Metamaterial-based double-sided multi-channel asymmetric encryption acoustical holography communication method, device and equipment

Abstract

The invention discloses a metamaterial-based double-sided multichannel asymmetric encryption acoustical holography communication device and a metamaterial-based double-sided multichannel asymmetric encryption acoustical holography communication method, which are characterized in that different image information is respectively transmitted through an amplitude channel and a phase channel, and image encryption is carried out in an initial sound field through a specific encryption metasurface device, that is, encryption sound fields are formed on two sides of an encryption metasurface; and placing a key metasurface of a corresponding channel on the encrypted sound field to restore and decrypt the holographic image. The metasurface can decouple and modulate the amplitude and the phase of the sound wave, and according to the time reversal symmetry and the sound wave superposition principle, the reflected sound field modulated by the metasurface can present the pre-designed amplitude-phase distribution. The encryption metasurface encrypts the initial acoustic holographic image by introducing a random matrix, so that the acoustic holographic image reflected by the encryption metasurface becomes a messy code image. The key metasurfaces are amplitude and phase channel keys in a transmission / reflection encrypted sound field, and the key metasurfaces can restore initial acoustic holographic images of corresponding channels.

Description

Technical Field

[0001] The present invention relates to the field of acoustic secure communication technology, and in particular to a double-sided multi-channel asymmetric encrypted acoustic holographic communication method, device and equipment based on metamaterials. Background Art

[0002] Acoustic holography has received great attention in recent years because it can project the sound field into any shape and position using acoustic metamaterials or metasurfaces. The physical quantity of the acoustic holographic image is the sound wave amplitude (or intensity), which represents the spatial distribution of sound energy and can be applied to sound field reconstruction or ultrasound therapy, etc. In traditional acoustic holography, the phase distribution of the hologram is negligible and usually does not affect the effect of the hologram, because we only focus on the energy distribution and its corresponding physical effects. However, in information communication, we need holographic images as information, and their physical effects are not important. In this case, the phase is another valuable information carrier, and its distribution contains information like the amplitude. Amplitude and phase can be two equivalent information channels. In different information communication fields, such as quantum communication, their basic principles are similar. At present, it is still a challenging problem to comprehensively and comprehensively make acoustic holography a mature technical means of acoustic communication. On the other hand, as an important guarantee of communication security, the encryption and decryption methods of information are also crucial. At present, the research on encryption methods in the transmission process of acoustic holographic images is also very limited. Summary of the invention

[0003] The purpose of the present invention is to address the problems existing in the background technology and propose a double-sided multi-channel asymmetric encrypted acoustic holographic communication method, device and equipment based on metamaterials; this communication technology can greatly broaden the channel capacity, improve communication security, and has practical application prospects. Amplitude-phase channel encrypted acoustic holographic communication provides a secure acoustic communication framework, which has a guiding role in various acoustic applications including secure communication and underwater communication.

[0004] The technical solution of the present invention:

[0005] The first aspect of the present invention provides an amplitude-phase dual-channel encrypted acoustic holographic communication device based on a metasurface, comprising a transmitting source array, a receiving end and at least 5 metasurfaces;

[0006] The transmitting source array is used to send pre-designed amplitude and phase dual-channel image information, wherein the dual-channel information should respectively contain the transmission information of the transmission field and the reflection field;

[0007] The receiving end is used to receive the sound signal in the sound field;

[0008] Among them, the metasurface includes 1 encryption metasurface and 4 key metasurfaces;

[0009] The key metasurfaces are respectively the transmitted sound field amplitude key, the transmitted sound field phase key, the reflected sound field amplitude key and the reflected sound field phase key;

[0010] The transmitting source array is used to transmit different image information that needs to be transmitted in the amplitude channel and the phase channel respectively;

[0011] The encrypted metasurface encrypts the holographic image emitted by the emission source array and generates garbled information on the transmission side and reflection side of the metasurface;

[0012] The amplitude key metasurface of the reflected field receives garbled information at the working position in the reflected encrypted sound field, and obtains the amplitude channel sound field in the reflected encrypted sound field after being decrypted and restored through its transmission;

[0013] The phase key metasurface of the reflected field receives garbled information at the working position in the reflected encrypted sound field, and obtains the decrypted and restored phase channel sound field in the reflected encrypted sound field through its transmission;

[0014] The amplitude key metasurface of the transmission field receives garbled information at its working position in the transmission encrypted sound field, and obtains the amplitude channel sound field in the transmission encrypted sound field after being decrypted and restored through its transmission;

[0015] The phase key metasurface of the transmitted field receives garbled information at its working position in the transmitted encrypted sound field, and obtains the decrypted and restored phase channel sound field in the transmitted encrypted sound field through its transmission.

