Cross-domain wireless acoustic communication system and method based on acoustic holography

Abstract

The invention discloses a wireless cross-domain acoustic communication system and method based on acoustical holography. The acoustical holography device used for cross-domain acoustic communication is composed of a single-layer acoustical holography phase plate, an array transducer and a camera vision module, each array element of the array transducer has a connected state and a non-connected state, and after a communication coding signal transmitted in water is received, the single-layer acoustical holography phase plate is connected with the camera vision module through the single-layer acoustical holography phase plate. The transducer array elements at the corresponding positions can be sequentially gated according to the sequence, dynamic regulation and control of an incident sound field are realized, the incident sound field passes through the single-layer holographic phase plate and is subjected to phase modulation to be transmitted to a water-air interface, the interface is deformed under the action of acoustic radiation force, and the camera vision module is used for capturing, analyzing and decoding the water surface deformation condition, so that the water surface deformation condition is obtained. And information wireless receiving across a water-air interface is completed. According to the invention, underwater information can be directly transmitted to the air, the equipment is simple, the requirement on the relative position of transmitting-receiving equipment is not strict, and the device is suitable for a liquid environment with any temperature, salinity and density.

Description

Technical Field

[0001] The present invention relates to a cross - domain communication technology, specifically a cross - domain wireless acoustic communication system and method based on acoustic holography. Background Art

[0002] Although traditional wireless communication technologies (such as radio frequency, light, acoustic communication, etc.) can achieve efficient real - time communication between multiple underwater anchors, due to the huge physical property differences between the upper and lower regions of the water surface, traditional communication means cannot achieve effective real - time communication between underwater sensors and air nodes. Therefore, water - air cross - domain communication remains a difficult problem in the field of marine communication. The breakthrough of this technology will provide rich and valuable data resources for research fields such as marine biology, climate change, and seabed resources. Especially between dynamic underwater devices such as submersibles and autonomous underwater vehicles (AUVs) and air devices (such as drones or satellite communication), maintaining real - time, efficient, and stable communication. Therefore, realizing real - time, efficient, and highly secure wireless cross - domain transmission of underwater information has important scientific significance and practical application value.

[0003] Currently, sonar - based acoustic communication technology is a commonly used means for underwater communication, which has advantages such as long propagation distance and stable transmission. However, the acoustic information transmitted underwater still cannot be directly transmitted to the air domain. This is mainly because sound waves will undergo severe reflection at the water - air interface and it is difficult to directly establish communication with air nodes. To solve this problem, some researchers have achieved effective transmission of underwater information through methods such as arranging underwater relay devices, cross - domain vehicles, and acoustic - RF signal collaborative communication. However, the above - mentioned technologies still have significant limitations: low communication efficiency, strong dependence on equipment, susceptibility to waves and water currents, and high environmental requirements. Therefore, how to achieve real - time communication and data transmission in the upper and lower water areas while minimizing signal relay devices has become a technology that urgently needs to be broken through. Summary of the Invention

[0004] In order to overcome the dilemma that existing underwater acoustic communication means cannot achieve cross - domain information transmission, and aiming at the deficiencies of poor stability, low security, and complex equipment in the existing optical - acoustic, acoustic - electromagnetic and other composite means for cross - domain information transmission, the present invention provides a solution for a cross - domain wireless acoustic communication system and method based on dynamic acoustic holography.

[0005] Existing technologies are difficult to effectively transmit wireless signals of sound waves and electromagnetic waves such as transducers and sonars in different medium domains. For example, it is difficult to continue to effectively transmit signal information from the water domain to the air domain, or from the air domain to the water domain. Underwater ripples cannot be transmitted to the water surface. The present invention designs a cross - domain wireless acoustic communication system and method for signal propagation between different medium domains based on an acoustic holographic structure, solving the technical problem of cross - domain wireless acoustic communication.

[0006] It is known that ultrasound, as a mechanical wave, will cause compressive-tensile changes in the background domain material when interacting with matter. Therefore, when acting on the water-air interface, it will cause the liquid surface to deform. Among them, the present invention uses a dynamic holographic sound field to dynamically control the deformation of the liquid surface, and visualizes the deformation of the liquid surface in the air domain in a visual manner, realizing end-to-end wireless reading of underwater information in the air domain and completing cross-domain wireless acoustic communication. Thus, based on the background technology, the present invention utilizes the mechanical characteristics of sound waves and their ability to cause deformation by acoustic radiation force on the liquid surface to carry out cross-domain wireless acoustic communication across the water-air interface. By directly, efficiently and real-time reading the deformation information of the liquid surface in the air domain using a visual method and decoding the transmission information content of underwater devices, the communication stability in a water surface fluctuation environment can be significantly improved, without the need for equipment to frequently surface, and the requirement for neutrality is not high.

[0007] Based on the incident sound field spatial multiplexing technology, the present invention further realizes the dynamic control of the holographic sound field and its dynamic liquid surface deformation by combining a partitioned electrode array transducer with incident sound field encoding and modulation characteristics and a conventional fixed holographic phase plate, and uses a camera vision module to realize fast and efficient reading and writing of underwater information, and compiles the text information transmitted underwater. In summary, by dynamically and highly resolving the control of the sound field and its deformation at the water-air interface, cross-domain reading of underwater information can be realized, effectively overcoming the propagation barrier of traditional acoustic communication technology at the water-air interface.

[0008] The technical solution of the present invention is as follows: 1. A cross-domain wireless acoustic communication system based on acoustic holography: It includes a partitioned electrode array transducer, placed underwater in the liquid, for transmitting acoustic wave signals to a single-layer acoustic holographic phase plate; It includes a single-layer acoustic holographic phase plate, also placed underwater in the liquid and above the partitioned electrode array transducer, and arranged close to the water surface of the liquid surface, for receiving acoustic wave signals and feeding them back to form a liquid surface pattern on the water surface of the liquid surface; It includes a camera vision module, placed in the air domain and facing upwards the water surface of the liquid surface above the single-layer acoustic holographic phase plate, for visually capturing and processing the liquid surface pattern on the water surface of the liquid surface, and analyzing the liquid surface pattern to obtain the information of the acoustic wave signal.

[0009] The probe end faces of the single-layer acoustic holographic phase plate and the partitioned electrode array transducer are arranged in parallel with an axial spacing distance along the propagation direction.

[0010] The spacing distance between the probe end faces of the single-layer acoustic holographic phase plate and the partitioned electrode array transducer can be on the order of several centimeters, and the specific distance is dozens to hundreds of times the working wavelength.

[0011] It also includes an information emission point and a switch control module. The information emission point can be placed under the liquid surface. The information emission point is electrically connected to the partitioned electrode array transducer through the switch control module. The original excitation signal is emitted by the information emission point, and the partitioned electrode array transducer is controlled by the switch control module to emit acoustic signals corresponding to the liquid surface pattern.

