Method for improving anti-detection ability of underwater equipment using hydrophones

Abstract

The present invention belongs to the field of underwater detection technology and relates to a method for improving the anti-detection ability of underwater equipment by using a hydrophone, which includes: the underwater equipment enters the water and is first powered on to work, and then the hydrophone is powered on to work; the hydrophone enables an active sonar system to actively detect surrounding targets. When the hydrophone detects an opponent's signal, it stops the active sonar detection and enables a passive sonar system to passively receive the opponent's signal; the hydrophone analyzes the frequency of the opponent's signal; the motor in the underwater equipment is turned on to make the underwater equipment float to the water surface, and the detected opponent information is reported to the ground receiving shore station. During the floating process of the underwater equipment, the working frequency of the motor is intermittently adjusted to switch between the single frequency and multiple frequencies of the opponent's signal. The present invention solves the problem that the underwater equipment is easily captured by the opponent when it emergently floats up after the hydrophone carried by the underwater equipment detects the opponent's signal, and improves the anti-detection ability of our underwater equipment.

Description

Technical Field

[0001] The present invention belongs to the technical field of underwater detection, and particularly relates to a method for improving the anti-detection ability of underwater devices by using hydrophones. Background Technique

[0002] Underwater devices widely used in marine environment monitoring include buoys, moored buoys, submersibles, underwater gliders, etc. Among them, many buoys are profiling buoys, which use buoyancy drive to achieve an autonomous process of diving, depth-fixed drifting, ascending for CTD measurement, surface communication, and then diving again, that is, periodically making up-and-down ocean profiles. They can carry different types of sensors (such as CTD, DO, CO2, etc.) to achieve profiling measurement of marine environmental elements. The data collected by the buoys can be transmitted to the ground receiving shore station through the satellite communication system; moored buoys are located entirely below the water surface and are fixed at specific positions by mooring systems. By installing sensors at different depths, they can achieve full-depth, fixed-point, long-term, continuous, multi-level, and multi-element synchronous observations, with advantages such as good concealment and being not easily damaged.

[0003] The above-mentioned underwater devices usually have the ability to dive and surface. When hydrophones for underwater acoustic detection and reception are installed on the underwater devices, they can play various key roles in the ocean; such as underwater communication monitoring of underwater opponent targets, mine detection, marine bioacoustic research, marine environment monitoring, seabed topography mapping, etc. Specifically, a hydrophone is a transducer that converts underwater acoustic signals into electrical signals and has wide applications in fields such as underwater detection. Hydrophone detection is divided into active sonar detection and passive sonar detection; active sonar detection is that the active sonar system generates electrical signals through a transmitter, converts the electrical signals into acoustic signals by a transducer and emits them into the water. When the sound wave encounters a target object, it will be reflected back. The reflected sound wave is received by the transducer and converted into an electrical signal. The receiver amplifies and processes the signal, and finally determines information such as the position, distance, speed, and shape of the underwater target based on information such as the time difference and frequency shift between the transmitted and received signals; passive sonar detection is that the passive sonar system mainly relies on the sounds emitted by underwater targets themselves, such as the mechanical noise and propeller noise of ships, the sounds of marine organisms, etc. The hydrophone receives these sound signals and analyzes and processes them to determine information such as the azimuth and type of the underwater target, and the passive sonar system itself does not emit sound waves.

[0004] When a hydrophone is mounted on an underwater device for detecting underwater opponent targets, the hydrophone is usually turned on underwater, and active sonar detection or passive sonar detection methods are used to monitor the surrounding targets in the ocean. When detecting devices such as the opponent's torpedoes, underwater vehicles, submarines, etc., the underwater device needs to quickly surface to the sea surface and report the opponent's information to the ground receiving shore station by means of drones or satellite communication, etc. However, there is a serious problem with this method. When the underwater device quickly surfaces, it is necessary to turn on devices such as the motor inside the underwater device, and the motor will generate noise during operation, which is extremely easy to be captured by the opponent, resulting in the opponent quickly slipping away. Even worse, the opponent captures the position of our device and interferes or destroys it. Summary of the Invention

[0005] In view of the deficiencies in the related art, the present invention provides a method for improving the anti-detection ability of underwater devices using hydrophones, aiming to solve the problem that the hydrophones carried by underwater devices are easily captured by opponents when the underwater devices quickly surface after detecting opponent signals, and improve the anti-detection ability of our underwater devices.

