CN113271154A - Multi-path spatial multiplexing acoustic communication method and system based on composite distorted sound waves - Google Patents
Multi-path spatial multiplexing acoustic communication method and system based on composite distorted sound waves Download PDFInfo
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Abstract
The invention discloses an acoustic communication method and system based on multipath spatial multiplexing of composite distorted sound waves, which realize real-time communication with high information density in free space by utilizing multipath transmission of the composite distorted sound waves, realize real-time accurate decoding of different channel information through a single-layer super surface under the condition of no need of large-scale microphone scanning and complex time-consuming post-processing, and break through the information capacity limitation of the existing acoustic communication based on spatial multiplexing.
Description
Technical Field
The present invention relates to an acoustic communication method and system, and in particular, to an acoustic communication method and system based on multipath spatial multiplexing of complex distorted sound waves.
Background
Currently, information transmission technology in underwater environments is an important issue for current research. Due to the absorption of high-frequency electromagnetic waves by seawater and the scattering of light waves by micro-organisms in the ocean, underwater communication based on electromagnetic waves and light waves can only be transmitted in short distance. At present, acoustic waves become an ideal carrier for long-distance underwater information transmission. However, too high frequency sound waves are also attenuated in underwater transmission and cannot propagate in a long distance, which greatly limits the bandwidth range of the communication system.
In order to improve the channel capacity and spectral efficiency of acoustic communication systems, orbital angular momentum encodes information as a new spatial degree of freedom independent of phase and amplitude. Based on orthogonality of orbital angular momentum, distorted sound waves carrying different orders of orbital angular momentum can independently carry information and are multiplexed in the same transmission path, so that acoustic communication capacity is improved, but the realization of the communication system needs complex microphone arrays for post-processing or needs multilayer super-surface to decode the sound waves, so that the communication system is obviously influenced by diffraction effect and energy loss, the maximum number of available communication channels is limited, and communication capacity and efficiency cannot be further improved.
Disclosure of Invention
The purpose of the invention is as follows: in view of the deficiencies in the prior art, it is an object of the present invention to provide an acoustic communication method and system based on multipath spatial multiplexing of complex distorted acoustic waves, which utilizes multipath distortion of acoustic waves to achieve a high quality and high information density acoustic communication system in free space without passive post-processing and sensor scanning. The advantages of coaxial and non-coaxial twisted sound wave multiplexing are combined, and the limitation of information transmission capacity in the existing space multiplexing mechanism is broken through. Meanwhile, the super-surface used for information decoding at the receiving end naturally has robustness to the multipath effect, can inhibit the channel crosstalk caused by the multipath effect and the diffraction effect, and realizes high-precision information decoding.
The technical scheme is as follows: the invention provides a multipath spatial multiplexing acoustic communication method based on composite distorted sound waves, which comprises the following steps:
(1) the transmitting end and the receiving end are provided with a plurality of transmitting units and receiving units, a plurality of transmission paths are formed by utilizing the multipath effect, each path transmits composite distorted sound waves formed by distorted sound waves carrying orbital angular momentum of different orders, and the distorted sound waves of different orders can independently carry information to transmit to form mutually independent channels.
(2) And at the transmitting end, encoding each group of data to be transmitted into the amplitude and the phase of each order of distorted sound wave, wherein the signal source of each transmitting unit is the encoded composite distorted sound wave signal. Each signal source transmits the synthesized sound wave signal to a corresponding receiving unit through free space.
Optionally, information modulation is performed on the distorted sound wave with the designated frequency by using a binary amplitude keying modulation technology, wherein an amplitude 0 represents data 0, and an amplitude 1 represents data 1; other modulation techniques, such as quadrature amplitude modulation, may also be used to encode data into the amplitude and phase of each order of the distorted acoustic wave.
(3) The composite distorted sound waves on each path are separated in space after being despiralized by the passive demultiplexer, and are focused to different positions according to the order of the distorted sound waves. A single microphone is placed at a focus to receive signals, received sound wave signals are originally input data streams, and received signal energy is greatly enhanced based on a focusing effect.
