480 results about "Hydrophone" patented technology

The invention belongs to the technical field of underwater topographic survey, and particularly relates to an underwater topographic survey system based on multi-sensor data fusion, which comprises a multi-beam sounding sonar, a laser radar sensor, an ultrasonic bathymeter, an optical fiber hydrophone, a side scan sonar and a data processing and fusion module. The invention further relates to an underwater topographic survey method, and the method adopts a Kalman filtering data fusion algorithm. According to the invention, multiple types of sensors such as a multi-beam sounding sonar, a laser radar, an ultrasonic bathymeter, an optical fiber hydrophone, a side-scan sonar and the like are integrated into the same system for the first time, and an acoustics, optics and mechanics multi-dimensional data acquisition system is formed.

The invention relates to the technical field of underwater acoustic engineering and ocean exploration, in particular to a multi-channel underwater acoustic signal transmitting and measuring system and a signal processing method, which are used for solving the problems that the existing multi-channel underwater acoustic signal processing generally depends on fixed threshold detection or simple time sequence alignment, and the signal processing efficiency is low. The problem that residual vibration, local noise abrupt change or multipath reverberation is easily misjudged as an effective first arrival signal in a complex underwater environment due to the fact that the influence of the physical response characteristic of a transducer on emission time calibration is not considered and effective verification on whether a candidate arrival structure accords with a sound wave propagation physical rule is lacked is solved. According to the invention, a multi-channel energy time sequence and hydrophone space geometrical relationship is fused through an underwater sound propagation initial physical judgment module, a judgment mechanism is constructed based on distance-time consistency of sound propagation, and self-consistent verification is realized by combining a cross-channel arrival sequence and sound velocity constraint. And the accuracy, the robustness and the physical interpretability of the judgment of the effective launching time of the underwater sound are obviously improved.

The invention provides a spherical complex vibration type vector hydrophone based on an MEMS accelerometer, and relates to the technical field of underwater acoustic signal detection, and the spherical complex vibration type vector hydrophone comprises an MEMS accelerometer, a built-in core, a piezoelectric ceramic spherical shell, a sound transmission sealing shell, and a suspension ring. The MEMS accelerometer is orthogonally arranged in the built-in core; the built-in core is nested in the lower half ball of the piezoelectric ceramic spherical shell; the upper hemisphere of the perforated piezoelectric ceramic spherical shell is adhered to the upper edge of the built-in core; the sound transmission sealing shell coats the piezoelectric ceramic spherical shell through an encapsulation process; the suspension ring is bonded with the sound transmission sealing shell, and the hydrophone is suspended on the fixing support for use. The composite hydrophone can detect sound pressure signals and vibration velocity signals at the same position underwater, solves the problem of omnidirectional detection of the composite hydrophone on the sound pressure signals, and has the advantages of small size, simple structure, high reliability, wide application range and the like.

The invention discloses a laser-induced sound cross-medium communication method based on passive relay PWM modulation, and relates to the technical field of cross-medium communication. The method comprises the following steps: adjusting the laser pulse width of to-be-sent information, and carrying out PWM modulation to obtain a PWM sequence; inputting the modulation sequence into a laser driving control module, and driving a laser to emit a laser pulse signal with specific pulse width change; laser energy is focused on the surface of a passive relay material, and when laser pulses with different pulse widths act on the material, different numbers of sound signals can be excited and generated; a receiving end captures sound signals propagating across media through a hydrophone, and demodulates the sound signals according to a mapping relation between pulse width and the number of the sound signals; and finally, original information is restored, so that cross-medium communication from air to water is completed. According to the invention, PWM modulation is combined with a passive relay material, and the system has the remarkable advantages of no need of underwater power supply, simple structure, high reliability and the like.