[0012] There are piezoelectric devices inside the partitioned electrode array transducer. The piezoelectric devices evenly discretize one side electrode of themselves into multiple independent array elements through a dicing machine. All array elements are externally connected to a switch circuit, and the switch circuit encodes and controls the electrical connection and disconnection of each array element, thereby realizing the dynamic encoding and regulation of the incident acoustic wave distribution under the input of a single-channel electrical signal, and further enabling the subdivision of the liquid surface pattern display for different displays at different positions.

[0013] The liquid surface deformation caused by the acoustic radiation force is completely determined by the spatial acoustic field distribution reconstructed under the combined action of the single-layer acoustic holographic phase plate and the array transducer. During the cross-domain communication process, the single-layer acoustic holographic phase plate remains fixed throughout, while the partitioned electrode array transducer can be dynamically electrically encoded and regulated to realize the dynamic reconstruction of the incident acoustic field.

[0014] After the incident acoustic field passing through the single-layer acoustic holographic phase plate reconstructs the target acoustic field at the water-air interface, based on the action of the acoustic radiation force, the liquid surface vibrates, showing the corresponding water surface ripple situation. At this time, the height of the water surface ripple bulge is related to the acoustic energy distribution of the ultrasonic field, so the regulation of the water surface ripple can be realized by adjusting the acoustic field distribution at the water-air interface.

[0015] Considering that the change of the water surface ripple will cause different light reflections, a camera vision module is arranged above the water surface to realize the real-time dynamic capture of the water surface ripple change, and the information encoded in the water surface ripple is decoded by the method of template matching; therefore, the text information transmitted underwater can be read in real time, efficiently and wirelessly by capturing the ripple map on the water-air interface in real time.

[0016] The single-layer acoustic holographic phase plate is made of a polymer by 3D printing. One side is an uneven surface and the other side is a flat surface.

[0017] The specific polymer adopts a conventional photosensitive resin material and is prepared by traditional 3D printing technology. The single-layer acoustic holographic phase plate is mainly composed of a substrate and an uneven structure located on the substrate.

[0018] II. A cross-domain wireless acoustic communication method for a cross-domain wireless acoustic communication system, the method includes: The partitioned electrode array transducer is excited to emit incident ultrasonic waves, which propagate to the single-layer acoustic holographic phase plate and undergo phase modulation, and then continue to propagate forward to the interface between different medium domains, such as the water-air interface. The interface between different medium domains undergoes different surface deformations under the action of acoustic radiation force, and holographic sound field reconstruction is realized on the interface. Meanwhile, the camera vision module above the interface visually captures, collects, and decodes the surface deformation of the interface, directly extracts and reads the underwater acoustic wave information on the liquid surface, and finally realizes end-to-end cross-domain wireless acoustic communication between the underwater device and the above-water device on the liquid surface.

[0019] At different times, the partitioned electrode array transducer sequentially emits different incident ultrasonic waves according to the time sequence. After being acted on by the single-layer acoustic holographic phase plate, different surface deformation patterns are formed on the interface according to the time sequence. The camera vision module visually collects the patterns of the surface deformation of the interface according to the time sequence to obtain visual images, and image analysis and processing are performed on the visual images collected according to the time sequence to obtain dynamic information.

[0020] The incident ultrasonic waves emitted by the partitioned electrode array transducer act on the interface through the single-layer acoustic holographic phase plate to form a surface deformation pattern encoded by a "seven-segment tube" pattern. The "seven-segment tube" pattern encoding has the characteristic of time-division multiplexing, specifically: The "seven-segment tube" pattern is an "8" character. Each side segment of the "8" character is used as a sub-unit for encoding. According to the encoding relationship in the following table, the combination relationship of whether all different sub-units are displayed is controlled, and different letter and number information is correspondingly presented on the interface: A B C D E F G H I Upper right vertical line Upper left and upper right vertical lines Upper and lower horizontal lines Upper right vertical line + middle horizontal line Upper right and lower right vertical lines Upper horizontal line + lower right vertical line Upper right and lower left vertical lines Upper and lower horizontal lines + lower right vertical line Upper, middle, and lower horizontal lines J K L M N O P Q R Upper left, upper right, and lower right vertical lines Middle horizontal line + upper right and lower right vertical lines Upper horizontal line + upper right and lower right vertical lines Upper horizontal line + upper left and upper right vertical lines Upper horizontal line + lower left and lower right vertical lines Upper and middle horizontal lines + upper left and upper right vertical lines Upper left, upper right, lower left, and lower right vertical lines Upper, middle, and lower horizontal lines + upper right vertical line Upper right, lower left, and lower right vertical lines S T U V W X Y Z 0 Upper and middle horizontal lines + upper right and lower right vertical lines Upper left and upper right vertical lines + middle and lower horizontal lines Upper and middle horizontal lines + upper left and lower right vertical lines Upper and lower horizontal lines + upper right and lower right vertical lines Upper and lower horizontal lines + upper left and upper right vertical lines Upper right, lower left, and lower right vertical lines + lower horizontal line Upper and lower horizontal lines + upper right and lower left vertical lines Upper and middle horizontal lines + upper left, upper right, and lower right vertical lines Upper, middle, and lower horizontal lines + upper right and lower left vertical lines 1 2 3 4 5 6 7 8 9 Upper, middle, and lower horizontal lines + upper right and lower right vertical lines Upper, middle, and lower horizontal lines + upper left and upper right vertical lines Upper horizontal line + upper left, upper right, lower left, and lower right vertical lines Middle horizontal line + upper left, upper right, lower left, and lower right vertical lines Upper and lower horizontal lines + upper left, upper right, and lower left vertical lines Middle and lower horizontal lines + upper left, upper right, and lower left vertical lines Upper and middle horizontal lines + upper left, upper right, lower left, and lower right vertical lines Upper and lower horizontal lines + upper left, upper right, lower left, and lower right vertical lines Upper, middle, and lower horizontal lines + upper left, upper right, lower left, and lower right vertical lines A total of 36 characters from letter A to Z and numbers 0 to 9 mentioned above can be variably converted to form a codebook for encoding and decoding.

[0021] The time-division multiplexing characteristic means that in the time dimension, it is possible to selectively choose whether to display or not.

[0022] According to the solution of the present invention, through actual testing, it can be achieved that an "8" character is displayed and presented in about 0.3s to 0.5s, and thus the frame rate is 2 to 3 character information per second.

[0023] In the solution of the present invention, a "seven-segment tube" pattern with the time-division multiplexing characteristic of the liquid surface deformation is specially designed, which can be combined with the system to perform cross-domain communication more efficiently.