[0006] The present invention provides a method for improving the anti-detection ability of underwater devices using hydrophones, including the following steps:

[0007] S1. Mount the hydrophone on the underwater device;

[0008] S2. The underwater device enters the water and first powers on and works, and then the hydrophone powers on and works;

[0009] S3. The hydrophone enables the active sonar system to actively detect the surrounding targets; when the hydrophone detects an opponent signal, stop the active sonar detection and enable the passive sonar system to passively receive the opponent signal;

[0010] S4. The hydrophone analyzes the frequency of the opponent signal;

[0011] S5. Turn on the motor inside the underwater device to make the underwater device float to the water surface, so as to report the detected opponent information to the ground receiving shore station; during the floating process of the underwater device, intermittently adjust the working frequency of the motor to switch between the single frequency and multiple frequencies of the opponent signal frequency.

[0012] In some of these embodiments, in step S5, when the underwater device starts to float, the intermittent adjustment of the motor working frequency is carried out according to the following steps:

[0013] S51. Adjust the working frequency of the motor to be equal to the frequency of the opponent signal and delay for seconds;

[0014] S52. Adjust the working frequency of the motor to a multiple frequency of the opponent signal frequency and delay for seconds;

[0015] S53. Repeat steps S51 - S52 until the underwater device floats to the water surface;

[0016] wherein, the number of delay seconds and are both random numbers.

[0017] In some embodiments, the multiple frequency is the double frequency or the triple frequency.

[0018] In some embodiments, the number of delay seconds is calculated according to the following steps:

[0019] C1. Whenever the adjustment of the motor operating frequency is completed, sort all the spectral noises monitored by the hydrophone at this time from small to large, and sequentially mark them with , calculate the difference between two adjacent noises according to formula (1) , and calculate the difference between two adjacent according to formula (2) ; wherein, is the total number of spectral noises; ; ;

[0020] (1);

[0021] (2);

[0022] C2. Starting from , sequentially determine whether satisfies and , wherein, is the noise mean value, calculated according to formula (3); when meets the requirements, then mark the value at this time as , and use as the spectral reference point of the spectral noise monitored by the hydrophone that exceeds the surrounding environmental noise;

[0023] (3);

[0024] C3. Calculate the standard deviation of the noise signal intensity exceeding the spectral reference point of the surrounding environmental noise according to formula (4);

[0025] (4);

[0026] C4. In step S51, when the operating frequency of the motor is adjusted to be equal to the frequency of the opponent signal, first calculate and , and then calculate the delay seconds according to Equation (5) ; in step S52, after adjusting the operating frequency of the motor to a multiple frequency of the opponent signal frequency, first calculate through steps C1 - C3 and , and then calculate the delay seconds according to Equation (6) ; where is a random number between the numerical values ;

[0027] (5);

[0028] (6).

[0029] In some embodiments, in step S5, the operating frequency of the motor is controlled in a PWM manner; whenever the adjustment of the motor operating frequency is completed, the rotation speed of the motor is also adjusted by adjusting the PWM duty cycle ; the PWM duty cycle is calculated according to Equation (7), where is the preset period of the PWM signal;

[0030] (7).

[0031] In some embodiments, the underwater device is a buoy; before performing step S5, first judge the current working state of the buoy; if the buoy is in a hovering state or a diving state, first stop the current working state of the buoy and then change to a floating state; if the buoy is in a floating state, continue to float.

[0032] In some embodiments, the underwater device is a submersible buoy; when performing step S5, the submersible buoy directly changes from an anchored state to a floating state.