The present invention discloses a cross-sound zone sound source localization method using dual hydrophones in a deep-sea environment, comprising: step 1: using the dual hydrophones to receive broadband signals radiated by a sound source in a specified sea area, and simultaneously using other hydroacoustic equipment to obtain environmental parameters of the sea area; step 2: using a time-spectral energy accumulation method to extract the arrival times of different sound lines from the received signal of one of the hydrophones, and estimating two multipath time delay differences; step 3: using a sound field calculation model BELLHOP to simulate two multipath time delay differences in different sound zones when the sound source is at different grid virtual points; step 4: calculating a cost function, and estimating the position of a target sound source; step 5: repeating steps 2 and 4 for the signal received by another hydrophone, and estimating the position of the target sound source; and step 6: performing a similarity analysis on four estimation results obtained by positioning the two hydrophones, and taking the average of the two estimation results with the greatest similarity as the final sound source position estimation result.

Systems and Methods for Labelling Sonar Data A computer-implemented method is provided of automatically labelling passive sonar hydrophone data for use as a supervised learning dataset, comprising: for a selected passive sonar hydrophone: obtaining actual received sound data throughout a detection time-period, obtaining a hydrophone location, and determining a maximum detection radius around the hydrophone location; retrieving timestamped vessel data associated with vessels within the maximum detection radius during the detection time-period, the timestamped vessel data comprising for each vessel: vessel location information and vessel identification information; determining, for a particular vessel identification information, an estimated received sound metric for each vessel throughout the detection time-period, based on the timestamped vessel data; labelling the actual received sound data, the labels including the particular vessel identification information and being associated with times during the detection time-period where the estimated received sound metric is above a threshold.

The utility model relates to an electrical system for a submarine sediment acoustic in-situ measurement device, which belongs to the technical field of submarine measurement electrical control and comprises a shipborne part and an underwater part which are connected through a photoelectric composite cable. The shipborne part is used for controlling the work of the underwater part; wherein the underwater part comprises a plurality of modular units which are connected through standardized interfaces, and the modular units comprise a main control unit, an acoustic measurement unit, a power amplifier unit, a transducer unit, a hydrophone unit and a power supply unit. According to the electrical system for the acoustic in-situ measurement device for the submarine sediments, through modular design, the adaptability and universality of the electrical system are improved; and moreover, a worker can add corresponding units or modules according to measurement requirements, so that the expandability of the system is improved, and different measurement scenes and requirements are better met.

The utility model belongs to the technical field of hydrophones, and particularly discloses a hydrophone filled with silicone oil, which comprises a first shell, a second shell, a printed circuit board assembly and a cable, the first shell is made of an underwater sound transmission material, one end of the first shell is connected with the second shell, a closed cavity is formed between the interior of the first shell and the second shell, and the closed cavity is filled with silicone oil; the printed circuit board assembly is integrated with a pre-amplifier chip and an MEMS chip used for sensing sound signals, and the printed circuit board assembly is arranged in the closed cavity and soaked in the silicone oil. The cable passes through the second housing, and the wiring end of the cable is connected with the board body of the printed circuit board assembly. According to the hydrophone filled with the silicone oil, the product structure is simplified, the number of parts is greatly reduced, and production and processing are facilitated; silicone oil is poured into the closed cavity, so that the printed circuit board assembly is completely soaked in the silicone oil, and meanwhile, a pre-amplifier is arranged in the hydrophone, so that the sensitivity and hydrostatic pressure resistance of the hydrophone are improved.

The present invention discloses an adaptive underwater low-frequency underwater acoustic transducer impedance matching device, which comprises a main control circuit, which sends a sweep frequency signal to an underwater power amplifier in a configuration stage and performs impedance matching calculation according to an electrical signal collected by an impedance detection circuit; in an adaptive operation stage, calculates an expected sound source response curve according to the transmitting power of the underwater power amplifier, obtains a power deviation in combination with the sound source signal collected by a hydrophone, obtains an impedance angle according to the electrical signal collected by the impedance detection circuit, and then performs impedance matching modification; an impedance array circuit realizes a circuit with adjustable inductance and inductance parameters to output the maximum power of the underwater acoustic transducer; in the configuration stage, the impedance detection circuit collects electrical signals of the impedance array circuit at various frequency points and transmits them to the main control circuit; in the adaptive operation stage, the electrical signals of the transmitting frequency points are collected and transmitted to the main control circuit; and an impedance switching circuit selectively connects the capacitors and inductors in the impedance array circuit by a relay according to the matching impedance of the main control circuit.

