Low-power underwater acoustic communication system for underwater navigation and ranging

Abstract

This application discloses a low-power underwater acoustic communication system for underwater navigation and ranging, relating to the field of underwater communication technology. It includes a digital signal processing platform for preprocessing the digital baseband signal to be transmitted to obtain a single-ended analog signal; a transmitting circuit module, comprising at least: a power amplification unit; the power amplification unit being a single chip integrating a PWM modulation circuit, a drive amplification circuit, and a power amplification circuit, wherein the power amplification unit sequentially performs PWM modulation, drive amplification, and power amplification on the single-ended analog signal to output a target amplified signal; and an underwater acoustic transducer for converting the target amplified signal into an acoustic signal and transmitting it into the water medium. This application can reduce energy loss during signal transmission.

Description

Technical Field

[0001] This application relates to the field of underwater communication technology, and in particular to a low-power underwater acoustic communication system for underwater navigation and ranging. Background Technology

[0002] In the complex marine environment, electromagnetic waves attenuate rapidly due to the high conductivity of water, rendering commonly used land-based radio communications (such as Wi-Fi, GPS, and BeiDou) virtually ineffective in deep water. While optical communication offers high speeds, its transmission distance is extremely short due to water turbidity and scattering. Therefore, sound waves, with their low attenuation underwater, have become the only effective medium for long-distance wireless communication and high-precision ranging. Underwater acoustic communication is not only a window for underwater vehicles (AUVs) and underwater robots (ROVs) to acquire external information, but also the physical basis for underwater acoustic positioning (such as LBL, SBL, and USBL).

[0003] While existing underwater acoustic communication equipment can achieve basic signal transmission, the transmitting circuits mostly adopt a discrete structure, consisting of independent cascaded circuits. The signal needs to pass through multiple discrete components and lengthy transmission lines in sequence. Each processing node will generate additional signal attenuation, and additional energy loss will be introduced due to the impedance of the transmission line, resulting in significant energy loss during signal transmission. Summary of the Invention

[0004] The purpose of this application is to provide a low-power underwater acoustic communication system for underwater navigation and ranging, which can reduce energy loss during signal transmission.

[0005] To achieve the above objectives, this application provides the following solution: In a first aspect, this application provides a low-power underwater acoustic communication system for underwater navigation and ranging, comprising: A digital signal processing platform is used to preprocess the digital baseband signal to be transmitted to obtain a single-ended analog signal; The transmitting circuit module includes at least: a power amplification unit; the power amplification unit is a single chip integrating a PWM modulation circuit, a drive amplification circuit and a power amplification circuit, the power amplification unit is used to sequentially perform PWM modulation, drive amplification and power amplification on the single-ended analog signal, and output the target amplified signal; An underwater acoustic transducer is used to convert the amplified target signal into an acoustic signal and transmit it into the water medium.

[0006] According to the specific embodiments provided in this application, the following technical effects are disclosed: This application provides a low-power underwater acoustic communication system for underwater navigation and ranging. The power amplification unit is constructed using a single chip that integrates a PWM modulation circuit, a drive amplification circuit, and a power amplification circuit. This integrates the multi-stage cascaded signal paths in traditional discrete solutions into the chip, thereby shortening the signal path and reducing the conduction loss introduced by the transmission line impedance. Attached Figure Description

[0007] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0008] Figure 1 This is a schematic diagram illustrating the structure of a low-power underwater acoustic communication system for underwater navigation and ranging, according to an embodiment of this application. Figure 2 This is a schematic diagram of the structure of a low-power underwater acoustic communication system for underwater navigation and ranging, as shown in another embodiment of this application. Figure 3 This is a circuit diagram of a transceiver switching module 600 shown in one embodiment of this application; Figure 4 This is a functional block diagram of the transmitting circuit module 200 shown in one embodiment of this application; Figure 5 A circuit diagram of a single-ended to differential circuit provided in an embodiment of this application; Figure 6 A circuit diagram of a power amplifier circuit provided in an embodiment of this application; Figure 7 A circuit diagram of an impedance matching circuit provided in an embodiment of this application; Figure 8 This is a functional block diagram of a receiving circuit module 500 shown in one embodiment of this application; Figure 9 This is a circuit diagram of an inverting preamplifier circuit according to an embodiment of this application; Figure 10 This is a circuit diagram of a filter circuit shown in one embodiment of this application; Figure 11 This is a circuit diagram of a variable gain amplifier circuit shown in one embodiment of this application; Figure 12 This is a functional module diagram of a receiving circuit module 500 shown in yet another embodiment of this application; Figure 13This is a circuit diagram of a lithium battery access module according to an embodiment of this application; Figure 14 This is a circuit diagram of a voltage conversion module shown in one embodiment of this application; Figure 15 This is a circuit diagram of a voltage conversion module shown in another embodiment of this application; Figure 16 This is a schematic diagram of a voltage conversion circuit shown in one embodiment of this application; Figure 17 This is a schematic diagram of a voltage conversion circuit shown in another embodiment of this application. Detailed Implementation

