Low-frequency acoustic wave green wireless power-carrying communication device

Abstract

The application discloses a kind of low-frequency acoustic green wireless energy-carrying communication devices, including signal frequency modulation coding and acoustic sending module, acoustic wave filter and sound-electricity conversion module, electric signal acquisition and demodulation decoding module and electric energy storage module;Wherein signal frequency modulation coding and acoustic sending module modulates information into waveform containing coded information, drives loudspeaker to generate acoustic wave;Acoustic wave filter and sound-electricity conversion module amplify and stimulate enhancement to the sound pressure of incident acoustic wave, convert through friction nanogenerator, generate high-output voltage signal;Electric signal acquisition and demodulation decoding module sends analog voltage signal into processor, identifies voltage frequency in electric signal, demodulates original information;Electric energy storage module stores the excess electric energy in acoustic wave filter and sound-electricity conversion module.The application greatly simplifies the complexity of communication system, realizes reliable communication, improves transmission information security, realizes energy storage and communication function multiplexing.

Description

Technical Field

[0001] This invention relates to the field of self-powered sensors and communications, specifically to a low-frequency acoustic wave green wireless power-carrying communication device. Background Technology

[0002] Self-powered sensing technology utilizes environmental energy resources, such as light, vibration, or heat, to provide the necessary electrical power for sensor nodes. This technology significantly reduces the energy requirements of sensor nodes, extends their lifespan, and reduces reliance on battery replacement and maintenance. Wang Z et al. achieved self-powered infrared wireless communication by integrating a triboelectric nanogenerator and an infrared transmitter (Wang Z, Jin Y, Lu C, et al. Triboelectric-nanogenerator-enabled mechanical modulation for infrared wireless communications[J]. Energy & Environmental Science[2023-06-06].DOI:10.1039 / D2EE00900E). Under a specific mechanical modulation protocol, different mechanical movements or structures of the triboelectric nanogenerator drive infrared light-emitting diodes to characterize the frequency and amplitude characteristics of the mechanical motion signals to transmit information. However, modulating infrared signals using triboelectric nanogenerators increases the hardware complexity of the device, significantly increasing costs. Furthermore, when controlling the triboelectric nanogenerator to generate modulated information through mechanical motion, the start and stop of the motion cannot be instantaneous; there is a beginning and an end process. During this process, the anti-interference performance required for accurate signal transmission and reception is extremely high. Moreover, during infrared wireless communication, there must be no obstacles obstructing the transmission and reception nodes; if the infrared signal is blocked, communication will be interrupted. Additionally, in this paper, the triboelectric nanogenerator is only used at the transmitting end to drive the infrared LED, while a pair of infrared LEDs are still used for signal transmission and reception.

[0003] Compared to mechanical modulation systems, acoustic communication technology offers a simpler and more effective solution, with advantages including simplified equipment structure and reduced deployment costs. The response time of acoustically driven sources during startup and shutdown is significantly better than that of mechanical transmissions, providing a faster response capability for establishing communication. More importantly, acoustic waves can easily bypass obstacles, while infrared communication requires fixed sending and receiving positions, unobstructed access, small deviation angles, and extremely short transmission distances. Yun HS et al. proposed a novel acoustic data transmission system based on Modulated Complex Lapped Transform (LCLT). By innovating modulation and demodulation methods, they achieved acoustic covert communication by embedding data into sound waves without interference (Yun HS, Cho K, Kim N S. Acoustic Data Transmission Based on Modulated Complex Lapped Transform[J].IEEE Signal Processing Letters,2009,17(1):67-70.DOI:10.1109 / LSP.2009.2032751.). In their designed acoustic communication system, the device for receiving sound waves still uses a conventional microphone sensor, which requires an additional power supply. The frequency band used in the acoustic communication process is 6-8kHz, and the energy loss of sound waves in this frequency band is very large when transmitted through the air. In addition, the modulation and demodulation method used to resist noise is relatively complex and not easy to implement in software or hardware. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention proposes a low-frequency acoustic wave green wireless power-carrying communication device. This device eliminates the need for additional power supply to the receiving node. Upon receiving low-frequency acoustic wave excitation, the acoustic wave filter at the receiving end, due to its inherent frequency selection and self-driving characteristics, can generate a strong response to a specific frequency band, producing a voltage signal with a large amplitude. The electrical signal amplitude generated by excitation in other frequency bands is low or negligible, thus achieving hardware noise immunity and effectively improving the signal-to-noise ratio.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] This invention proposes a low-frequency acoustic wave green wireless energy-carrying communication device, including a signal frequency modulation coding and acoustic wave transmission module, an acoustic wave filtering and acoustic-to-electrical conversion module, an electrical signal acquisition and demodulation decoding module, and an energy storage module.