The invention also provides a multipath spatial multiplexing acoustic communication system based on the composite distorted sound waves, which comprises a transmitting end and a receiving end, wherein the transmitting end and the receiving end are provided with N pairs of transmitting units and receiving units to form a plurality of non-coaxial transmission paths, and sound beams transmitted by each path are formed by compounding the distorted sound waves carrying different-order orbital angular momentum. Each transmitting unit transmits a composite distorted sound beam containing M orbital angular momentum modes, and distorted sound waves of each order of orbital angular momentum can independently carry information to be transmitted to form NM independent data channels;
encoding each group of data streams consisting of 0 and 1 to the amplitude and phase of sound waves of a group of channels to be used as a signal source; the distorted sound waves of different orders are used as carrier waves to carry different information for transmission, and a plurality of groups of independent signal channels are formed.
The transmitting end takes an active loudspeaker array as a transmitting unit and is used for synthesizing multi-order coaxial distorted sound waves and transmitting the multi-order coaxial distorted sound waves to a receiving unit corresponding to the receiving end through free space; the receiving end takes a passive demultiplexer designed based on a metamaterial as a receiving unit, and carries out deswirl on the composite distorted sound waves, namely, each order of distorted sound waves are converted into plane waves, and the deswirled sound waves are separated and converged to different positions; a microphone is arranged at the convergence point of each order of distorted sound waves and is used for receiving sound wave signals carrying original coded information.
Specifically, the method comprises the following steps:
(1) at the transmitting end, N active loudspeaker arrays are separated in space and used as N transmitting units, each transmitting unit can generate multiplexing distorted sound waves with M orbital angular momentums so as to form N multiplied by M independent data transmission channels, and each group of data streams consisting of 0 and 1 is encoded on the amplitude and phase of each order of distorted sound waves to be used as a signal source;
(2) and a single-layer super surface is arranged at the receiving end and consists of N passive demultiplexers based on the metamaterial, and the N demultiplexers correspond to the N transmitting units at the transmitting end.
Each demultiplexer can realize the derotation of each composite distorted sound wave and focus the composite distorted sound waves to different positions according to the order of orbital angular momentum carried by the distorted sound waves. Thus, acoustic signals carrying information can be detected by placing only one microphone at each focal point.
Wherein each transmitting unit is an active speaker array for generating a composite twisted sound beam on each path. The active loudspeaker array is formed by arranging 10 loudspeakers in 1 circle at equal intervals, the angle interval of each loudspeaker is 36 degrees, and the radius of the array is 15 cm. An Arduino Mega2560 single chip microcomputer is adopted to input signals to each loudspeaker and independently control the amplitude and the phase of each signal; namely, the Arduino Mega2560 singlechip provides input signals for 10 loudspeakers and independently controls the amplitude and the phase of each input signal, thereby generating composite distorted sound waves carrying first-order and negative first-order orbital angular momentum.
Wherein the communication environment is free space; optionally, the N transmitting units and the N receiving units are arranged in a linear or circular manner.
Wherein M represents the number of paths, N represents the number of distorted sound waves, and M and N are positive integers; optionally, M ═ 2, N ═ 2; the multiplexed distorted sound waves are synthesized by the distorted sound waves carrying first-order orbital angular momentum and negative first-order orbital angular momentum, and the whole communication system has two propagation paths.
Preferably, the active speaker array is formed by 10 speakers arranged in a circle at equal intervals, each speaker is at an angular interval of 36 °, and the array radius is 15 cm.
Preferably, the linear distance of the transmitting unit and the corresponding receiving unit is 1.2 m.
Preferably, the centers of two adjacent speaker arrays are spaced apart by 70 cm.
Preferably, the size of the demultiplexer is 50cm × 50cm, and the thickness is 5 cm; the center-to-center spacing between two adjacent demultiplexers is 70 cm.
The passive demultiplexer is formed by a single-layer plane structure formed by sequentially arranging a plurality of basic units; the basic unit is a mixed structure with a resonant cavity array on one side and a straight pipe on the other side, and the straight pipe heights h of different basic units1Different. Namely: the passive demultiplexer based on the metamaterial is a single-layer plane structure formed by specially arranging a plurality of basic units, each basic unit is designed into a mixed structure consisting of a side loading resonant cavity array and a straight pipe, and the difference of each basic unit is that the heights of the straight pipes forming the basic units are different.
