Underwater acoustic line spectrum target detection method based on vector hydrophone

Abstract

The invention relates to an underwater acoustic line spectrum target detection method based on a vector hydrophone, which belongs to the field of underwater acoustic passive detection technology. The invention solves the problem that when the target position is unknown, the traditional vector hydrophone processing cannot obtain a robust spatial gain. The invention uses a single vector hydrophone and a compass system carried by a small platform to obtain compass data and acoustic data, and through signal processing and rotation directivity, obtains overlapping vector detection data pointing in different directions according to a pre-formed angle, and then obtains a robust spatial gain of an unknown position target through power spectrum analysis and maximum value detection, thereby realizing the detection of long-distance, low signal-to-noise ratio, low-frequency line spectrum targets. The method of the invention can be applied to underwater acoustic line spectrum target detection.

Description

Technical Field

[0001] The present invention belongs to the technical field of underwater acoustic passive detection, and in particular relates to a method for underwater acoustic line spectrum target detection. Background Art

[0002] Compared to pressure hydrophones, vector hydrophones offer additional spatial processing gain, making them particularly advantageous for underwater acoustic line spectrum target detection. This is especially true for processing low-frequency signals, as they do not require an increased aperture and can directly achieve spatial gain by leveraging vector spatial directivity. The spatial directivity gain of a single vector hydrophone varies depending on the processing method used, and robust spatial gain is only achieved when the vector combination points in the direction of the target. Therefore, conventional vector hydrophone processing still fails to achieve robust spatial gain when the target's position is unknown. In practice, the position of low-SNR targets is often unknown, making the acquisition of vector spatial gain uncontrollable. Summary of the Invention

[0003] The purpose of the present invention is to solve the problem that traditional vector hydrophone processing cannot obtain robust spatial gain when the target orientation is unknown, and to propose an underwater acoustic line spectrum target detection method based on vector hydrophone.

[0004] The technical solution adopted by the present invention to solve the above technical problems is: an underwater acoustic line spectrum target detection method based on a vector hydrophone, the method specifically comprising the following steps:

[0005] Step 1: Use the single vector hydrophone on the platform to receive the acoustic pressure and array velocity channel acoustic signals, and use the electronic compass on the platform to collect the three-dimensional attitude data of the single vector hydrophone relative to the geodetic coordinates;

[0006] Step 2: Based on the collected three-dimensional attitude data, the array velocity channel acoustic signal is corrected to obtain the array velocity channel acoustic signal in the geodetic coordinate system;

[0007] Step 3: Set M pre-pointing angles, and then obtain vector detection data corresponding to the M pre-pointing angles based on the array velocity channel acoustic signal in the geodetic coordinate system;

[0008] The specific process of step 3 is as follows:

[0009] Step 31: Set M pre-direction angles. The pre-direction angle refers to the angle by which the acoustic signal of the array velocity channel in the earth coordinate system is rotated. The i-th pre-direction angle is recorded as i=1,2,…,M;

[0010] Step 32: Pre-angle according to the direction The x-axis velocity signal v in the geodetic coordinate system x '(t) and the y-axis velocity signal v y '(t) rotates to obtain the pre-pointing angle The corresponding array speed output signal v ci '(t), that is, pointing to the pre-angle Corresponding vector detection data;

[0011]

[0012] Step 4: Calculate the power spectrum of the vector detection data at each pre-pointing angle based on the vector detection data corresponding to each pre-pointing angle. i (f)>, i=1,2,…,M;

[0013] Step 5: According to the power spectrum of the vector detection data of each pre-angled direction, a power spectrum to be detected S is obtained. max (f)>

[0014] Step 6: Detection power spectrum max (f)>Perform line spectrum detection to obtain line spectrum target detection results.

[0015] Furthermore, the platform is a submersible buoy, UUV or UG.

[0016] Furthermore, the data collected by the electronic compass include the heading angle α(t), the pitch angle β(t) and the roll angle γ(t).