[0033] Based on the above technical solutions, the method for improving the anti-detection ability of an underwater device using a hydrophone in the embodiments of the present invention, through the combined application of active sonar detection and passive sonar detection by the hydrophone, dynamically changing the motor frequency to a single frequency or multiple frequencies of the opponent signal during the upward floating process of the underwater device, and dynamically adjusting the motor speed, etc., solves the problem that when the hydrophone carried by the underwater device detects the opponent signal and the underwater device emergently floats upward, it is easily captured by the opponent due to the operation of the motor, and improves the anti-detection ability of our underwater device. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of this application. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0035] Figure 1 Schematic diagram of various underwater devices equipped with hydrophones when underwater;

[0036] Figure 2 Flowchart of the method for improving the anti-detection ability of underwater devices using hydrophones according to the present invention;

[0037] Figure 3 Flowchart of intermittently regulating the working frequency of the motor in step S5 of the present invention. Detailed implementation manners

[0038] Next, the technical solutions in the embodiments will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0039] In the description of the present invention, it should be understood that the terms "center", "lateral", "longitudinal", "upper", "lower", "top", "bottom", "inner", "outer", "left", "right", "front", "rear", "vertical", "horizontal", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus cannot be construed as a limitation on the present invention.

[0040] In the description of the present invention, it should be noted that unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected, or indirectly connected through an intermediate medium, and can be the internal communication of two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0041] Referring to Figures 1 - 3 as shown, the present invention provides a method for improving the anti-detection ability of underwater devices using hydrophones, and the method includes the following steps:

[0042] S1. Mount the hydrophone on an underwater device, as Figure 1 shown; the underwater device has the ability to dive and surface, including but not limited to profile drifters, deep-sea profile drifters, air-dropped profile buoys, deep-sea moorings, unmanned underwater vehicles, manned underwater vehicles, underwater gliders, etc.

[0043] S2. The underwater device enters the water and first powers on and works, and then the hydrophone powers on and works.

[0044] S3. The hydrophone enables the active sonar system to actively detect surrounding targets; when the hydrophone detects the opponent's signal, it immediately deactivates the active sonar system, that is, stops active sonar detection, so as to avoid being detected by the opponent or arousing the opponent's alertness, and then enables the passive sonar system to passively receive the opponent's signal without actively emitting signals.

[0045] Further explanation: Active sonar detection has the advantage of high detection accuracy, especially strong detection ability for stationary targets, but it is easy to be exposed because it actively emits signals; passive sonar detection has the advantage of good concealment because it only receives signals, and has good detection effect on dynamic targets, but it cannot directly measure the distance and is relatively difficult to detect silent targets; therefore, through the combined application of active sonar detection and passive sonar detection, the opponent's target can be quickly detected, and then the opponent's target can be better detected covertly.

[0046] S4. The hydrophone analyzes the frequency of the opponent's signal; the analysis method is well-known to those skilled in the art and will not be elaborated here.

[0047] S5. Turn on the motor inside the underwater device, and the motor starts to work to make the underwater device quickly float to the water surface, so as to report the detected opponent information to the ground receiving shore station; it should be noted that the opponent information such as the opponent's signal and signal frequency obtained by the hydrophone is stored in the communication module of the underwater device. After the underwater device floats to the water surface, the communication module of the underwater device reports the opponent information to the ground receiving shore station through a drone or satellite.

[0048] Further explanation: During the floating process of the underwater device, intermittently adjust the working frequency of the motor inside the underwater device to make the working frequency of the motor switch between the single frequency (i.e., the same frequency) and the multiple frequencies of the opponent's signal, that is, dynamically change the working frequency of our underwater device motor; therefore, even if the opponent's detection device detects the noise signal generated by the motor during the floating of our underwater device, it will be the harmonic frequency of the opponent's own signal frequency or multiple frequencies, and then the detected signal of ours will be regarded as irrelevant noise and discarded; thus, it is beneficial for our underwater device to quickly float to the water surface to report the opponent information without the opponent's perception and seize the opportunity.

[0049] In the above-described exemplary embodiments, while the underwater device is operating normally, through the combined application of active sonar detection and passive sonar detection by the hydrophone, the opponent's target can be quickly detected, and the opponent's target can be covertly detected, and then the opponent's signal frequency can be analyzed. During the upward floating process of the underwater device, by dynamically changing the motor frequency to a single frequency or multiple frequencies of the opponent's signal frequency, even if the opponent's detection device detects the noise signal generated by the motor during the upward floating of our underwater device, it is very difficult to distinguish whether it is the frequency or harmonic generated by itself, so it is difficult to identify our underwater device. Therefore, the possibility of our underwater device being captured by the opponent during the upward floating process due to the motor operation is avoided, and the anti-detection ability of our underwater device is significantly improved.

