A broadband sound field directional control method based on tapered intercept beam deflection

Abstract

The present invention discloses a broadband sound field directional control method based on tapered interception beam deflection, which uses a hydrophone array to collect the sound field information of the controlled sound source, and extracts the characteristics of the controlled sound source from it, and regards the controlled sound source as a transmitting sound source, and forms a joint transmitting array with the active control sound source, and aligns the transmitting beam sidelobe of the joint transmitting array with the direction of the control sound field to be suppressed through the principle of time delay beam forming and Chebyshev amplitude weighting, so as to achieve broadband energy suppression under the interference of multiple columns of sound waves in this direction and adjacent angles. The present invention is based on the principle of multi-column sound wave interference destructive, and uses the existing plane wave array processing technology, which is simple to implement; the present invention uses beam forming technology to adjust the delay and amplitude, and the beam sidelobe area can be flexibly deflected, so as to achieve broadband sound field cancellation in any specified direction, and has good angle tolerance; there is no need to perform discrete Fourier transform processing on the transmitting data block, and the amount of calculation is small, which is conducive to real-time control of the sound field.

Description

Technical Field

[0001] The invention belongs to the field of underwater sound field control, and in particular relates to a broadband sound field directional control method based on tapered intercepted beam deflection. Background Art

[0002] With the development of noise control technology, the control of low-frequency and local sound fields has received increasing attention. Some technologies have become increasingly mature in the fields of automobile noise control and active noise reduction of headphones, and research in the field of underwater stealth has also received increasing attention.

[0003] The linear control technology of the sound field usually achieves the purpose of weakening the local sound field intensity of the controlled sound source by presetting the amplitude, phase and frequency of the active control sound source and utilizing the sound field interference effect between the active control sound source and the controlled sound source. Since the narrowband beam deflection technology has different phase and amplitude weightings at different frequencies, to process broadband signals, it can only transform the transmitted signal into the frequency domain through discrete Fourier transform, and then perform narrowband beam deflection on the sub-bands respectively. This method has a large amount of calculation, and the block processing makes it difficult to take into account the real-time performance of the active sound field control system. However, time-domain broadband beamforming and Chebyshev amplitude weighting can quickly calculate the weight vector of the controlled source and realize directional suppression of broadband sound fields. Summary of the invention

[0004] The purpose of the present invention is to provide a broadband sound field directional control method based on tapered intercept beam deflection to address the shortcomings of existing sound field control technology. The present invention is based on time-delay broadband beamforming technology and Chebyshev amplitude weighting, and achieves broadband suppression of the sound field intensity in a specific direction of the controlled source by regulating the time delay and amplitude of the active control source.

[0005] The object of the present invention is achieved through the following technical solution: a broadband sound field directional control method based on tapered intercept beam deflection, comprising the following steps:

[0006] 1) Acquisition of sound field information of controlled sound source: First, the sound pressure signal of the controlled sound source is received by the hydrophone array arranged in the sound field collection area, and the signal parameters are extracted according to the received information, including the frequency, amplitude and phase of the controlled sound source; and the source sound field is reconstructed according to the sound propagation model;

[0007] 2) Directional sound field tapered interception control: The active control source and the controlled source are combined into a joint transmitting array, and the sound field information of the controlled sound source extracted in step 1) is combined with the beam deflection direction to obtain the array element delay, and then the tapered interception vector is obtained by Chebyshev weighting; the control weight vector of the tapered interception beam deflection algorithm is calculated to control the emission of the active sound source and realize broadband control of the sound field in this direction.

[0008] Furthermore, in step 2), the active control sound source and the controlled sound source are combined into a joint transmitting array; the number of the active control sound sources is assumed to be M, and according to the positional relationship between each active control sound source and the controlled sound source reconstructed in step 1), a tapered intercept beam deflection method is used on the controlled sound source to perform broadband sound field control; including:

[0009] First, the quasi-suppression direction φ is given i , calculate the main beam of the lowest frequency component of the broadband signal as φ i The beam pattern diagram of the direction; and obtain the main lobe width Δφ from it nn ;

[0010] Then use the beam steering algorithm to generate the transmit signal vector s(φ s ,t), the main beam direction φ s Set to angles other than the angle; Under the far-field plane wave condition, in the joint transmitting array, the transmitting signal vector s(φ s ,t), can be expressed as:

[0011] s(φ s ,t)=[s0(t),s0(t-τ1(φ s )),s0(t-τ2(φ s )),...,s0(t-τ M (φ s ))] H (1)

[0012] Among them, s0(t) represents the emission signal of the controlled sound source; τ m (φ s ) is the mth active control sound source at an azimuth angle of φ s When , the time delay relative to the controlled sound source, m = 1, 2, ..., M; the superscript H is the conjugate transpose operator;

[0013] Finally, the tapered intercept vector t generated by the Chebyshev window function is used to perform amplitude weighting on the transmit signal of each array element to obtain the transmit signal s of the joint transmit array tb (φ s ,t):

[0014] s tb (φ s ,t)=t⊙s(φ s ,t) (4)

[0015] Furthermore, in step 2), the tapered intercept vector t required for amplitude weighting is generated by a Chebyshev window, and the window function t(m) is defined as:

[0016]

[0017]

[0018] Wherein, m is the corresponding array element number, and SLL is the set sidelobe height.