[0007] The signal frequency modulation encoding and sound wave transmission module is used to form a waveform containing encoded information through frequency modulation, perform digital-to-analog conversion and power amplification to drive the speaker to generate sound waves, and transmit the sound waves wirelessly to the sound wave filtering and acoustic-to-electric conversion module to send the information to be transmitted.

[0008] The acoustic wave filtering and acoustic-to-electric conversion module is used to amplify and excite the sound pressure of incident sound waves in a specific frequency band. Without applying an external power supply, it converts the acoustic wave signal containing coded information into an analog electrical signal containing coded information through a triboelectric nanogenerator, generating a high-output voltage signal, which is then transmitted to the electrical signal acquisition, demodulation, and decoding module.

[0009] The electrical signal acquisition and demodulation / decoding module is used to acquire analog voltage signals and send them to the processor. By identifying the voltage frequency in the electrical signal, it demodulates the original information from the electrical signal containing coded information.

[0010] The energy storage module is used to store excess energy from the acoustic wave filtering and acoustic-to-electrical conversion module.

[0011] Furthermore, the signal frequency modulation and coding and sound wave transmission module is wirelessly connected to the sound wave filtering and acoustic-to-electrical conversion module; the sound wave filtering and acoustic-to-electrical conversion module is wiredly connected to both the electrical signal acquisition, demodulation, and decoding module and the energy storage module. This interconnectivity allows the energy carried by the sound waves to be converted into information after acoustic-to-electrical conversion, with the remaining portion stored as energy by the energy storage module, thus achieving energy-carrying green communication.

[0012] Furthermore, the signal frequency modulation coding and acoustic wave transmission module is configured to perform the following actions:

[0013] When sending image information, a start word is set, and the image is read out as a one-dimensional array and converted into binary form. Binary digital frequency modulation is used to map the 0s and 1s in the binary representation to two corresponding signals of different frequencies, forming a waveform containing the image's encoded information. When sending text information, a start word is set, and the text is converted into a corresponding one-dimensional array using ASCII encoding. This one-dimensional array is then converted into binary form. Binary digital frequency modulation is used to map the 0s and 1s in the binary representation to two corresponding signals of different frequencies, forming a waveform containing the text's encoded information.

[0014] The waveform is converted from digital to analog and then sent to a power amplifier to drive the speaker to emit sound waves.

[0015] Furthermore, the two different frequency signals satisfy the following: First, the triboelectric nanogenerator has the best electrical performance when excited at low frequencies, so the selected acoustic frequency needs to be low, and the emitted acoustic frequency should be between 20-200Hz; Second, the two selected modulation frequencies need to refer to the acoustic resonant frequency of the acoustic filter, with the acoustic resonant frequency as the center frequency, and the two modulation frequencies located on both sides of the center frequency to obtain a better signal-to-noise ratio, achieve the purpose of hardware anti-interference, and prevent aliasing between the two frequencies during demodulation.

[0016] Furthermore, the acoustic filtering and acoustic-to-electric conversion module includes an acoustic filtering section and an acoustic-to-electric conversion section.

[0017] The acoustic filtering part consists of an incident surface with an opening, a neck tube placed in the opening of the incident surface, a cavity, and a flexible bottom, forming an acoustic filter. The neck tube is placed inside the cavity. The volume of the acoustic filter cavity, the radius of the opening at the top, and the length of the neck of the acoustic filter opening are designed using finite element numerical calculation.

