Dual-sided multi-channel asymmetric encryption acoustic holographic communication method, device and equipment based on metamaterials

Abstract

The application discloses a double-sided multi-channel asymmetric encryption acoustic holographic communication device and method based on metamaterials, different image information is transmitted through two channels of amplitude and phase, image encryption is carried out in the initial sound field through a specific encryption super surface device, that is, an encrypted sound field is formed on both sides of the encryption super surface, and a key super surface of the corresponding channel is placed in the encrypted sound field to restore and decrypt the holographic image. The super surface of the application can decouple the amplitude and phase of the modulated sound wave, according to the time reversal symmetry and the superposition principle of the sound wave, the reflected sound field after the super surface modulation can present the pre-designed amplitude and phase distribution. The encryption super surface encrypts the initial sound holographic image by introducing a random matrix, so that the sound holographic image reflected after the encryption super surface becomes a random code image. The key super surface is the amplitude and phase channel key in the transmission / reflection encrypted sound field, and it can restore the initial sound holographic image of the corresponding channel.

Description

TECHNICAL FIELD

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

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

[0003] The present application aims to solve the problems in the background art and provides a double-sided multi-channel asymmetric encryption acoustic holographic communication method, device and equipment based on metamaterials. This communication technology can greatly expand the channel capacity, improve the communication security, and has practical application prospect. The amplitude-phase channel encryption acoustic holographic communication provides a secure acoustic communication framework, which has a guiding role for various acoustic applications including secure communication and underwater communication.

[0004] The technical scheme of the present application is as follows:

[0005] The first aspect of the present application provides an amplitude-phase double-channel encryption acoustic holographic communication device based on metasurface, which comprises a transmitting source array, a receiving end and at least 5 metasurfaces.

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

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

[0008] Among them, the metasurface includes one encryption metasurface and four key metasurfaces.

[0009] The key metasurfaces are respectively a transmission sound field amplitude key, a transmission sound field phase key, a reflection sound field amplitude key and a reflection sound field phase key;

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

[0011] The encryption metasurface encrypts the holographic image transmitted by the transmitting source array, and generates scrambled information on the transmission side and the reflection side of the metasurface;

[0012] The amplitude key metasurface of the reflection field receives the scrambled information at the working position in the reflection encrypted sound field, and obtains the amplitude channel sound field in the decrypted and restored reflection encrypted sound field through transmission thereof;

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

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

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

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

[0017] Preferably, the encryption metasurface encrypts the channel-coupled holographic image transmitted by the transmitting source array by introducing a random number encryption matrix, and after encryption, scrambled images that cannot read any information are obtained in the encrypted sound field whether in the amplitude channel or in the phase channel.

[0018] The key metasurface is designed according to the pre-planned holographic image to be transmitted and the working position, receives the corresponding scrambled information at the working position in the encrypted sound field, and can obtain the decrypted and restored sound field through transmission thereof. In the corresponding transmission encrypted sound field or reflection encrypted sound field, according to the type of the decryption metasurface, the original holographic image of the corresponding channel can be obtained. For example, in the sound field after transmission of the reflection sound field amplitude key metasurface, there is only one holographic image in the amplitude channel and the phase channel, that is, the reflection field amplitude channel holographic image to be transmitted is designed at the beginning.

[0019] Preferably, the metasurface independently modulates the reflection sound wave amplitude and phase.

[0020] Preferably, different key metasurfaces reflect different channel information from the encrypted sound field.

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

[0022] The second aspect of the present application provides a two-sided multi-channel asymmetric encryption sound holographic communication method based on metamaterials, applied to the communication device described above, comprising the following specific steps:

[0023] S1, pre-designing image information to be transmitted, the amplitude channel and the phase channel transmitting different image information;

[0024] S2, determining the transmission parameter matrix of the source array, including the amplitude matrix and the phase matrix;

[0025] S3, arranging the encryption metasurface at a pre-set position, and the encryption metasurface being arranged at a certain angle with the source array;

[0026] S4, arranging the key metasurface at a pre-set position in the encrypted sound field after transmission / reflection by the encryption metasurface.