[0024] The liquid surface deformation can be regarded as composed of seven independent sub-units using the "seven-segment tube" pattern with time-division multiplexing characteristics. Each side segment of the "8" character is used as a sub-unit and can be selectively and dynamically displayed during the entire communication process. After the camera vision module collects and decodes the combined pattern displayed on the water surface, it can read the text information transmitted underwater in real time.

[0025] The spatial selective display of the seven sub-units of the "seven-segment tube" pattern combines 36 different patterns, which are used to encode 26 letters and 10 digits, realizing the encrypted cross-domain transmission of text information, and there is no need to control the direction of visual acquisition. Visual acquisition is uniquely corresponding in any direction.

[0026] The "seven-segment tube" pattern contains 7 different independent binary coding units. All these binary coding units can form a total of 2 7 to the power of possible situations. However, many of these patterns are symmetric and similar from multiple perspectives. The present invention only sets 36 different pattern encodings, and these patterns are uniquely corresponding, and there is no possibility of being similar or repeated.

[0027] The fixed single-layer acoustic holographic phase plate integrates the fusion phase information corresponding to the "seven-segment tube" pattern in its phase distribution. Each sub-unit of the "seven-segment tube" pattern is time-division gated by the partitioned electrode array transducer; and, after the camera vision module captures the image of the liquid surface pattern on the water surface, it then uses a convolutional neural network model to identify and process the image to obtain the "seven-segment tube" pattern information therein.

[0028] In specific implementation, the position between the partitioned electrode array transducer and the single-layer acoustic holographic phase plate is kept fixed, and the relative distance from the water surface is kept as constant as possible.

[0029] After the partitioned electrode array transducer receives the information of any underwater target in-situ in the form of 0 / 1 data stream, it automatically transforms into a transducer array excitation coding array, and triggers the generation of a corresponding incident sound field. After being regulated by the single-layer acoustic holographic phase plate, a corresponding "seven-segment tube" situation is reconstructed on the water surface, and after being received by the camera vision module in the air domain, information decoding and reading are carried out.

[0030] In summary, the implementation process of the water-air interface cross-domain wireless acoustic communication based on dynamic acoustic holography of the present invention can be divided into the following three processes: (1) Underwater information encryption: First, according to the number of array elements N×N of the electrode partitioned array transducer, 36 letter and digit text information are respectively encoded into N 2The binary data stream of bits. Then, according to the text information to be transmitted by the underwater base station, the corresponding binary data stream is sent to the electrode partition array transducer to control the excitation of each element.

[0031] (2)Dynamic excitation of the ultrasonic field and interface reconstruction: For the binary data stream received by the electrode partition array transducer, with N 2 bits of data as one character, it is first expanded into an N×N 0 / 1 matrix data and input into the switching system to control the excitation / turn-off of each element of the partitioned electrode array transducer, thereby exciting the generation of the target incident sound field. Then, the excited incident sound field continues to be transmitted to the single-layer acoustic holographic phase plate, where phase modulation is realized and it continues to propagate to the far field. The target sound field will be reconstructed at the water-air interface, and due to the acoustic radiation force, the liquid surface will deform, showing different "seven-segment tube" patterns.

[0032] (3)Reading of the water surface ripple information in the air domain: Then, using the camera vision module arranged in the air domain, the ripple situation on the liquid surface is collected and input into the trained convolutional neural network. The captured ripple data is subjected to pattern matching. By matching with the ripple situations corresponding to 36 numbers and text information, the text information transmitted underwater is decoded.

[0033] When a string of text information consisting of m characters is transmitted underwater, the underwater signal transmitting station will transmit a string of m×N 2 binary data stream to the dynamic acoustic holographic device, and encode and convert it into the corresponding m N×N 0 / 1 matrices. The electrode partition array transducer is excited at different frame rates to generate the corresponding incident sound fields. After being combined with the single-layer acoustic holographic phase plate, m corresponding "seven-segment tube" multiplexing patterns are sequentially reconstructed on the liquid surface. The camera vision module in the air domain captures the ripple deformation on the liquid surface frame by frame in real time and decodes and outputs it, and then reads the text information consisting of m characters transmitted by the underwater signal transmitting station, completing the water-air cross-domain wireless acoustic communication.

[0034] To simultaneously achieve the optimized time-division multiplexing coding of 36 letters and digital texts, the specific process is designed as follows: (1)First, divide the "seven-segment tube" pattern into seven independent components, and regard them as seven target sound fields P1 0 ~ P7 0 , which are n×n matrices. Based on the principle of uniform acoustic energy, the electrode partition excitation regions corresponding to each component are selected as evenly as possible, denoted as A1~A7, which are N×N 0 / 1 matrices used to control the point coding of the electrode partition array transducer. Where N<<n.

[0035] (2)Then, the above seven target sound fields P10 ~P7 0 The excitation conditions A1 to A7 of the seven electrode partitions are brought into the multi-plane iterative angular spectrum method to optimize the designed coded phase distribution on the single-layer acoustic holographic phase plate. φ b . The design process of the multi-plane iterative angular spectrum method is divided into a forward propagation process and a backward propagation process.

[0036] Among them, before the iterative optimization starts, the phase distribution on the single-layer acoustic holographic phase plate φ b is set to an arbitrary value (n×n pixels), and the partitioned electrode array transducer plane z with an excitation sound field distribution of = 0 p 0i ( x , y , z = 0) = A i is extended to an n×n matrix, and the spectral distribution on the plane of = 0 is calculated through Fourier transform: z = 0) = ∫∫ P 0i ( k x , k y , z = 0)d p 0i ( x , y , z = 0)d x d y ; and after multiplying this spectrum by the phase factor H ( k x , k y , z = l ) = e^( jk z l ), its spectral distribution extrapolated along the positive z-axis to the incident side plane of the single-layer acoustic holographic phase plate z = l is calculated: P ’ i ( k x , k y , z = l ) = P 0i ( k x, k y , z =0)* H ( k x , k y , z = l ), where k z = ( k 0 2 - k x 2 - k y 2 ) 1 / 2 . Then, the sound field distribution on the incident side plane of the single-layer acoustic holographic phase plate is obtained through inverse Fourier transform p i ’ ( x , y , z = l ) = ∫∫ P ’ i ( k x , k y , z = l )d k x d k y .

[0037] The forward propagation process of the multi-plane iterative angular spectrum method is as follows: Therefore, the sound field distribution on the transmission side of the single-layer acoustic holographic phase plate can be expressed as: p i ’’ ( x , y , z = l ) = p i ’ ( x , y , z = l ) * e^( jφ b ). Similarly, the spectral distribution of this plane is calculated using Fourier transform: P i ’’ ( k x ,k y , z = l ) = ∫∫ p i ’’ ( x , y , z = l )d x d y , and extrapolate further along the positive z - axis to the target plane z = L the spectral distribution on: P i ’’’ ( k x , k y , z = L ) = P i ’’ ( k x , k y , z = l ) * H ( k x , k y , z = L-l ), and then calculate using the inverse Fourier transform z = L the sound field distribution on: p i ’’’ ( x , y , z = L ) = ∫∫ P i ’’’ ( k x , k y , z = L )d k x d k y .