[0016] Preferably, the emission source array obtains the emission parameter matrix from the pre-designed holographic image information through time reversal symmetry, and the image in the emitted original sound field is a coupled image, that is, both the amplitude channel and the phase channel can see two coupled image information.

[0017] Preferably, the encrypted metasurface encrypts the channel-coupled holographic image emitted by the emission source array by introducing a random number encryption matrix. After encryption, a garbled image in which no information can be read is obtained in either the amplitude channel or the phase channel in the encrypted sound field.

[0018] The key metasurface is designed according to the holographic image and working position that need to be transmitted in advance. The corresponding garbled information is received at the working position in the encrypted sound field, and the decrypted and restored sound field can be obtained through its transmission. In the corresponding transmitted encrypted sound field or reflected encrypted sound field, the original holographic image of the corresponding channel can be obtained according to the type of decryption metasurface. For example, in the sound field after transmission through the reflected sound field amplitude key metasurface, there is only one holographic image for both the amplitude channel and the phase channel, that is, the holographic image of the reflected field amplitude channel that is designed to be transmitted at the beginning.

[0019] Preferably, the metasurface freely and independently modulates the amplitude and phase of the reflected acoustic wave.

[0020] Preferably, different key metasurfaces reflect information of different channels from the encrypted acoustic field.

[0021] Preferably, the key metasurface decouples the channel coupling in the original unencrypted sound field when decrypting and restoring information.

[0022] The second aspect of the present invention provides a double-sided multi-channel asymmetric encrypted acoustic holographic communication method based on metamaterials, which is applied to the above-mentioned communication device and includes the following specific steps:

[0023] S1. Pre-design the image information to be transmitted. The amplitude channel and the phase channel transmit different image information.

[0024] S2. Determine the emission parameter matrix of the emission source array, including the amplitude matrix and the phase matrix;

[0025] S3. Arrange the encrypted metasurface at a preset position, with the encrypted metasurface and the emission source arranged at a certain angle;

[0026] S4. Arrange the key metasurface at a preset position in the encrypted sound field after transmission / reflection of the encryption metasurface.

[0027] Preferably, there is time reversal symmetry between the pre-designed transmission image information and the emission parameter matrix of the emission source array, and each emission source in the emission source array can be regarded as a point source of an acoustic spherical surface wave; the wave function of the acoustic spherical surface wave can be expressed as:

[0028]

[0029] Where p represents the sound pressure, A represents the amplitude, represents the phase, r represents the propagation distance of the spherical wave, k is the wave number of the sound wave, and i is the imaginary unit; the holographic image is the superposition of these spherical waves, the amplitude channel is the amplitude of the sound wave after superposition, and the phase channel is the phase of the sound wave after superposition.

[0030] Preferably, the metasurface can arbitrarily modulate the amplitude and phase of the reflected and transmitted sound waves, and destroy the preset image information in the original sound field by introducing a random number matrix, so that the image information becomes garbled code in the encrypted sound field.

[0031] Preferably, different key metasurfaces are designed according to predetermined channel image information and placement positions, and the received garbled information is amplitude-phase modulated to obtain the original image information of the corresponding channel in the decrypted sound field transmitted therethrough.

[0032] The third aspect of the present invention provides a double-sided multi-channel asymmetric encrypted acoustic holographic communication device based on metamaterials, which is applied to the above-mentioned communication device and is characterized in that it includes an array of 256 ultrasonic transducers with a diameter of 1 cm, an FPGA controller, a memory and a processor, and a transducer probe for receiving ultrasonic waves;

[0033] Among them, the memory stores computer-readable instructions, and when the computer-readable instructions are executed by the processor, the steps in the above-mentioned double-sided multi-channel asymmetric encrypted acoustic holographic communication method based on metamaterials are executed.

