MVDR deconvolution method based on horizontal line array

Abstract

The invention discloses an MVDR deconvolution method based on a horizontal linear array. The method comprises the following steps: step 1, setting a horizontal uniform linear array parameter and a sound source signal parameter; 2, sound source signals and noise are constructed, array data received by a horizontal array are obtained through analog simulation calculation, and an array data covariance matrix is calculated; 3, performing MVDR beam forming on the array element data received by the horizontal line array to obtain MVDR output power; 4, solving a beam directional diagram of the horizontal line array; and 5, carrying out deconvolution through an R-L algorithm to obtain the original azimuth distribution of the signal. The beam width generated through deconvolution beam forming is narrow, the sidelobe level is low, calculation is simple, and the calculated amount is equivalent to that of a CBF algorithm.

Description

Technical Field

[0001] The invention relates to the field of underwater acoustic signal processing, and in particular to an MVDR deconvolution method based on a horizontal linear array. Background Art

[0002] Horizontal line arrays are usually located in underwater environments to detect and separate weak signals and estimate their arrival direction from strong interference sources and environmental noise. Traditional conventional beamforming (CBF) algorithms have high robustness, but the main lobe of the beam is wide, making it difficult to detect multiple targets in the same beam, and the sidelobe level is high, making it difficult to detect weak signals in the presence of strong interference.

[0003] High-resolution beamforming based on the inversion of the signal covariance matrix, such as the minimum variance distortionless response (MVDR) algorithm, produces narrow beamwidth and low sidelobes, but is sensitive to signal mismatch. Assuming the signal is stationary, the sample covariance matrix requires many snapshots to ensure fast convergence and minimal power loss at the beam output. For large aperture arrays with multiple elements, high-resolution algorithms usually perform poorly when the number of snapshots is small. Summary of the invention

[0004] The object of the present invention is to provide an MVDR deconvolution method based on a horizontal line array to solve the problems of wide main lobe and high side lobe level of the existing beam forming method in the background technology.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] A MVDR deconvolution method based on a horizontal line array, the method comprising the following steps:

[0007] Step 1, setting the horizontal uniform line array parameters and the sound source signal parameters;

[0008] Step 2, constructing the sound source signal s(t) and the noise n(t), obtaining the array data received by the horizontal array through simulation calculation, and calculating the array data covariance matrix;

[0009] Step 3, performing MVDR beamforming on the array data received by the horizontal line array to obtain MVDR output power;

[0010] Step 4, solving the beam pattern of the horizontal linear array;

[0011] Step 5: Deconvolute the signal using the RL algorithm to obtain the original azimuth distribution of the signal.

[0012] Preferably, in step 1, the element spacing of the horizontal array is set λ is the wavelength, which sets the length, frequency, direction, and signal-to-noise ratio of the sound source signal.

[0013] Preferably, in step 2, the signal s(t-τ) reaching the horizontal line array under far-field conditions is m ) is characterized by The calculation array receives data x(t)=a(θ 0 )s(t)+n(t), a(θ 0 ) is the array steering vector, θ 0 is the direction of the sound source, j is an imaginary number, ω is the angular frequency, T M It is the time delay between the sound source signal received by the Mth array element and the first array element.

[0014] Preferably, in step 3, the MVDR output power B MVDR (sinθ)=w H Rw, w is the MVDR beamforming weight vector, a(θ 0 ) is the array steering vector, R is the array data covariance matrix, and H is the transpose.

[0015] Preferably, in step 4, the beam pattern of the horizontal linear array is Where c is the speed of sound in water, M is the number of elements in the horizontal linear array, λ is the wavelength, and θ is the horizontal angle.

[0016] Preferably, in step 5, based on the MVDR output power B MVDR (sinθ) and beam pattern B p (sinθ), through the RL algorithm The sound source energy distribution function is obtained by solving, where is the horizontal scanning angle.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] Compared with the existing conventional methods, the beam width generated by the deconvolution beamforming in the present invention is narrow, the sidelobe level is low, the calculation is simple, and the calculation amount is equivalent to that of the CBF algorithm. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a flow chart of the MVDR deconvolution method based on horizontal line array of the present invention.

[0020] Figure 2 It is the beam pattern of the horizontal linear array at 0° azimuth.

[0021] Figure 3 It is the azimuth spectrum of MVDR and the method of the present invention.

[0022] Figure 4 for Figure 3 A partial enlarged view of . DETAILED DESCRIPTION

[0023] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work belong to the protection scope of the present invention.

[0024] Reference Figure 1 As shown, the MVDR deconvolution method based on horizontal line array includes the following steps:

[0025] Step 1: Set the relevant parameters of the horizontal uniform line array and the sound source signal.

[0026] In this embodiment, the number of array elements of the horizontal linear array is set to 90, the array element spacing is set to 1m, the signal lengths of sound sources 1 and 2 are set to 1000, the frequencies are set to 1500Hz, the signal-to-noise ratios are set to 15dB, and the azimuths are set to -35° and -45° respectively. The underwater sound speed is 1500m / s.

[0027] Step 2: construct the sound source signal s(t) and noise n(t), obtain the array data received by the horizontal array through simulation calculation, and calculate the array data covariance matrix.

