Passive relay-based cross-medium communication method and device

Abstract

The invention provides a cross-medium communication method and device based on a passive relay. The method comprises the following steps: forwarding a signal from an underwater sound transmitting end to a radio frequency receiving end based on the passive relay; the passive relay receives an underwater acoustic signal and sends an electric signal corresponding to the underwater acoustic signal to the radio frequency switch; the power supply interface of the radio frequency switch is in short circuit with the control interface, so that the radio frequency switch is converted into a voltage-impedance controller, and the radio frequency impedance of the voltage-impedance controller is changed due to the change of an electric signal loaded on the control interface, so that a backscattering signal fed back to the radio frequency receiving end is modulated. According to the scheme, the using method of the radio frequency switch in the passive relay is different from the conventional using method, and the relay is not externally connected with a power supply, so that the problem that the power supply of the water surface relay equipment is troublesome to replace is solved, and normal communication can be ensured.

Description

Technical Field

[0001] The present invention relates to the technical field of underwater Internet of Things, and particularly to a cross-media communication method and device based on passive relay. Background Art

[0002] With the rapid development of the underwater Internet of Things (Subsea IoT), underwater nodes are increasingly widely used in fields such as environmental monitoring and industry.

[0003] The underwater Internet of Things realizes data collection and transmission through the three-layer cooperation of underwater sensors, surface relay devices, and aerial platforms. The underwater layer consists of low-power sensor nodes deployed on the seabed or in the water body, and uses underwater acoustic backscattering technology or underwater optical communication (such as SLIPT system) for short-distance data transmission, taking into account low energy consumption and anti-interference characteristics. The surface layer receives underwater signals through communication modules carried by buoys or ships and converts them into radio frequency or satellite signals. The aerial layer uses unmanned aerial vehicles or low-earth orbit satellites to achieve wide-area coverage and is responsible for remotely transmitting the data relayed by the surface to the land data center.

[0004] However, current surface relay devices usually need to be connected to a power source, and the replacement of the power source of the surface relay device is often troublesome and affects normal communication. Summary of the Invention

[0005] In view of this, embodiments of the present invention provide a cross-media communication method and device based on passive relay to eliminate or improve one or more defects existing in the prior art.

[0006] One aspect of the present invention provides a cross-media communication method based on passive relay, which forwards signals from an underwater acoustic transmitter to a radio frequency receiver based on a passive relay;

[0007] The passive relay receives an underwater acoustic signal and sends the electrical signal corresponding to the underwater acoustic signal to a radio frequency switch;

[0008] The power supply interface and the control interface of the radio frequency switch are short-circuited to make the radio frequency switch convert into a voltage-impedance controller, and the change of the electrical signal loaded on the control interface will cause the radio frequency impedance of the voltage-impedance controller to change, thereby modulating the backscattered signal fed back to the radio frequency receiver.

[0009] With the above solution, the usage of the radio frequency switch in the passive relay in this solution is different from the conventional usage. The traditional radio frequency switch realizes communication by adjusting the amplitude of the reflected signal through two states of on / off. However, in the traditional usage method, the radio frequency switch needs to be powered, while in this application, no external power supply is connected to the relay, thus solving the problem that the replacement of the power source of the surface relay device is relatively troublesome and ensuring normal communication.

[0010] In some embodiments of the present invention, the passive relay converts the underwater acoustic signal from the underwater acoustic transmitting end into an electrical signal through piezoelectric ceramics.

[0011] In some embodiments of the present invention, the radio frequency switch is an ADG902 radio frequency switch.

[0012] In some embodiments of the present invention, in the step of short-circuiting the power supply interface and the control interface of the RF switch to convert the RF switch into a voltage-impedance controller, the power supply interface and the control interface of the RF switch are short-circuited, so that the RF switch is equivalent to a MOSFET device, realizing the conversion of the voltage of the electrical signal to the resistance. The conversion formula is as follows:

[0013]

[0014] Among them, r DS Indicates the converted resistance value, U in is the input electrical signal voltage, U th represents the threshold voltage, and k is a preset calculation constant.

[0015] Using the above solution, the impedance of the RF switch can be adjusted by inputting the underwater acoustic signal, U in ≥U th When r DS You can use U in Control, at this time it works in the triode area, U in th When , the signal is cut off and cannot be controlled by the underwater acoustic signal.