[0034] Compared with the prior art, the present invention has the following beneficial technical effects:

[0035] 1. Expanded new acoustic holographic communication channels, using phase information as a channel for communication transmission;

[0036] 2. Solved the problem of dual-channel image information transmission coupling. Each channel has a corresponding key, realizing asymmetric encryption of acoustic holography. The decrypted information does not contain the original information of other channels.

[0037] 3. High image fidelity, the metasurface can independently modulate the amplitude and phase of reflected and transmitted waves. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 It is a schematic diagram of the overall technical route of the present invention;

[0039] Figure 2 is a schematic diagram of an emission source array of the present invention;

[0040] Figure 3 Schematic diagram of coupled image information in the emission source array and the original sound field in Example 1 of the present invention;

[0041] Figure 4 This is a schematic diagram of garbled information in the encrypted sound field after the encrypted metasurface reflection / transmission in Example 1 of the present invention;

[0042] Figure 5 Schematic diagram of the decryption process in the transmission encrypted sound field in Example 1 of the present invention;

[0043] Figure 6 Schematic diagram of the decryption process in the reflected encrypted sound field in Example 1 of the present invention;

[0044] Figure 7 Schematic diagram of the metasurface used in Example 1 of the present invention independently modulating the amplitude and phase of the acoustic wave;

[0045] Figure 8 Schematic diagram of the process and results of using metasurface encryption and decryption in Example 2 of the present invention;

[0046] Fig. 9 It is a schematic diagram of a wireless multi-channel parallel communication device based on acoustic holography in Embodiment 3 of the present invention;

[0047] Fig.10 The figure is a flow chart of the encrypted acoustic holographic communication method in an embodiment of the present invention. DETAILED DESCRIPTION

[0048] Example 1

[0049] This embodiment provides a double-sided multi-channel asymmetric encrypted acoustic holographic communication method based on metamaterials, such as Figure 1 As shown, in the embodiment of the present invention, the amplitude channel image pre-designed for transmission is letter AB, and the phase channel image pre-designed for transmission is letter CD, where A and C are the amplitude channel and phase channel image information transmitted to the transmission receiving end, respectively, and B and D are the amplitude channel and phase channel image information transmitted to the reflection receiving end, respectively. Figure 2 As shown), the emission is Figure 3 The amplitude channel and phase channel information that can be intercepted in the original sound field shown are coupled, that is, AB can be seen in the phase channel and CD can be seen in the amplitude channel, resulting in information leakage.

[0050] like Figure 4 As shown, the encrypted metasurface is at a 45° angle to the source array. Construct a random number array with element values ​​of 0 to 1 and a random number array with element values ​​of 0 to 2π. The number of matrix rows and columns is consistent with the number of cell rows and columns of the encrypted metasurface. The incident sound wave amplitude received by each cell is multiplied by the corresponding element value in the random number matrix of 0 to 1 to obtain the wave source amplitude matrix in the reflected encrypted sound field. Similarly, the incident sound phase value received by each cell is added to the corresponding element value in the random number matrix of 0 to 2π to obtain the wave source phase value matrix in the reflected encrypted sound field.

[0051] Then construct a random number array with element values ​​of 0 to 1 and a random number array with element values ​​of 0 to 2π. The number of rows and columns of the matrix is ​​consistent with the number of rows and columns of the cells of the encrypted metasurface. The acoustic wave modulation at the transmission end is performed after the reflected wave modulation. Therefore, the amplitude of the transmitted acoustic wave is the amplitude of the incident acoustic wave minus the amplitude of the reflected acoustic wave, and then multiplied by the corresponding element value in the random number matrix of 0 to 1 to obtain the wave source amplitude matrix in the transmitted encrypted acoustic field. However, the phase of the transmitted acoustic wave is independent of the reflected acoustic wave, and the corresponding element value in the random number matrix of 0 to 2π can be modulated into the wave source phase value matrix in the transmitted encrypted acoustic field.

[0052] like Figure 5As shown, a transmission amplitude key is placed at the working position in the transmission encrypted sound field. After the key is transmitted, the amplitude and phase channels in the sound field only contain the letter A, and no coupling will occur, so no irrelevant information will be leaked.