The invention discloses a rock sample crack measurement method and system based on the seismoelectric effect, and relates to the field of rock sample crack measurement, and the method comprises the steps: building a rock sample crack measurement system based on the seismoelectric effect, arranging hydrophones and electrodes in an array in a vertical direction, collecting sound field and electric field signals at the two sides of a rock sample, and carrying out the measurement of the rock sample crack. And then comparing and analyzing the electric field response difference between the complete rock sample and the crack-containing rock sample by adopting a sound source and electrode synchronous movement scanning technology so as to identify the crack interface. According to the rock sample crack measurement method based on the seismoelectric effect, the seismoelectric signals excited by the double interfaces are captured at the same time through the electrodes on the two sides, and effective identification of the crack interface is achieved through the signal amplitude difference, the attenuation characteristic and the waveform characteristic.

The invention discloses a water supply pipeline leakage identification method based on a hydrophone signal under a noise background, and the method comprises the steps: collecting a Mel spectrogram of the hydrophone signal of a preset water supply pipeline under different working conditions, marking the noise background of the Mel spectrogram, inputting the Mel spectrogram into an improved ESRGAN network based on the marking, and carrying out the recognition of the leakage of the water supply pipeline. The method comprises the following steps: inputting a single-channel de-noised Mel spectrogram into an AlexNet classification network to obtain a fixed-size feature graph of leakage features, flattening and activating the fixed-size feature graph to obtain a leakage identification classification result, taking leakage identification classification as a training label, and performing five-fold cross validation training on the classification network by using a training set, a validation set and the training label to obtain a leakage identification classification result. And obtaining a leakage identification model, and outputting a leakage identification result based on the leakage identification model. According to the method, effective denoising is carried out through multi-direction convolution and residual dense blocks, the classification precision and generalization ability are improved in combination with the improved AlexNet network, and meanwhile good interpretability is achieved.

The invention provides a resonant bionic cilia vector hydrophone based on a quartz tuning fork and an underwater acoustic system, and relates to the technical field of micro-mechanical electronics. A vibration detection mechanism in the hydrophone comprises two quartz tuning forks located in a first axial direction and two quartz tuning forks located in a second axial direction, the first axial direction is perpendicular to the second axial direction, one end of each quartz tuning fork is fixed, and the other end of each quartz tuning fork is connected with a vibration acquisition mechanism; and the vibration acquisition mechanism is connected with the quartz tuning forks and is used for driving the two quartz tuning forks in the same axial direction to generate symmetrical frequency deviation under the action of sound waves. According to the embodiment of the invention, the excellent frequency stability and strain sensitivity of the double-end fixed tuning fork can be utilized to realize efficient conversion of sound signals and generation of corresponding electric signals, digital signal output can be conveniently realized, high-sensitivity detection of the sound signals can be effectively realized, the influence of common-mode signals can be inhibited, the anti-interference performance is good, and the detection precision is high. And the underwater sound detection effect is greatly improved.

The utility model provides a piezoelectric MEMS accelerometer and a piezoelectric vector hydrophone, and belongs to the technical field of sound wave sensing. The piezoelectric MEMS accelerometer comprises a base body, wherein the middle part of the base body is provided with a cylindrical through area; the mass block is cylindrical and is arranged in the through area, and an annular area is formed between the mass block and the base body; the multiple cantilever beams are evenly arranged in the annular area in the circumferential direction of the mass block, the two ends of each cantilever beam are connected with the mass block and the base body respectively, each cantilever beam comprises a substrate layer, a lower electrode layer, a piezoelectric layer and an upper electrode layer which are sequentially stacked, a through hole used for exposing the lower electrode layer is formed in the piezoelectric layer, and a through hole used for exposing the upper electrode layer is formed in the upper electrode layer. The upper electrode layer comprises an inner electrode and an outer electrode which are arranged at intervals in the radial direction of the mass block, and the inner electrode and the outer electrode are located in opposite cantilever beam deformation areas. The piezoelectric MEMS accelerometer provided by the utility model is adjustable in sensitivity and flexible to use.