[0019] The beneficial effects of the present invention are as follows:

[0020] 1) The present invention is based on the principle of multi-column acoustic wave interference and destructive interference, and utilizes the existing planar wave array processing technology. It is simple to implement and has important significance in practical application fields such as low-frequency directional stealth of underwater targets;

[0021] 2) The present invention uses beamforming technology to adjust the delay and amplitude, and the beam sidelobe area can be flexibly deflected, thereby achieving broadband sound field cancellation in any specified direction and having good angle tolerance;

[0022] 3) The present invention adopts time-domain beamforming technology, which does not require discrete Fourier transform processing of the transmitted data blocks, reduces the amount of calculation, and is conducive to real-time control of the sound field. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram of the sound field directional control method of the present invention;

[0024] Figure 2 It is a schematic diagram of the controlled sound source and the active control sound source array of the present invention;

[0025] Figure 3 It is a schematic diagram of the sound field simulation of the controlled sound source composite active control sound source of the present invention; wherein, a is the tapered intercepted beam pattern diagram of each frequency point (the main beam is in the 0° direction), b is the tapered intercepted beam pattern diagram of each frequency point with the main beam in the 70° direction, and c is the sound pressure signal of the "controlled sound source" and the sound pressure signal after the tapered intercepted beam deflection control. DETAILED DESCRIPTION

[0026] The present invention will be further described below in conjunction with the accompanying drawings.

[0027] like Figure 1 As shown, the present invention provides a broadband sound field directional control method based on tapered intercepted beam deflection, which is used for sound field directional control to realize sound energy redistribution. The present invention uses a hydrophone array to collect the sound field information of the controlled sound source, and extracts the characteristics of the controlled sound source (including frequency, amplitude and phase signal parameters) therefrom. On this basis, the controlled sound source is regarded as a transmitting sound source, and the controlled sound source and the active control sound source form a "joint transmitting array". Through the principle of time-delay beamforming and Chebyshev amplitude weighting, the transmitting beam sidelobe of the "joint transmitting array" is aligned with the direction of the control sound field to be suppressed, thereby realizing broadband energy suppression under the interference of multiple columns of sound waves in this direction and adjacent angles. Specifically, the following steps are included:

[0028] 1) Acquisition of sound field information of controlled sound source.

[0029] First, the sound pressure signal of the controlled sound source is received by the hydrophone array arranged in the sound field collection area. The signal parameters such as the frequency, amplitude and phase information of the controlled sound source are extracted according to the received information; and according to the near-field and far-field sound propagation characteristics, the controlled sound source is reconstructed as s0(t) as a point source.

[0030] 2) Directional sound field tapering and wave velocity control.

[0031] The active control sound source and the controlled sound source form a "joint transmission array". Assume that the number of active control sound sources is M. According to the positional relationship between each active control sound source and the controlled sound source reconstructed in step 1), the tapered intercept beam deflection method is used on the "controlled sound source" to perform broadband sound field control.

[0032] First, the quasi-suppression direction φ is given i , calculate the main beam of the lowest frequency component of the broadband signal as φ i The beam pattern diagram of the direction; and obtain the main lobe width Δφ from it nn (Here the main lobe width refers to the width between the left and right null points of the main lobe).

[0033] Then use the conventional beam steering algorithm to generate the transmit signal vector s(φ s ,t), the main beam direction φ s Set to Under far-field plane wave conditions, in the “joint transmit array”, the transmit signal vector s(φ s ,t), can be expressed as:

[0034] s(φ s ,t)=[s0(t),s0(t-τ1(φ s )),s0(t-τ2(φ s )),...,s0(t-τ M (φ s ))] H (1)

[0035] Among them, s0(t) represents the emission signal of the controlled sound source; τ m (φ s ) is the mth active control sound source at an azimuth angle of φ s When , the time delay relative to the controlled sound source is m=1,2,...,M; the superscript H is the conjugate transpose operator.

[0036] The tapered intercept vector t required for amplitude weighting is generated by a Chebyshev window, and the window function t(m) is defined as:

[0037]

[0038]

[0039] Wherein, m is the corresponding array element number, and SLL is the set sidelobe height.

[0040] Finally, the tapered intercept vector generated by the Chebyshev window function is used to perform amplitude weighting on the transmit signal of each array element to obtain the transmit signal s of the “joint transmit array” tb (φ s ,t):

[0041] s tb (φ s ,t)=t⊙s(φ s ,t) (4)

[0042] After the transmission signal of each channel is obtained, the signal is sent to the multi-channel power amplifier connected to the transmission array for signal transmission, forming a superimposed sound field with the controlled sound source. This process is equivalent to the signal transmission of the "joint transmission array". The tapered intercept beam deflection of the "joint transmission array" is realized by linear weighting and delay of the actively controlled sound source, so as to achieve the purpose of directional control of the sound field.

