Underwater acoustic line spectrum target detection method based on vector hydrophone

Abstract

The invention discloses an underwater acoustic line spectrum target detection method based on a vector hydrophone, and belongs to the technical field of underwater acoustic passive detection. According to the method, the problem that the robust spatial gain cannot be obtained by the traditional vector hydrophone processing under the condition that the target orientation is unknown is solved. A single vector hydrophone carried by a small platform and a compass system are used for obtaining compass data and acoustic data, through signal processing and directivity rotation, vector detection data which point to different directions and are overlapped with each other are obtained according to a pre-formed angle, and through a power spectrum analysis and maximum value detection mode, the detection result is obtained. The robust space gain of an unknown azimuth target can be obtained, and detection of a long-distance, low-signal-to-noise-ratio and low-frequency line spectrum target is achieved. The method can be applied to underwater acoustic line spectrum target detection.

Description

Technical Field

[0001] The 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 with pressure hydrophones, vector hydrophones have additional spatial processing gain, so they are more advantageous in underwater acoustic line spectrum target detection, especially for the processing of low-frequency signals. They do not need to increase the aperture, and can directly obtain spatial gain by using vector spatial directivity. When different processing methods are used, the spatial directivity gain of a single vector hydrophone is different, and a robust spatial gain can only be obtained when the vector combination points to the target direction. Therefore, for the case where the target position is unknown, the use of traditional vector hydrophone processing still cannot obtain a robust spatial gain. In practice, the position of low signal-to-noise ratio targets is often unknown, which leads to the uncontrollability of obtaining vector spatial gain. 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: Receive the acoustic pressure and array velocity channel acoustic signals using the single vector hydrophone carried on the platform, and collect the three-dimensional attitude data of the single vector hydrophone relative to the geodetic coordinates using the electronic compass carried on the platform;

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

[0007] Step 3, setting M pre-pointing angles, and then obtaining 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 geodetic 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 direction 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 according to 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 pointing to the pre-angle, 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 an 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 an 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 attitude transfer matrix R(t) based on the collected attitude 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 as angle pre-formation, and the cross-spectrum S of the vector detection data pointing to the pre-formed 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 a sliding average method to convert 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 pointing pre-angle.

[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-angle i i (f) is:

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

[0039] 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 a sliding average method to convert 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 pointing pre-angle.

[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 pointing pre-angle 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] Aiming at the problem of underwater long-distance weak target detection, the present invention proposes an underwater acoustic line spectrum target detection method based on vector hydrophone. Compass data and acoustic data are obtained by using a single vector hydrophone and a compass system carried by a small platform. Through signal processing and rotating directivity, overlapping vector detection data pointing to different directions are obtained according to the pre-formed angle. Then, through power spectrum analysis and maximum value detection, the robust spatial gain of unknown azimuth targets can be obtained, and the detection of long-distance, low signal-to-noise ratio, and low-frequency line spectrum targets can be realized. BRIEF DESCRIPTION OF THE DRAWINGS

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

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

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

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

[0053] Figure 5 It is a motion situation diagram of line spectrum target fixed-point detection reception;

[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 implementation mode nine;

[0056] Figure 8 is a power spectrum diagram to be measured obtained based on the method of specific implementation mode eight;

[0057] Fig. 9 is a power spectrum diagram to be measured obtained based on the method of specific implementation mode nine; ​

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

[0059] Fig.11 Based on the method of the eighth specific implementation mode, a single-line spectrum target vector hydrophone PVc to be measured power spectrum history diagram is obtained;

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

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

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

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

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

[0065] Fig.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 The present embodiment is described as follows. The present embodiment describes an underwater acoustic line spectrum target detection method based on a vector hydrophone, and the method specifically comprises the following steps:

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

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

[0069] Step 3: using the method of pre-forming directivity of vector azimuth, rotating to form directivities in different directions through signal processing, setting M pre-forming directivity angles, and then obtaining vector detection data corresponding to the M pre-forming 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 geodetic 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 direction 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 bilateral directivity M is 2, and the minimum value of unilateral directivity M is 4. The M pre-forming angles are uniformly distributed in the horizontal azimuth range of 0 to 360 degrees, starting from 0 degrees. Since beam preforming is only performed in the two-dimensional horizontal plane to form horizontal directivity, even if a three-dimensional vector hydrophone is used, the z-axis signal obtained after compass correction is not required.

[0075] Step 4: Calculate the power spectrum of the vector detection data at each pre-pointing angle according to 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 pointing to the pre-angle, 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 of the 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)>Compare with the detection threshold. If it is greater than the detection threshold, it is directly determined as 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. Different from 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 a plurality of pre-angled vector detection data by rotating the directivity, and forms a robust spatial processing gain for each unknown target position by overlapping the pre-angles. The method of the present invention is simple, has a small amount of calculation and a robust gain.

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

[0081] The 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 may also be other small platforms.

[0083] Specific implementation method three: This implementation method is different from specific implementation method one in that the data collected by the electronic compass includes the heading angle α(t), the pitch angle β(t) and the roll angle γ(t).

[0084] The 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 pressure and array velocity channel acoustic signals.

[0086] Specific implementation method 4: This implementation method is different from specific implementation method 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] The other steps and parameters are the same as those in the third specific implementation manner.

[0088] Specific implementation mode 5: This implementation mode is different from specific implementation mode 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), and 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] The other steps and parameters are the same as those in the third specific implementation manner.