[0028] In step 2 of the present invention, under far-field conditions, the sound source signal s(t-τα) reaching the sound array is approximately expressed as That is to say in, represents the time delay between the sound source signal received by the αth array element and the 1st array element, c is the underwater sound speed, θ is the horizontal angle, j is an imaginary number, ω is the angular frequency, ω = 2πf, f is the frequency; at this time, the received data x(t) of the horizontal array is calculated using the sound source signal reaching the acoustic array:

[0029]

[0030] in is the array steering vector, θ 0 is the direction of the sound source; thus, the array data covariance matrix R = x(t)x H (t), H is the transpose.

[0031] Step 3: Perform MVDR beamforming on the received array data to obtain MVDR output power.

[0032] In step 3 of the present invention, the calculation formula of MVDR beamforming is as follows: the MVDR output power B is calculated as follows: MVDR ;

[0033] B MVDR (sinθ)=w H R

[0034] Where w is the MVDR beamforming weight vector, R is the covariance matrix of the array data obtained in step 2, is the array steering vector, θ is the horizontal angle, and H is the transpose.

[0035] In this embodiment, when the array element spacing is half a wavelength, the array steering vector a(θ) can be expressed as the following formula.

[0036]

[0037] Step 4: Calculate the beam pattern of the horizontal array using the following formula:

[0038]

[0039] Where c is the speed of sound in water, M is the number of elements in the horizontal linear array, λ is the wavelength, and θ is the horizontal angle.

[0040] In this embodiment, the beam pattern of the horizontal array is obtained by calculation as follows: Figure 2 shown.

[0041] Step 5: Deconvolute the sound source signal using the RL algorithm to obtain the original azimuth distribution.

[0042] Deconvolution is an ill-posed problem. For the special case where both the output power and the beam pattern are positive definite functions, the solution is unique and can be solved using the Richardson-Lucy (RL) algorithm.

[0043] In the present invention, sinθ is used as a variable to ensure that the beam pattern is translationally invariant with respect to the steering angle, so as to apply the RL algorithm to beamforming.

[0044] In step 5 of the present invention, the RL algorithm is used to During the deconvolution process, the MVDR output power B MVDR (sinθ) and beam pattern B p (sinθ) as the input value, the sound source energy distribution function can be solved The sound source energy distribution function consists of multiple Dirac pulses representing the direction of the sound source:

[0045]

[0046] In the formula, is the horizontal scanning angle, S i is the signal strength, δ is the Dirac pulse function, sinθ i is the true signal angle, and K represents the total number of true targets.

[0047] Combination Figure 3 and 4 It can be seen that the method of the present invention can obtain a narrower beam width and lower side lobes compared to MVDR.

[0048] The present invention deconvolves the MVDR output power, can restore the original signal distribution, and obtain a narrower beam width and low side lobe. Deconvolution is often used to solve the deblurring problem in image processing, wherein the deconvolution effect is excellent when both the input and the output are positive numbers.

[0049] The above-described embodiments are only preferred solutions of the present invention and are not intended to limit the present invention in any form. Other variations and modifications are possible without exceeding the technical solutions described in the claims.

Claims

1. A MVDR deconvolution method based on horizontal line array, It is characterized in that The method comprises the following steps: Step 1, setting the horizontal uniform line array parameters and the sound source signal parameters; Step 2, constructing the sound source signal s(t) and the noise n(t), obtaining the array data received by the horizontal array through simulation calculation, and calculating the array data covariance matrix; Step 3, performing MVDR beamforming on the array data received by the horizontal line array to obtain MVDR output power; Step 4, solving the beam pattern of the horizontal linear array; Step 5: Deconvolute the signal using the RL algorithm to obtain the original azimuth distribution of the signal.

2. The MVDR deconvolution method based on horizontal line array as claimed in claim 1, It is characterized in that In step 1, the element spacing of the horizontal array is set λ is the wavelength, which sets the length, frequency, direction, and signal-to-noise ratio of the sound source signal.

3. The MVDR deconvolution method based on horizontal line array as claimed in claim 1, It is characterized in that In step 2, the signal s(t-τ) reaching the horizontal line array under far-field conditions is m ) is characterized by The calculation array receives data x(t)=a(θ 0 )s(t)+n(t), a(θ 0 ) is the array steering vector, θ 0 is the direction of the sound source, j is an imaginary number, ω is the angular frequency, T M It is the time delay between the sound source signal received by the Mth array element and the first array element.

4. The MVDR deconvolution method based on horizontal line array as claimed in claim 1, It is characterized in that In step 3, the MVDR output power B MVDR (sinθ)=w H Rw, w is the MVDR beamforming weight vector, a(θ 0 ) is the array steering vector, R is the array data covariance matrix, and H is the transpose.

5. The MVDR deconvolution method based on horizontal line array as claimed in claim 1, It is characterized in that In step 4, the beam pattern of the horizontal linear array is Where c is the speed of sound in water, M is the number of elements in the horizontal linear array, λ is the wavelength, and θ is the horizontal angle.

6. The MVDR deconvolution method based on horizontal line array as claimed in claim 1, It is characterized in that In step 5, based on the MVDR output power B MVDR (sinθ) and beam pattern B p (sinθ), through the RL algorithm The sound source energy distribution function is obtained by solving, where θ is the horizontal scanning angle.

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