[0016] In some embodiments of the present invention, when operating in the triode region, the reflection coefficient is determined according to the following formula:

[0017]

[0018] Where Γ represents the reflection coefficient, Z A represents the antenna impedance, represents the conjugate of the antenna impedance, r DS Indicates the converted resistance value.

[0019] By adopting the above scheme and combining the above two equations, this scheme can obtain the input electrical signal U in To control the reflection coefficient, and then the electrical signal U in The waveform is mapped to the amplitude of the backscattered signal.

[0020] In some embodiments of the present invention, the passive relay is further provided with a clamping circuit, which is connected to the control interface of the RF switch. The clamping circuit includes a capacitor and a diode. The passive relay receives an electrical signal and raises the voltage of the electrical signal through the clamping circuit.​

[0021] In some embodiments of the present invention, the formula for the clamping circuit to raise the voltage of the electrical signal is expressed as:

[0022] y = A sin(2πft) + A - U f ;

[0023] where y represents the voltage of the electrical signal after being raised, A represents the amplitude of the electrical signal before being raised, t represents time, f represents frequency, and U f represents the forward voltage drop value of the diode.

[0024] With the above scheme, in the first negative half-cycle of the signal, the diode D1 conducts, and the capacitor C1 is charged to A - U f . After the capacitor is fully charged, the signal source and the capacitor form a parallel relationship. Therefore, the voltage range of the signal is raised, adding a DC component with a value of A - U f to the output voltage signal.

[0025] In some embodiments of the present invention, the underwater acoustic transmitting end of the method adopts a dual-channel pulse generation circuit. The structure of the channel is a capacitor and a switch. When the capacitor of one channel is connected to the transformer, the capacitor of the other channel is connected to the power supply for energy storage.

[0026] In some embodiments of the present invention, during the pulse modulation process at the underwater acoustic transmitting end, each time slot corresponds to a code. According to the bit value of the code, the corresponding time slot is determined to transmit a pulse.

[0027] The embodiments of the present invention provide a cross-media communication device based on passive relay. The device includes a passive relay module and a radio frequency receiving end module;

[0028] The passive relay module forwards the signal from the underwater acoustic transmitting end to the radio frequency receiving end module;

[0029] The passive relay module receives the underwater acoustic signal and sends the electrical signal corresponding to the underwater acoustic signal to the radio frequency switch;

[0030] The power supply interface and the control interface of the radio frequency switch are short-circuited to convert the radio frequency switch into a voltage-impedance controller. The change in the electrical signal loaded on the control interface will cause the radio frequency impedance of the voltage-impedance controller to change, thereby modulating the backscattered signal fed back to the radio frequency receiving end module.

[0031] The additional advantages, objectives, and features of the present invention will be partially described below, and will become partially apparent to those of ordinary skill in the art after studying the following text, or can be learned from the practice of the present invention. The objectives and other advantages of the present invention can be pointed out and obtained specifically in the description and the accompanying drawings.

[0032] Those skilled in the art will understand that the purposes and advantages achievable by the present invention are not limited to those specifically described above, and the above and other purposes achievable by the present invention will be more clearly understood according to the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The drawings described herein are used to provide a further understanding of the present invention, form a part of this application, and do not constitute a limitation to the present invention.

[0034] Figure 1 It is a schematic diagram of the architecture of an embodiment of the cross-media communication method based on passive relay of this solution;

[0035] Figure 2 It is a schematic diagram of the overall architecture of the cross-media communication method based on passive relay of this solution;

[0036] Figure 3 It is a schematic diagram of the signal propagation of this solution;

[0037] Figure 4 It is a schematic diagram of the use of the existing ADG902;

[0038] Figure 5 It is a schematic diagram of the voltage-reflection coefficient curve of the ADG902 under non-standard conditions of this solution;

[0039] Figure 6 It is a schematic diagram of the architecture of another embodiment of the cross-media communication method based on passive relay of this solution;

[0040] Figure 7 It is a schematic diagram of the circuit of the underwater acoustic transmitter of this solution;

[0041] Figure 8 It is a schematic diagram of PPM modulation of the underwater acoustic transmitter of this solution. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0042] To make the purposes, technical solutions, and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below in conjunction with the embodiments and the drawings. Here, the illustrative embodiments of the present invention and their descriptions are used to explain the present invention, but do not constitute a limitation to the present invention.

[0043] Here, it should also be noted that in order to avoid obscuring the present invention due to unnecessary details, only the structures and / or processing steps closely related to the solution according to the present invention are shown in the drawings, while other details less related to the present invention are omitted.