[0038] After the forward propagation is completed, the phase on the target image plane z = L on φ i’’’ ( x, y , z = L )= arg ( p i ’’’ ( x , y , z = L )) is reserved, where arg () is the phase extraction function. At the same time, replace its amplitude with the target sound field distribution; obtain z = L the sound field on the plane q i ’’’ ( x, y , z = L )=*e^(j φ i ’’’ ( x, y , z = L ))。

[0039] The backpropagation process is as follows: Calculate the spectral distribution of the target plane z = L by Fourier transform: Q i ’’’ ( k x , k y , z = L )=∫∫ q i ’’’ ( x, y , z = L )d x d y , and then multiply the spectrum by the phase factor H ( k x , k y , z =( l-L ))=e^( jk z ( l-L )) and then calculate its extrapolation along the negative z-axis to the plane z = l on the transmission side of the single-layer acoustic holographic phase plate Q i ’’ (k x , k y , z = l )= Q i ’’’ ( k x , k y , z = L )* H ( k x , k y , z =( l-L ))。The sound field distribution on the transmission side of the single-layer acoustic holographic phase plate is calculated through inverse Fourier transform. q i ’’ ( k x , k y , z = l )=∫∫ Q i ’’ ( k x , k y , z = l )d k x d k y 。And based on the sound field distribution on the incident side of the single-layer acoustic holographic phase plate p i ’ ( x , y , z = l ), the fused phase distribution on the single-layer acoustic holographic phase plate is calculated as: φ 0=∑ arg ( q i ’’ ( k x , k y , z = l )* conj ( p i ’ ( x ,y , z = l ))), where conj () is the conjugate function.

[0040] And perform a binarization operation on the fused phase distribution φ 0, and the updated binary phase distribution is φ b = 0 or π, when cos( φ 0) > 0, φ b = 0; when cos( φ 0) <= 0, φ b = π.

[0041] After approximately 60 forward and backward propagation iterations, the encoded fused phase distribution on the single-layer acoustic holographic phase plate is finally obtained φ b .

[0042] And based on the above encoded fused phase distribution, prepare the single-layer acoustic holographic phase plate. Based on the three-medium theory, set the thickness h 1 and h 2 of the encoded thickness units of the spatial array. The design process is as follows: Set the working frequency to f , and the transmitted sound field after the incident plane wave passes through two encoding units with thicknesses h 1 and h 2 can be expressed as: P 1 = e^ i ( k 0 h 1 ) and P 2 = e^ i ( k 0 h 2 ). And the phase difference between the two should satisfy: φ = arg( P 1 - P 2 ) = π.

[0043] According to the determined unit thicknesses h 1 and h 2Based on the encoded fusion phase distribution φ b Perform 3D printing preparation. Finally, the single-layer acoustic holographic phase plate for incident sound field phase modulation is obtained.

[0044] Meanwhile, the electrode on one side of the conventionally polarized ultrasonic piezoelectric sheet is discretely separated into N×N independent units by a dicing machine. After leading out the leads of each independent area using a flexible circuit board, it is fixed in the housing, and matching layers and backings are deposited on both sides respectively, and then the electrode partition array transducer with N×N independent units is prepared.

[0045] Under actual working conditions, the electrode partition array transducer and the single-layer acoustic holographic phase plate are placed in parallel at a distance of z = l After that, the end of the lead on the flexible circuit board is connected to the switch circuit to realize the electrical coding control of the single-channel input ultrasonic excitation signal, control the on / off of each element, and realize the real-time electrical control of the incident sound field.

[0046] In the present invention, each element of the array transducer has two states: on / non-on. After receiving the communication coding signal transmitted in water, the transducer elements at the corresponding positions can be sequentially selected in order, and the dynamic regulation of the incident sound field can be realized. Then, the regulated incident sound wave continues to propagate forward to the single-layer holographic phase plate and undergoes phase modulation, and further propagates to the water-air interface; under the action of the acoustic radiation force of the plane sound field, the water surface will undergo target deformation. At this time, an image recognition device can be used in the air domain to capture and process the deformation of the water surface, realize the direct reception of underwater information in the air domain, and complete the wireless reception of information across the water-air interface.

[0047] The present invention realizes the dynamic real-time reconstruction of the target plane holographic sound field by using an electrode partition array transducer with the characteristic of spatial multiplexing of the incident sound field and combining it with a conventional acoustic holographic phase plate. Due to its mechanical characteristics, the reconstructed holographic sound field in space will generate corresponding water surface deformation on the liquid surface when acting on the water-air interface. Then, a camera vision module arranged in the air domain above the liquid surface is used to capture the water surface deformation and decode its coding information, thereby realizing the wireless real-time cross-domain reading of underwater information.

[0048] The dynamic acoustic holographic system directly realizes the dynamic regulation of the water surface ripple shape by encoding and controlling the electrode partition array transducer, wirelessly transmits underwater information directly to the air domain, has a compact structure, high resolution, and good real-time performance, can directly read underwater information from any angle through the existing camera vision module, and has strong operability and simple equipment.

[0049] Moreover, in terms of implementation, based on the incident acoustic wave spatial multiplexing technology, an array transducer with electrode partitioning is used to achieve dynamic regulation of the incident sound field under a single-channel ultrasonic signal excitation. It is combined with a fixed holographic phase plate arranged axially in parallel to jointly achieve dynamic reconstruction of the holographic sound field, enabling the liquid surface to show dynamic changes in water ripples. Through time-division multiplexing of each unit part of the "seven-segment tube" pattern, 36 alphabetic and numeric information can be encoded into the ripple situation. And by encoding the excitation regions of each element of the electrode-partitioned array transducer for excitation, the target reproduction of the ripple pattern on the water surface is realized, and the text information transmitted underwater is directly read and decoded using the camera vision module.

[0050] The entire communication process of the present invention includes: underwater information acoustic communication - encoding excitation of the partitioned electrode array transducer - sound field reconstruction on the liquid surface - sound radiation force causing deformation of the liquid surface - identification and decoding by the camera vision system. In summary, based on the above dynamic acoustic holographic device with the ability of dynamic sound field regulation, researchers can simply and conveniently use the visual method to wirelessly and real-time read underwater information, realizing wireless cross-domain acoustic communication between water and air, which is of great significance to fields such as modern ocean research, ocean resource development, and military applications.