[0043] The present invention draws on and improves the principle of conventional beamforming to suppress interference in a specific direction through low side lobes, realizes broadband directional sound field control through time-delay beamforming, and then reduces the side lobes through Chebyshev weighting to achieve the purpose of broadband sound field control, while having good angle tolerance. According to the principle of acoustic wave interference, when the phase and amplitude of the active control sound source and the controlled sound source meet a certain relationship, the coherent cancellation of the sound waves can be achieved, thereby reducing the sound field intensity of the controlled source in the cancellation area. If the number of actively controlled sound sources increases, the control effect of the sound field can be further improved through the interference of multiple columns of sound waves, that is, beam control. Based on the principles of time-delay beamforming and Chebyshev amplitude weighting, the present invention aligns the transmitting beam sidelobes of the "joint transmitting array" composed of the active control source and the controlled source with the direction of the control sound field to be suppressed, thereby achieving broadband energy suppression under the interference of multiple columns of sound waves in this direction and adjacent angles.

[0044] like Figure 2 As shown in FIG. 1 , to verify the effectiveness of the present invention, in this embodiment, the intended suppression direction φ = 0°, the array is set to 7-element ULA, the sound speed is 1500 m / s, the array element spacing is 1.07 m, which is the half wavelength of a 700 Hz signal, and the side lobe peak level of the Chebyshev window is set to -40 dB. The composite sound field of the controlled sound source and the active control sound source is shown in FIG. Figure 3 As shown; among them, Figure 3a is the tapered intercept beam pattern diagram of the main beam at 0° at 500Hz, 600Hz, and 700Hz. After obtaining the main lobe width information, it can be seen that when the main beam direction is set to 70°, the intended suppression direction will be located in the sidelobe area of ​​the beam pattern diagram; Figure 3 b is the tapered intercept beam pattern diagram with the main beam at 70°. It can be seen that all frequency components in the intended suppression direction φ=0° are weakened by sidelobe suppression. It can be seen that the tapered intercept algorithm effectively suppresses the broadband sound field in a directionally controlled manner. Figure 3 c shows the sound pressure signal before and after the tapered intercept beam deflection control when the sound pressure signal of the "controlled sound source" is a linear frequency modulation signal of 500-700Hz. The simulation results show that the tapered intercept beam deflection algorithm can stably weaken the sound field of the broadband "controlled sound source".

[0045] The contents described in the embodiments of this specification are merely an enumeration of the implementation forms of the inventive concept. The protection scope of the present invention should not be regarded as limited to the specific forms described in the embodiments. The protection scope of the present invention also extends to equivalent technical means that can be conceived by those skilled in the art based on the inventive concept.

Claims

1. A broadband sound field directional control method based on tapered intercept beam deflection, characterized in that: The following steps are involved: 1) Acquisition of sound field information of the controlled sound source: First, the sound pressure signal of the controlled sound source is received by the hydrophone array arranged in the sound field collection area, and the signal parameters are extracted according to the received information, including the frequency, amplitude and phase of the controlled sound source; And reconstruct the source sound field according to the sound propagation model; 2) Directional sound field tapered interception control: The active control source and the controlled source form a joint transmission array, and the sound field information of the controlled sound source extracted in step 1) is combined with the beam deflection direction to obtain the array element delay, and then the tapered interception vector is obtained by Chebyshev weighting; the control weight vector of the tapered interception beam deflection algorithm is calculated to control the emission of the active sound source and realize broadband control of the sound field in this direction; The active control sound source and the controlled sound source form a joint transmitting array; the number of the active control sound sources is assumed to be M, and according to the positional relationship between each active control sound source and the controlled sound source reconstructed in step 1), a tapered intercept beam deflection method is used on the controlled sound source to perform broadband sound field control; including: First, the quasi-suppression direction φ is given i , calculate the main beam of the lowest frequency component of the broadband signal as φ i beam pattern of the direction; and The main lobe width Δφ is obtained from nn ; Then use the beam steering algorithm to generate the transmit signal vector s(φ s ,t), the main beam direction φ s Set to angles other than the angle; Under the far-field plane wave condition, in the joint transmitting array, the transmitting signal vector s(φ s ,t), expressed as: s(φ s ,t)=[s0(t),s0(t-τ1(φ s )),s0(t-τ2(φ s )),...,s0(t-τ M (f s ))] H (1) Among them, s0(t) represents the emission signal of the controlled sound source; τ m (φ s ) is the mth active control sound source at an azimuth angle of φ s When , the time delay relative to the controlled sound source, m = 1, 2, ..., M; the superscript H is the conjugate transpose operator; Finally, the tapered intercept vector t generated by the Chebyshev window function is used to perform amplitude weighting on the transmit signal of each array element to obtain the transmit signal s of the joint transmit array tb (φ s ,t): s tb (f s ,t)=t⊙s(φ s ,t) (4).

2. According to claim 1, the broadband sound field directional control method based on tapered intercept beam deflection is characterized in that: In step 2), the tapered intercept vector t required for amplitude weighting is generated by a Chebyshev window, and the window function t(m) is defined as: Wherein, m is the corresponding array element number, and SLL is the set sidelobe height.

Images