[0050] Reference Figures 1 - 3 As shown, in some embodiments, in step S5, when the underwater device starts to float upward, the intermittent regulation of the motor operating frequency in the underwater device is carried out according to the following steps:

[0051] S51. Adjust the operating frequency of the motor to be equal to the frequency of the opponent's signal, and delay for seconds, that is, the motor in the underwater device operates at the same frequency as the opponent, and make the underwater device float upward for seconds;

[0052] S52. Adjust the operating frequency of the motor to a multiple frequency of the opponent's signal frequency, and delay for seconds, that is, the motor in the underwater device operates at a frequency several times that of the opponent, and make the underwater device float upward for seconds;

[0053] S53. Repeat steps S51 - S52 until the underwater device floats to the water surface;

[0054] Among them, the delay seconds and are both random numbers.

[0055] The above-described exemplary embodiments refine the specific means of intermittent regulation of the motor operating frequency; through the motor frequency switching and the random delay setting after switching, the signal recognition and tracking logic of the opponent's detection device are disrupted and confused, effectively reducing the risk of being discovered and locked by the opponent, providing a reliable concealment guarantee for the upward floating of our underwater device, and further improving the anti-detection ability of our underwater device.

[0056] In some embodiments, the multiple frequency is a double frequency or a triple frequency.

[0057] In some embodiments, the calculation of the delay seconds is carried out according to the following steps:

[0058] C1. Whenever the adjustment of the motor operating frequency is completed, all the spectral noises monitored by the hydrophone at this time are sorted from small to large, and are sequentially marked with in decibels, where is the total number of spectral noises monitored by the hydrophone at this time.

[0059] Calculate the difference between two adjacent noises according to Equation (1) , and calculate the difference between two adjacent according to Equation (2) ; where ; ;

[0060] (1);

[0061] (2).

[0062] C2. Starting from , sequentially determine whether satisfies and , where is the noise mean value, calculated according to Equation (3);

[0063] (3);

[0064] When satisfies and , then mark the value at this time as , and use as the spectral reference point of the spectral noise monitored by the hydrophone that exceeds the ambient noise.

[0065] C3. Calculate the standard deviation of the noise signal intensity that exceeds the spectral reference point of the ambient noise according to Equation (4);

[0066] (4).

[0067] C4. In step S51, when the operating frequency of the motor is adjusted to be equal to the frequency of the opponent's signal, first calculate and at the current motor operating frequency through steps C1 - C3, and then calculate the delay seconds according to Equation (5); where is a random number between the values , is the total number of spectral noises monitored by the hydrophone in step C1;

[0068] (5).

[0069] In step S52, after adjusting the operating frequency of the motor to a multiple frequency of the opponent signal frequency, first calculate the and at the current motor operating frequency through steps C1 - C3, and then calculate the delay seconds according to formula (6) ; where is a random number between the numerical values , and is the total number of spectral noises monitored by the hydrophone in step C1;

[0070] (6).

[0071] In the above - mentioned schematic embodiments, signals exceeding the ambient noise can be accurately found, and values of the exceeding part are taken. The larger the exceeding value , that is, the stronger the detected opponent signal, it proves that the opponent is closer to us. The calculated delay seconds and have a relatively long duration, that is, the number of frequency conversions is reduced; the smaller the exceeding value , that is, the weaker the detected opponent signal, it proves that the opponent is farther from us. The calculated delay seconds and have a relatively short duration, that is, the number of frequency conversions is increased; taking a random number for in formula (5) and formula (6) discretizes the algorithm of this scheme, limits the maximum period value and period range of the motor frequency switching, and avoids the too - long duration of the delay seconds and .

[0072] In some embodiments, in step S5, the operating frequency of the motor is controlled in a PWM manner; specifically, the operating frequency of the local motor is controlled by using the STM32 PWM (Pulse Width Modulation) method; the control method of the motor operating frequency is briefly introduced below.