[0051] The cross-domain wireless acoustic communication scheme based on dynamic acoustic holography provided by the present invention has the following beneficial effects: (1) Based on the acoustic radiation force, the present invention establishes direct communication between a conventional underwater sonar system and an above-water optical system by deforming the liquid surface by ultrasound as the transmission medium. Wireless cross-domain acoustic communication between underwater and air can be achieved using simple devices.

[0052] The method can realize real-time and efficient air transmission of underwater information without a relay system surfacing, and has the characteristics of high security, high real-time performance, and simple structure, which can effectively promote the development of fields such as ocean resource exploration, deep-sea operations, and salvage.

[0053] (2) The dynamic acoustic holographic system used in the present invention has a compact structure, strong operability, and high reliability. The entire acoustic holographic system only needs to arrange an ultrasonic transducer and an acoustic holographic phase plate in parallel. Under the input of a single-channel ultrasonic signal, rapid changes in the shape of the water surface ripples can be achieved through spatial electrical encoding of each element, and the frame rate can reach tens of thousands of frames. At the same time, using the "seven-segment tube" as the encrypted transmission pattern for text information can realize encrypted transmission of underwater transmission information, which has the advantage of high security.

[0054] The wireless cross-domain acoustic communication device based on acoustic holography proposed by the present invention can directly transmit underwater information into the air. The device is simple and has no strict requirements on the relative positions of the transmitting and receiving devices, and is applicable to liquid environments with arbitrary temperature, salinity, and density. Description of the Drawings

[0055] To more clearly illustrate the embodiments of the present invention and their design solutions, the accompanying drawings required for this embodiment will be briefly introduced below. The accompanying drawings in the following description are only partial embodiments of the present invention. For those of ordinary skill in the art, other accompanying drawings can be obtained based on these drawings without creative efforts.

[0056] Figure 1 It is the schematic diagram of the cross - domain wireless acoustic communication technology based on dynamic acoustic holography for Embodiments 1 and 2 of the present invention.

[0057] Figure 2 It is the sectional electrode array transducer and the preparation flow chart for Embodiments 1 and 2 of the present invention. Among them, (a) shows that the electrode on one side of the piezoelectric sheet is discretized into independent sectional electrodes, (b) shows the flexible circuit board for independently controlling the electrical signal input of each sectional electrode, and (c) shows welding the flexible circuit board to the sectional electrodes. Figure 3 It is the design flow chart of the electrode excitation regions corresponding to each component unit of the "seven - segment display" and the encoded fusion phase distribution design for Embodiments 1 and 2 of the present invention. Among them, (a) shows the electrode regions corresponding to the a - g components of the "seven - segment display", (b) shows that the incident sound field generated by the local excitation of the sectional electrode transducer, after being modulated by the fixed acoustic holographic phase plate, reconstructs the a part of the "seven - segment display" on the target plane, and (c) shows different sectional electrode excitation regions and the target sound field patterns reconstructed by them on the target plane.

[0058] Figure 4 It is the three - dimensional and two - dimensional structure diagrams of the single - layer acoustic holographic phase plate for Embodiments 1 and 2 of the present invention. Among them, (a) shows the three - dimensional structure diagram of the acoustic holographic phase plate, and (b) shows the sectional view of the acoustic holographic phase plate along the A - A plane.

[0059] Figure 5 It is the time - division multiplexing "seven - segment display" patterns corresponding to 36 letters and digital information and their corresponding electrode excitation situations for Embodiments 1 and 2 of the present invention.

[0060] Figure 6 It is the full flow chart of the encoding and air - domain decoding of character information and text information for Embodiments 1 and 2 of the present invention.

[0061] Figure 7 It is the diagram of the holographic sound field reconstruction result and the experimental result of the present invention.

[0062] Figure 8 It is the schematic diagram of the static cross - domain wireless acoustic communication process for the letter "H" in Embodiment 1; Figure 9 It is the schematic diagram of the dynamic cross - domain wireless acoustic communication process for the text data "123HELLO" in Embodiment 2.

[0063] Description of the reference numerals in the drawings: Information emission point 1, switch control module 2, partitioned electrode array transducer 3, single-layer acoustic holographic phase plate 4, camera vision module 5. Detailed implementation manners

[0064] To enable those skilled in the art to better understand the technical solutions of the present invention and to implement them, the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. 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 scope of protection of the present invention.

[0065] In the description of the present invention, it should be understood that the terms "middle", "upper", "lower", "left", "right", "lateral", "longitudinal", "horizontal", "vertical", "axial", "mirror image", "length", "width", "thickness", 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 technical solutions of the present invention and simplifying the description, rather than indicating or implying that the device or equipment referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation of the present invention. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion. In the description of the present invention, unless otherwise specified, the meaning of "a plurality of" is two or more, which will not be elaborated here.

[0066] As Figure 1 shown, the system includes a single-layer acoustic holographic phase plate, a partitioned electrode array transducer 3, and a camera vision module.

[0067] The partitioned electrode array transducer 3 is placed underwater and below the single-layer acoustic holographic phase plate, and is used to emit acoustic wave signals upward to the single-layer acoustic holographic phase plate; upward can be vertically upward or obliquely upward.

[0068] The single-layer acoustic holographic phase plate 4 is placed underwater, above the partitioned electrode array transducer 3 and at a spaced distance, and is arranged close to the water surface, and is used to receive the acoustic wave signals and feedback them to form a liquid surface pattern on the water surface; The camera vision module 5 is placed in the air domain and faces upward the water surface above the single-layer acoustic holographic phase plate 4, and is used to visually capture and process the deformation of the liquid surface pattern on the water surface, and analyze the liquid surface pattern to obtain the information of the acoustic wave signals.

[0069] The camera vision module 5 does not need to be placed parallel to the single-layer acoustic holographic phase plate 4 and the partitioned electrode array transducer 3 underwater, and can usually be placed obliquely, as long as it can capture a complete liquid surface pattern facing upward the water surface above the single-layer acoustic holographic phase plate 4.

[0070] In specific implementation, the single-layer acoustic holographic phase plate 4 and the partitioned electrode array transducer 3 are both placed underwater. The probe end faces of the single-layer acoustic holographic phase plate 4 and the partitioned electrode array transducer 3 are arranged in parallel at an axial interval along the propagation direction. Under their combined action, the holographic sound field reconstruction at the water-air interface and the deformation of the water surface ripples are realized.

[0071] The specific implementation also includes an information emission point 1 and a switch control module 2. The information emission point 1 is electrically connected to the partitioned electrode array transducer 3 through the switch control module 2. The original excitation signal is emitted by the information emission point 1, and the partitioned electrode array transducer 3 is controlled by the switch control module 2 to emit acoustic wave signals corresponding to the liquid surface pattern.