The invention relates to an underwater acoustic transducer which can resist long-term work under the condition of deep sea high water pressure, is high in sensitivity, wide in band, low in noise and high in electromagnetic interference resistance, is used in deep sea detection and communication sonar systems, and solves the problems that an existing underwater acoustic transducer is low in receiving sensitivity along with increase of water pressure, poor in long-term work corrosion resistance and low in cost. And noise of the hydrophone and external electromagnetic interference cause signal interference. A novel high polymer material is adopted to reduce acoustic impedance, enhance the coupling effect with seawater and reduce sound wave reflection loss. Meanwhile, by optimizing the internal structure design, the stability and durability of the device under the deep sea high pressure condition are ensured. And the hydrophone shell is made of an alloy material with good corrosion resistance, so that the hydrophone shell is prevented from being corroded in a marine environment for a long time, and the service life is prolonged. By improving the design and manufacturing process of the transducer, the transducer can cover acoustic signals in a broadband range, and the multi-spectrum requirement of a deep sea detection and communication system is met. Advanced noise suppression technology and shielding measures are adopted, noise of the hydrophone is effectively reduced, external electromagnetic interference resistance is improved, and it is guaranteed that high-quality acoustic data are obtained in a complex deep sea environment. In conclusion, the invention provides the hydrophone which is excellent in working performance in the deep sea high-pressure environment, has the characteristics of high sensitivity, broadband response and the like, can effectively resist the influence of a severe environment, and provides key technical support for deep sea detection and a communication sonar system.

The invention relates to a single hydrophone distance-depth positioning method based on multi-OFDM symbol joint processing, which is suitable for two-dimensional positioning of an underwater sound source. The method comprises: emitting, by a sound source, a plurality of OFDM symbols comprising pilot frequencies; the single hydrophone receives the signal and constructs a multi-measurement vector (MMV) model based on pilot frequency; a maximum likelihood method is adopted to estimate multi-path propagation time delay; and constructing a cost function in combination with the geometric model, and inverting the horizontal distance and depth of the sound source. The method does not need a multi-array element structure, has the advantages of high positioning precision, strong robustness, simple deployment and the like, and is particularly suitable for resource-limited platforms such as UUVs, buoys and distributed underwater nodes. Pool experiments and multiple application verifications show that the scheme of the invention shows excellent airspace resolution and background noise suppression performance in an underwater sound multipath environment, and is suitable for multiple types of underwater passive positioning scenes.

The utility model belongs to the technical field of vibration and noise reduction, and relates to an external interference noise suppression module integrated in a hydrophone. The module comprises a high-characteristic-impedance metal round rod and two low-characteristic-impedance rubber round rods, the rubber round rods are connected to the two ends of the metal round rod, the cross sectional areas of the metal round rod and the rubber round rods for transmitting interference elastic waves are the same, and the lengths of the two rubber round rods are different, so that half-wavelength total transmission is restrained. The interference longitudinal wave passes through the noise suppression module, most energy is lost, and the interference noise is effectively suppressed. The utility model has the effects and benefits that the external interference noise is reduced, and the anti-interference level of the hydrophone is improved. The device is widely applied to noise suppression design of the hydrophone, is simple in structure, is convenient to integrate in the hydrophone, and can stably work in seawater for a long time.

The invention discloses a low-noise audio acquisition circuit based on an underwater glider. The low-noise audio acquisition circuit comprises a controller module used for controlling all modules and data transmission; the data storage module is used for storing effective data transmitted by the controller module and the processor module; the data interaction module is used for collecting state information of the underwater glider and sending the state information to the data storage module; the data processing module comprises an operational amplifier, a gain amplifier, a fully differential amplifier and a hydrophone for collecting audio information; audio information collected by the hydrophone is firstly subjected to preliminary amplification and impedance matching through the operational amplifier, then enters the gain amplifier to be subjected to flexible gain adjustment and signal optimization, is further amplified through the fully differential amplifier and inhibits common-mode interference, and finally, the audio information is transmitted to the analog-to-digital converter to complete analog-to-digital conversion. The processor module processes the received audio information and transmits the processed audio information to the data storage module.