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

[0028]

[0029] In the formula, p represents sound pressure, A represents amplitude, represents 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 superposed sound wave, and the phase channel is the phase of the superposed sound wave.

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

[0031] Preferably, different key metasurfaces are designed according to pre-set channel image information and placement positions, and the received random code information is amplitude and phase modulated, so that the original image information of the corresponding channel is obtained in the decrypted sound field transmitted by the key metasurface.

[0032] The third aspect of the present application provides a double-sided multi-channel asymmetric encryption acoustic holographic communication device based on metamaterial, which is applied to the communication device and has the characteristics that it comprises a 256-ultrasound transducer array with a diameter of 1cm, a FPGA controller, a memory, a processor and a transducer probe for receiving ultrasound waves.

[0033] The memory stores computer readable instructions, and the computer readable instructions are executed by the processor to perform the steps of the double-sided multi-channel asymmetric encryption acoustic holographic communication method based on metamaterial.

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

[0035] 1. Expands a new acoustic holographic communication channel, and phase information is also used as a channel for communication transmission.

[0036] 2. Solves the coupling problem of double-channel image information transmission, each channel has a corresponding key, realizes asymmetric encryption of acoustic holography, and the decrypted information does not contain the original information of other channels.

[0037] 3. High image fidelity, the metasurface can independently modulate the reflection and transmission amplitude and phase. BRIEF DESCRIPTION OF DRAWINGS

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

[0039] Figure 2 It is a schematic diagram of the transmitting source array of the present application.

[0040] Figure 3 It is a schematic diagram of the coupling image information in the transmitting source array and the original sound field in embodiment 1 of the present application.

[0041] Figure 4 It is a schematic diagram of the random code information in the encrypted sound field after reflection / transmission of the encryption metasurface in embodiment 1 of the present application.

[0042] Figure 5 It is a schematic diagram of the decryption process in the transmission encrypted sound field in embodiment 1 of the present application.

[0043] Figure 6 It is a schematic diagram of the decryption process in the reflection encrypted sound field in embodiment 1 of the present application.

[0044] Figure 7 It is a schematic diagram of the independent modulation of the amplitude and phase of the sound wave by the metasurface used in embodiment 1 of the present application.

[0045] Figure 8 It is a schematic diagram of the encryption and decryption process and result using the metasurface in embodiment 2 of the present application.

[0046] Figure 9 Figure 3 is a schematic diagram of a wireless multi-channel parallel communication device based on acoustic holography in an embodiment of the present application;

[0047] Figure 10 Figure 4 is a flow chart of an encryption acoustic holography communication method in an embodiment of the present application. DETAILED DESCRIPTION

[0048] Embodiment 1

[0049] This embodiment provides a double-sided multi-channel asymmetric encryption acoustic holography communication method based on metamaterials, as shown in FIG. 1. In an embodiment of the present application, the pre-designed transmission amplitude channel image is the letter AB, and the pre-designed transmission phase channel image is the 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. The amplitude channel and phase channel information that can be intercepted in the original sound field emitted by the transmitting source array (40 kHz ultrasonic transducer array, as shown in FIG. 2) are coupled, that is, AB can be seen in the phase channel, and CD can be seen in the amplitude channel, causing information leakage. Figure 1 Figure 2 Figure 3