[0017] Preferably, the single vector hydrophone is a two-dimensional vector hydrophone, and the sound pressure signal received by the single vector hydrophone is recorded as p(t). The received array velocity channel acoustic signal includes the array velocity signal v in the x-axis direction in the carrier coordinate system. x (t) and the y-axis velocity signal v y (t).

[0018] Preferably, the single vector hydrophone is a three-dimensional vector hydrophone, and the sound pressure signal received by the single vector hydrophone is recorded as p(t). The received array velocity channel acoustic signal includes the array velocity signal v in the x-axis direction in the carrier coordinate system. x (t), y-axis direction velocity signal v y (t) and the z-axis velocity signal v z (t).

[0019] Preferably, the specific process of step 2 is:

[0020] Construct the posture transfer matrix R(t) based on the collected posture data:

[0021] ​​

[0022] The x-axis direction velocity signal v in the carrier coordinate system is calculated using the attitude transfer matrix R(t). x (t) and the y-axis velocity signal v y (t) To make amendments:

[0023]

[0024] Among them, v x '(t) is the x-axis velocity signal in the geodetic coordinate system, v y '(t) is the array velocity signal in the y-axis direction in the geodetic coordinate system.

[0025] Preferably, the specific process of step 2 is:

[0026] Construct the posture transfer matrix R(t) based on the collected three-dimensional posture data:

[0027]

[0028] The x-axis direction velocity signal v in the carrier coordinate system is calculated using the attitude transfer matrix R(t). x (t), y-axis direction velocity signal v y (t) and the z-axis velocity signal v z (t) To make amendments:

[0029]

[0030] Among them, v x '(t) is the x-axis velocity signal in the geodetic coordinate system, v y '(t) is the y-axis velocity signal in the geodetic coordinate system, v z '(t) is the array velocity signal in the z-axis direction in the geodetic coordinate system.

[0031] Preferably, the specific process of step 4 is:

[0032] Step 41: Take the cross spectrum of sound pressure and array velocity to make angle pre-forming, and the cross spectrum S of the vector detection data pointing to the pre-forming angle of the i-th direction i (f) is:

[0033] S i (f) = p(f)·v ci '*(f)

[0034] Among them, p(f) is the Fourier transform result of the sound pressure signal p(t), v ci '(f) is v ci The Fourier transform result of '(t), the superscript "*" indicates conjugation and "·" indicates multiplication;

[0035] Step 42: Use sliding average to calculate the cross-spectrum result S i (f) Average to obtain the average periodogram i (f)>, the average periodogram i (f)>Power spectrum of the vector detection data with the i-th pre-angle pointing direction.

[0036] Preferably, the specific process of step 4 is:

[0037] Step 41: The cross spectrum S of the vector detection data pointing to the pre-angled direction of the i-th direction i (f) is:

[0038] S i (f) = pv ci '(f)·pv ci '*(f)

[0039] Wherein, the superscript “*” indicates conjugation and “·” indicates multiplication; pv ci '(f) is pv ci '(t)'s Fourier transform result, pv ci '(t)=p(t)+v ci '(t), pv ci '*(f) is pv ci '*(t)'s Fourier transform result, pv ci '*(t)=p(t)+v ci '*(t);

[0040] Step 42: Use sliding average to calculate the cross-spectrum result S i (f) Average to obtain the average periodogram i (f)>, the average periodogram i (f)>Power spectrum of the vector detection data with the i-th pre-angle pointing direction.

[0041] Furthermore, the specific process of step 5 is as follows:

[0042] For the jth frequency:

[0043] max (f j )>=max( i (f j )〉), i=1,2,…,M

[0044] in, i (f j )> is the power spectrum of the vector detection data at the i-th pre-angled direction i (f)>, the power value corresponding to the jth frequency, <S​​​​​​​​max (f j )> is the maximum value of the power value corresponding to the jth frequency in the power spectrum of all vector detection data;

[0045] Similarly, the maximum power value corresponding to each frequency is obtained respectively;

[0046] The power spectrum to be detected is composed of the maximum power value corresponding to each frequency max (f)>.