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

[0091] When measuring, 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] The other steps and parameters are the same as those in the fourth embodiment.

[0097] Specific implementation example 7: This implementation example is different from specific implementation example 5 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 velocity signal v in the z-axis direction 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] The 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 implementation eight: This implementation is different from specific implementation 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 as angle pre-formation, and the cross-spectrum S of the vector detection data pointing to the pre-formed 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 a sliding average method to convert 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 pointing pre-angle.

[0111] The other steps and parameters are the same as those in the sixth or seventh embodiment.

[0112] Specific implementation method 9: This implementation method is different from specific implementation methods 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-angle i i (f) is:​​

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

[0115] 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 a sliding average method to convert 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 pointing pre-angle.

[0117] The other steps and parameters are the same as those in the sixth or seventh embodiment.

[0118] Specific implementation method ten: This implementation method is different from the specific implementation method 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 pointing pre-angle 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] The other steps and parameters are the same as those in the first embodiment.

[0125] The present invention overlaps and covers multiple rotation angles, and takes the maximum value as the vector space directivity output of the detection quantity, thereby obtaining a robust spatial processing gain for unknown azimuth targets and improving the detection capability of weak line spectrum targets. If the existing spatial gain acquisition method is directly applied to target detection, the detection effect is difficult to guarantee because the spatial gain cannot be obtained. Moreover, the method of the present invention has a spatial gain effect for detecting targets within the working frequency band of the vector hydrophone, and has good adaptability.

[0126] Experimental Section

[0127] 1. Suppose there is a single-frequency line spectrum target with a straight heading and a motion situation like 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 at the same time; 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 method of vector azimuth pre-pointing, the directivity is rotated by signal processing to obtain the overlapping vector detection data v pointing to different pre-pointing angles ci '(t), the 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 FIG. 1 shows the beam coverage result of pre-forming 4 beams using the method of the eighth specific implementation mode. Figure 4 The method of the ninth embodiment is used to pre-generate the beam coverage result of 4 beams. When the target is in the due north direction, Figure 6 FIG. 4 shows the power spectrum of each beam obtained by using the method of the eighth specific implementation mode. 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 tested. max ​​(f)>, the power spectrum to be measured obtained based on the method of the eighth specific implementation method 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 Fig. 9 As shown in , the role 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 Fig.10 , Fig.11 , Fig.12 As shown, Fig.10 It is the power spectrum diagram of single sound pressure detection. Fig.11 is a vector power spectrum history diagram obtained based on the method of specific implementation mode eight, Fig.12 is a vector power spectrum history diagram obtained based on the method of the ninth specific implementation mode; in step 6, by defining a threshold Figure 8 and Fig. 9 The power spectrum to be tested is tested for line spectrum detection, and the line spectrum detection results at each moment are obtained, and the line spectrum frequency is given. Fig.11 The process map and Fig.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 Fig.10 , Fig.11 , Fig.12 It can be seen that the vector line spectrum detection process is obviously clearer than the sound pressure process. Fig.13 yes Fig.10 , Fig.11 , Fig.12 From the comparison results of the line spectrum power spectrum slices at a moment in the process, it can be seen that the directional power spectrum image 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 implementation method nine is higher than that of specific implementation method 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 is as follows: Figure 5 shown. Fig.14 is the result of the sound pressure line spectrum process. Fig.15 The sound pressure line spectrum process results of four angles are preformed by the method of the eighth specific implementation mode. Fig.16 This is the result of pre-forming the sound pressure line spectrum at four angles using the method of the ninth embodiment. Fig.14 , Fig.15 , Fig.16 It can be seen that for the case of dual targets, no matter in which direction the targets are, the method of the present invention can obtain clearer line spectrum results than single sound pressure detection. Fig.17 yes Fig.14 , Fig.15 , Fig.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 calculation examples of the present invention are only used to explain the calculation model and calculation process of the present invention in detail, and are not intended to limit the implementation methods of the present invention. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made based on the above description. It is impossible to list all the implementation methods here. All obvious changes or modifications derived from the technical solution of the present invention are still within the scope of protection of the present invention.

Claims

1. An underwater acoustic line spectrum target detection method based on vector hydrophone, characterized in that: The method specifically comprises the following steps: Step 1: Receive the acoustic pressure and array velocity channel acoustic signals using the single vector hydrophone carried on the platform, and collect the three-dimensional attitude data of the single vector hydrophone relative to the geodetic coordinates using the electronic compass carried on the platform; Step 2: Based on the collected three-dimensional attitude data, the acoustic signal of the array velocity channel is corrected to obtain the acoustic signal of the array velocity channel in the geodetic coordinate system; Step 3, setting M pre-pointing angles, and then obtaining 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 as follows: 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 geodetic 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 direction 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 according to 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 pointing to the pre-angle 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, a UUV or a UG.

3. The underwater acoustic line spectrum target detection method based on vector hydrophone according to claim 1 is 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 velocity signal v in the z-axis direction 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 attitude transfer matrix R(t) based on the collected attitude 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 is 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 velocity signal v in the z-axis direction 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 as angle pre-formation, and the cross-spectrum S of the vector detection data pointing to the pre-formed 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 '(t) Fourier transform result, superscript "*" indicates conjugation, "·" indicates multiplication; Step 42: Use a sliding average method to convert 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 pointing pre-angle.​​ 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-angle i i (f) is: S i (f)=pv ci '(f)·pv ci '*(f) 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); Step 42: Use a sliding average method to convert 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 pointing pre-angle.​​ 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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