[0018] The acoustic-to-electric conversion section employs a contact-separation triboelectric nanogenerator, comprising a positively charged material, a conical device, a spacer ring, an electronegative film, a perforated plate, and electrodes. The positively charged material is coated onto the conical device, forming a conical device with one side coated with conductive positively charged material. Its top surface is fixed to the center of the flexible bottom of the acoustic filter, while its bottom surface is a circular surface coated with positively charged conductive material. The spacer ring, a ring structure slightly higher than the conical device, is fixed between the flexible bottom of the acoustic filter and the perforated plate, ensuring that the positive and negative charged layers can achieve contact separation when the triboelectric nanogenerator is excited by the flexible bottom surface. The membrane is a dielectric material with an electrode on one side of its surface as an extraction electrode. Its main purpose is to extract the charge from the electronegative membrane. The electronegative membrane can be polarized to improve the output performance of the triboelectric nanogenerator. The electronegative membrane is fixed on a perforated plate. The perforated plate is used to expel air from the area near the charged layer, thereby reducing resistance. When the acoustic signal acts on the flexible bottom of the acoustic filter, the resulting vibration will cause a conical device coated with a conductive positive material on one side to come into contact with and separate from the perforated plate on which the electronegative membrane is fixed. A conductive current is formed between the positive and negative material electrodes, converting acoustic energy into an electrical signal.

[0019] Furthermore, the acoustic filtering and acoustic-to-electrical conversion module is configured to perform the following actions:

[0020] When a sound wave containing modulation information is transmitted through the air medium to the sound wave filter section, if its spectral components contain the resonant frequency of the sound wave filter section, the sound wave filter section will generate a strong response to this frequency and its surrounding frequency bands, amplifying the sound pressure of the incident sound signal in the frequency band containing the encoded information, thereby effectively enhancing the excitation of the flexible substrate. For other frequency components, because the frequencies deviate significantly from the resonant frequency of the sound wave filter section, and due to the structural characteristics of the sound wave filter, it can suppress sound waves in other frequency bands.

[0021] In the acoustic-to-electric conversion section, when resonance occurs, the sound pressure inside the cavity is significantly amplified compared to the sound pressure in the external environment, creating a significant pressure difference on the flexible bottom surface of the acoustic filter. This excites the flexible bottom surface to reciprocate, and the conical device fixed to the flexible bottom surface will also reciprocate. The resulting vibration causes the conical device, coated with a positively charged material on one side, to come into contact with and separate from the perforated plate with a fixed electronegative membrane. Based on the principles of contact electrification and electrostatic induction, alternating current is generated between the electrodes, completing the acoustic-to-electric conversion and storing the electrical energy after the acoustic-to-electric conversion.

[0022] Furthermore, the electrical signal acquisition, demodulation, and decoding module acquires electrical signal data, demodulates the voltage signal using the 2FSK demodulation principle, and recovers the original information to ultimately achieve communication. The generated electrical signal can be further demodulated and decoded, and its contained electrical energy can be stored, realizing the functional reuse of green communication and energy storage.

[0023] Furthermore, the energy storage module converts AC power into DC power through a full-bridge rectifier and stores energy by charging a capacitor.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0025] (1) Without adding an external signal amplifier and power supply, the acoustic resonance effect of the acoustic filter enhances the excitation of the nanogenerator by the acoustic wave of a specific frequency band. The acoustic-electric conversion is realized by the triboelectric nanogenerator, generating an electrical signal with a high voltage amplitude, which contains the transmitted information. Furthermore, this original information can be obtained by demodulation, which greatly simplifies the complexity of the communication system.

[0026] (2) By optimizing the communication effect through acoustic wave drive, compared with the existing acoustic wave communication, it is not necessary to increase the complexity of the modulation method. Through the design of a specific acoustic wave filter structure, the sound pressure at the communication frequency band is amplified and the sound pressure at other frequencies is reduced, thereby achieving the purpose of physical enhancement of useful signals and hardware noise immunity, reducing the difficulty and bit error rate during modulation and demodulation, and realizing reliable communication.

[0027] (3) Through experimental testing, the present invention demonstrates good noise resistance and can transmit text and images even under certain interference. Due to its noise resistance, embedding sound wave signals containing encoded information into music can achieve the effect of acoustically concealed communication, thereby improving the security of transmitted information.

[0028] (4) The electrical energy generated after the sound-to-electric conversion can be stored to achieve the effect of energy-carrying green communication and realize the functional reuse of energy storage and communication. Attached Figure Description

[0029] Figure 1 This is an overall structural diagram of the device of the present invention.

[0030] Figure 2 This is a structural diagram of the signal frequency modulation coding and sound wave transmission module of the present invention.

