOA and polarization parameters corresponding to the K maximum points.

The present invention may also include:

1. During the rotation of the array, the time delay Δτ between the selected two consecutive array elements is much greater than the data sampling period of the receiver, and the rotation speed of the array satisfies: Where f _s is the sampling frequency of the receiver, and L is the number of snapshots.

2. X ₁ and X ₂ are M×1-dimensional array receiving data vectors composed of the receiving data of single dipole antenna element 1 and single dipole antenna element 2 respectively; where X ₁ =Φ ₁ A ₁ S +N ₁ , X ₂ ＝Φ ₂ A ₂ S+N ₂ , Φ＝diag{Φ ₁ ,Φ ₂ }, Φ ₁ ＝Φ ₂ ＝diag{1,exp(-j2πfΔτ),...,exp(-j2πf( M-1) Δτ)}, Φ ₁ and Φ ₂ respectively represent the additional phase matrix obtained after the rotation of the single dipole antenna array element 1 and the single dipole antenna array element 2; is a 2M×K dimensional array manifold moment, with respectively represent the M×K dimensional array manifold moments obtained after the rotation of single dipole antenna element 1 and single dipole antenna element 2, is the steering vector corresponding to source k (k=1, 2,...K), U _k is the spatial domain steering vector matrix when source k is incident on 2M virtual array elements, and its calculation formula is B is the polarization-sensitive matrix corresponding to the virtual array, and its specific expression is b _m ＝[sin(2π(m-1)/2M), cos(2π(m-1)/2M)] is the polarization sensitive vector of virtual array element m; is the steering vector in the polarization space domain corresponding to source k.

The advantage of the present invention is that: the present invention samples the output data of the rotating array elements. Due to the rotation of the array, the positions of the array elements corresponding to each sampling point are different, thereby constructing a receiving array of a virtual polarization-sensitive uniform circular array. Data vector, the mathematical modeling of the virtual polarization-sensitive uniform circular array is carried out, and the joint estimation of DOA and polarization parameters of the incident signal is realized by using the MUSIC algorithm. The polarization-sensitive rotating array only contains two single dipole antennas, which effectively reduces the scale of the receiving system and signal processing system, and can avoid the influence of channel inconsistency on the direction finding results to a certain extent. The beneficial effect of the invention is that low-cost, high-precision joint estimation of two-dimensional DOA and polarization parameters can be realized.

The advantages of the present invention are as follows:

For the first time, it is proposed to use a single dipole polarization-sensitive antenna to construct a polarization-sensitive rotating array, and the rotation speed of the array and the requirements of the array are explained;

For the first time, a joint estimation method of two-dimensional DOA and polarization parameters using the polarization-sensitive rotating array is proposed, using the rotation of the array to construct a virtual polarization-sensitive uniform circular array, and mathematically modeling the array model of the uniform circular array, and using The MUSIC algorithm estimates the DOA and planning parameters of the incident signal.

Description of drawings

Fig. 1 is a flowchart of the present invention;

Figure 2 is a schematic diagram of the rotation of two antenna arrays;

Figure 3a is the true value of the fixed polarization parameter, when γ=40, η=50, the corresponding spatial spectrum; Figure 3b is the true value of the fixed polarization parameter, when γ=60, η=70, the corresponding spatial spectrum Figure 3c is the fixed DOA true value, when θ=125, φ=15, the corresponding polarization spectrum; Figure 3d is the fixed DOA true value, θ=55, φ=25, the corresponding polarization spectrum;

Fig. 4 shows the RMSE under the channel inconsistency between the method of the present invention and the joint parameter estimation algorithm based on the polarization sensitive array.

detailed description

The present invention is described in more detail below in conjunction with accompanying drawing example:

1-4, a polarization-sensitive rotating array composed of two single-dipole antennas according to the present invention includes two single-dipole antenna array elements conformal to the edge of the antenna dish, and the antenna dish has a certain The speed R (r/s) rotates at a constant speed, and the characteristic is that the antenna disk is located in the xoy plane, and the single dipole antenna element 1 and the element 2 are respectively placed on the positive semi-axis and the negative semi-axis of the x-axis, and the distance from the coordinate The distance from the origin is d; during the rotation of the antenna disk, the plane where the antenna disk is located is always perpendicular to the rotation axis; in order to ensure the stability of the sampling data, during the rotation of the array, the time delay between the selected two consecutive array elements Δτ is much larger than the data sampling period of the receiver, and there is Then the rotation speed of the array can be obtained to satisfy: Where f _s is the sampling frequency of the receiver, L is the number of snapshots, and 2M is the number of elements of the virtual polarization-sensitive uniform circular array. Usually the speed R is set to 10~20r/s, according to The value range of time delay Δτ can be obtained.