[0072] The partitioned electrode array transducer is used to excite and generate ultrasonic signals. There are piezoelectric devices inside the partitioned electrode array transducer 3. The piezoelectric devices evenly discretize one side electrode of themselves into multiple independent array elements through a dicing machine, and the electrode on the other side remains intact as a whole electrode surface without any treatment. All array elements are externally connected to a switch circuit. Through an external switch system, the gating / turning off of each array element can be independently controlled. Specifically, the switch circuit can encode and control the electrical connection and disconnection of each array element, thereby realizing the dynamic encoding regulation of the incident acoustic wave distribution under a single-channel electrical signal input. Then, the incident sound field excited by the partitioned electrode array transducer is incident on the single-layer acoustic holographic phase plate for spatial phase regulation, and further the display of the liquid surface pattern is subdivided for different displays at different positions.

[0073] The specific implementation is as Figure 2 shown, which is the physical diagram and preparation process of the partitioned electrode transducer 3 with the ability of dynamic regulation of the incident sound field provided by the present invention. Among them, the single-side electrode of the piezoelectric sheet of the partitioned electrode array transducer 3 is discretely separated into N×N independent units by a dicing machine, as Figure 2 in (a), and each electrode area is independently led out through a flexible circuit board as Figure 2 in (b) and then sequentially connected to the switch control module 2 and the ultrasonic excitation signal. Finally, the flexible circuit board is welded to the partitioned electrode as Figure 2 in (c). Furthermore, the on / off of each discrete array element can be encoded and controlled by the switch control module 2 to realize the dynamic regulation of the incident sound field.

[0074] The single-layer acoustic holographic phase plate 4 is made of a polymer by 3D printing. One side is an uneven surface and the other side is a flat surface. And based on the three-medium theory, the thickness of the spatially distributed thickness units matches the frequency, and the transmission phase delay difference between the two (the two units with larger and smaller spatially distributed thicknesses) is exactly equal to π.

[0075] In specific implementation, two types of thickness units with thicknesses of h1 and h2 are arranged in a spatial array on the single-layer acoustic holographic phase plate printed by 3D. Therefore, the acoustic holographic phase plate appears flat on one side and uneven on the other side. Based on the three-medium theory, for two phase modulation units with thicknesses of h1 and h2, when the working frequency is f, the phase difference of the transmitted sound fields corresponds to exactly π. Therefore, spatial coding phase modulation of the incident sound field can be achieved.

[0076] As Figure 3 shown, the "seven-segment tube" pattern for water-air cross-domain communication provided by the present invention is as Figure 3 shown in (c) of

[0077] . Based on the multi-plane iterative angular spectrum method of time-division multiplexing, the electrode excitation regions corresponding to the above seven patterns are designed, denoted as A1~A7, and are all N×N 0 / 1 matrices, where N is the number of columns / rows of the partitioned electrodes. Figure 3 , it is set that the partitioned electrode array transducer 3 and the single-layer acoustic holographic phase plate 4 are respectively located at z =0mm and z=l =50 mm, and the "seven-segment tube" pattern is set at z = L =80 mm, and the sound pressure distributions P1 0 ~ P7 0 (n×n) are respectively as shown on the right side of (a) of Figure 3 . At the same time, the encoded fusion phase distribution φ b on the single-layer acoustic holographic phase plate 4 is initialized to an arbitrary value (n×n), and A1~A7 are also extended to an n×n matrix, where is the resolution of the target sound field, representing the number of rows / columns of the discrete data of the sound wave.

[0078] First, using the forward propagation model, calculate the distribution of the incident sound field incident on the single-layer acoustic holographic phase plate 4 ( z=l =50 mm): Calculate the sound field distribution on the z =0 plane through Fourier transform p 0i ( x , y , z =0)= A i of the spectral distribution P 0i ( k x , k y , z =0)=∫∫ p 0i ( x ,y , z =0)d x d y ; and push the spectrum along the positive z-axis outward to the plane of the single-layer acoustic holographic phase plate 4 z = l= 50 mm incident side, and obtain its spectrum distribution as P ’ i ( k x , k y , z = l ). And obtain the acoustic field distribution on the plane of the single-layer acoustic holographic phase plate through inverse Fourier transform z = l The acoustic field distribution on the incident side is p i ’ ( x , y , z = l )=∫∫ P ’ i ( k x , k y , z = l )d k x d k y .

[0079] Next, based on the above seven incident acoustic field distributions p i ’ ( x , y , z = l ) and the target acoustic field distribution P1 0 ~ P7 0 , use the multi-plane iterative angular spectrum method to design the fusion coding phase on the single-layer acoustic holographic phase plate φ b , and the multi-plane iterative angular spectrum method includes two processes: forward propagation and backward propagation. The specific steps are as follows: S1: The forward propagation process is as follows: The acoustic field distribution on the plane of the single-layer acoustic holographic phase plate 4 z = l= 50 mm transmission side can be expressed as: p i ’’ ( x , y, z = l )= p i ’ ( x , y , z = l )*e^( jφ b )。Similarly, calculate its spectral distribution using Fourier transform as P i ’’ ( k x , k y , z = l )=∫∫ p i ’’ ( x , y , z = l )d x d y ,and extrapolate this spectrum along the positive z-axis to the target plane z = L= 80 mm, and obtain the spectral distribution of the target plane as P i ’’’ ( k x , k y , z = L ),and calculate its sound field distribution using inverse Fourier transform as p i ’’’ ( x , y , z = L )=∫∫ P i ’’’ ( k x , k y , z = L )d k x d k y 。

[0080] S2: After the forward propagation is completed, for the phase distributions on the target plane z = L in the cases of 7 incident sound fields respectively φi ’’’ ( x, y , z = L )= arg ( p i ’’’ ( x , y , z = L )) is reserved, where arg () is the phase extraction function. Update the target plane z = L The sound field distribution on q i ’’’ ( x, y , z = L )=P i 0 *e^(j φ i ’’’ ( x, y , z = L ).

[0081] S3: The backpropagation process is as follows: Calculate the spectral distribution of the target plane z = L as Q i ’’’ ( k x , k y , z = L )=∫∫ q i ’’’ ( x, y , z = L )d x d y , and extrapolate this spectrum along the negative z-axis to the plane of the single-layer acoustic holographic phase plate 4 z = l transmission side, and its spectral distribution is Q i ’’ ( k x , k y , z = l ). And calculate its sound field distribution through inverse Fourier transform as q i’’ ( k x , k y , z = l ) = ∫∫ Q i ’’ ( k x , k y , z = l )d k x d k y 。

[0082] S4: Based on the sound field distribution on the incident side of the single-layer acoustic holographic phase plate 4 p i ’ ( x , y , z = l ) and the sound field distribution on the transmission side obtained by the backpropagation process q i ’’ ( k x , k y , z = l ), calculate the fused phase distribution on the single-layer acoustic holographic phase plate 4 as: φ 0 = ∑ arg ( q i ’’ ( k x , k y , z = l ) * conj ( p i ’ ( x , y , z = l ))), where conj () is the conjugate function. And perform a binarization operation on φ 0, update the binary phase distribution φ b = 0 or π, when cos( φ 0) > 0, φ b = 0; when cos(φ When 0) <= 0 φ b = π

[0083] After approximately 60 forward and backward propagation iterations, the encoded fusion phase distribution on the single-layer acoustic holographic phase plate 4 is finally obtained φ b .