The invention discloses a wide dynamic underwater sound acquisition method suitable for an underwater glider and a hydrophone, and the method comprises the steps: configuring a unique hydrophone into four parallel band-pass filtering and amplifying circuits, each band-pass filtering and amplifying circuit having different acquisition frequency bands; after the underwater glider enters water, underwater sound collection is carried out based on the only installed hydrophone, and underwater sound signals of four collection frequency bands are collected at the same time through four parallel band-pass filtering and amplifying circuits. Through four paths of differentiated gains and frequency segmentation, the wide dynamic full frequency band can be covered, the dynamic range is improved, a single hydrophone integrates four channels, cables and installation space among multiple devices are saved, and the underwater glider compact layout is adapted; the channels are activated on demand, the total power consumption can be reduced, and the endurance time is prolonged. Under the conditions of low power consumption and limited volume of the underwater glider, wide dynamic range signal acquisition can be realized, and signals can be processed in real time.

A system and corresponding method perform underwater distance determination. The system comprises a hydrophone unit (HU) located at a reference point, a first sensor module (SM), and a second SM, each located underwater. The first SM sends a first sensor-to-hydrophone data signal and a first sensor-to-hydrophone synchronization signal to the HU and sends a first inter-sensor synchronization signal to the second SM. The second SM sends, responsive to receipt of the first inter-sensor synchronization signal from the first SM, a second inter-sensor synchronization signal to the first SM. The second SM sends a second sensor-to-hydrophone data signal to the HU. The first SM measures a time value representing a total travel time of the first inter-sensor synchronization signal from the first SM and second inter-sensor synchronization signal from the second SM and calculates a distance between the first SM and second SM based on the time value measured.

The invention provides a high-sensitivity deepwater micro-electro-mechanical hydrophone, belongs to the field of underwater acoustic transducers, and solves the problem that an existing hydrophone cannot give consideration to sensitivity and deepwater work at the same time. The sensor comprises a sensitive chip, a silicon backing layer and a gas-liquid balance module, in the sensitive chip, an upper molybdenum electrode layer, a piezoelectric aluminum nitride film and a lower molybdenum electrode layer are sequentially located in an upper insulating layer, and a silicon device layer is located between the upper insulating layer and a lower insulating layer; the silicon backing layer is fixedly connected with the lower insulating layer, a backing liquid cavity and a micro-connection channel are arranged in the silicon backing layer, and the micro-connection channel is communicated with the backing liquid cavity; the gas-liquid balance module is fixedly connected to the silicon backing layer, a gas-liquid balance micro-channel is arranged in the gas-liquid balance module, the gas-liquid balance micro-channel is filled with liquid, one end of the gas-liquid balance micro-channel is communicated with the micro-connection channel, the gas-liquid balance module is provided with an elastic sealing layer, and the elastic sealing layer is arranged on the silicon backing layer. The elastic sealing layer is used for sealing the other end of the gas-liquid balance microchannel. The pressure-resistant performance can be improved, and the sensitivity is not degraded.

The invention discloses a sensitization type MEMS hydrophone and a preparation method thereof. The sensitization type MEMS hydrophone comprises a sensitization type elastic substrate, a lower electrode assembly, a PZT piezoelectric sensitive assembly, an upper electrode assembly and an insulating material layer. The lower electrode assembly, the PZT piezoelectric sensitive assembly and the upper electrode assembly are sequentially arranged on the surface of the sensitization type elastic substrate from bottom to top, and the insulating material layers are arranged on the surface of the sensitization type elastic substrate, in the lower electrode assembly, in the PZT piezoelectric sensitive assembly and in the upper electrode assembly respectively. Therefore, the interior of the lower electrode assembly, the interior of the PZT piezoelectric sensitive assembly and the interior of the upper electrode assembly are insulated. The lower electrode assembly and the upper electrode assembly are led out through conductive cables and connected in series, electric signals generated by the PZT piezoelectric sensitive assembly are output through the lower electrode assembly and the upper electrode assembly, and signal measurement is achieved through a circuit and a test system. The MEMS hydrophone has the advantages of being compact in structure, high in sensitivity, high in anti-interference capacity and the like, and the application range of the MEMS hydrophone is widened.