The invention principle is as follows: the orbital angular momentum in the invention is used as a space degree of freedom independent of amplitude and phase to form a complete set of orthogonal bases, so that the distorted sound waves carrying different orbital angular momenta can be coaxially superposed in space, and different information is encoded into the amplitude and phase of the distorted sound waves of different orders to be transmitted. The new space freedom degree of non-coaxiality is introduced, the multipath transmission of the multiplexed distorted sound waves is realized, and the number of the available communication channels of the system is further increased. And at a receiving end, the information decoding of the multipath composite distorted sound wave is realized by utilizing the single-layer super surface. The single-layer super surface is composed of a plurality of super material-based demultiplexers, each demultiplexer is used for receiving and decoding the composite distorted sound waves from the corresponding transmitting unit, when the multiplexed signals pass through the demultiplexers, the distorted sound waves with different orders are deswirled into plane waves and are focused to different positions according to the orders of orbital angular momentum carried by the plane waves, and the sound signals received by a single microphone at the focal point represent the information carried by the orbital angular momentum.
The receiving end does not need a complex sensor array to scan a sound field and perform time-consuming post-processing, multi-channel information of the whole communication system can be accurately decoded in real time based on a single-layer super surface, and only a single microphone is needed to receive signals at each focus. The sound intensity of the focus area is obviously enhanced, so that the signal-to-noise ratio of the received signal is improved, and the long-distance transmission and the low bit error rate in the communication process are ensured. Meanwhile, the super surface has strong direction selectivity, has certain robustness to channel crosstalk caused by acoustic diffraction and multipath effect, and can realize high-precision information decoding of signals without post-processing.
The technical difficulty of the invention is that: considering that the diffraction effect of the distorted sound wave carrying higher orbital angular momentum orders is more significant when the distorted sound wave propagates in the free space, the reduction of the transverse size of the emission source also increases the diffraction of the distorted sound wave in the propagation process, and the crosstalk effect and the energy loss caused by the sound wave diffraction in the communication need to detect signals by using a large-scale sensor array and perform complex post-processing on the detected signals to offset, so that the improvement of the orbital angular momentum orders and the reduction of the emission unit and the receiving unit are hindered, and therefore, the existing acoustic communication system based on the orbital angular momentum multiplexing cannot obtain more available communication channels and realize higher spatial information density due to the limitations of the orbital angular momentum orders and the emission/receiving sizes. Meanwhile, the post-processing mode based on the complex sensor array scanning or the multi-layer super-surface demodulation reduces the efficiency and accuracy of information decoding, and limits the application of the information decoding in practice. Although the reliability of multiplexing information using non-coaxial twisted waves in optics has been proven, its implementation requires complex and time-consuming equalization algorithms to suppress channel crosstalk due to multipath effects and diffraction effects, which are much stronger for acoustic waves. In addition, passive devices for decoding optically distorted beams in real time are too bulky to be directly applied to acoustic waves having macroscopic wavelengths. This poses fundamental limitations to further increase of spatial information density using existing acoustic communication mechanisms.
The transmitting end and the receiving end of the communication system are provided with a plurality of transmitting units and receiving units to form a plurality of non-coaxial transmission paths, and the sound beam transmitted by each path is formed by compounding distorted sound waves carrying different orbital angular momentum. Encoding each group of data streams consisting of 0 and 1 to the amplitude and phase of sound waves of a group of channels to be used as a signal source; the distorted sound waves of different orders are used as carrier waves to carry different information for transmission, and a plurality of groups of independent signal channels are formed. Each transmitting unit is an active loudspeaker array used for synthesizing multi-order coaxial distorted sound waves and is transmitted to a receiving unit corresponding to the receiving end through free space. The receiving unit is a passive demultiplexer designed based on a metamaterial, the demultiplexer can realize respective derotation of the composite distorted sound waves, namely, each order of distorted sound waves are converted into plane waves, and the derotated sound waves are converged to different positions. A microphone is placed at the convergence point of each order of the distorted sound waves to receive the sound wave signal carrying the original encoded information while its acoustic energy is amplified. The multi-path spatial multiplexing acoustic communication method and system based on the composite distorted sound waves realize high-information-density real-time communication in free space by utilizing the multi-path transmission of the composite distorted sound waves, realize real-time accurate decoding of different channel information through a single-layer super surface under the condition of not needing large-scale microphone scanning and complex and time-consuming post-processing, and break through the information capacity limitation of the existing acoustic communication based on the spatial multiplexing.