[0073] In the timers of STM32, the frequency of the PWM signal is jointly determined by the timer clock source frequency ftimer, the prescaler coefficient PSC (Prescaler), and the auto-reload value ARR (Auto Reload Register). The timer clock source usually comes from the system clock or other clock sources. For example, the system clock of STM32 is fsys. First, the clock source fsys is divided by the prescaler PSC to obtain the actual timer clock source frequency ftimer, and its calculation formula is: ftimer = fsys / (PSC + 1); then, the timer counter counts at the frequency of ftimer. When the value of the counter reaches the auto-reload value ARR, the counter will restart from 0 and complete one cycle. Therefore, the period T of the PWM signal is T = (ARR + 1) / ftimer, and the frequency f = ftimer / (ARR + 1).

[0074] To change the frequency f of the PWM, it can be achieved by adjusting the prescaler coefficient PSC and the auto-reload value ARR. When PSC is increased, the timer clock source frequency ftimer decreases, and the frequency f of the PWM signal also decreases accordingly; when ARR is increased, with the timer clock source frequency ftimer remaining unchanged, the time required for the counter to count to ARR becomes longer, the PWM period becomes longer, and the frequency f decreases; conversely, decreasing PSC or ARR can increase the frequency f of the PWM. In practical applications, according to the specific system clock source frequency ftimer and the required PWM frequency f, the prescaler coefficient PSC and the auto-reload ARR are adjusted flexibly. After the PWM frequency f is applied to the motor, it controls the working frequency of the motor inside the underwater device.

[0075] In step S5, whenever the adjustment of the motor working frequency is completed, the motor speed is also adjusted by adjusting the PWM duty cycle The PWM duty cycle refers to the ratio of the high-level time to the period in the pulse wave, expressed as a percentage; the PWM duty cycle is calculated according to Equation (7), where is the preset period of the PWM signal;

[0076] (7).

[0077] The above schematic embodiments refine the adjustment method of the motor speed and the calculation method of the PWM duty cycle; The larger it is, that is, the stronger the detected opponent signal, which proves that the opponent is closer to us. The calculated duty cycle is smaller, that is, the motor speed is adjusted slower to avoid being detected by the opponent and improve the safety and concealment of the underwater device when surfacing. The smaller it is, that is, the weaker the detected opponent signal is, which proves that the opponent is farther away from us, and the calculated duty cycle is larger. That is, the motor speed is adjusted faster to make the underwater device float up quickly. Thus, during the floating process of the underwater device, the motor speed is dynamically adjusted according to the strength of the opponent signal, so that the underwater device can float to the water surface quickly and safely.

[0078] In some embodiments, the underwater device is a buoy. Before performing step S5, first judge the current working state of the buoy. If the buoy is in a hovering state or a diving state, first stop the current working state of the buoy and then switch to the floating state. If the buoy is in the floating state, continue to float. In some embodiments, the underwater device is a submersible buoy. When performing step S5, the submersible buoy directly changes from the anchored state to the floating state.

[0079] Through the description of multiple embodiments of the method for improving the anti-detection ability of underwater devices using hydrophones according to the present invention, it can be seen that the present invention has at least one or more of the following advantages:

[0080] 1) While the underwater device is working normally, through the combined application of active sonar detection and passive sonar detection by the hydrophone, the opponent target can be quickly detected, and the opponent target can be detected covertly, and then the opponent signal frequency can be analyzed;

[0081] 2) During the floating process of the underwater device, by dynamically changing the motor frequency to a single frequency or multiple frequencies of the opponent signal frequency, even if the opponent detection device detects the noise signal generated by the motor during the floating of our underwater device, it will be regarded as the noise generated by the opponent's own signal frequency or harmonic frequency and will not be concerned, avoiding the possibility of our underwater device being captured by the opponent due to the motor working during the floating process;

[0082] 3) During the floating process of the underwater device, through the random delay setting after the motor frequency is switched, the signal recognition and tracking logic of the opponent detection device is disrupted and confused, effectively reducing the risk of being discovered and locked by the opponent, and further improving the anti-detection ability of our underwater device;

[0083] 4) During the floating process of the underwater device, by adjusting the PWM duty cycle according to the strength of the opponent signal, the dynamic adjustment of the motor speed is realized, so that the underwater device can float to the water surface quickly and safely;

[0084] 5) In summary, the present invention can solve the problem that the underwater device is easily captured by the opponent due to the motor working when the hydrophone carried by the underwater device detects the opponent signal and the underwater device floats up urgently, significantly improve the anti-detection ability of our underwater device, and is conducive to our underwater device floating to the water surface quickly and safely without the opponent's perception to report the opponent information in time.