[0047] The beneficial effects of the present invention are:

[0048] To address the problem of detecting weak underwater targets at long distances, this paper proposes a method for underwater acoustic line spectrum target detection based on a vector hydrophone. This method utilizes a single vector hydrophone and a compass system mounted on a small platform to acquire compass and acoustic data. Through signal processing and directivity rotation, overlapping vector detection data pointing in different directions is generated based on pre-determined angles. Power spectrum analysis and maximum value detection are then used to determine the robust spatial gain of targets of unknown orientation, enabling the detection of long-range, low-signal-to-noise ratio, and low-frequency line spectrum targets. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 is a flow chart of the method of the present invention;

[0050] Figure 2 is a schematic diagram of the directivity of the velocity channel of the vector hydrophone array;

[0051] Figure 3 This is a schematic diagram of the pre-angle directivity of the vector hydrophone sound pressure array PVc cross spectrum when pre-formed into four angles;

[0052] Figure 4 This is a schematic diagram of the pre-formed directivity of the vector hydrophone sound pressure array velocity P+Vc when pre-formed into four angles;

[0053] Figure 5 It is the motion situation diagram received by fixed-point detection of line spectrum targets;

[0054] Figure 6 is a power spectrum diagram of each beam obtained by using the method of specific implementation mode eight;

[0055] Figure 7 is a power spectrum diagram of each beam obtained by using the method of specific embodiment nine;

[0056] Figure 8 The power spectrum to be measured is obtained based on the method of the eighth embodiment;

[0057] Figure 9 The power spectrum to be measured is obtained based on the method of the ninth embodiment; ​

[0058] Figure 10 This is a simulation diagram of the low-frequency line spectrum process of the single-line spectrum target sound pressure hydrophone;

[0059] Figure 11 Based on the method of the eighth embodiment, a power spectrum diagram of the single-line target vector hydrophone PVc to be measured is obtained;

[0060] Figure 12 Based on the method of the ninth embodiment, a single-line spectrum target vector hydrophone P+Vc power spectrum diagram to be measured is obtained;

[0061] Figure 13 It is a normalized comparison diagram of single target power spectrum history slices;

[0062] Figure 14 This is a simulation diagram of the low-frequency line spectrum process of the double-line spectrum target sound pressure hydrophone;

[0063] Figure 15 It is the power spectrum diagram of the dual-line target vector hydrophone PVc to be measured;

[0064] Figure 16 It is the power spectrum diagram of the dual-line target vector hydrophone P+Vc to be measured;

[0065] Figure 17 It is a normalized comparison chart of the power spectrum process slices of the dual-line spectrum target. DETAILED DESCRIPTION

[0066] Specific implementation method 1. Combination Figure 1 This embodiment describes a method for underwater acoustic line spectrum target detection based on a vector hydrophone, and the method specifically includes the following steps:

[0067] Step 1: Use the single vector hydrophone on the platform to receive the acoustic pressure and array velocity channel acoustic signals, and use the electronic compass on the platform to collect the three-dimensional attitude data of the single vector hydrophone relative to the geodetic coordinates;

[0068] Step 2: Based on the collected three-dimensional attitude data, the array velocity channel acoustic signal is corrected to obtain the array velocity channel acoustic signal in the geodetic coordinate system;

[0069] Step 3: Using the vector azimuth pre-directivity method, signal processing is used to rotate and form directivities in different directions, set M pre-directivity angles, and then obtain vector detection data corresponding to the M pre-directivity angles based on the array velocity channel acoustic signal in the geodetic coordinate system;

[0070] The specific process of step 3 is as follows:

[0071] Step 31: Set M pre-direction angles. The pre-direction angle refers to the angle by which the acoustic signal of the array velocity channel in the earth coordinate system is rotated. The i-th pre-direction angle is recorded as i=1,2,…,M;

[0072] Step 32: Pre-angle according to the direction The x-axis velocity signal v in the geodetic coordinate system x '(t) and the y-axis velocity signal v y '(t) rotates to obtain the pre-pointing angle The corresponding array speed output signal v ci '(t), that is, pointing to the pre-angle Corresponding vector detection data;

[0073]

[0074] It should be noted that the minimum value of M for bilateral directivity is 2, and the minimum value for unilateral directivity is 4. The M pre-formed pointing angles are uniformly distributed over the horizontal azimuth range of 0 to 360 degrees, starting at 0°. Because beamforming is performed only in the two-dimensional horizontal plane to create horizontal directivity, even when using a three-dimensional vector hydrophone, a compass-corrected z-axis signal is not required.