Has the advantages that:
(1) the invention provides an acoustic communication method and system based on multipath spatial multiplexing of composite distorted sound waves, which realizes a communication system with high spatial information density in free space, breaks through the number of channels of the existing acoustic communication based on orbital angular momentum multiplexing, and further improves the communication capacity and efficiency.
(2) Compared with the existing bulky optical communication system, the mechanism adopts a single-layer super surface with reasonable design and compact three-dimensional size to receive and decode the information carried by the transmitting sound beam. The designed super-surface has strong space selectivity, and any oblique incident distorted sound wave can not obviously influence the sound intensity at a designated focus, so that the system has inherent robustness on the increase of crosstalk effect, a simple and low-cost receiving system is designed under the condition of no need of sensor scanning and post-processing, and the error rate far lower than the forward error correction standard is realized.
(3) The received signal has enhanced amplitude and original phase information, which not only obviously improves the signal-to-noise ratio, but also embodies the compatibility of the mechanism of the invention with the traditional multiplexing technology and signal processing, and can further improve the capacity and the precision of transmission data. Meanwhile, the communication system realizes high spatial information density of record creation, which is ensured by the compactness of a transmitting end and a receiving end and the introduction of non-coaxial distorted sound waves as new coding freedom degrees.
(4) Furthermore, due to the single layer super-surface design, with high transmission and parallel interaction between all its elementary cells and the incident acoustic beam, the system can be easily extended to have more communication channels, while reducing the increased hardware complexity and power consumption in conventional communication mechanisms.
Drawings
Fig. 1 is a schematic diagram of the principle of the present invention.
Fig. 2 is a schematic diagram of an acoustic communication system based on multipath spatial multiplexing of complex distorted sound waves, which is provided by experiments according to the present invention.
Fig. 3 is a schematic diagram of an active speaker array used in experiments conducted in accordance with the present invention.
FIG. 4 is a diagram of the basic cell structure constituting the demultiplexer and its various straight tube heights h1 corresponding to the phase shift and transmittance of the acoustic wave; wherein, the diagram a is a basic unit structure schematic diagram, and the diagram b is a sound wave phase shift and transmissivity curve diagram.
Fig. 5 is a schematic diagram of the continuous and discrete phase distribution and structure of a demultiplexer used in experiments performed by the present invention.
Fig. 6 is an enlarged schematic diagram of the demultiplexer.
FIG. 7 is a comparison chart of 50bits information input and output results in four channels.
Fig. 8 shows the experimental results of transmitting a complex image using four channels and comparing the complex image with a target image.
Detailed Description
The present invention will be described in further detail with reference to examples.
As shown in fig. 1, N pairs of transmitting units and receiving units are arranged at a transmitting end and a receiving end, each transmitting unit can transmit a composite distorted acoustic beam including M orbital angular momentum modes, and distorted acoustic waves of each order of orbital angular momentum can independently carry information for transmission, so that NM independent data channels are formed. Note that the arrangement of the transmitting units and the receiving units may be various, and a linear or circular arrangement may be applicable.
In the invention, an active loudspeaker array is used as a transmitting unit at a transmitting end to generate multi-order orbital angular momentum composite distorted sound beams, and a plurality of demultiplexers are used as receiving units at a receiving end to receive a composite sound field from the corresponding transmitting unit. Due to diffraction caused by propagation of sound waves in free space, each receiving unit not only receives sound waves from a corresponding transmitting unit, but also receives divergent sound waves of other transmitting units, so that crosstalk between channels is generated. The composite distorted sound waves are converted into plane waves after passing through the demultiplexer and are separated in space, the distorted sound waves of different orders are focused to different positions, and original information carried by each order of distorted sound waves can be accurately extracted by using a single microphone to receive sound signals in a specified area, so that the communication system can detect all transmitted information by using the number of microphones which is the same as the number of channels.
As shown in fig. 2, in this embodiment, M is 2, and N is 2, that is, two active speaker arrays are provided at the transmitting end, and each transmitting unit transmits a distorted sound wave compounded by first-order and negative-first-order orbital angular momentum, thereby forming four channels for information transmission. The single-layer super surface of the receiving end is composed of two demultiplexers, two microphones are arranged behind each demultiplexer and are respectively positioned on the focuses of the first-order distorted sound waves and the negative first-order distorted sound waves, and the microphones are used for receiving sound signals focused to the focuses through the demultiplexers so as to obtain information transmitted by the channels.