[0085] Finally, it should be noted that the embodiments in this specification are described in a progressive manner. Each embodiment focuses on the differences from other embodiments. For the same or similar parts among the embodiments, reference can be made to each other.

[0086] The above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that: modifications can still be made to the specific implementation manners of the present invention or equivalent replacements can be made to some technical features without departing from the spirit of the technical solutions of the present invention, and they should all be covered within the scope of the technical solutions claimed by the present invention.

Claims

1. A method for improving the anti-detection capability of underwater equipment using a hydrophone, characterized in that: The following steps are involved: S1. Load the hydrophone onto the underwater equipment; S2, the underwater equipment enters the water and is powered on first, and then the hydrophone is powered on; S3, the hydrophone activates the active sonar system to actively detect surrounding targets; when the hydrophone detects the opponent's signal, the active sonar detection is stopped and the passive sonar system is activated to passively receive the opponent's signal; S4, the hydrophone analyzes the frequency of the opponent's signal; S5, turning on the motor in the underwater device to make the underwater device float to the surface of the water, so as to report the detected opponent information to the ground receiving shore station; During the surfacing process of the underwater device, the operating frequency of the motor is intermittently regulated to switch between a single frequency and a multiple frequency of the opponent signal frequency; the intermittent regulation of the operating frequency of the motor is performed according to the following steps: S51, adjusting the operating frequency of the motor to be equal to the frequency of the opponent's signal, and delaying Second; S52, adjusting the operating frequency of the motor to a multiple of the opponent's signal frequency, and delaying Second; S53, repeating steps S51 to S52 until the underwater device floats to the surface of the water; The delay time is in seconds. and are all random numbers; the delay seconds are calculated according to the following steps: C1. Whenever the motor operating frequency is adjusted, all the spectrum noises monitored by the hydrophone are sorted from small to large, and the noises are sorted in order of Mark and calculate the difference between two adjacent noises according to formula (1) , according to formula (2) to calculate the adjacent The difference ;in, is the total amount of spectral noise; ； ； (1)； (2)； C2, from Start by judging Is it satisfied? and ,in, is the noise mean, calculated according to formula (3); when When the requirements are met, Values ​​are marked as ,Will As a frequency spectrum reference point exceeding the surrounding environment noise in the frequency spectrum noise monitored by the hydrophone; (3)； C3. Calculate the standard deviation of the noise signal strength exceeding the reference point of the ambient noise spectrum according to formula (4) ; (4)； C4. In step S51, after the operating frequency of the motor is adjusted to be equal to the frequency of the opponent signal, the operation frequency of the motor is calculated through steps C1 to C3. and , and then calculate the delay seconds according to formula (5) In step S52, after the operating frequency of the motor is adjusted to a multiple of the opponent's signal frequency, the first step is to calculate through steps C1 to C3 and , and then calculate the delay seconds according to formula (6) ;in, For numerical values A random number between (5)； (6)。 2. The method for improving the anti-detection capability of underwater equipment using a hydrophone according to claim 1, characterized in that: The multiple frequency is double frequency or triple frequency.

3. The method for improving the anti-detection capability of underwater equipment using a hydrophone according to claim 1, characterized in that: In step S5, the operating frequency of the motor is controlled by PWM. After the adjustment of the operating frequency of the motor is completed, the PWM duty cycle is adjusted. The speed of the motor is adjusted in the manner of: Calculate according to formula (7), where is the period of the preset PWM signal; (7)。 4. The method for improving the anti-detection capability of underwater equipment using a hydrophone according to any one of claims 1 to 3, characterized in that: The underwater device is a buoy; before executing step S5, first determine the current working state of the buoy; if the buoy is in a hovering state or a diving state, first stop the current working state of the buoy and then switch to a floating state; if the buoy is in a floating state, continue to float.

5. The method for improving the anti-detection capability of underwater equipment using a hydrophone according to any one of claims 1 to 3, characterized in that: The underwater device is a submerged buoy; when executing step S5, the submerged buoy directly changes from an anchored state to a floating state.

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