[0075] Step 4: Calculate the power spectrum of the vector detection data at each pre-pointing angle based on the vector detection data corresponding to each pre-pointing angle. i (f)>, i=1,2,…,M;

[0076] Step 5: According to the power spectrum of the vector detection data of each pre-angled direction, a power spectrum to be detected S is obtained. max (f)>

[0077] Step 6: Detection power spectrum max (f)>Perform line spectrum detection to obtain line spectrum target detection results.

[0078] Power spectrum to be detected max (f)> Perform line spectrum detection to obtain the frequency information of each line spectrum. The specific process of line spectrum detection is as follows: first, the continuous spectrum background trend needs to be extracted. The continuous spectrum extraction can be done by using the bidirectional α filtering method, the double-pass separation window method, the sorting truncation method, etc. Then, a fixed detection threshold is added to the power spectrum to be detected. max (f)> is compared with the detection threshold. If it is greater than the detection threshold, it is directly determined to be line spectrum information. Then, the local peak value of the frequency domain greater than the detection threshold is taken, and the frequency corresponding to the peak value is the line spectrum frequency of the target.

[0079] ​​​​Compared with the sound pressure system, the spatial signal processing gain can be obtained by utilizing the directivity of the vector hydrophone. Unlike the traditional vector hydrophone detection, which cannot obtain robust gain when the target position is unknown and the spatial gain is only valid for the natural pointing direction of the vector array, the method of the present invention generates multiple pre-angled vector detection data by rotating the directivity, and uses the pre-angled overlap to form a robust spatial processing gain for each unknown target. The method of the present invention is simple, has low computational complexity, and has robust gain.

[0080] Specific embodiment 2: This embodiment differs from specific embodiment 1 in that the platform is a submersible buoy, a UUV (Unmanned Underwater Vehicle) or a UG (Underwater Glider).

[0081] Other steps and parameters are the same as those in the first embodiment.

[0082] The platforms that can be used in this embodiment include but are not limited to the above-mentioned platforms, and can also be other small platforms.

[0083] Specific embodiment three: This embodiment differs from specific embodiment one in that the data collected by the electronic compass include the heading angle α(t), the pitch angle β(t) and the roll angle γ(t).

[0084] Other steps and parameters are the same as those in the first embodiment.

[0085] In this embodiment, the measurement error of each attitude angle is required to be no greater than 1°, and each attitude angle is collected synchronously with the acoustic signals of the sound pressure and array velocity channels.

[0086] Specific embodiment 4: This embodiment differs from specific embodiment 3 in that the single vector hydrophone is a two-dimensional vector hydrophone, and the sound pressure signal received by the single vector hydrophone is recorded as p(t). The received array velocity channel acoustic signal includes the array velocity signal v in the x-axis direction in the carrier coordinate system. x (t) and the y-axis velocity signal v y (t).

[0087] Other steps and parameters are the same as those in the third embodiment.

[0088] Specific embodiment 5: This embodiment is different from the specific embodiment 3 in that the single vector hydrophone is a three-dimensional vector hydrophone, and the sound pressure signal received by the single vector hydrophone is recorded as p(t). The received array velocity channel acoustic signal includes the array velocity signal v in the x-axis direction under the carrier coordinate system. x (t), y-axis direction velocity signal v y (t) and the z-axis velocity signal v z (t).

[0089] Other steps and parameters are the same as those in the third embodiment.