Fig. 3 shows an active speaker array of 10 speakers used in the system, which are equally spaced in 1 turn with a radius of 15 cm. Wherein speakers 1, 3, 5, 7, 9 are used to generate the distorted sound beam carrying first order orbital angular momentum, and speakers 2, 4, 6, 8, 10 are used to generate the distorted sound beam carrying negative first order orbital angular momentum. The amplitude and phase of each loudspeaker input signal are controlled by an Arduino Mega2560 singlechip.
Each set of binary data streams consisting of 0 and 1 is encoded for information transmission at the amplitude and phase of each order of the distorted acoustic wave. The invention utilizes a binary amplitude keying modulation technology to carry out information modulation on the distorted sound wave with the designated frequency, wherein the amplitude value 0 represents data 0, and the amplitude value 1 represents data 1. Other modulation techniques, such as quadrature amplitude modulation, may also be used to encode data into the amplitude and phase of each order of the distorted acoustic wave.
The composite distorted sound waves on each path are converted into plane waves respectively after passing through the demultiplexer and are focused to different positions, a microphone is placed at each focal point to receive a time domain signal, and the normalized amplitude (0, 1) of the sound waves detected by the microphone represents the originally input binary data stream.
The working principle of the demultiplexer is to realize the composite torsion by manipulating the phase function distributed in the super surfaceAnd simultaneously demultiplexing and focusing the curved sound beams, multiplying each order of reverse distortion phase factor of the multiplexed distorted sound beams by the corresponding focusing phase according to the superposition principle, and then adding to obtain the phase distribution on the demultiplexer. As shown in fig. 4 a, the basic unit of the demultiplexer in this embodiment is designed as an acoustic hybrid structure, and is composed of a side-loaded resonant cavity array and a straight pipe, which are respectively used for adjusting and controlling the propagation phase of the incident acoustic wave and improving the transmission efficiency. Total height h of basic unit is 0.25 lambda, and height of straight pipe of constituent unit is h1By adjusting the geometric parameter h1The phase modulation and transmittance variation of the cells for the incident acoustic wave can be obtained, as shown in b of fig. 4, from which the basic cells constituting the demultiplexer can be seen as a function of h1Can produce an arbitrary phase shift from 0 to 2 pi while maintaining a transmission close to 1 as required by the mechanism of the present invention. We discretize the phase distribution required for demodulating the first-order and negative-order complex distorted sound waves in this embodiment into distribution of four phase points of pi/4, 3 pi/4, 5 pi/4 and 7 pi/4, and use four basic units (marked with four points in b of fig. 4) to realize the above-mentioned regulation of the four discrete phase points of the incident sound waves and arrange them according to the required phase distribution, so as to obtain the single-layer demultiplexer shown in fig. 5 and 6. The demultiplexer has a size of 5 λ x 5 λ, is made up of 20 × 20 basic elements, has a thickness I of 0.5 λ in the propagation direction, λ being the wavelength of the incident sound wave, and, for example, in the subsequent results, the background medium is air, and its density and sound velocity are 1.21kg/m, respectively3And 343m/s, the frequency of the incident sound wave is 3430Hz, and the wavelength λ thereof is 0.1 m. If the distorted sound wave demultiplexers with other orders are designed, the arrangement modes of the four basic units are changed according to the dispersed target phase distribution.
The following tests were performed on the communication system proposed by the present invention, specifically as follows:
frequency f of incident sound wave03430Hz, period TC＝2.92×10-4And s, the material of the demultiplexer is ABS plastic. Other materials with sufficient acoustic impedance can also be used to make the designed structure, only the acoustic impedance of the material is 300 times greater than that of airThat is, for example, various metals, alloys, and the like can be used as the candidate material.
The present embodiment first proves the effectiveness of the proposed mechanism by an example of parallel independent transmission of four sets of 50bits data streams. In this embodiment, the two paths transmit a twisted beam composed of first order and negative first order, which are formed into four independent channels (labeled channel 1 to channel 4) for transmitting four sets of data streams. Four sets of data streams are encoded in 2ASK format onto the amplitude of the distorted acoustic waves in each channel. The data-carrying signal is pulse modulated with a pulse period of 20T0Each pulse period contains 1 bit of data. A comparison of the decoded data streams in the four channels with the target signal is plotted in fig. 7. Obviously, the decoded information flow is consistent with the input information flow without any distortion, which shows that the mechanism proposed by the invention can realize real-time and high-precision information decoding even without complex post-processing.