[0044] Introduction to the prior art:

[0045] Prior art one

[0046] Direct water-to-air communication technology transmits data directly across the water-air interface through special signal modalities. Typical solutions include: (1) TARF, which uses millimeter-wave radar to detect the vibration displacement of the water surface and analyze underwater acoustic signals. It relies on high-precision radar to locate the water surface vibration and extracts the acoustic information of underwater nodes through signal processing algorithms. (2) Amphilight uses lasers to establish an optical communication link between underwater robots (such as drones) and aerial nodes, and encodes underwater data by modulating the laser intensity or frequency.

[0047] Disadvantages of the prior art one

[0048] The core defects of direct water-to-air communication technology stem from the insufficient hardware alignment mechanism and environmental adaptability relied on in its technical solutions. For example, TARF requires millimeter-wave radar to accurately cover the water surface vibration area, while Amphilight relies on strict optical path alignment for laser communication. Such technical characteristics are extremely prone to cause coverage deviation or optical path interruption due to waves or equipment drift in a dynamic water surface environment, significantly reducing the stability of the communication link. In addition, millimeter-wave radar is easily interfered by water surface reflection clutter, and laser communication is sensitive to water transparency and suspended matter. Such technical characteristics lead to an increase in signal misjudgment rate and deterioration of signal-to-noise ratio in turbid waters or strong light environments.

[0049] Prior art two

[0050] The communication scheme based on active relay uses buoys or surface nodes as relays to convert underwater acoustic signals into radio frequency (RF) or optical signals for forwarding. A typical solution decodes through an underwater acoustic modem, stores the information in a microprocessing unit, and then forwards it through a radio frequency modem.

[0051] Disadvantages of the prior art two

[0052] The main defects of the active relay scheme stem from the complex signal processing link and multi-module integration requirements in its technical solutions. In the active relay scheme, the ADC, MCU, and radio frequency transmission module need to run continuously, resulting in the system power consumption being concentrated in the signal decoding and re-encoding processes, relying on external power sources or frequent battery replacements, and being difficult to deploy for a long time. At the same time, the relay node needs to completely decode the acoustic signal and then re-encode it into a radio frequency signal. The processing flow introduces an additional delay of hundreds of milliseconds to seconds, which cannot meet the requirements of scenarios with high real-time requirements (such as emergency event response). In addition, the relay node needs to integrate multi-module hardware such as acoustic receivers, MCUs, and radio frequency transmitters. Precise parameter calibration is required during deployment, and the maintenance cost increases linearly with the number of nodes, making it difficult to achieve plug-and-play lightweight deployment.

[0053] In the application of the prior art, it is difficult for underwater nodes to efficiently transmit data to aerial nodes above the water surface. The core challenge lies in the low communication efficiency across the water-air medium. Radio waves can propagate long distances in air but attenuate extremely quickly in water. Traditional underwater communication mainly relies on acoustic links, but when passing through the water-air interface, it generates a reflection loss of more than 30 dB, resulting in a significant drop in signal strength and making it impossible to directly achieve reliable communication with aerial nodes across the water-air interface. A reliable cross-media communication solution needs to solve two major problems:

[0054] Differences in medium characteristics: The physical characteristics of signal transmission in different media (water and air) are significantly different, and a single signal mode is difficult to adapt to both media simultaneously.

[0055] Dynamic environment limitations: In a real water environment (such as a lake or ocean), the dynamic change of the water surface height makes it difficult for communication devices to maintain precise alignment, directly affecting the stability of the communication link.

[0056] As Figure 1 、 2 and shown in 3, the present invention proposes a cross-media communication method and device based on passive relay. The method forwards the signal from the underwater acoustic transmitter to the RF receiver based on passive relay;

[0057] The passive relay receives the underwater acoustic signal and sends the corresponding electrical signal of the underwater acoustic signal to the RF switch;

[0058] The power supply interface and the control interface of the RF switch are short-circuited to convert the RF switch into a voltage-impedance controller. The change of the electrical signal loaded on the control interface will cause the RF impedance of the voltage-impedance controller to change, thereby modulating the backscattered signal fed back to the RF receiver.

[0059] In the specific implementation process, the RF receiver in the air first broadcasts a single-tone carrier signal in the air. The antenna of the relay reflects the single-tone carrier signal to generate a reflected signal. By adjusting the reflection coefficient of the carrier signal, the relay can modulate the received underwater acoustic information onto the reflected signal.