[0031] Figure 3 This is a structural diagram of the acoustic wave filtering and acoustic-to-electric conversion module of the present invention.

[0032] Figure 4 This is an exploded view of the acoustic wave filtering and acoustic-to-electric conversion module of the present invention.

[0033] Figure 5 This is an exploded view of the acoustic filter of the present invention.

[0034] Figure 6 This is an exploded view of the acoustic-electric conversion structure of the present invention.

[0035] Figure 7 This is a schematic diagram of the power generation principle of the triboelectric nanogenerator of the present invention.

[0036] Figure 8 It is the voltage signal obtained by acoustic wave excitation generated by a 60-second frequency sweep from 50Hz to 150Hz in an embodiment of the present invention.

[0037] Figure 9 This is a structural diagram of the signal acquisition, demodulation, and decoding module of the present invention.

[0038] Figure 10 This is a schematic diagram of how the electrical energy generated by the sound-to-electricity conversion is sent to the energy storage module in an embodiment of the present invention.

[0039] Figure 11 This is a comparison diagram of the results from the sending and receiving ends of a PNG format bitmap with an image depth of 1 according to an embodiment of the present invention.

[0040] Figure 12 This is a time-domain waveform diagram of the transmitting end in an embodiment of the present invention.

[0041] Figure 13 This is a spectrum diagram of the transmitting end in an embodiment of the present invention.

[0042] Figure 14 This is a time-domain waveform diagram of the receiving end in an embodiment of the present invention.

[0043] Figure 15 This is a spectrum diagram of the receiving end in an embodiment of the present invention.

[0044] Figure 16 This is a comparison diagram of the results from the text content sending end and receiving end in an embodiment of the present invention.

[0045] Figure 17 This is a time-domain waveform diagram of the music embedded during image transmission in an embodiment of the present invention.

[0046] Figure 18 This is a time-domain waveform diagram of the transmitting end when using cloth as an obstacle during image transmission in an embodiment of the present invention.

[0047] Figure 19 This is a spectrum diagram of the transmitting end when using cloth as an obstacle during image transmission in an embodiment of the present invention.

[0048] Figure 20 This is a time-domain waveform diagram of the receiving end when using cloth as an obstacle during image transmission in an embodiment of the present invention.

[0049] Figure 21 This is a spectrum diagram of the receiving end when using cloth as an obstacle during image transmission in an embodiment of the present invention.

[0050] Figure 22 This is a time-domain waveform diagram of the music embedded during text transmission in an embodiment of the present invention.

[0051] Figure 23 This is a time-domain waveform diagram of the transmitting end when using a PLA board as an obstacle during text transmission in an embodiment of the present invention.

[0052] Figure 24 This is a spectrum diagram of the transmitting end when using a PLA board as an obstacle during text transmission in an embodiment of the present invention.

[0053] Figure 25 This is a time-domain waveform diagram of the receiving end when using a PLA board as an obstacle during text transmission in an embodiment of the present invention.

[0054] Figure 26 This is a spectrum diagram of the receiving end when using a PLA board as an obstacle during text transmission in an embodiment of the present invention.

[0055] Figure 27 This is a charging curve of a 22μF capacitor with a rated voltage of 25V via an energy storage module within 60 seconds, according to an embodiment of the present invention.

[0056] The numbers in the diagram represent the following: 1-opening, 2-incident surface, 3-cavity, 4-flexible bottom, 5-spacer ring, 6-perforated plate, 7-neck tube, 8-positively charged material, 9-conical device, 10-electronegative film, 11-electrode. Detailed Implementation

[0057] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0058] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0059] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0060] Secondly, the present invention is described in detail with reference to the schematic diagrams. When detailing the embodiments of the present invention, for ease of explanation, the cross-sectional views illustrating the device structure may be partially enlarged, not according to the usual scale. Furthermore, the schematic diagrams are merely examples and should not limit the scope of protection of the present invention. In addition, actual fabrication should include three-dimensional spatial dimensions of length, width, and depth.

[0061] This invention proposes a low-frequency acoustic wave green wireless power-carrying communication device, such as... Figure 1 As shown, it includes a signal frequency modulation and encoding and sound wave transmission module, a sound wave filtering and sound-to-electric conversion module, an electrical signal acquisition and demodulation decoding module, and an energy storage module.

