An underwater vehicle detection system and method based on acoustic and seismic signals for shallow sea environments.

Abstract

This application relates to the field of underwater detection technology, and particularly to an underwater vehicle detection system and method based on acoustic and seismic signals for shallow sea environments. The system includes a hydrophone, a seismic sensor, a phase shifter, a multiplier, an integrator, and a comparator. The hydrophone receives acoustic signals from the vehicle and outputs an acoustic electrical signal; the seismic sensor receives seismic signals generated by liquid-solid coupling and outputs a seismic electrical signal; the phase shifter delays the phase of the acoustic electrical signal; the multiplier multiplies the delayed acoustic electrical signal and the seismic electrical signal; the integrator integrates the product signal to obtain a correlation function value; and the comparator compares this value with a noise threshold to determine the presence of a vehicle target. This system integrates dual-physics field signal detection, effectively suppressing environmental noise, improving detection anti-interference capability and reliability, accurately detecting vehicle targets in shallow seas, and allowing for flexible setting of the detection radius to achieve focused detection within a specific distance range.

Description

Technical Field

[0001] This application relates to the field of underwater detection technology, and in particular to an underwater vehicle detection system and method based on acoustic and seismic signals for shallow sea environments. Background Technology

[0002] Shallow waters, due to their complex hydrological environment, varied seabed topography, and significant media coupling effects, have become important areas for underwater vehicles (UVs), placing extremely high demands on their detection technologies. The mechanical wave signals radiated by UVs during navigation are the core information source for target detection. These waves propagate not only as sound waves in seawater but also as seismic waves through the seabed medium via the liquid-solid coupling between seawater and the seabed. However, current detection technologies for UVs in shallow waters still face numerous technical bottlenecks and application limitations.

[0003] Existing methods for detecting underwater vehicles in shallow waters mainly rely on single physical field signal detection. The mainstream technology is acoustic detection based on hydrophones. This technology relies on the propagation characteristics of sound waves in seawater to achieve target perception. It has good detection effects in open deep sea areas. However, in shallow sea environments, due to factors such as sea surface reflection, seabed scattering, and environmental noise superposition, the acoustic signal is prone to distortion and attenuation, resulting in a significant reduction in the signal-to-noise ratio. It is not sensitive enough for detecting long-distance, low-noise vehicles and is easily affected by environmental interference such as marine biological noise and ship navigation noise, leading to misjudgment and missed detection.

[0004] While a few detection technologies targeting submarine seismic waves can capture seismic wave signals radiated by ships and avoid some interference from the seawater medium on sound waves, the submarine seismic wave field contains multiple wave types, such as compression waves, shear waves, and Scholte surface waves. The propagation characteristics of different wave types vary greatly, and the density and composition inhomogeneity of the seabed medium can lead to complex propagation paths and large time delay fluctuations in seismic wave signals. Single seismic wave detection is easily affected by the seabed geological environment, making it difficult to achieve stable and accurate target identification. Summary of the Invention

[0005] The purpose of this application is to overcome the above-mentioned deficiencies of the prior art, thereby providing an underwater vehicle detection system and method based on acoustic and seismic signals for shallow sea environments.

[0006] To address the aforementioned technical problems, the technical solution provided in this application offers an underwater vehicle detection system based on acoustic and seismic signals for shallow sea environments, comprising: Hydrophones are used to receive acoustic signals propagating in seawater from underwater vehicles and output acoustic electrical signals. A seismic wave sensor is used to receive seismic wave signals generated in the seabed medium due to the propagation of mechanical waves radiated by underwater vehicles through the liquid-solid coupling between seawater and the seabed medium, and to output seismic wave electrical signals. A phase shifter, electrically connected to a hydrophone, is used to perform phase delay processing on acoustic electrical signals to obtain delayed acoustic electrical signals. The multiplier, electrically connected to the phase shifter and the seismic wave sensor, is used to perform multiplication operations on the delayed acoustic wave electrical signal and the seismic wave electrical signal to obtain a product signal; An integrator, connected to the multiplier, is used to integrate the product signal over a preset working period to obtain a correlation function value between the acoustic signal and the seismic signal; and A comparator, connected to the integrator, is used to compare the correlation function value with a preset environmental noise reference threshold, and based on the comparison result, to determine whether there is an underwater vehicle target, so as to realize the detection of underwater vehicle targets.