[0050] As shown in FIG. 3, the encryption metasurface is at a 45° angle with the transmitting source array. A random number array with element values of 0-1 and a random number array with element values of 0-2π are constructed, and the number of rows and columns of the matrix is consistent with the number of rows and columns of the unit cells of the encryption metasurface. The amplitude of the incident sound received by each unit cell is multiplied by the corresponding element value in the 0-1 random number matrix to obtain the wave source amplitude matrix in the reflected encrypted sound field. Similarly, the phase value of the incident sound received by each unit cell is added to the corresponding element value in the 0-2π random number matrix to obtain the wave source phase value matrix in the reflected encrypted sound field. Figure 4 Again, a random number array with element values of 0-1 and a random number array with element values of 0-2π are constructed, and the number of rows and columns of the matrix is consistent with the number of rows and columns of the unit cells of the encryption metasurface. The transmission sound wave modulation is performed after the reflection wave modulation, so the transmission sound wave amplitude is the incident sound wave amplitude minus the reflected sound wave amplitude, and then multiplied by the corresponding element value in the 0-1 random number matrix to obtain the wave source amplitude matrix in the transmission encrypted sound field. However, the phase of the transmission sound wave is irrelevant to the reflection sound wave, and the corresponding element value in the 0-2π random number matrix can be modulated to become the wave source phase value matrix in the transmission encrypted sound field.

[0051]

[0052] Figure 5 ​​​​​As shown, if the transmission amplitude key is placed at the working position in the transmission encryption sound field, the amplitude and phase channels in the sound field after the key is transmitted will only contain the letter A, and there will be no coupling, so no unrelated information will be leaked.

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

[0054] like Figure 6 As shown, if the reflection amplitude 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 will only contain the letter B, and there will be no coupling. Therefore, no unrelated information will be leaked.

[0055] If a reflective phase key is placed at the working position in the reflective encrypted sound field, the amplitude and phase channels in the sound field after the key is transmitted will only contain the letter D, and there will be no coupling, so no unrelated information will be leaked.

[0056] like Figure 7 As shown, all the cells of the metasurface have similar structures, differing only in the values ​​of the geometric parameters w, p, s, and a. w and d determine the amplitude of the reflected wave, while p determines the phase lag of the reflected wave. The specific relationships are 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 cell, which is melamine sound-absorbing sponge. The phase of the transmitted wave is related to parameter *a*, as shown in the following relationship: Figure 7 As shown in the image.

[0060] Example 2

[0061] To illustrate the flexibility of the technology involved, such as Figure 8 As shown, in this embodiment, the original image of the amplitude channel at the transmission end is the emblem of Southeast University, the original transmitted image of the phase channel is the emblem of the School of Mechanical Engineering of Southeast University, the original transmitted image of the amplitude channel at the reflection end is the letters SEU, and the original transmitted image of the phase channel is the letters ME. The sound field is first transmitted through the transmitter 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 image.

[0062] Example 3

[0063] The present embodiment provides a wireless multi-channel parallel communication device based on acoustic holography. Please refer to Figure 9 The acoustic emission array is a phased array composed of 256 transducers emitting at a frequency of 40 kHz. The sensors are arranged in a 16x16 grid, built on a single integrated printed circuit board (PCB). On one side of the PCB, the ultrasonic emitters are soldered, while on the other side, a field programmable gate array (FPGA) (EP4CE6E22C8N - ALTERA IV core board), a shift register (74HC595, TI), a driver (MIC4127) and a decoupling capacitor (ceramic 50V 0.1F) are mounted. The signal of each emitter is generated by the FPGA. The shift register demultiplexes each digital line coming from the FPGA into 8 channels, and the driver boosts the channel voltage from the logic voltage to the supply voltage (up to 20 volts peak to peak (Vp-p)). The calculation of the phase and amplitude to be emitted is performed on an external computer and then sent to the FPGA at 203,400 bauds through a serial universal asynchronous receiver-transmitter (UART) protocol. Double buffering is implemented in the FPGA to generate the signal without interruption; one buffer stores the emission pattern coming from the computer, while the second buffer is used by the FPGA to continuously generate the emission signal.

[0064] The embodiments of the present application are described in detail above with reference to the accompanying drawings, but the present application is not limited thereto, and various changes can be made within the knowledge of those skilled in the art without departing from the spirit of the present application.