[0060] In the specific implementation process, the underwater acoustic transmitter is located underwater and generates a high-power PPM-modulated underwater acoustic signal through a pulse generation circuit. The passive relay floats on the water surface, receives the acoustic signal from underwater, and converts it into an RF signal through backscattering. The RF receiver is deployed in the air, receives the RF signal forwarded by the passive relay, and synchronizes and decodes the signal.

[0061] In this solution, due to the limitation of passive energy, the relay cannot actively transmit wireless signals. The relay needs to use backscatter communication to transmit signals to the RF receiver in the air. Specifically, the receiver first broadcasts a single-tone carrier signal in the air. The antenna of the relay reflects the single-tone carrier signal, generating a reflected signal. By adjusting the reflection coefficient of the carrier signal, the relay can modulate the received underwater acoustic information onto the reflected signal.

[0062] Adopting the above solution, the usage of the RF switch in this passive relay is different from the conventional usage. The traditional RF switch adjusts the amplitude of the reflected signal through two states of on / off to achieve communication. However, in the traditional usage method, the RF switch needs to be powered, while in this application, no external power supply is connected to the relay, thus solving the problem that it is rather troublesome to replace the power supply of the water surface relay device and ensuring normal communication.

[0063] In some embodiments of the present invention, the passive relay converts the underwater acoustic signal of the underwater acoustic transmitter into an electrical signal through a piezoelectric ceramic.

[0064] In some embodiments of the present invention, the RF switch adopts an ADG902 RF switch.

[0065] Specifically, as Figure 4 shown, the traditional backscatter circuit needs to provide DC power supply, which is difficult to meet the requirements of the passive relay. Figure 1 The circuit diagram of the backscatter of this solution is shown. The ADG902 RF switch is a digital RF switch. By short-circuiting the power supply interface and the control interface of the ADG902 RF switch, at this time, the ADG902 can be converted into a voltage-impedance controller. The change of the voltage signal loaded on the control port will cause the RF impedance of the device to change, thereby modulating the RF backscatter signal. This circuit does not require DC power supply for the device.

[0066] In the conventional usage of the ADG902 RF switch, generally, a stable voltage needs to be supplied through VDD to make it work in the standard state. In the standard working state, if the input signal at the CTRL port is greater than the threshold, the ADG902 enters the on state, otherwise it enters the off state. In the on and off states, the amplitude of the backscatter signal has two states of high and low, which can be used for 0 / 1 bit modulation.

[0067] In some embodiments of the present invention, in the step of short-circuiting the power supply interface and the control interface of the RF switch to convert the RF switch into a voltage-impedance controller, the power supply interface and the control interface of the RF switch are short-circuited, making the RF switch equivalent to a MOSFET device, realizing the conversion of the voltage of the electrical signal to resistance. The conversion formula is as follows:

[0068]

[0069] Among them, r DS represents the converted resistance value, U in is the voltage of the input electrical signal, U th represents the threshold voltage, and k is a preset calculation constant.

[0070] Adopting the above scheme, the impedance of the RF switch can be regulated by inputting an underwater acoustic signal. When U in ≥U th r DS can be regulated by U in At this time, it works in the triode region. When U in <U th the signal is cut off and cannot be regulated by the underwater acoustic signal.

[0071] In some embodiments of the present invention, when working in the triode region, the reflection coefficient is determined according to the following formula:

[0072]

[0073] Among them, Γ represents the reflection coefficient, Z A represents the antenna impedance, represents the conjugate of the antenna impedance, r DS represents the converted resistance value.

[0074] Specifically,

[0075] Adopting the above scheme and combining the above two equations, this scheme can regulate the reflection coefficient through the input electrical signal U in and then map the waveform of the electrical signal U in to the amplitude of the backscattered signal.

[0076] In some embodiments of the present invention, the passive relay is further provided with a clamping circuit. The clamping circuit is connected to the control interface of the RF switch. The clamping circuit includes a capacitor and a diode. The passive relay receives an electrical signal and raises the voltage of the electrical signal through the clamping circuit.

[0077] Adopting the above scheme, since the RF switch only responds to the voltage in the Figure 5 triode region, in order to make full use of the output signal of the piezoelectric ceramic hydrophone, a clamping circuit is used to raise the voltage signal and increase the part of the signal in the triode region.

[0078] After the underwater acoustic signal is received by the piezoelectric ceramic hydrophone, it is converted into a voltage signal and input into the circuit. The underwater acoustic signal can be regarded as a sine wave signal with an amplitude of A.