The utility model relates to the technical field of scanning arrays, in particular to a near-field holographic scanning array which comprises a vertical pipe, a plug block, a plurality of supports, a plurality of auxiliary frames and a plurality of hydrophones. The supports are detachably arranged at the lower end of the vertical pipe through the plug blocks and distributed around the axis of the vertical pipe. The plurality of hydrophones are distributed on the support through the auxiliary frame, the auxiliary frame is connected with the support in a sliding mode, and the near-field holographic scanning array can be conveniently disassembled, assembled and transported through the near-field holographic scanning array.

The invention provides a self-calibration high-strength optical fiber hydrophone based on an end face reflection principle, and relates to the technical field of hydrophones. Comprising the steps that a laser light source emits a first laser beam, and an optical fiber isolator suppresses reflection and outputs a second laser beam. And the optical fiber variable optical attenuator adjusts the incident power and outputs a third laser beam. The 1 * 2 optical fiber coupler splits the laser beam into a fourth laser beam and a fifth laser beam, and the first photoelectric detector monitors power. The optical fiber circulator transmits the fifth laser beam to the optical fiber sensing module, generates reflected light and transmits the reflected light to the second photoelectric detector, and the second photoelectric detector converts the reflected light into a voltage signal. The data acquisition card acquires the signals, the signal demodulation processing unit calculates sound pressure sensitivity according to a mapping relation formula of the voltage signals and sound pressure, and the standard voltage module provides standard voltage for the data acquisition card. The problem that in the prior art, a high-strength hydrophone cannot be repeatedly used and cannot be self-calibrated after being damaged is solved.

The invention provides a deep-sea high hydrostatic pressure resistant ionic polymer hydrophone structure and an assembly method, and belongs to the technical field of underwater acoustic sensing, the deep-sea high hydrostatic pressure resistant ionic polymer hydrophone structure comprises an upper shell, a shielding copper net, a substrate, a circuit board, a lower shell, a dry state sensitive film, a screw, a pressing plate, a positive electrode and a negative electrode, the shielding copper net is arranged at the top of the lower shell, a dry-state sensitive film is fixed on the front surface of the substrate, a circuit board is adhered to the back surface of the substrate, the substrate is inserted into the lower shell, a cavity at the lower part of the substrate is encapsulated and cured, and after the pressure-resistant shell is packaged, water is injected into the shell of the ionic polymer hydrophone and defoaming is performed. And finally, sealing and curing the water injection hole of the lower shell by using a sealant to form the ionic membrane polymer hydrophone. According to the invention, perfect packaging, low sound wave loss and good low-frequency sensitivity of the hydrophone in a deep water condition can be ensured, and the hydrophone has important popularization and application values for the work of the hydrophone in a deep sea level.

The invention discloses a water supply pipeline leakage positioning method, which comprises the following steps: arranging hydrophones at two ends of a water supply pipeline to be detected, collecting sound wave signals of the water supply pipeline to be detected, carrying out band-pass filtering pretreatment on the sound wave signals, and decomposing noisy signals into a series of intrinsic mode functions through variational mode decomposition; dividing the intrinsic mode functions into noise dominant components and signal dominant components by calculating sample entropy values of the intrinsic mode functions; performing wavelet threshold denoising processing on the noise dominant component, and reconstructing the processed noise component and the signal dominant component to obtain a denoised signal; and performing generalized cross-correlation operation on the denoised signal by adopting an improved weighting function to obtain a time difference estimated value. According to the invention, through improved time delay estimation after precise component classification, a coherence function is introduced, and through enhancement of a high-coherence frequency band and suppression of a low-coherence frequency band, the positioning precision in a low signal-to-noise ratio environment is significantly improved, the anti-interference capability is enhanced, and the method adapts to a multi-scene pipe network environment.