[0090] Specific embodiment 6: This embodiment differs from specific embodiment 4 in that, when the single vector hydrophone is a two-dimensional vector hydrophone, the specific process of step 2 is as follows:

[0091] During measurement, only the heading angle of the two-dimensional vector hydrophone changes, and the pitch angle and roll angle are both 0°. The attitude transfer matrix R(t) is constructed based on the collected attitude data:

[0092]

[0093] The x-axis direction velocity signal v in the carrier coordinate system is calculated using the attitude transfer matrix R(t). x (t) and the y-axis velocity signal v y (t) To make amendments:

[0094]

[0095] Among them, v x '(t) is the x-axis velocity signal in the geodetic coordinate system, v y '(t) is the array velocity signal in the y-axis direction in the geodetic coordinate system.

[0096] Other steps and parameters are the same as those in the fourth embodiment.

[0097] Specific embodiment seven: This embodiment differs from specific embodiment five in that, when the single vector hydrophone is a three-dimensional vector hydrophone, the specific process of step 2 is as follows:

[0098] Construct the posture transfer matrix R(t) based on the collected three-dimensional posture data:

[0099]

[0100] The x-axis direction velocity signal v in the carrier coordinate system is calculated using the attitude transfer matrix R(t). x (t), y-axis direction velocity signal v y (t) and the z-axis velocity signal v z (t) To make amendments:

[0101]

[0102] Among them, v x '(t) is the x-axis velocity signal in the geodetic coordinate system, v y '(t) is the y-axis velocity signal in the geodetic coordinate system, v z'(t) is the array velocity signal in the z-axis direction in the geodetic coordinate system.

[0103] It should be noted that the form of the attitude transfer matrix R(t) includes but is not limited to the form given in this embodiment. When the definitions of the three coordinate axes of the right-handed coordinate system or the geodetic coordinate system change, the form of the attitude transfer matrix R(t) will change accordingly. The forms of the attitude transfer matrix R(t) will not be listed one by one here.

[0104] Other steps and parameters are the same as those in the fifth embodiment.

[0105] Since the platform carrying a single vector hydrophone may be a moving platform, or the coordinate axis definition of the carrier coordinate system may be inconsistent with the coordinate axis definition of the geodetic coordinate system, in order to obtain the results in the geodetic coordinate system, it is necessary to correct the array velocity channel acoustic signal vector data to point to the due north and due east coordinate axes of the geodetic coordinate system through compass correction.

[0106] Specific embodiment eight: This embodiment differs from specific embodiment six or seven in that the specific process of step 4 is as follows:

[0107] Step 41: Take the cross spectrum of sound pressure and array velocity to make angle pre-forming, and the cross spectrum S of the vector detection data pointing to the pre-forming angle of the i-th direction i (f) is:

[0108] S i (f) = p(f)·v ci '*(f)

[0109] Among them, p(f) is the Fourier transform result of the sound pressure signal p(t), v ci '(f) is v ci The Fourier transform result of '(t), the superscript "*" indicates conjugation and "·" indicates multiplication;

[0110] Step 42: Use sliding average to calculate the cross-spectrum result S i (f) Average to obtain the average periodogram i (f)>, the average periodogram i (f)>Power spectrum of the vector detection data with the i-th pre-angle pointing direction.

[0111] Other steps and parameters are the same as those in specific implementation manner six or seven.

[0112] Specific embodiment 9: This embodiment differs from specific embodiment 6 or 7 in that the specific process of step 4 is as follows:

[0113] Step 41: The cross spectrum S of the vector detection data pointing to the pre-angled direction of the i-th direction i (f) is:​​

[0114] S i (f) = pv ci '(f)·pv ci '*(f)

[0115] Wherein, the superscript “*” indicates conjugation and “·” indicates multiplication; pv ci '(f) is pv ci '(t)'s Fourier transform result, pv ci '(t)=p(t)+v ci '(t), pv ci '*(f) is pv ci '*(t)'s Fourier transform result, pv ci '*(t)=p(t)+v ci '*(t);

[0116] Step 42: Use sliding average to calculate the cross-spectrum result S i (f) Average to obtain the average periodogram i (f)>, the average periodogram i (f)>Power spectrum of the vector detection data with the i-th pre-angle pointing direction.

[0117] Other steps and parameters are the same as those in specific implementation manner six or seven.