[0007] As an improvement to the above technical solution, the system further includes: a first amplification and filtering circuit and a second amplification and filtering circuit, wherein the first amplification and filtering circuit is located between the hydrophone and the phase shifter, and is used to amplify and filter the acoustic electrical signal of the hydrophone to obtain a conditioned acoustic electrical signal; the phase shifter receives the conditioned acoustic electrical signal and performs phase delay processing on the conditioned acoustic electrical signal; the second amplification and filtering circuit is located between the seismic wave sensor and the multiplier, and is used to amplify and filter the seismic electrical signal of the seismic wave sensor to obtain a conditioned seismic electrical signal; the multiplier performs multiplication operations on the delayed acoustic electrical signal and the conditioned seismic electrical signal.

[0008] As an improvement to the above technical solution, the system further includes: a bottom-mounted instrument compartment, which serves as an installation platform for the detection system and is submerged on the seabed; the hydrophone is installed on the outer top surface of the bottom-mounted instrument compartment, and the seismic wave sensor is installed on the inner bottom surface of the bottom-mounted instrument compartment.

[0009] As an improvement to the above technical solution, the phase shifter introduces a time delay based on the acoustic electrical signal. The time delay for: ; in, To detect the radius of the area, The propagation velocity of the shear wave in the seismic wave is denoted as . This represents the speed at which sound waves travel in seawater.

[0010] As an improvement to the above technical solution, the phase shifter adjusts the introduced time delay. By controlling the radius R of the detection area, a ring-shaped detection area centered on the bottom-mounted instrument compartment is formed underwater.

[0011] As an improvement to the above technical solution, the relevant function value for: ; in, It is a seismic wave electrical signal. It is a delayed acoustic wave electrical signal, where T is the preset working period and t is the time variable.

[0012] As an improvement to the above technical solution, the comparator outputs a decision signal indicating the presence of an underwater vehicle target when the correlation function value is greater than the preset environmental noise reference threshold.

[0013] As an improvement to the above technical solution, the hydrophone includes: a piezoelectric ceramic transducer for converting underwater acoustic wave signals into electrical acoustic wave signals in the form of electrical charges; the seismic wave sensor includes: a piezoelectric accelerometer for converting seabed seismic wave signals into electrical seismic wave signals in the form of electrical charges.

[0014] As an improvement to the above technical solution, the first amplification and filtering circuit and the second amplification and filtering circuit have the same configuration and both include a high-pass filter.

[0015] To achieve another objective of the present invention, the present invention also provides a method for underwater vehicle detection based on acoustic and seismic signals in shallow sea environments, comprising: Step 1: Use a hydrophone to receive the sound wave signals propagating in the seawater from the underwater vehicle and convert them into acoustic electrical signals; Step 2: Use a seismic wave sensor to receive the seismic wave signals formed in the seabed medium due to the propagation of mechanical waves radiated by underwater vehicles through the liquid-solid coupling between seawater and the seabed medium, and convert them into seismic wave electrical signals. Step 3: Apply a time delay to the acoustic signal using a phase shifter. ; Step 4: Multiply the delayed acoustic signal and the seismic signal using a multiplier; Step 5: Integrate the product signal using an integrator within a preset working period T to obtain the correlation function value between the acoustic signal and the seismic signal; Step 6: Compare the cross-correlation function value with a preset environmental noise reference threshold, and based on the comparison result, determine whether there is an underwater vehicle target, so as to realize the detection of underwater vehicle targets.

[0016] The advantage of this application lies in its proposal of an underwater vehicle detection system and method based on acoustic and seismic signals for shallow sea environments. This system utilizes dual-physics field fusion to detect underwater vehicles in shallow sea environments, aiming to solve the technical challenges of single hydrophone detection being susceptible to complex hydrological environments and having a low signal-to-noise ratio, and single seismic wave detection being susceptible to interference from seabed geological conditions and having unstable identification. The system integrates a hydrophone and a seismic wave sensor in a bottom-mounted instrument compartment, simultaneously receiving acoustic signals radiated by the same underwater vehicle and seismic wave signals propagating through liquid-solid coupling. A phase shifter applies a time delay to the acoustic electrical signal related to the detection area radius, and multipliers and integrators perform cross-correlation calculations on the two signals, effectively suppressing uncorrelated environmental noise and extracting target features from the complex shallow sea background field.