[0062] The signal frequency modulation and encoding and sound wave transmission module is wirelessly connected to the sound wave filtering and sound-to-electric conversion module; the sound wave filtering and sound-to-electric conversion module is wiredly connected to both the electrical signal acquisition and demodulation / decoding module and the energy storage module.

[0063] like Figure 2 As shown, the signal frequency modulation encoding and sound wave transmission module is used to modulate information to form a waveform containing encoded information, perform digital-to-analog conversion and power amplification, and then drive a speaker to generate sound waves. These sound waves are then wirelessly transmitted to the sound wave filtering and acoustic-to-electrical conversion module. The specific content is as follows:

[0064] When sending image information using LabVIEW software, the process involves first setting a start word and then reading the image as a one-dimensional array and converting it into binary form. Then, using binary digital frequency modulation, the 0s and 1s in the binary representation are mapped to two corresponding signals with different frequencies, forming a waveform containing the image's encoded information. Similarly, when sending text information, the process involves first setting a start word and converting the text into a corresponding one-dimensional array using ASCII encoding. This one-dimensional array is then converted into binary form. Finally, using binary digital frequency modulation, the 0s and 1s in the binary representation are mapped to two corresponding signals with different frequencies, forming a waveform containing the text's encoded information.

[0065] During message transmission, a start word needs to be set, and the decoding time is determined by setting the start word. To reduce conflicts between the start word and the text content, when sending a PNG bitmap with an image depth of 1, the hexadecimal representation of the start word is 89504E47; if sending text information, the hexadecimal representation of the start word is 24242424.

[0066] like Figure 3-5 As shown, the acoustic wave filtering and acoustic-to-electric conversion module is used to amplify and excite the sound pressure of incident sound waves in a specific frequency band. Without applying an external power supply, it converts the acoustic wave signal containing coded information into an analog electrical signal containing coded information through a triboelectric nanogenerator, generating a high-output voltage signal, which is then transmitted to the electrical signal acquisition, demodulation, and decoding module.

[0067] The acoustic filtering and acoustic-to-electric conversion module includes an acoustic filtering section and an acoustic-to-electric conversion section. The acoustic filtering section consists of an incident surface 2 with an opening 1, a neck tube 7 placed in the opening of the incident surface, a cavity 3, and a flexible bottom 4, forming an acoustic filter. The neck tube 7 is placed inside the cavity 3. The volume of the acoustic filter cavity 3, the opening radius at the top, and the length of the acoustic filter opening neck tube 7 are designed using finite element numerical calculations.

[0068] The acoustic-to-electric conversion section employs a contact-separated triboelectric nanogenerator, which includes a positively charged material 8, a conical device 9, a spacer ring 5, an electronegative membrane 10, a perforated plate 6, and an electrode 11. The positively charged material 8 is coated onto the conical device 9, forming a conical device 9 with one side coated with conductive positively charged material. Its top surface is smaller than its bottom surface, and the top surface is fixed at the center of the flexible acoustic filter base 4. The bottom surface is a circular surface coated with the positively charged conductive material 8. The spacer ring 5 is an annular structure slightly higher than the conical device 9, fixed between the flexible acoustic filter base 4 and the perforated plate 6. The electronegative membrane 10 is a dielectric material, with an electrode 11 on one side of its surface serving as a lead-out electrode, and is fixed to the perforated plate 6.

[0069] In the acoustic filtering section, when an acoustic signal enters the 9mm high neck tube 7 of the acoustic filter through a 12.8mm diameter opening 1 on the incident surface 2 of the 3mm thick acoustic filter, it reaches the cavity 3 of the acoustic filter (45mm high, 94mm inner diameter, and 99mm outer diameter). Near 85Hz, the acoustic filter generates acoustic resonance, causing the air inside the cavity to vibrate violently, amplifying the incident sound pressure and causing the 0.5mm thick, 99mm diameter flexible base 4 to vibrate violently. The incident surface 2, cavity 3, flexible base 4, and neck tube 7 of the acoustic filter are all made of PLA (Polylactic acid), fabricated using 3D printing technology.