At the same time, the present invention provides a method for joint estimation of two-dimensional DOA and polarization parameters using the polarization-sensitive rotating array, and the specific steps are as follows:

Step (1): Place two single dipole polarization-sensitive antennas at (d, 0) and (0, d) in the XOY plane respectively, set the rotation speed of the antenna dish to R, and make the antenna dish rotate at this speed Rotate counterclockwise at a constant speed, and ensure that the antenna dish is perpendicular to the rotating shaft while rotating;

Step (2): During the counterclockwise rotation of each single dipole antenna for half a cycle, select 2M (M is a positive integer) array output data at equal time intervals Δτ to form a virtual single dipole polarization-sensitive Received data vector X=[X ₁ ,X ₂ ] ^T ＝ΦAS+N of uniform circular array;

S is the incident signal vector of K×1 dimension, and K is the number of incident sources;

N=[N ₁ , N ₂ ] ^T is a 2M×1-dimensional array receiving noise vector, where N ₁ and N ₂ are M×1-dimensional array element 1 and array element 2 receiving noise vectors;

Using the formula Φ＝diag{Φ ₁ ,Φ ₂ } and Φ ₁ ＝Φ ₂ ＝diag{1,exp(-j2πfΔτ),…,exp(-j2πf(M-1)Δτ)} to find out that due to two single dipoles The sub-antennas are rotated to obtain an additional phase matrix Φ generated by the sampling delay between the elements in the rotating array, where f is the frequency of the incident signal.

Exploitation and b _m = [sin(2π(m-1)/2M), cos(2π(m-1)/2M)] to obtain the polarization-sensitive matrix B of the virtual polarization-sensitive uniform circular array; use the formula Obtain the steering vector in the polarization space domain corresponding to the DOA of the incident signal and all possible values of the polarization parameters; use the formula Obtain the spatial steering vector matrix corresponding to the DOA of the incident signal and all possible values of the polarization parameters; and then use Obtain the steering vectors corresponding to the DOA of the incident signal and all possible values of the polarization parameters, which are used for the construction of the subsequent spectral function.

Step (2): Calculate the covariance matrix R _x =E{XX ^H } according to the received data vector, and E{ } represents expectation;

The actual received data matrix is of finite length, then the covariance matrix can be calculated using maximum likelihood estimation Among them, L is the snapshot number.

Step (3): Carry out eigenvalue decomposition on the covariance matrix R _x to obtain 2M eigenvalues and corresponding eigenvectors;

The eigenvalue decomposition of R _x can be obtained

Step (4): arrange the 2M eigenvalues of R _x in descending order, and use the eigenvectors corresponding to the last 2M-K small eigenvalues of the covariance matrix R _x to form a noise subspace U _N ;

Arrange its eigenvalues in descending order as λ ₁ ≥ λ ₂ …≥ λ _M , and their corresponding eigenvectors are ν ₁ , ν ₂ ,…, ν _M , and the eigenvectors are mutually orthogonal, then the noise of R Subspace U _N =[ν _K+1 ,ν _K+2 ,...,ν _2M ].

Step (5): Use formula Construct the spectral function for joint estimation of two-dimensional DOA and polarization parameters, θ is called the azimuth angle, φ is called the elevation angle, γ is called the polarization auxiliary angle, and η is called the polarization phase difference;

Step (6): Change the values of θ, φ, γ and η in the spectral function, search the spectral peaks of the constructed spectral function, and find out the values of DOA and polarization parameters corresponding to K maximum points.