[0017] Compared to existing technologies, the core advantage of this application lies in constructing an adjustable ring-shaped detection area through signal processing, significantly improving detection reliability and anti-interference capabilities. By adjusting the time delay parameter of the phase shifter, the system can flexibly set the detection radius centered on the sensor, achieving focused detection of targets within a specific distance range. Simultaneously, since sound waves and seismic waves originating from the same target are strongly correlated, while marine environmental noise does not possess this characteristic, the decision mechanism based on the cross-correlation function can greatly reduce false alarm and missed alarm rates, providing a high-precision and highly adaptable technical solution for detecting quiet or long-range underwater vehicles in shallow sea environments. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of environmental parameters in a Pekeria waveguide on an elastic seabed. Figure 2 Correlation coefficient curve between acoustic field signal of underwater target and seismic wave signal; Figure 3 A schematic diagram of an underwater vehicle detection system based on acoustic and seismic signals for shallow sea environments, provided in Embodiment 1 of this application; Figure 4 A flowchart illustrating the workflow of an underwater vehicle detection system based on acoustic and seismic signals for shallow marine environments, provided in Embodiment 1 of this application. Figure 5 The circuit diagram of an underwater vehicle detection system based on acoustic and seismic signals for shallow sea environments provided in Embodiment 1 of this application. Detailed Implementation

[0019] The technical solutions provided in this application are further illustrated below with reference to the embodiments.

[0020] Example 1 This embodiment discloses an underwater vehicle detection system based on acoustic and seismic signals for shallow sea environments. It performs joint correlation detection of acoustic and seismic signals from underwater vehicles in shallow sea environments. First, it receives acoustic signals propagating in the water and seismic signals propagating on the seabed generated by the underwater vehicle. Then, it performs joint signal processing by correlating the two signals and calculating the correlation coefficient to detect the underwater vehicle target. The detection device is equipped with a hydrophone and a seismic sensor. These two sensors obtain alternating signals from corresponding directions. These alternating signals from different physical fields are multiplied by a phase shifter to increase the time delay, then integrated by an integrator. A comparator compares the integrated value with an environmental noise reference threshold. When the integrated value reaches a preset threshold, it automatically determines that a target exists.

[0021] In shallow sea environments, underwater vehicles radiate mechanical wave signals into the surrounding marine environment as sound sources. Besides propagating as sound waves, some signal energy also propagates far into the distance as seismic waves through the liquid-solid coupling of seawater and the seabed. The seismic wave field simultaneously exhibits the propagation characteristics of compression waves, shear waves, and Scholte surface waves. Underwater sound waves can be received by hydrophones, while seabed seismic waves can be detected by vibration sensors placed on the seabed. When detecting underwater targets, the sound and seismic wave signals, as signals from the same source (both originating from the vehicle's own radiation), are strongly correlated due to their different propagation paths. Therefore, the vehicle can be detected using methods that detect the correlation between sound and seismic wave signals. Figure 1The diagram illustrates environmental parameters in a Pekeria waveguide on an elastic seabed. The velocity of sound in seawater is approximately 1500 m / s; in a water-bearing, silty seabed with an average density of 1500 kg / m³, the velocity of shear waves in seismic waves is 800 m / s, and the velocity of compression waves is 1800 m / s. It is evident that for the same signal receiving point, the arrival times of the acoustic and seismic signals from the same sound source (underwater vehicle) are different. Therefore, the correlation method for detecting underwater targets can be used by delaying the signals using a phase shifter, cross-correlating the delayed physical field signal with the other physical field signal, and calculating the correlation coefficient. Since noise from the same target source propagates through two different propagation paths—sound and seismic waves—there is a correlation between their acoustic and seismic signals, while environmental noise is random, anisotropic, and uncorrelated. Therefore, the presence of a target can be determined by the magnitude of the correlation coefficient between the acoustic and seismic signals of the underwater vehicle, thus achieving the purpose of detection. Furthermore, the magnitude of the time delay introduced by the phase shifter is related to the distance between the observation point and the target vehicle. Therefore, the detection distance can be controlled by controlling the magnitude of the time delay: the magnitude of the time delay can be controlled to form a ring control area of ​​a corresponding radius underwater. When the underwater vehicle enters this ring area, the detection device is activated.

[0022] Therefore, hydrophones can be installed on the watertight instrument compartment located on the seabed to receive acoustic signals radiated by underwater vehicles. Vibration sensors can be installed on the inner bottom of the watertight instrument compartment to receive seismic wave signals propagating from the seabed. The signals from the hydrophone and vibration sensor are amplified and low-pass filtered by signal conditioning circuits. The acoustic signal from the hydrophone is then multiplied by the seismic wave electrical signal from the seismic sensor in a multiplier after passing through a phase shifter. When the correlation coefficient between the two signals is at its maximum, a peak appears in the correlation coefficient curve. When the peak exceeds the detection threshold, a decision result is output, indicating that the underwater vehicle has been detected, thus completing the target detection.