[0118] Specific embodiment ten: This embodiment differs from specific embodiment one in that the specific process of step 5 is as follows:

[0119] For the jth frequency:

[0120] max (f j )>=max( i (f j )〉), i=1,2,…,M

[0121] in, i (f j )> is the power spectrum of the vector detection data at the i-th pre-angled direction i (f)>, the power value corresponding to the jth frequency, max (f j )> is the maximum value of the power value corresponding to the jth frequency in the power spectrum of all vector detection data;

[0122] Similarly, the maximum power value corresponding to each frequency is obtained respectively;

[0123] The power spectrum to be detected is composed of the maximum power value corresponding to each frequency max ​​​​​​​​(f)>.

[0124] Other steps and parameters are the same as those in the first embodiment.

[0125] The present invention achieves robust spatial processing gain for targets of unknown orientation by overlapping multiple rotation angles and taking the maximum value as the vector spatial directivity output of the detected variable. This improves the detection capability of weak line spectrum targets. Existing spatial gain acquisition methods, when directly applied to target detection, fail to achieve sufficient spatial gain and thus struggle to guarantee detection effectiveness. Furthermore, the present method achieves spatial gain for targets within the operating frequency band of the vector hydrophone, demonstrating excellent adaptability.

[0126] Experimental part

[0127] 1. Suppose there is a single-frequency line spectrum target with a straight course and a movement pattern such as Figure 5 The line spectrum target 1 shown has a frequency of 100 Hz and an input spectrum level signal-to-noise ratio of 10 dB, and is processed according to the vector line spectrum detection steps of the present invention:

[0128] First, according to step 1, a single vector hydrophone is placed on a moving or stationary platform, and acoustic signals and compass attitude information are collected and stored simultaneously. Then, according to step 2, a three-dimensional attitude correction is performed based on the three-dimensional attitude data, sound pressure, and array velocity channel acoustic data obtained in step 1, and the vector array velocity signal of the three-dimensional array velocity data in the geodetic coordinate system is obtained as v x '(t),v y '(t) and v z '(t); Then according to step 3, using the vector azimuth pre-pointing method, by signal processing rotation directivity, to obtain the overlapping vector detection data v pointing to different pre-pointing angles ci '(t), the vibration velocity directivity diagrams for the cases of 0° and 90° are as follows Figure 2 As shown; follow step 4 to calculate the vector detection power spectrum pointing to each angle i (f)>, such as Figure 3 The figure shows the beam coverage result of pre-forming 4 beams using the method of the eighth embodiment. Figure 4 The beam coverage result of 4 beams is pre-formed by the method of the ninth embodiment. When the target is in the north direction, Figure 6 FIG. 1 shows the power spectrum of each beam obtained by using the method of the eighth embodiment. Figure 7 The figure shows the power spectra of each beam obtained by the method of the ninth embodiment. Since the directivity angles of the power spectra of each beam are different, the received signal target strength is also different. According to step 5, the maximum value of the power spectra of the vector detection data at each angle is taken to obtain a power spectrum to be measured. max ​​(f)>, the power spectrum to be measured obtained based on the method of the eighth embodiment is as follows Figure 8 As shown, the power spectrum to be measured obtained based on the method of the ninth embodiment is as follows: Figure 9 As shown in , the purpose of this step is to always take the maximum beam power output when the target direction is unknown, so that the target will not be missed due to the directivity of a single beam power. The power spectrum history of each moment can be plotted into a history diagram, such as Figure 10 、 Figure 11 、 Figure 12 As shown, Figure 10 It is the power spectrum diagram of single sound pressure detection. Figure 11 is a vector power spectrum history diagram obtained based on the method of specific embodiment eight, Figure 12 The vector power spectrum history diagram obtained based on the method of the ninth embodiment; in step 6, the threshold is defined. Figure 8 and Figure 9 The power spectrum to be tested is tested to obtain the line spectrum detection results at each moment and give the line spectrum frequency. Figure 11 The process map and Figure 12 Line spectrum target detection is performed at each moment in the history diagram, and the frequency information is measured to obtain the final line spectrum detection result and all frequency information.