[0070] like Figure 6 As shown, the function of the acoustic-to-electric conversion section is realized by a triboelectric nanogenerator. A conical device 9 is fixed at the center of the flexible base 4. The top of the conical device 9 is a ring with an inner diameter of 7 mm, an outer diameter of 11 mm, and a height of 0.8 mm. Below the ring is a quasi-conical structure with a circular surface at its bottom having a diameter of 56.25 mm. To make the quasi-conical structure sufficiently lightweight and reduce its impact on the flexible base, the interior of the conical device 9 is hollow. In this embodiment, the wall thickness of the conical device 9 is 0.6 mm and its height is 3.9 mm. The bottom circular surface of the conical device 9 is coated with multi-walled carbon nanotubes, which serve as the positively charged material 8. Around the flexible base 4, there is a circular spacer ring 5 with an inner diameter of 94 mm, an outer diameter of 99 mm, and a height of 4.2 mm. On the opposite side of the flexible base 4, a perforated plate 6 is placed, on which is an aluminum electrode 11. This electrode serves as the lead-out electrode for the electronegative membrane 10, which is made of FEP (Fluorinated ethylene propylene). The perforated plate 6 is 1.5 mm thick and has 2 mm diameter through-holes for air exhaust, reducing the impact of air damping on moving parts. The spacer ring 5, perforated plate 6, and conical device 9 are all made of PLA and are manufactured using 3D printing technology.

[0071] Figure 7 This is a schematic diagram illustrating the working principle of a triboelectric nanogenerator. When sound enters the acoustic filter cavity, the flexible PLA base causes the conical device 9 to vibrate. When the surface coated with multi-walled carbon nanotubes 8, acting as a positively charged material, comes into contact with and separates from the FEP electronegative film 10 on the perforated plate, electrons flow back and forth between the electrodes to form a conductive current, based on the principles of contact electrification and electrostatic induction.

[0072] Figure 8The voltage waveform was obtained through a frequency sweep experiment on the acoustic wave filtering and acoustic-to-electric conversion module. The sweep time was 100 seconds, and the frequency range was 50-150Hz. As shown in the figure, the device has a strong response from 65Hz to 105Hz, enabling it to generate high-quality acoustic-to-electric conversion signals. Therefore, when performing binary digital frequency modulation, a 65Hz sine wave is used to represent 0 in binary, and a 105Hz sine wave is used to represent 1. In the signal frequency modulation encoding and acoustic wave transmission module, a LabVIEW program was used to set the carrier frequency to 85Hz and the frequency offset to 20Hz for binary digital frequency modulation.

[0073] like Figure 9 The electrical signal acquisition, demodulation, and decoding module shown uses a 4070 acquisition card in a PXI chassis to acquire voltage signals and implements demodulation and decoding through LabVIEW software programming. When a sound wave signal is received, the decoding time can be determined by setting a start word. To reduce conflicts between the start word and the text content, when sending image information, if the image is a PNG bitmap with an image depth of 1, the hexadecimal representation of the start word is 89504E47; if sending text information, the start word can be set to $$$$, with a hexadecimal representation of 24242424. Once the start word of the information is confirmed, useful information can be found in a segment of sound wave signal, thereby recovering the information it carries.

[0074] like Figure 10 The charging curve shown is a diagram of the energy storage module rectifying the electrical signal after the sound-to-electric conversion and charging the capacitor. The energy storage module includes a rectifier module and an energy storage capacitor. The rectifier module is a full-bridge rectifier circuit composed of four diodes, which is connected in parallel to the terminals of the sound-to-electric conversion module. The rectifier circuit converts the AC power after the sound-to-electric conversion into DC power, which charges the subsequent capacitor and stores the energy.

[0075] This invention simplifies the communication system design by enabling the sensor to be self-powered, eliminating the need for additional sensors while still achieving communication. The hardware design provides some noise immunity, and the embedded music effectively protects information security, enabling stealthy communication. Furthermore, excess electrical energy can be stored during communication, achieving the goal of energy-carrying communication.

[0076] Example 1:

[0077] Sending end such as Figure 11The transmitted image uses binary digital frequency modulation, with 65Hz representing the binary digit 0 and 105Hz representing the binary digit 1. The transmission rate is 20 bits / s. The information is embedded in the music, and the hexadecimal representation of the start word is set to 89504E47 at the receiving end. The time-domain waveform and spectrum of the transmitted sound signal are as follows: Figure 12 and Figure 13 As shown, when the sound pressure level is 95 dB, the time-domain waveform and spectrum received by the receiver are as follows: Figure 14 and Figure 15 As shown.