[0023] The phase shifter delay is set according to the detection distance; the detection threshold of the correlation coefficient is determined by the correlation coefficient between acoustic noise and seismic noise in the marine environment. Since the correlation coefficient is low, it can be determined by obtaining statistical values ​​through multiple experiments.

[0024] The purpose of this application is to detect underwater vehicle targets by employing a cross-correlation function of acoustic / seismic wave field signals to detect the radiated noise of underwater vehicles. The peak value method is used to detect the presence or absence of a target: ; in, It is a seismic wave field signal. The signal is a sound field signal, T is the working period, and t is the time variable. Multiplying the two signals and then integrating yields the correlation function. Since the distribution of sound field and seismic noise in the marine environment is anisotropic and random, the correlation is weak. Taking a bottom-based detection platform as the observation point, as an underwater vehicle travels from far to near, the sound wave signal and seismic wave signal in its radiated noise signal change with distance attenuation. The signal-to-noise ratio change caused by the relative distance change will then result in the correlation function spatially appearing as follows: Figure 2 The correlation curve shown has a peak value variation.

[0025] When no underwater vehicles pass by and there is no target, the sound field and seismic field noise in the marine environment are random and uncorrelated, and the value of their correlation function is low. A reference threshold can be obtained through actual measurement and statistics. The peak value of the correlation function when a target passes by is compared with this reference threshold. If it is higher than this threshold, it is judged that there is a target.

[0026] And the sound field signal Add a delay Obtain the sound field signal with added time delay. The above equation becomes: ; Delay The value of is determined by the radius R of the detection area: ; Therefore, this application performs joint correlation processing on the acoustic and seismic signals of an underwater vehicle target: delaying the acoustic signal by a specific time delay. The signal is then multiplied by the seismic wave signal and integrated by the integrator to obtain the correlation function. The peak value of the correlation function is compared with a reference threshold in the marine environment. If the peak value exceeds the reference threshold, it is determined that there is an underwater vehicle target in the detection area.

[0027] Corresponding joint detection devices, such as Figure 3 As shown, it consists of a bottom-mounted instrument compartment, hydrophones, seismic detectors, amplification and filtering circuits, phase shifters, multipliers, integrators, and comparators. The hydrophones are mounted on the top surface of the bottom-mounted instrument compartment, and the seismic detectors are installed inside the bottom-mounted instrument compartment. Figure 4 As shown, the underwater acoustic signal received by the hydrophone is conditioned by the amplification and filtering circuit, then enters the phase shifter, where a time delay is added, and then enters the multiplier. The seismic detector receives the seismic wave signal propagating from the seabed, which is conditioned by the amplification and filtering circuit and then enters the multiplier. The multiplier multiplies the time-delayed acoustic signal with the seismic wave signal, and the product is integrated by the integrator. The integrated value is then compared with the environmental detection threshold by the comparator. If the value exceeds the detection threshold, the comparator flips and outputs a high level as a start signal.

[0028] Among them, the hydrophone uses a piezoelectric ceramic transducer, and the seismic detector uses a piezoelectric accelerometer. Both of them use piezoelectric ceramic as their sensitive element and output the same charge signal. They are matched and use the same amplification and filtering circuit for signal conditioning to avoid phase error caused by differences in circuit structure.

[0029] The working process of the relevant detection device is as follows: Figure 4 As shown, the acoustic signal received by the hydrophone is amplified and filtered by the amplification and filtering circuit, thus removing some environmental noise. The amplified and filtered acoustic signal then enters the phase shifter, which delays the acoustic signal. The seismic signal received by the seismic sensor is amplified and filtered by the amplification and filtering circuit, thus removing some environmental noise. The seismic and acoustic signals enter the multiplier, which multiplies the two signals. The product enters the integrator, which integrates the product of the seismic and acoustic signals within the signal period. The integral value enters the comparator, whose comparison threshold is the environmental noise threshold. The environmental noise threshold refers to the upper limit of the correlation coefficient of environmental noise measured by the hydrophone and the seismic sensor when no target passes by (this can be measured multiple times before the formal detection work, and the maximum value is taken). When the integral value is greater than the comparison threshold, the comparator flips and outputs a high level as a start-up signal.