Next, a complex binary image "Lena" is transmitted in real time through experiments, and the image includes 432 × 416 pixels, and the pixel with the pixel value 0 is represented by data 0, and the pixel with the pixel value 255 is represented by data 1. As shown in fig. 7, the target image is divided into four parts and transmitted through four channels at the same time. By combining the four measured data streams together, an output image is obtained and the result is plotted in fig. 8, which shows a very high image restoration quality without significant difference from the target image. In experiment, the communication system of the invention measures the average bit error rate of four channels as low as 9.2 x 10-4Approximately an order of magnitude lower than the forward error correction standard. This verifies the strong robustness of the proposed mechanism to crosstalk effects, which can enable high precision and high capacity information communication while avoiding the dependence of traditional computer-based post-processing on latency and energy consumption. Compared with the original single-path orbital angular momentum multiplexing mechanism, the transmission rate in the mechanism provided by the invention is increased by a factor, namely, the number of paths is multiplied by the total number of orbital angular momentum modes in each path. High-quality and high-spatial information density real-time image transmission is realized by utilizing multipath spatial multiplexing of distorted sound waves。
Fig. 7 and 8 experimentally prove that the proposed acoustic communication method and system based on multipath spatial multiplexing of composite distorted sound waves introduces non-coaxial distorted sound waves as a new coding degree of freedom, so that the communication system has more high-quality transmission channels, and the communication capacity and the spectral efficiency of the system are improved while the system stability is ensured. The demultiplexer based on the metamaterial used at the receiving end has strong direction selectivity and high robustness on channel crosstalk caused by diffraction effect, and meanwhile, the focusing mechanism of the demultiplexer improves the signal-to-noise ratio of signal detection at a focus, so that high-precision decoding of signals is realized without post-processing. This also ensures that the communication system of the present invention can be extended to more transmission paths and orbital angular momentum modes, propagating further distances. Note that the communication capacity and spectral efficiency of our system can be further improved by using higher order shift keying coded data.
Claims (10)
1. A multipath spatial multiplexing acoustic communication method based on composite distorted sound waves is characterized by comprising the following steps:
(1) a plurality of transmitting units and receiving units are arranged at a transmitting end and a receiving end to form a plurality of non-coaxial transmission paths, and each path transmits composite distorted sound waves formed by distorted sound waves carrying orbital angular momentum of different orders to form mutually independent channels;
(2) at a transmitting end, encoding each group of data to be transmitted into the amplitude and phase of each order of distorted sound wave, wherein a signal source of each transmitting unit is a coded composite distorted sound wave signal, and each channel of signal source transmits the synthesized sound wave signal to a corresponding receiving unit through free space;
(3) the composite distorted sound wave on each path is separated in space after being de-rotated, and is focused to different positions according to the order of the distorted sound wave, and a microphone for receiving signals is arranged at the focal point.
2. The method of claim 1 for acoustic communication based on multipath spatial multiplexing of complex distorted acoustic waves, wherein: in the step (2), each group of data to be transmitted is modulated by binary amplitude keying or quadrature amplitude modulation, and the data is encoded into the amplitude and phase of each order of distorted sound waves.
3. An acoustic communication system based on multipath spatial multiplexing of complex distorted sound waves, characterized by: the system comprises a transmitting end and a receiving end, wherein the transmitting end and the receiving end are provided with N pairs of transmitting units and receiving units, and each transmitting unit transmits a composite distorted sound beam containing M orbital angular momentum modes to form NM groups of independent data channels; encoding each group of data stream to the amplitude and phase of the sound wave of a group of channels to be used as a signal source;
the transmitting end takes N active loudspeaker arrays as N transmitting units, is used for synthesizing multi-order coaxial distorted sound waves, and transmits the multi-order coaxial distorted sound waves to a receiving unit corresponding to the receiving end through free space; the receiving end takes N passive demultiplexers designed based on metamaterials as N receiving units, carries out despiralization on the composite distorted sound waves, and separates and gathers the despiralized sound waves to different positions; a microphone is arranged at the convergence point of each order of distorted sound waves and is used for receiving sound wave signals carrying original coding information; wherein M and N are both positive integers.