[0084] As shown in Figure 4 (a) and (b) of are respectively the three-dimensional and two-dimensional structural schematic diagrams of the single-layer acoustic holographic phase plate 4. Among them, the single-layer acoustic holographic phase plate 4 includes two thickness encoding units arranged in space, with thicknesses of h 1 and h 2 respectively, and the following relationship is satisfied between the two: h 1 - h 2 = λ / 2; where λ = f / c is the wavelength of the ultrasonic wave. At this time, the two thickness units are arranged according to the encoded fusion phase distribution φ b .

[0085] At the same time, as shown in Figure 5 , the seven sub-parts of the "seven-segment tube" are spatially combined to encrypt and represent 36 letters and numbers. At this time, the 36 "seven-segment tube" patterns correspond one by one to the 36 pieces of information of A~Z and 0~9

[0086] It should be noted that there are no patterns that are the same after rotation or mirroring among the 36 reconstructed patterns. Therefore, there are not high requirements for the placement position of the air-domain camera vision module 5

[0087] After the electrode partition array transducer 3 and the single-layer acoustic holographic phase plate 4 are designed, the electrode partition array transducer 3 and the single-layer acoustic holographic phase plate 4 are placed horizontally and underwater

[0088] Next, in combination with Figures 6 - 9 the water-air cross-domain wireless acoustic communication technology based on dynamic acoustic holography in the embodiments of the present invention will be described Based on Figure 6As shown in the figure, cross - domain communication is carried out using a visual module above the liquid surface. First, by encoding, the excitation and non - excitation of each element in the electrode partition array transducer 3 are controlled to generate different target incident sound fields. During the forward propagation of this incident sound field, it will be modulated by the single - layer acoustic holographic phase plate 4 and continue to propagate to the water - air interface to form a target holographic sound field. This target holographic sound field will generate different patterns on the liquid surface based on the acoustic radiation force. Then, a camera vision model 5 system above the liquid surface is used to collect the liquid surface ripples.

[0089] Before the start of the water - air cross - domain communication, first, the camera is used to collect 36 "seven - segment tube" patterns from different angles under different lighting conditions. After manually tagging, they are used as the training set of the convolutional neural network for training the neural network for recognizing the "seven - segment tube" liquid surface ripple images. After training is completed, this neural network model can be used to decode and output the liquid surface ripple patterns captured in the actual situation. The results are as Figure 7 shown, and the characters '5', '4', '0', '1', '9' can be read. Further, combining Embodiment 1 and 2 to illustrate the underwater information real - time communication technology: Embodiment

[0090] As Figure 8 shown, based on dynamic acoustic holography, static cross - domain wireless acoustic communication for the letter "H" is carried out, including the following steps: S1: Based on Figure 6 and Figure 8 , select the "seven - segment tube" pattern corresponding to the letter "H" and its 0 / 1 matrix electrode region distribution (8 * 8 matrix), and encode it into a 64 - character binary data stream of "0100010011000".

[0091] S2: After the underwater signal emission point 1 wirelessly transmits the above 64 - character binary data stream underwater to the switch control module 2, the switch control module 2 reconverts this 64 - character data into an 8 * 8 electrode mechanism region to control the connection / disconnection of each excited element of the partitioned electrode array transducer 3.

[0092] S3: The incident sound field generated by excitation is as Figure 3 in (b), and under the combined action with the single - layer acoustic holographic phase plate 4, a target "seven - segment tube" holographic sound field distribution is generated at the water - air interface, and corresponding liquid surface deformation is generated based on the acoustic radiation force.

[0093] S4: After using the camera acquisition system 5 above the water surface to efficiently capture the water surface ripple situation in real - time, it is input into the trained neural network, and the water surface ripples are decoded by means of template matching to finally obtain the underwater character information of "H". Embodiment

[0094] As Figure 9 shown, for the dynamic cross-domain wireless acoustic communication of the text data "123HELLO" based on dynamic acoustic holography, the following steps are included: S1: Based on Figure 6 and Figure 9 , determine the "seven-segment tube" patterns corresponding to 8 characters and the distribution of 8 0 / 1 matrix electrode regions (8*8 matrix) in the text data "123HELLO", expand the 8 8*8 matrix data into a 64-character binary data stream of "0100010011000", and directly splice them in order into an 8*64 binary data stream.

[0095] S2: After the underwater signal transmitter 1 wirelessly transmits the above 8*64 character binary data stream underwater to the switch control module 2, convert the 8*64 character data into 8 8*8 electrode excitation regions at intervals of 64 characters, and sequentially control the connection / disconnection of each element of the partitioned array transducer 3 to sequentially excite and generate 8 incident sound field distributions at a certain frame rate.

[0096] S3: Under the combined action of the dynamically changing incident sound field and the single-layer acoustic holographic phase plate 4, 8 target "seven-segment tube" holographic sound field distributions will be dynamically reconstructed at a certain frame rate at the water-air interface, and corresponding dynamic liquid surface deformations will be generated based on the action of acoustic radiation force.

[0097] S4: After the camera acquisition system 5 above the water surface captures the water surface ripple situation in real time and efficiently at the same frame rate, input it into the trained neural network, and decode the water surface ripple through template matching to finally obtain the text information of "123HELLO" underwater in real time.

[0098] The above results show that through the joint work of dynamic acoustic holography and the camera vision module, real-time encrypted communication of underwater information can be achieved, with good real-time performance and operability.

[0099] In the above embodiments, the descriptions of each embodiment have their own emphases. For the parts not detailed in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0100] The above has introduced the embodiments of the present application in detail. Specific examples are used in the present invention to elaborate on the principle and implementation manner of the present invention. The descriptions of the above embodiments are only used to help understand the method and its core idea of the present invention; at the same time, for those of ordinary skill in the art, according to the idea of the present invention, there will be changes in the specific implementation methods and application scopes. In summary, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A cross - domain wireless acoustic communication system based on acoustic holography, characterized in that: It includes a partitioned electrode array transducer (3) placed under the liquid for transmitting acoustic wave signals to a single - layer acoustic holographic phase plate; It includes a single - layer acoustic holographic phase plate (4) placed under the liquid, above the partitioned electrode array transducer (3) and close to the liquid surface, for receiving acoustic wave signals and feeding them back to form a liquid - surface pattern on the liquid surface; It includes a camera vision module (5) placed in the air domain and facing upwards the liquid surface above the single - layer acoustic holographic phase plate (4), for visually capturing and processing the liquid - surface pattern on the liquid surface, and parsing the liquid - surface pattern to obtain the information of the acoustic wave signals.