[0030] When the seismic wave shear velocity at the seabed is 800 m / s, the sound velocity is 1500 m / s, the operating frequency of the pre-amplifier and filter circuit is designed to be 10 Hz, and the detection distance is 100 meters, the time delay of the phase shifter is: ; The work cycle is: ; The phase shift is: ; 3) Specific implementation circuit as follows Figure 5 As shown: Hydrophone T1 is a piezoelectric ceramic transducer that converts acoustic signals into electrical signals; seismic wave sensor T2 is a piezoelectric accelerometer that converts seismic wave signals into electrical signals; the hydrophone signal and the seismic wave signal are respectively amplified and filtered by circuits U1A and U2A. Circuits U1A and U2A have the same structure and parameters. Taking U1A as an example, the amplification factor is determined by resistors R1 and R2 in the amplification and filtering circuit U1A. Amplification factor of amplifier filter circuit U1A : The resistor R4 in the amplifier and filter circuit U1A is an impedance matching resistor, and it is set to 100MΩ.

[0031] The filter frequency of the amplifier-filter circuit U1A is determined by the capacitor C1, resistor R1, and resistor R2 of the amplifier-filter circuit U1A, and it is a high-pass filter. Filter cutoff frequency : ; The hydrophone signal, after being filtered and amplified, enters phase shifter U1B. Phase shifter U1B is an all-pass phase shifting circuit. The gain of phase shifter U1B... The resistor of phase shifter U1B and resistance Decide: If we take R5 = R3, then .

[0032] The phase shift of phase shifter U1B is determined by its resistor R11 and capacitor C2, and the phase shift constant is... for;

[0033] After phase shifting, the hydrophone signal is delayed; the seismic wave sensor signal is also amplified and filtered before being combined with the delayed hydrophone signal into multiplier U3. Multiplier U3 is an integrated analog multiplier AD633, which multiplies the hydrophone signal and the seismic wave sensor signal.

[0034] The product of the two signals enters integrator U2B, which integrates the product, with an integration time constant. Determined by resistor R9 and capacitor C3 of integrator U2B: After integration, the correlation function between the hydrophone signal and the seismic wave sensor signal is obtained.

[0035] The correlation function is input to the positive input of comparator U4, an integrated analog comparator LM339. Its negative input is the reference terminal, which receives the ambient noise threshold voltage. This threshold voltage represents the upper limit of the correlation coefficient of marine environmental noise when no underwater vehicle is present. It can be obtained through multiple measurements and is a preset comparison threshold. When the correlation function between the hydrophone signal and the seismic sensor signal exceeds the ambient noise threshold, comparator U4 flips, outputting a high level, indicating the presence of an underwater vehicle target; otherwise, comparator U4 outputs a low level.

[0036] Example 2 This embodiment provides a method for underwater vehicle detection based on acoustic and seismic signals in shallow sea environments, including: Step 1: Use a hydrophone to receive the sound wave signals propagating in the seawater from the underwater vehicle and convert them into acoustic electrical signals; Step 2: Use a seismic wave sensor to receive the seismic wave signals formed in the seabed medium due to the propagation of mechanical waves radiated by underwater vehicles through the liquid-solid coupling between seawater and the seabed medium, and convert them into seismic wave electrical signals. Step 3: Apply a time delay to the acoustic signal using a phase shifter. ; Step 4: Multiply the delayed acoustic signal and the seismic signal using a multiplier; Step 5: Integrate the product signal using an integrator within a preset working period T to obtain the correlation function value between the acoustic signal and the seismic signal; Step 6: Compare the cross-correlation function value with a preset environmental noise reference threshold, and based on the comparison result, determine whether there is an underwater vehicle target, so as to realize the detection of underwater vehicle targets.

[0037] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to the embodiments, those skilled in the art should understand that modifications or equivalent substitutions to the technical solutions of the present invention do not depart from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. An underwater vehicle detection system based on acoustic and seismic signals for shallow sea environments, comprising: Hydrophones are used to receive acoustic signals propagating in seawater from underwater vehicles and output acoustic electrical signals. A seismic wave sensor is used to receive seismic wave signals generated in the seabed medium due to the propagation of mechanical waves radiated by underwater vehicles through the liquid-solid coupling between seawater and the seabed medium, and to output seismic wave electrical signals. A phase shifter, electrically connected to a hydrophone, is used to perform phase delay processing on acoustic electrical signals to obtain delayed acoustic electrical signals. The multiplier, electrically connected to the phase shifter and the seismic wave sensor, is used to perform multiplication operations on the delayed acoustic wave electrical signal and the seismic wave electrical signal to obtain a product signal; An integrator, connected to the multiplier, is used to integrate the product signal within a preset working period to obtain a correlation function value between the acoustic signal and the seismic signal. and A comparator, connected to the integrator, is used to compare the correlation function value with a preset environmental noise reference threshold, and based on the comparison result, to determine whether there is an underwater vehicle target, so as to realize the detection of underwater vehicle targets.