[0079] In some embodiments of the present invention, the formula for the clamping circuit to raise the voltage of the electrical signal is expressed as:

[0080] y = A sin(2πft) + A - U f ;

[0081] where y represents the voltage of the electrical signal after being raised, A represents the amplitude of the electrical signal before being raised, t represents time, f represents frequency, and U f represents the forward voltage drop value of the diode.

[0082] Adopting the above scheme, in the first negative half-cycle of the signal, diode D1 conducts, and capacitor C1 is charged to A - U f . After the capacitor is fully charged, the signal source and the capacitor form a parallel relationship. Therefore, the voltage range of the signal is raised, adding a DC component with a value of A - U f to the output voltage signal.

[0083] As Figure 6 shown, most of the raised signals satisfy the voltage range in the triode region. The response of the RF switch to the control signal has been greatly improved.

[0084] In some embodiments of the present invention, the underwater acoustic transmitting end of the method adopts a dual-channel pulse generation circuit. The structure of the channel is a capacitor and a switch. When the capacitor of one channel is connected to the transformer, the capacitor of the other channel is connected to the power supply for energy charging.

[0085] In some embodiments of the present invention, during the pulse modulation process at the underwater acoustic transmitting end, each time slot corresponds to a code. According to the bit value of the code, the corresponding time slot is determined to emit a pulse.

[0086] Adopting the above scheme, in order to increase the communication distance of the underwater acoustic link, high-power underwater acoustic communication equipment is required. For a low-power underwater sensor network, it is not feasible to use high power of hundreds of watts for underwater acoustic transmission. To alleviate the contradiction between the transmission power and the communication distance, this scheme modulates instantaneous high-power underwater acoustic pulses through a dual-channel pulse generation circuit for underwater communication transmission.

[0087] Since the instantaneous large current release may cause damage to the battery or power supply, the pulse generation circuit first stores the energy of the pulse in the capacitor, and then the switch controls the energy to be released from the capacitor to the transducer to complete the output of the pulse. After the capacitor discharges, it needs to be recharged to release the pulse again. To ensure that the power of adjacent symbols is consistent, two capacitors are designed to alternately charge and discharge. As Figure 7 shown, when capacitor C2 discharges, the next pulse discharges through C3. This design can ensure that each capacitor has at least one symbol length of charging time, so as to ensure that each capacitor discharge is completed in a fully charged state.

[0088] Figure 8 shows the symbol structure of PPM modulation. Each symbol is divided into 2 N time slots. Each time slot corresponds to a code. According to the bits to be encoded, a time slot is selected to transmit a pulse. The receiving end demodulates the signal by detecting which time slot the signal is in.

[0089] The hardware required for the method includes:

[0090] Underwater acoustic transmitter: a custom integrated circuit implemented by a PCB board, connected to a piezoelectric underwater acoustic transducer.

[0091] Passive relay: a custom integrated circuit implemented by a PCB board, connected to an antenna and a piezoelectric underwater acoustic transducer.

[0092] RF receiving end: USRP (a software-defined radio device) and a laptop computer. The USRP generates a single-tone carrier as the RF front end, receives the backscattered signal, and the laptop computer completes the decoding.

[0093] Algorithm implementation: The program of the underwater acoustic transmitter is burned into the single-chip microcomputer inside the integrated circuit. The code of the RF receiving end runs on the laptop computer.

[0094] An embodiment of the present invention provides a cross-media communication device based on a passive relay. The device includes a passive relay module and an RF receiving end module;

[0095] The passive relay module forwards the signal from the underwater acoustic transmitter to the RF receiving end module;

[0096] The passive relay module receives the underwater acoustic signal and sends the corresponding electrical signal of the underwater acoustic signal to the RF switch;

[0097] The power supply interface and the control interface of the RF switch are short-circuited to convert the RF switch into a voltage-impedance controller. The change of the electrical signal loaded on the control interface will cause the RF impedance of the voltage-impedance controller to change, so as to modulate the backscattered signal fed back to the RF receiving end module.

[0098] Those of ordinary skill in the art should understand that the various exemplary components, systems, and methods described in connection with the embodiments disclosed herein can be implemented in hardware, software, or a combination of both. Specifically, whether to implement in hardware or software depends on the specific application and design constraints of the technical solution. A person skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered to exceed the scope of the present invention. When implemented in hardware, it can be, for example, an electronic circuit, an application-specific integrated circuit (ASIC), appropriate firmware, a plug-in, a functional card, and so on. When implemented in software, the elements of the present invention are programs or code segments used to perform the required tasks. The program or code segment can be stored in a machine-readable medium or transmitted through a data signal carried in a carrier wave on a transmission medium or a communication link.