Claims

1. A dual-sided multi-channel asymmetric encryption acoustic holographic communication device based on metamaterials, characterized in that, The array of transmitting sources, a receiving end and five super surfaces are included; The array of transmitting sources is used to send the pre-designed image information of amplitude and phase channels; The receiving end is used to receive the sound signals in the sound field and to perform sound field scanning and imaging; The super surface includes one encryption super surface and four key super surfaces; The key super surfaces are respectively the transmission sound field amplitude key, the transmission sound field phase key, the reflection sound field amplitude key and the reflection sound field phase key; The array of transmitting sources transmits different image information needed to be transmitted in the amplitude channel and the phase channel, wherein the amplitude channel and the phase channel both contain two parts of contents, one part is the image information sent to the transmission end of the encryption super surface, and the other part is the image information sent to the reflection end of the encryption super surface; The encryption super surface encrypts the holographic image transmitted by the array of transmitting sources to generate scrambled information; the encryption super surface encrypts the channel-coupled holographic image transmitted by the array of transmitting sources by introducing a random number encryption matrix; The amplitude key super surface receives the scrambled information in the corresponding encrypted sound field, and obtains the decrypted and restored amplitude channel sound field through its transmission; The phase key super surface receives the scrambled information in the corresponding encrypted sound field, and obtains the decrypted and restored phase channel sound field through its transmission; The key super surface decouples the channel coupling in the original unencrypted sound field when decrypting and restoring the information.

2. The dual-sided multi-channel asymmetric encryption acoustic holography communication device based on metamaterial according to claim 1, wherein, The array of transmitting sources obtains the transmission parameter matrix by time reversal symmetry of the pre-designed holographic image information, and the image of any channel in the original sound field transmitted is the image coupled by two channel information.

3. The dual-sided multi-channel asymmetric encryption acoustic holography communication device based on metamaterial of claim 1, wherein, The super surface freely and independently modulates the transmission and reflection of sound wave amplitude and phase.

4. The dual-sided multi-channel asymmetric encryption acoustic holography communication device based on metamaterial of claim 1, wherein, Different key super surfaces reflect different channel information from the encrypted sound field.

5. A method for two-sided multi-channel asymmetric encryption acoustic holographic communication based on metamaterials, characterized in that, The method includes the following specific steps: S1, pre-designing image information needed to be transmitted, different image information is transmitted in the amplitude channel and the phase channel; S2, determining the transmission parameter matrix of the array of transmitting sources, including amplitude matrix and phase matrix; S3, arranging the encryption super surface at the pre-designed position, and the encryption super surface is arranged at an angle of 45° with the array of transmitting sources; S4, arranging the key super surface at the pre-designed position in the encrypted sound field after transmission and reflection of the encryption super surface, and performing acoustic holographic communication based on the double-sided multi-channel asymmetric encryption acoustic holographic communication method of super material according to any one of claims 1-4.

6. The dual-sided multi-channel asymmetric encryption acoustic holography communication method based on metamaterials of claim 5, wherein: There is time reversal symmetry between the pre-designed transmission image information and the transmission parameter matrix of the array of transmitting sources, and each transmitting source in the array of transmitting sources can be regarded as a point source of sound spherical wave; the wave function of the sound spherical wave is represented as: ； wherein represents the sound pressure, represents the amplitude, represents the phase, represents the propagation distance of the spherical wave, is the sound wave number, is the imaginary unit; the holographic image is a 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.

7. The dual-sided multi-channel asymmetric encryption acoustic holography communication method based on metamaterials of claim 5, wherein, The super surface can arbitrarily modulate the amplitude and phase of the reflected sound wave, and by introducing a random number matrix, the pre-designed image information in the original sound field is destroyed, so that the image information becomes scrambled code in the encrypted sound field; different key super surfaces design the received scrambled code information according to the pre-designed channel image information and the placement position, and modulate the amplitude and phase, so as to obtain the original image information of the corresponding channel in the decrypted sound field reflected by the key super surface.

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