2. The cross-domain wireless acoustic communication system based on acoustic holography according to claim 1, characterized in that: The probe end faces of the single - layer acoustic holographic phase plate (4) and the partitioned electrode array transducer (3) are arranged in parallel with an axial spacing distance along the propagation direction.

3. The cross-domain wireless acoustic communication system based on acoustic holography according to claim 1, wherein: It also includes an information emission point (1) and a switch control module (2). The information emission point (1) is electrically connected to the partitioned electrode array transducer (3) through the switch control module (2). The original excitation signal is emitted from the information emission point (1), and the switch control module (2) controls the partitioned electrode array transducer (3) to emit acoustic wave signals corresponding to the liquid - surface pattern.

4. A cross-domain wireless acoustic communication system based on acoustic holography according to claim 1, characterized in that: Inside the partitioned electrode array transducer (3), there are piezoelectric device components. The piezoelectric device components evenly discretize one - side electrode of themselves into multiple independent array elements through a dicing machine. All the array elements are externally connected to a switch circuit, and the switch circuit encodes and controls the electrical connection and disconnection of each array element, thereby realizing the dynamic encoding regulation of the incident acoustic wave distribution under the input of a single - channel electrical signal, and further enabling the subdivision of the liquid - surface pattern display for different displays at different positions.

5. A cross-domain wireless acoustic communication system based on acoustic holography according to claim 1, characterized in that: The single - layer acoustic holographic phase plate (4) is made of a polymer by means of 3D printing, with one side being an uneven surface and the other side being a flat surface.

6. A cross-domain wireless acoustic communication method applied to the cross-domain wireless acoustic communication system according to any one of claims 1-5, characterized in that: The method includes: The partitioned electrode array transducer (3) is excited to emit incident ultrasonic acoustic waves. After propagating to the single - layer acoustic holographic phase plate (4), phase modulation occurs, and then it continues to propagate forward to the interface between different medium domains. Under the action of acoustic radiation force, the surface of the interface between different medium domains deforms, and holographic sound - field reconstruction is realized on the interface; At the same time, the camera vision module (5) above the interface is used to visually capture, collect, and decode the surface deformation of the interface, directly extract the acoustic wave information under the liquid surface, and finally realize the end - to - end cross - domain wireless acoustic communication between the devices under the liquid surface and on the liquid surface.

7. The cross - domain wireless acoustic communication method according to claim 6, characterized in that: The partitioned electrode array transducer (3) emits different incident ultrasonic acoustic waves in sequence according to the time sequence at different times. After being acted on by the single - layer acoustic holographic phase plate (4) on the interface, different surface deformations are formed according to the time sequence. The camera vision module (5) visually collects the patterns of the surface deformations of the interface according to the time sequence to obtain visual images, and image analysis and processing are performed on the visual images collected according to the time sequence to obtain dynamic information.

8. The cross - domain wireless acoustic communication method according to claim 6, characterized in that: The incident ultrasonic wave emitted by the partitioned electrode array transducer (3) acts on the interface through the single-layer acoustic holographic phase plate (4) to form a surface deformation encoded with a "seven-segment tube" pattern. The "seven-segment tube" pattern encoding has the characteristic of time-division multiplexing, specifically: The "seven-segment tube" pattern is the character "8". Each side segment of the "8" character is used as a sub-unit for encoding. According to the encoding relationship in the following table, the combination relationship of whether all different sub-units are displayed is controlled, and different letter and number information is correspondingly presented on the interface: A: Upper right vertical line B: Upper left and upper right vertical lines C: Upper and lower horizontal lines D: Upper right vertical line + middle horizontal line E: Upper right and lower right vertical lines F: Upper horizontal line + lower right vertical line G: Upper right and lower left vertical lines H: Upper and lower horizontal lines + lower right vertical line I: Upper, middle, and lower horizontal lines J: Upper left, upper right, and lower right vertical lines K: Middle horizontal line + upper right and lower right vertical lines L: Upper horizontal line + upper right and lower right vertical lines M: Upper horizontal line + upper left and upper right vertical lines N: Upper horizontal line + lower left and lower right vertical lines O: Upper and middle horizontal lines + upper left and upper right vertical lines P: Upper left, upper right, lower left, and lower right vertical lines Q: Upper, middle, and lower horizontal lines + upper right vertical line R: Upper right, lower left, and lower right vertical lines S: Upper and middle horizontal lines + upper right and lower right vertical lines T: Upper left and upper right vertical lines + middle and lower horizontal lines U: Upper and middle horizontal lines + upper left and lower right vertical lines V: Upper and lower horizontal lines + upper right and lower right vertical lines W: Upper and lower horizontal lines + upper left and upper right vertical lines X: Upper right, lower left, and lower right vertical lines + lower horizontal line Y: Upper and lower horizontal lines + upper right and lower left vertical lines Z: Upper and middle horizontal lines + upper left, upper right, and lower right vertical lines 0: Upper, middle, and lower horizontal lines + upper right and lower left vertical lines 1: Upper, middle, and lower horizontal lines + upper right and lower right vertical lines 2: Upper, middle, and lower horizontal lines + upper left and upper right vertical lines 3: Upper horizontal line + upper left, upper right, lower left, and lower right vertical lines 4: Middle horizontal line + upper left, upper right, lower left, and lower right vertical lines 5: Upper and lower horizontal lines + upper left, upper right, and lower left vertical lines 6: Middle and lower horizontal lines + upper left, upper right, and lower left vertical lines 7: Upper and middle horizontal lines + upper left, upper right, lower left, and lower right vertical lines 8: Upper and lower horizontal lines + upper left, upper right, lower left, and lower right vertical lines 9: Upper, middle, and lower horizontal lines + upper left, upper right, lower left, and lower right vertical lines There are a total of 36 characters from letter A to Z + numbers 0 to 9 as mentioned above.

9. The cross-domain wireless acoustic communication method according to claim 8, characterized in that: The fixed single-layer acoustic holographic phase plate integrates the fusion phase information corresponding to the "seven-segment tube" pattern in its phase distribution. Each sub-unit of the "seven-segment tube" pattern is time-divisionally gated by the partitioned electrode array transducer.

10. The cross-domain wireless acoustic communication method according to claim 8, wherein: After the camera vision module (5) captures the image of the liquid surface pattern on the water surface visually, the convolutional neural network model is used to identify and process the image to obtain the "seven-segment tube" pattern information therein.

Images