4. The acoustic communication system based on multipath spatial multiplexing of complex distorted acoustic waves of claim 3, wherein: the arrangement mode of the N transmitting units and the N receiving units is linear or circular.
5. The acoustic communication system based on multipath spatial multiplexing of complex distorted acoustic waves of claim 3, wherein: m2, N2, the said multiplexing distortion sound wave is synthesized by the distortion sound wave carrying the orbital angular momentum of the first order and the minus first order, the whole communication system has two propagation paths.
6. The acoustic communication system based on multipath spatial multiplexing of complex distorted acoustic waves of claim 3, wherein: the active speaker array is formed by 10 speakers arranged in a circle at equal intervals, and the angular interval of each speaker is 36 degrees.
7. The acoustic communication system based on multipath spatial multiplexing of complex distorted acoustic waves of claim 3, wherein: the passive demultiplexer is formed by a single-layer plane structure formed by sequentially arranging a plurality of basic units; the basic unit is a mixed structure with a resonant cavity array on one side and a straight pipe on the other side, and the straight pipe heights h of different basic units1Different.
8. The acoustic communication system based on multipath spatial multiplexing of complex distorted acoustic waves of claim 3, wherein: the corresponding straight-line distance between the transmitting unit and the receiving unit is 1.2 m.
9. The acoustic communication system based on multipath spatial multiplexing of complex distorted acoustic waves of claim 3, wherein: the center spacing of two adjacent speaker arrays was 70 cm.
10. The acoustic communication system based on multipath spatial multiplexing of complex distorted acoustic waves of claim 3, wherein: the size of the demultiplexer is 50cm multiplied by 50cm, and the thickness is 5 cm; the center-to-center spacing between two adjacent demultiplexers is 70 cm.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114696919A (en) * | 2022-03-31 | 2022-07-01 | 南京大学 | Orbital angular momentum multiplexing method based on space-time thermoacoustic super surface |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20160043794A1 (en) * | 2014-08-08 | 2016-02-11 | Solyman Ashrafi | Systems and methods for focusing beams with mode division multiplexing |
| CN105471803A (en) * | 2015-12-09 | 2016-04-06 | 深圳大学 | Millimeter wave high speed modulation and demodulation system and method based on antenna array |
| CN107332629A (en) * | 2017-06-27 | 2017-11-07 | 南京大学 | A kind of method for transmitting signals multiplexed based on acoustics orbital angular momentum |
| CN108599871A (en) * | 2018-05-07 | 2018-09-28 | 中国科学院声学研究所 | A kind of underwater acoustic communication method and system based on orbital angular momentum multiplexing technology |
| CN112199899A (en) * | 2020-08-25 | 2021-01-08 | 南京大学 | Single-source generation method and generation device for orbital angular momentum in two-dimensional fluctuation system |
-
2021
- 2021-04-23 CN CN202110445288.3A patent/CN113271154B/en active Active
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20160043794A1 (en) * | 2014-08-08 | 2016-02-11 | Solyman Ashrafi | Systems and methods for focusing beams with mode division multiplexing |
| CN105471803A (en) * | 2015-12-09 | 2016-04-06 | 深圳大学 | Millimeter wave high speed modulation and demodulation system and method based on antenna array |
| CN107332629A (en) * | 2017-06-27 | 2017-11-07 | 南京大学 | A kind of method for transmitting signals multiplexed based on acoustics orbital angular momentum |
| CN108599871A (en) * | 2018-05-07 | 2018-09-28 | 中国科学院声学研究所 | A kind of underwater acoustic communication method and system based on orbital angular momentum multiplexing technology |
| CN112199899A (en) * | 2020-08-25 | 2021-01-08 | 南京大学 | Single-source generation method and generation device for orbital angular momentum in two-dimensional fluctuation system |
Non-Patent Citations (1)
| Title |
|---|
| 梁彬等: "声波的"漩涡"——声学轨道角动量的产生、操控与应用", 《物理》 * |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114696919A (en) * | 2022-03-31 | 2022-07-01 | 南京大学 | Orbital angular momentum multiplexing method based on space-time thermoacoustic super surface |
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