[0099] It should be clear that the present invention is not limited to the specific configurations and processes described above and illustrated in the figures. For the sake of brevity, detailed descriptions of known methods are omitted here. In the above embodiments, several specific steps are described and illustrated as examples. However, the method process of the present invention is not limited to the specific steps described and illustrated. Those skilled in the art can make various changes, modifications, and additions, or change the order between steps after understanding the spirit of the present invention.

[0100] In the present invention, the features described and / or illustrated for one embodiment can be used in the same or a similar manner in one or more other embodiments, and / or combined with the features of other embodiments or replace the features of other embodiments.

[0101] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, various changes and modifications can be made to the embodiments of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A cross-media communication method based on passive relay, characterized in that The method forwards signals from an underwater acoustic transmitter to a radio frequency receiver based on passive relay; The passive relay receives underwater acoustic signals and sends the corresponding electrical signals to a radio frequency switch; The power supply interface and the control interface of the radio frequency switch are short-circuited to convert the radio frequency switch into a voltage-impedance controller. The change of the electrical signal loaded on the control interface will cause the radio frequency impedance of the voltage-impedance controller to change, thereby modulating the backscattered signal fed back to the radio frequency receiver; 2. The cross-media communication method based on passive relay according to claim 1, wherein The passive relay converts the underwater acoustic signal of the underwater acoustic transmitter into an electrical signal through a piezoelectric ceramic; 3. The cross-media communication method based on passive relay according to claim 1, characterized in that The radio frequency switch uses an ADG902 radio frequency switch; 4. The cross-media communication method based on passive relay according to any one of claims 1-3, characterized in that, In the step of short-circuiting the power supply interface and the control interface of the radio frequency switch to convert the radio frequency switch into a voltage-impedance controller, the power supply interface and the control interface of the radio frequency switch are short-circuited, making the radio frequency switch equivalent to a MOSFET device to achieve the conversion of voltage to resistance of the electrical signal. The conversion formula is as follows: Among them, r DS represents the converted resistance value, U in is the voltage of the input electrical signal, U th represents the threshold voltage, and k is a preset calculation constant.

5. The cross-media communication method based on passive relay according to claim 4, characterized in that When operating in the triode region, the reflection coefficient is determined according to the following formula: where Γ represents the reflection coefficient, Z A represents the antenna impedance, represents the conjugate of the antenna impedance, r DS represents the converted resistance value.

6. The cross-media communication method based on passive relay according to claim 1, characterized in that The passive relay is also provided with a clamping circuit. The clamping circuit is connected to the control interface of the radio frequency switch. The clamping circuit includes a capacitor and a diode. The electrical signal received by the passive relay is lifted in voltage through the clamping circuit; 7. The cross-media communication method based on passive relay according to claim 6, wherein The formula for the clamping circuit to lift the voltage of the electrical signal is expressed as: y = A sin(2πft) + A - U f ; Among them, y represents the voltage of the electrical signal after lifting, A represents the amplitude of the electrical signal before lifting, t represents time, f represents frequency, and U f represents the forward voltage drop value of the diode.

8. The cross-media communication method based on passive relay according to claim 1, characterized in that, The underwater acoustic transmitter of the method uses a dual-channel pulse generation circuit. The structure of the channel is a capacitor and a switch. When the capacitor of one channel is connected to a transformer, the capacitor of the other channel is connected to a power supply for energy storage; 9. The cross-media communication method based on passive relay according to claim 8, characterized in that, During the pulse modulation of the underwater acoustic transmitter, each time slot corresponds to a code. According to the bit value of the code, the corresponding time slot is determined to transmit a pulse; 10. A passive-relay-based cross-media communication device applying the method according to any one of claims 1-9, characterized in that, The device includes a passive relay module and a radio frequency receiver module; The passive relay module forwards signals from the underwater acoustic transmitter to the radio frequency receiver module; The passive relay module receives underwater acoustic signals and sends the corresponding electrical signals to a radio frequency switch; The power supply interface and the control interface of the radio frequency switch are short-circuited to convert the radio frequency switch into a voltage-impedance controller. The change of the electrical signal loaded on the control interface will cause the radio frequency impedance of the voltage-impedance controller to change, thereby modulating the backscattered signal fed back to the radio frequency receiver module;

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