[0129] contrast Figure 10 、 Figure 11 、 Figure 12 It can be seen that the vector line spectrum detection process is obviously clearer than the sound pressure process. Figure 13 yes Figure 10 、 Figure 11 、 Figure 12 From the comparison results of the line spectrum power spectrum slices at a moment in time, it can be seen that the power spectrum image forming directionality has a lower background than the conventional method when detecting the line spectrum, that is, the line spectrum detection signal-to-noise ratio of the method of the present invention is higher, and additional spatial gain can be obtained, and the signal-to-noise ratio of specific embodiment nine is higher than that of specific embodiment eight.

[0130] 2. There are two line spectrum targets. The frequency of target 1 is 100Hz and the frequency of target 2 is 120Hz. The movement situation is as follows: Figure 5 shown. Figure 14 is the result of the sound pressure line spectrum process, Figure 15 The sound pressure line spectrum history results of four angles are preformed using the method of the eighth embodiment. Figure 16 This is the result of pre-forming the sound pressure line spectrum at four angles using the method of the ninth embodiment. Figure 14 、 Figure 15 、 Figure 16 It can be seen that for the case of dual targets, no matter which direction the targets are in, the method of the present invention can obtain clearer line spectrum results than single sound pressure detection. Figure 17 yes Figure 14 、 Figure 15 、 Figure 16 By comparing the slices, it can be seen that for multi-line spectrum targets, the method of the present invention is still effective without knowing the target direction in advance.

[0131] The above examples are merely illustrative of the calculation model and process of the present invention and are not intended to limit the embodiments of the present invention. Persons skilled in the art will readily appreciate that other variations or modifications based on the above description are possible. This list of embodiments is not exhaustive; however, any obvious variations or modifications derived from the technical solution of the present invention remain within the scope of protection of the present invention.

Claims

1. An underwater acoustic line spectrum target detection method based on a vector hydrophone, characterized in that: The method specifically comprises the following steps: Step 1: Use the single vector hydrophone on the platform to receive the acoustic pressure and array velocity channel acoustic signals, and use the electronic compass on the platform to collect the three-dimensional attitude data of the single vector hydrophone relative to the geodetic coordinates; Step 2: Based on the collected three-dimensional attitude data, the array velocity channel acoustic signal is corrected to obtain the array velocity channel acoustic signal in the geodetic coordinate system; Step 3: Set M pre-pointing angles, and then obtain vector detection data corresponding to the M pre-pointing angles based on the array velocity channel acoustic signal in the geodetic coordinate system; The specific process of step 3 is: Step 31: Set M pre-direction angles. The pre-direction angle refers to the angle by which the acoustic signal of the array velocity channel in the earth coordinate system is rotated. The i-th pre-direction angle is recorded as Step 32: Pre-angle according to the direction The x-axis velocity signal v in the geodetic coordinate system x '(t) and the y-axis velocity signal v y '(t) rotates to obtain the pre-pointing angle The corresponding array speed output signal v ci '(t), that is, pointing to the pre-angle Corresponding vector detection data; Step 4: Calculate the power spectrum of the vector detection data at each pre-pointing angle based on the vector detection data corresponding to each pre-pointing angle. i (f)>, i=1,2,…,M;​ Step 5: Obtain a power spectrum to be detected based on the power spectrum of the vector detection data at each pre-angled direction max (f)>​ Step 6: Detection power spectrum max (f)>Perform line spectrum detection to obtain line spectrum target detection results.​ 2. The underwater acoustic line spectrum target detection method based on vector hydrophone according to claim 1 is characterized in that: The platform is a submersible buoy, UUV or UG.

3. The underwater acoustic line spectrum target detection method based on vector hydrophone according to claim 1, characterized in that: The data collected by the electronic compass include the heading angle α(t), the pitch angle β(t) and the roll angle γ(t).

4. The underwater acoustic line spectrum target detection method based on vector hydrophone according to claim 3 is characterized in that: The single vector hydrophone is a two-dimensional vector hydrophone. The sound pressure signal received by the single vector hydrophone is recorded as p(t). The received array velocity channel acoustic signal includes the array velocity signal v in the x-axis direction in the carrier coordinate system. x (t) and the y-axis velocity signal v y (t).