[0053] When a transmission phase key is placed at the working position in the transmission encrypted sound field, the amplitude and phase channels in the sound field after the key is transmitted only contain the letter C, and no coupling will occur, so no irrelevant information will be leaked.

[0054] like Figure 6 As shown, a reflection amplitude key is placed at the working position in the reflection encryption sound field. After the key is transmitted, the amplitude and phase channels in the sound field only contain the letter B, and no coupling will occur, so no irrelevant information will be leaked.

[0055] When a reflection phase key is placed at the working position in the reflection encryption sound field, the amplitude and phase channels in the sound field after the key is transmitted only contain the letter D, and no coupling will occur, so no irrelevant information will be leaked.

[0056] like Figure 7 As shown in the figure, all the unit cells of the metasurface have similar structures, and only the geometric parameters w, p, s, and a are different. w and d determine the amplitude of the reflected wave, and p determines the phase lag of the reflected wave. The specific relationship is as follows:

[0057]

[0058] Where A is the amplitude of the reflected sound wave, ф is the phase delay of the reflected sound wave, and λ is the wavelength of the sound wave in the air.

[0059] The amplitude of the transmitted wave is related to the thickness s of the sound-absorbing medium in the unit cell, which is melamine sound-absorbing sponge. The phase of the transmitted wave is related to the parameter a, as shown in the following figure: Figure 7 as shown in .

[0060] Example 2

[0061] To illustrate the flexibility of the technology involved, Figure 8 As shown, in this embodiment, the original image of the amplitude channel at the transmission end is the logo of Southeast University, the original transmission image of the phase channel is the logo of the School of Mechanical Engineering of Southeast University, the original transmission image of the amplitude channel at the reflection end is the letters SEU, and the original transmission image of the phase channel is the letters ME. It is first transmitted by the transmitting source array, then transmitted and reflected by the encryption metasurface, and finally decrypted by the corresponding key metasurface to obtain the decrypted sound field. Figure 8 The encryption and decryption process and results can be clearly seen in the

[0062] Example 3

[0063] This embodiment provides a wireless multi-channel parallel communication device based on acoustic holography. Fig. 9 The acoustic emission array is a phased array consisting of 256 transducers with a transmission frequency of 40kHz. The transducers are arranged in a 16×16 grid and built on a single integrated printed circuit board (PCB). On one side of the PCB, the ultrasonic transmitter is soldered, while on the other side, a field programmable gate array (FPGA) (EP4CE6E22C8N—ALTERAIV core board), shift register (74HC595, TI), driver (MIC4127) and decoupling capacitor (ceramic 50V 0.1F) are installed. The signal of each transmitter is generated by the FPGA. The shift register demultiplexes each digital line from the FPGA into 8 channels, and the driver boosts the channel voltage from the logic voltage to the power supply voltage (up to 20 peak-to-peak voltage (Vp-p)). The calculation of the phase and amplitude to be transmitted is performed on an external computer and then sent to the FPGA at 203,400 baud via a serial universal asynchronous receiver-transmitter (UART) protocol. A double buffer is implemented in the FPGA to generate the signal continuously; one buffer stores the transmit pattern from the computer, while the second buffer is used by the FPGA to continuously generate the transmit signal.

[0064] The embodiments of the present invention are described in detail above with reference to the accompanying drawings, but the present invention is not limited thereto, and various changes can be made within the knowledge scope of technicians in the relevant technical field without departing from the purpose of the present invention.

Claims

1. A double-sided multi-channel asymmetric encrypted acoustic holographic communication device based on metamaterials, characterized in that: It includes a transmitting source array, a receiving end and five metasurfaces; The transmitting source array is used to send image information of pre-designed amplitude and phase channels; The receiving end is used to receive the sound signal in the sound field and perform sound field scanning and imaging; Among them, the metasurface includes 1 encryption metasurface and 4 key metasurfaces; The key metasurfaces are respectively the transmitted sound field amplitude key, the transmitted sound field phase key, the reflected sound field amplitude key and the reflected sound field phase key; The transmitting source array transmits different image information to be transmitted in the amplitude channel and the phase channel respectively, wherein the amplitude channel and the phase channel each contain two parts of content, one part is the image information sent to the transmission end of the encrypted metasurface, and the other part is the image information sent to the reflection end of the encrypted metasurface; The encryption metasurface encrypts the holographic image emitted by the emission source array to generate garbled information; The amplitude key metasurface receives garbled information at its working position in the corresponding encrypted sound field, and obtains the decrypted and restored amplitude channel sound field through its transmission; The phase key metasurface receives garbled information at its working position in the corresponding encrypted sound field, and obtains the decrypted and restored phase channel sound field through its transmission.