Referring to Figure 2, it is a schematic diagram of the rotation of two antenna arrays. There are two array elements, a single dipole array element 1 and an array element 2, in the horizontal position of the space. On the antenna dish with a radius of r, it is now assumed that the baseline 1-2 rotates counterclockwise at a constant speed on the XOY plane with the Z axis as the rotation axis, and the rotation period of the array element is T. After Δt (Δt<T) time, the array element 1 and 2 are rotated to the positions of array elements 1' and 2' respectively.

Referring to Fig. 3, it is the estimated spectrogram of the method, wherein Fig. 3a and Fig. 3b are the spatial spectrogram corresponding to the true value of the polarization parameter, and the value of the azimuth angle and the elevation angle corresponding to the spectral peak position is the DOA estimation of the incident signal value; Fig. 3c and Fig. 3d are the polarization spectra corresponding to the true value of DOA, and the polarization auxiliary angle and polarization phase difference corresponding to the spectral peak position are the estimated polarization parameters of the incident signal.

Claims (3)

1. a kind of single dipole polarization sensitive rotation array DOA and polarization parameter combined estimation method, it is characterized in that：Including antenna Disk and the single dipole bay 1 and single dipole bay 2 conformal with antenna plate edge, antenna bay are even with rotating speed R Speed rotation；Antenna bay is located in xoy planes, and single dipole bay 1 and single dipole bay 2 are respectively placed in into x The positive axis of axle and negative semiaxis, the distance of range coordinate origin is d；Antenna bay is in rotary course, plane where antenna bay It is vertical with the holding of rotary shaft moment；

(1) during each single dipole antenna rotation half period, choose 2M array by constant duration Δ τ and export Data, constitute reception data vector X=[X of virtual single dipole polarization sensitive uniform circular array₁,X₂]^T=Φ AS+N, S are K × 1 The incoming signal vector of dimension, K is incident information source number, N=[N₁,N₂]^TArray received noise vector, N are tieed up for 2M × 1₁With N₂Respectively For the array element 1 that M × 1 is tieed up noise vector is received with array element 2；

(2) covariance matrix R is calculated according to reception data vector_x=E { XX^H, E { } represents to ask expectation；

(3) to covariance matrix R_xEigenvalues Decomposition is carried out, 2M characteristic value and character pair vector is tried to achieve；

(4) by R_x2M characteristic value carry out descending arrangement, utilize covariance matrix R_xRear 2M-K small characteristic value character pairs Vector opens into noise subspace U_N；

(5) formula is utilizedConstruction two dimension DOA combines with polarization parameter to be estimated The spectral function of meter；

(6) value of θ, φ, γ and η in spectral function are changed, the spectral function to construction carries out spectrum peak search, finds out K maximum The corresponding DOA of point and polarization parameter value.

2. a kind of single dipole polarization sensitive rotation array DOA according to claim 1 and polarization parameter Combined estimator side Method, it is characterized in that：

During array rotation, data sampling weeks of the time delay Δ τ much larger than receiver between two continuous array elements of selection Phase, the rotating speed of array rotation is met：Wherein f_sFor receiver sample frequency, L is fast umber of beats.

3. a kind of single dipole polarization sensitive rotation array DOA according to claim 2 and polarization parameter Combined estimator side Method, it is characterized in that：

X₁With X₂Tie up array and connect in the M being respectively made up of the reception data of single dipole bay 1 and single dipole bay 2 × 1 Receive data vector；Wherein X₁=Φ₁A₁S+N₁, X₂=Φ₂A₂S+N₂, Φ=diag { Φ₁,Φ₂, Φ₁=Φ₂=diag { 1, exp (- j2 π F Δ τ) ..., exp (- j2 π f (M-1) Δ τ) }, Φ₁And Φ₂Single dipole bay 1 and single dipole bay 2 are represented respectively The additive phase matrix obtained after rotation； Array manifold square is tieed up for 2M × K,WithAfter representing that single dipole bay 1 and single dipole bay 2 rotate respectively Obtained M × K dimension array manifold squares,For correspondence information source k (k=1,2 ... K) Steering vector, U_kSpatial domain steering vector matrix during 2M Virtual array is incided for information source k, its calculating formula isB is virtual array pair The polarization sensitive matrix answered, its expression isb_m=[sin (2 π (m-1)/2M), cos (2 π (m- 1)/2M)] be Virtual array m polarization sensitive vector； For correspondence information source k polarized spatial domain steering vector.