[0078] Observation revealed that although the amplitude of the time-domain waveform at the receiving end fluctuated, it did not affect the accuracy of the frequency and had almost no impact on the completion of the communication process. During this communication, the bit error rate was only 0.0378%, indicating a very satisfactory communication performance.

[0079] Sending end such as Figure 16 The text transmitted at the sending end uses ASCII encoding and binary digital frequency modulation, with 65Hz representing the binary digit 0 and 105Hz representing the binary digit 1. The transmission rate is 20 bits / second. The information is embedded in music, and the hexadecimal representation of the start word is set to 24242424 at the receiving end. The transmitted content is $$$$The Smart Sensing and Intelligent Devices Group from Nanjing University of Posts and Telecommunications. During this communication, the bit error rate is 0. The larger the amplitude of the music signal, the better the sound concealment effect, but the greater the interference to the transmitted information. Here, even when the music signal amplitude reaches 40% of the information amplitude, the entire communication process can still be completed.

[0080] Example 2:

[0081] To verify that acoustic communication can still proceed despite obstacles, an obstacle was added for experimentation in this embodiment. Specifically, a light-blocking cloth was used as an obstacle between the signal frequency modulation and coding module and the acoustic transmission module, as well as the acoustic filtering and acoustic-to-electric conversion module, while image transmission was performed. When the sound pressure level was around 100dB, at the transmitting end... Figure 11 The transmitted image uses binary digital frequency modulation, with 65Hz representing the binary digit 0 and 105Hz representing the binary digit 1, at a transmission rate of 20 bits / second, embedding the information as follows: Figure 17 In the music shown, the hexadecimal representation of the start word is set to 89504E47 at the receiving end. The time-domain waveform and spectrum of the sound wave signal at the transmitting end are as follows: Figure 18 and Figure 19 As shown, the time-domain waveform and spectrum received by the receiver are as follows: Figure 20 and Figure 21 As shown. By observing the experimental results, it can be found that when using cloth as an obstacle, the bit error rate of acoustic communication is only 0.0378%, while if infrared communication is used, there can be no light-blocking obstacles in the channel to interfere.

[0082] To test whether acoustic communication can still proceed when encountering obstacles with much greater stiffness than fabric, a PLA board was used as the obstacle in this embodiment. The Young's modulus of PLA material is approximately 3 GPa or higher. Specifically, text was transmitted while the signal frequency modulation and encoding module, acoustic wave transmission module, acoustic wave filtering module, and acoustic-to-electrical conversion module were obstructed by the PLA board. When the sound pressure level was 100 dB, at the transmitting end... Figure 15 The text transmitted from the sending end uses ASCII encoding and binary digital frequency modulation, with 65Hz representing the binary digit 0 and 105Hz representing the binary digit 1. The transmission rate is 20 bits / second. The information is embedded in a piece of music, and the music waveform is as follows: Figure 22 As shown, the time-domain waveform and spectrum of the transmitting acoustic signal are as follows: Figure 23 and Figure 24 As shown, the hexadecimal representation of the start word is set to 24242424 at the receiving end; the time-domain waveform and spectrum received by the receiving end are as follows: Figure 25 and Figure 26 As shown in the figure. During this communication process, the bit error rate was 0. Simultaneously, the energy storage module was used to charge a 22μF capacitor with a rated voltage of 25V, and the resulting charging curve is shown in the figure. Figure 27 As shown, the capacitor voltage increased from 0 to 561.59mV in 60 seconds.

[0083] The above description is merely an exemplary embodiment of the present invention and does not limit the scope of patent protection of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the scope of patent protection of the present invention.

Claims

1. A low-frequency acoustic wave green wireless power-carrying communication device, characterized in that, include The signal frequency modulation encoding and sound wave transmission module is used to form a waveform containing encoded information after frequency modulation, perform digital-to-analog conversion and power amplification to drive the speaker to generate sound waves, and transmit the sound waves wirelessly to the sound wave filtering and acoustic-to-electric conversion module. The acoustic wave filtering and acoustic-to-electric conversion module is used to amplify and excite the sound pressure of incident sound waves in a specific frequency band. Without applying an external power supply, it converts the acoustic wave signal containing coded information into an analog electrical signal containing coded information through a triboelectric nanogenerator, generating a high-amplitude output voltage signal, which is then transmitted to the electrical signal acquisition, demodulation and decoding module. The electrical signal acquisition and demodulation / decoding module is used to acquire analog voltage signals and send them to the processor. By identifying the voltage frequency in the electrical signal, it demodulates the original information from the electrical signal containing coded information. The energy storage module is used to store excess energy from the acoustic wave filtering and acoustic-to-electrical conversion module.