5. The underwater acoustic line spectrum target detection method based on vector hydrophone according to claim 3 is characterized in that: The single vector hydrophone is a three-dimensional vector hydrophone. The sound pressure signal received by the single vector hydrophone is recorded as p(t). The received array velocity channel acoustic signal includes the array velocity signal v in the x-axis direction under the carrier coordinate system. x (t), y-axis direction velocity signal v y (t) and the z-axis velocity signal v z (t).

6. The underwater acoustic line spectrum target detection method based on vector hydrophone according to claim 4 is characterized in that: The specific process of step 2 is: Construct the posture transfer matrix R(t) based on the collected posture data: The x-axis direction velocity signal v in the carrier coordinate system is calculated using the attitude transfer matrix R(t). x (t) and the y-axis velocity signal v y (t) To make amendments: Among them, v x '(t) is the x-axis velocity signal in the geodetic coordinate system, v y '(t) is the array velocity signal in the y-axis direction in the geodetic coordinate system.

7. The underwater acoustic line spectrum target detection method based on vector hydrophone according to claim 5, characterized in that: The specific process of step 2 is: Construct the posture transfer matrix R(t) based on the collected three-dimensional posture data: The x-axis direction velocity signal v in the carrier coordinate system is calculated using the attitude transfer matrix R(t). x (t), y-axis direction velocity signal v y (t) and the z-axis velocity signal v z (t) To make amendments: Among them, v x '(t) is the x-axis velocity signal in the geodetic coordinate system, v y '(t) is the y-axis velocity signal in the geodetic coordinate system, v z '(t) is the array velocity signal in the z-axis direction in the geodetic coordinate system.

8. The underwater acoustic line spectrum target detection method based on vector hydrophone according to claim 6 or 7, characterized in that: The specific process of step 4 is as follows: Step 41: Take the cross spectrum of sound pressure and array velocity to make angle pre-forming, and the cross spectrum S of the vector detection data pointing to the pre-forming angle of the i-th direction i (f) is: S i (f)=p(f)·v ci '*(f) Among them, p(f) is the Fourier transform result of the sound pressure signal p(t), v ci '(f) is v ci The Fourier transform result of '(t), the superscript "*" indicates conjugation, and "·" indicates multiplication; Step 42: Use sliding average to calculate the cross-spectrum result S i (f) Average to obtain the average periodogram i (f)>, the average periodogram i (f)>Power spectrum of the vector detection data with the i-th pre-angle pointing direction.​​ 9. The underwater acoustic line spectrum target detection method based on vector hydrophone according to claim 6 or 7, characterized in that: The specific process of step 4 is as follows: Step 41: The cross spectrum S of the vector detection data pointing to the pre-angled direction of the i-th direction i (f) is: S i (f)=pv ci '(f)·pv ci '*(f) Wherein, the superscript "*" indicates conjugation, "·" indicates multiplication; pv ci '(f) is pv ci '(t)'s Fourier transform result, pv ci '(t)=p(t)+v ci '(t), pv ci '*(f) is pv ci '*(t)'s Fourier transform result, pv ci '*(t)=p(t)+v ci '*(t); Step 42: Use sliding average to calculate the cross-spectrum result S i (f) Average to obtain the average periodogram i (f)>, the average periodogram i (f)>Power spectrum of the vector detection data with the i-th pre-angle pointing direction.​​ 10. The underwater acoustic line spectrum target detection method based on vector hydrophone according to claim 1, characterized in that: The specific process of step 5 is as follows: For the jth frequency: <S max (f j )>=max(<S i (f j )>),i=1,2,…,M in, i (f j )> is the power spectrum of the vector detection data at the i-th pre-angled direction i (f)>, the power value corresponding to the jth frequency, max (f j )> is the maximum value of the power value corresponding to the jth frequency in the power spectrum of all vector detection data;​​​ Similarly, the maximum power value corresponding to each frequency is obtained respectively; The power spectrum to be detected is composed of the maximum power value corresponding to each frequency max (f)>.​

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