The invention discloses a float type MEMS vector hydrophone system, and belongs to the technical field of underwater acoustic detection and ocean sensing. The system comprises a buoy, an MEMS vector hydrophone unit, a signal conditioning circuit, an electronic compass module and an output interface unit. The MEMS vector hydrophone unit is installed at the bottom of the buoy, the signal conditioning circuit and the electronic compass module are installed inside the buoy, and the output interface unit is installed at the top of the buoy and comprises two independent watertight plugging interfaces which output analog and digital signals respectively. The system is high in structural integration level, high in attitude sensing capability, excellent in signal quality and suitable for application scenes such as ocean buoy laying, underwater array deployment and distributed underwater acoustic observation.

The invention relates to a wave node tube and method for measuring a vibration velocity vector sensor, the wave node tube is composed of a cylindrical tube body, four standard pressure-resistant hydrophones and four high-pressure-resistant transmitting transducers, the four high-pressure-resistant transmitting transducers are of the same batch and the same model and are arranged oppositely in pairs, and the sound axes are perpendicular to each other; the standard pressure-resistant hydrophones are positioned on a sound axis and are arranged in a central symmetry manner; when in use, a measured sensor is in the center of the corrugated tube. The node tube can be used for measuring a vibration velocity vector sensor, and during measurement, the push-pull effect is generated by controlling the vibration phase of the transducer, so that the radiation impedance during vibration of the transducer is greatly reduced; and finally, by controlling the vibration amplitude of the transducer, the direction of a vibration velocity field in the tube can be controlled, and a pressure-resistant rotating device does not need to be developed.

The application discloses a net cage fish feeding state recognition method based on high-low frequency dual hydrophones, comprising: deploying a low-frequency hydrophone and a high-frequency hydrophone at the same monitoring point in the net cage, and continuously collecting underwater acoustic signals jointly; performing time-frequency analysis on the collected underwater acoustic signals, extracting low-frequency energy features and high-frequency pulse features respectively, and constructing a joint feature sequence for feeding state discrimination; performing sequence feature calculation on the joint feature sequence, and recognizing the fish feeding state according to the judgment baseline and the state discrimination rule, including before feeding, during feeding and after feeding. The application realizes accurate recognition of the net cage fish feeding state through high-low frequency dual hydrophone cooperative sensing, improved time-frequency analysis, dual threshold pulse detection and joint state discrimination.

The invention relates to the technical field of MEMS (Micro Electro Mechanical System) sensors, and discloses a cap cilia MEMS vector hydrophone, which comprises cap cilia used for sensing sound to generate vibration for transmission; the center mass block is arranged at the bottom of the cap-shaped cilium, the cap-shaped cilium is located in the center of the top of the center mass block, and the center mass block is used for receiving vibration transmitted by the cap-shaped cilium and diffusing the vibration; the four cantilever beams are fixedly connected to the front face, the rear face, the left face and the right face of the center mass block respectively and used for receiving vibration transmitted by the center mass block and generating deformation. And the square frame is arranged outside the four cantilever beams. The cap-shaped cilia has a larger sound wave receiving area than the traditional cilia, the cap-shaped structure can generate larger on-beam stress on the cantilever beam when receiving sound pressure signals with the same size, so that the piezoresistor generates larger resistance change, the hydrophone is simple and mature in manufacturing process, the cap-shaped cilia does not need secondary integration, and the cost is low. And the consistency of the hydrophone is ensured.

An embedded hydrophone sensor in a hydraulic body such as pipe, fitting, or flow meter (PIPE) that includes a thinned "pipe" wall membrane of radius R, that has a profile that provides sufficient flexural deflection under pressure with effective thickness t_pipe. A piezo-electric element connected to the pipe membrane using a glue or mechanical means, while the piezo membrane thickness should be less than pipe_membrane thickness multiplied by (maximum_strain_Piezo / maximum_strain_Pipe).