2. The double-sided multi-channel asymmetric encrypted acoustic holographic communication device based on metamaterials according to claim 1 is characterized in that: The emission source array obtains the emission parameter matrix from the pre-designed holographic image information through time reversal symmetry, and the image of any channel in the emitted original sound field is the image after the information of two channels is coupled.

3. The double-sided multi-channel asymmetric encrypted acoustic holographic communication device based on metamaterials according to claim 1, characterized in that: The encrypted metasurface encrypts the channel-coupled holographic image emitted by the emission source array by introducing a random number encryption matrix.

4. The double-sided multi-channel asymmetric encrypted acoustic holographic communication device based on metamaterials according to claim 1, characterized in that: The metasurface freely and independently modulates the amplitude and phase of the transmitted / reflected acoustic waves.

5. The double-sided multi-channel asymmetric encrypted acoustic holographic communication device based on metamaterials according to claim 1, characterized in that: Different key metasurfaces reflect information of different channels from the encrypted acoustic field.

6. The double-sided multi-channel asymmetric encrypted acoustic holographic communication device based on metamaterials according to claim 1, characterized in that: The key metasurface decouples the channel coupling in the original unencrypted sound field when decrypting and restoring information.

7. A double-sided multi-channel asymmetric encrypted acoustic holographic communication method based on metamaterials, applied to the device according to any one of claims 1 to 6, characterized in that: The specific steps include: S1. Pre-design the image information to be transmitted. The amplitude channel and the phase channel transmit different image information. S2. Determine the emission parameter matrix of the emission source array, including the amplitude matrix and the phase matrix; S3. Arrange the encrypted metasurface at a preset position, with the encrypted metasurface and the emission source arranged at a certain angle; S4. Arrange the key metasurface at a preset position in the encrypted sound field after transmission / reflection of the encryption metasurface.

8. The double-sided multi-channel asymmetric encrypted acoustic holographic communication method based on metamaterials according to claim 7, characterized in that: There is time reversal symmetry between the pre-designed transmission image information and the emission parameter matrix of the emission source array. Each emission source in the emission source array can be regarded as a point source of an acoustic spherical surface wave. The wave function of the acoustic spherical surface wave can be expressed as: Where p represents the sound pressure, A represents the amplitude, represents the phase, r represents the propagation distance of the spherical wave, k is the wave number of the sound wave, and i is the imaginary unit; the holographic image is the superposition of these spherical waves, the amplitude channel is the amplitude of the sound wave after superposition, and the phase channel is the phase of the sound wave after superposition.

9. The double-sided multi-channel asymmetric encrypted acoustic holographic communication method based on metamaterials according to claim 7, characterized in that: The metasurface can arbitrarily modulate the amplitude and phase of the reflected sound wave, and by introducing a random number matrix, it destroys the preset image information in the original sound field, making the image information become garbled in the encrypted sound field; different key metasurfaces are designed according to the predetermined channel image information and placement position, and the received garbled information is modulated in amplitude and phase, and the original image information of the corresponding channel is obtained in the decrypted sound field reflected by it.

10. A double-sided multi-channel asymmetric encrypted acoustic holographic communication device based on metamaterials, applied to the communication device according to any one of claims 1 to 6, characterized in that: It includes an array of 256 ultrasonic transducers with a diameter of 1 cm, an FPGA controller, a memory and a processor, and a transducer probe for receiving ultrasonic waves; Wherein, the memory stores computer-readable instructions, and when the computer-readable instructions are executed by the processor, the steps in the double-sided multi-channel asymmetric encrypted acoustic holographic communication method based on metamaterials as described in any one of claims 7 to 9 are executed.

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