2. The underwater vehicle detection system based on acoustic and seismic signals for shallow sea environments according to claim 1, characterized in that, Also includes: The first amplification and filtering circuit and the second amplification and filtering circuit, wherein... The first amplification and filtering circuit is located between the hydrophone and the phase shifter, and is used to amplify and filter the acoustic electrical signal of the hydrophone to obtain a conditioned acoustic electrical signal; the phase shifter receives the conditioned acoustic electrical signal and performs phase delay processing on the conditioned acoustic electrical signal. The second amplification and filtering circuit is located between the seismic wave sensor and the multiplier. It is used to amplify and filter the seismic wave electrical signal from the seismic wave sensor to obtain a conditioned seismic wave electrical signal. The multiplier performs a multiplication operation on the delayed acoustic wave electrical signal and the conditioned seismic wave electrical signal.

3. The underwater vehicle detection system based on acoustic and seismic signals for shallow sea environments according to claim 1, characterized in that, Also includes: A bottom-mounted instrument compartment serves as an installation platform for the detection system and is submerged on the seabed; the hydrophone is installed on the external top surface of the bottom-mounted instrument compartment, and the seismic wave sensor is installed on the internal bottom surface of the bottom-mounted instrument compartment.

4. The underwater vehicle detection system based on acoustic and seismic signals for shallow sea environments according to claim 3, characterized in that, The phase shifter introduces a time delay based on the acoustic electrical signal. The time delay for: ； in, To detect the radius of the area, The propagation velocity of the shear wave in the seismic wave is denoted as . This represents the speed at which sound waves travel in seawater.

5. The underwater vehicle detection system based on acoustic and seismic signals for shallow sea environments according to claim 4, characterized in that, The phase shifter adjusts the introduced time delay. By controlling the radius R of the detection area, a ring-shaped detection area centered on the bottom-mounted instrument compartment is formed underwater.

6. The underwater vehicle detection system based on acoustic and seismic signals for shallow sea environments according to claim 4, characterized in that, The relevant function value for: ； in, It is a seismic wave electrical signal. It is a delayed acoustic wave electrical signal, where T is the preset working period and t is the time variable.

7. The underwater vehicle detection system based on acoustic and seismic signals for shallow sea environments according to claim 1, characterized in that, The comparator outputs a decision signal indicating the presence of an underwater vehicle target when the correlation function value is greater than the preset environmental noise reference threshold.

8. The underwater vehicle detection system based on acoustic and seismic signals for shallow sea environments according to claim 1, characterized in that, The hydrophone includes a piezoelectric ceramic transducer for converting underwater acoustic wave signals into electrical acoustic wave signals in the form of electrical charges; the seismic wave sensor includes a piezoelectric accelerometer for converting seabed seismic wave signals into electrical seismic wave signals in the form of electrical charges.

9. The underwater vehicle detection system based on acoustic and seismic signals for shallow sea environments according to claim 1, characterized in that, The first and second amplification and filtering circuits have the same configuration and both include a high-pass filter.

10. A method for underwater vehicle detection based on acoustic and seismic signals in shallow sea environments, comprising: Step 1: Use a hydrophone to receive the sound wave signals propagating in the seawater from the underwater vehicle and convert them into acoustic electrical signals; Step 2: Use a seismic wave sensor to receive the seismic wave signals formed in the seabed medium due to the propagation of mechanical waves radiated by underwater vehicles through the liquid-solid coupling between seawater and the seabed medium, and convert them into seismic wave electrical signals. Step 3: Apply a time delay to the acoustic signal using a phase shifter. ; Step 4: Multiply the delayed acoustic signal and the seismic signal using a multiplier; Step 5: Integrate the product signal using an integrator within a preset working period T to obtain the correlation function value between the acoustic signal and the seismic signal; Step 6: Compare the cross-correlation function value with a preset environmental noise reference threshold, and based on the comparison result, determine whether there is an underwater vehicle target, so as to realize the detection of underwater vehicle targets.

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