2. The low-frequency acoustic wave green wireless power-carrying communication device according to claim 1, characterized in that, The signal frequency modulation and coding and sound wave transmission module is wirelessly connected to the sound wave filtering and sound-to-electric conversion module; the sound wave filtering and sound-to-electric conversion module is wiredly connected to the electrical signal acquisition and demodulation decoding module and the power storage module, respectively.

3. The low-frequency acoustic wave green wireless power-carrying communication device according to claim 1, characterized in that, The signal frequency modulation and coding and acoustic wave transmission module is configured to perform the following actions: Depending on the type of input information, there are two scenarios: (1) When sending image information, set the start word and read the image through a one-dimensional array and convert it into binary form. Through binary digital frequency modulation, the binary 0 and 1 are mapped into two different frequency signals that correspond one-to-one, forming a waveform containing the image encoding information. (2) When sending text information, set the start word and convert the text into a corresponding one-dimensional array using ASCII encoding. Then, convert the one-dimensional array into binary form and use binary digital frequency modulation to map the binary 0 and 1 into two different frequency signals that correspond one-to-one, forming a waveform containing the encoded information of the text. The waveform is converted from digital to analog and then sent to a power amplifier to drive the speaker to emit sound waves.

4. The low-frequency acoustic wave green wireless power-carrying communication device according to claim 3, characterized in that, The two signals of different frequencies must meet the following requirements: the frequency of the emitted sound wave should be in the range of 20-200Hz; the center frequency is the acoustic resonant frequency, and the two modulation frequencies are located on both sides of the center frequency.

5. The low-frequency acoustic wave green wireless power-carrying communication device according to claim 1, characterized in that, The acoustic wave filtering and acoustic-to-electric conversion module includes an acoustic wave filtering section and an acoustic-to-electric conversion section; The acoustic filtering part consists of an incident surface (2) with an opening (1), a neck tube (7) placed in the opening of the incident surface, a cavity (3), and a flexible bottom (4) to form an acoustic filter, and the neck tube (7) is placed inside the cavity (3); the volume of the acoustic filter cavity (3), the opening radius at the top, and the length of the acoustic filter opening neck tube (7) are designed using finite element numerical calculation. The acoustic-electric conversion part adopts a contact-separated triboelectric nanogenerator, which includes a positively charged material (8), a conical device (9), a spacer ring (5), an electronegative membrane (10), a perforated plate (6), and an electrode (11). The positively charged material (8) is coated on the conical device (9) to form a conical device with one side coated with conductive positively charged material. Its top surface is fixed at the center of the flexible bottom (4) of the acoustic filter, and its bottom surface is a circular surface coated with positively charged conductive material. The spacer ring (5) is fixed between the flexible bottom (4) of the acoustic filter and the perforated plate (6). The electronegative membrane (10) is a dielectric material, and one side of its surface has an electrode (11) as an output electrode, which is fixed on the perforated plate (6). The outer periphery of the side of the perforated plate (6) with the electronegative membrane (10) is connected to the spacer ring (5).

6. The low-frequency acoustic wave green wireless power-carrying communication device according to claim 5, characterized in that, The acoustic filtering and acoustic-to-electric conversion module is configured to perform the following actions: In the acoustic filtering section, acoustic resonance is generated to amplify the incident acoustic wave in the frequency band containing the encoded information and to suppress acoustic signals in other frequency bands. In the acoustic-electric conversion section, when the acoustic signal acts on the flexible bottom (4) of the acoustic filter, the resulting vibration causes the conical device (9) coated with positively charged material (8) on one side to contact and separate from the perforated plate (6) with a fixed electronegative membrane (10), forming an alternating current between the electrodes, completing the acoustic-electric conversion, and storing the electrical energy after the acoustic-electric conversion.

7. The low-frequency acoustic wave green wireless power-carrying communication device according to claim 1, characterized in that, The energy storage module converts AC power into DC power through a full-bridge rectifier and stores energy by charging a capacitor.

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