[0009] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0010] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0011] Example 1 This embodiment provides a low-power underwater acoustic communication system for underwater navigation and ranging, such as... Figure 1 As shown, it mainly includes: a digital signal processing platform 100, a transmitting circuit module 200, and an underwater acoustic transducer 300.

[0012] The digital signal processing platform 100 is used to preprocess the digital baseband signal to be transmitted to obtain a single-ended analog signal.

[0013] The transmitting circuit module 200 is a high-efficiency drive chain, serving as the source of signal transmission. Its main function is to amplify the power of the single-ended analog signal, converting it into a high-power analog signal suitable for underwater acoustic channel transmission, ensuring the underwater acoustic transducer receives a stable analog signal. It includes at least: a power amplification unit 210 (…). Figure 1 (not shown in the image). The power amplification unit is a single chip integrating a PWM modulation circuit, a drive amplification circuit, and a power amplification circuit. The power amplification unit is used to sequentially perform PWM modulation, drive amplification, and power amplification on the single-ended analog signal to output the target amplified signal.

[0014] The underwater acoustic transducer 300 is used to convert the target amplified signal into an acoustic signal and transmit it into the water medium.

[0015] The digital signal processing platform 100 can be implemented using an FPGA or DSP chip to perform preprocessing functions such as encoding, modulation, and framing of the digital baseband signal. Specifically, in transmit mode, the digital signal processing platform 100 preprocesses the digital baseband signal to be transmitted before digital-to-analog conversion to generate a single-ended analog signal. This preprocessing process includes digital modulation (such as BPSK, QPSK), pulse shaping filtering, etc., to ensure that the spectrum of the generated analog signal meets the requirements for underwater acoustic channel transmission.

[0016] The power amplifier unit 210 is responsible for amplifying the low-power differential signal processed in the pre-stage to a high-power signal sufficient to drive the underwater acoustic transducer. Specifically: The core function of the PWM modulation circuit 211 is to use a high-frequency triangular wave or sawtooth wave as a carrier wave, compare it with the input modulation signal, and thus generate a series of high-frequency pulses whose width varies with the instantaneous amplitude of the input signal. Through this modulation method, the subsequent power amplifier circuit 213 can operate in a highly efficient switching mode, because the PWM signal only has two states: high and low. This avoids the enormous heat generated by the power transistors operating in the linear region in analog power amplifiers, thereby greatly improving the overall electroacoustic conversion efficiency.

[0017] Although the narrow pulse signal generated by PWM modulation contains all the information, its driving capability is extremely weak and cannot directly drive high-power switching devices. Therefore, the driver amplifier circuit 212 acts as a "signal shaping and power booster." Its task is to boost the voltage and current of the PWM signal to a level sufficient to quickly and fully turn the power switching transistor on or off. Specifically, the driver amplifier circuit 212 receives the weak signal from the PWM modulation stage and, through a dedicated driver chip or a push-pull circuit composed of discrete components, generates a drive pulse with a large instantaneous current output capability, achieving steep rising and falling edges. The steep switching edges are crucial, as they significantly reduce the conduction time of the power transistor in the switching transition region, thereby greatly reducing switching losses.

[0018] Finally, the PWM pulse signal from the driver amplifier circuit 212 controls the switching of the high-power switching transistor in the power amplifier circuit 213, thus "cutting" the energy of the DC power supply into high-voltage, high-current AC components in the form of pulses. This circuit typically uses a full-bridge or half-bridge topology.

[0019] In this embodiment, the underwater acoustic transducer 300 can be made of PZT piezoelectric ceramic material, and its resonant frequency is designed to be 12kHz, covering the commonly used frequency bands for underwater acoustic communication. In transmission mode, the underwater acoustic transducer 300 converts the target amplified signal S_out into an acoustic signal and radiates it into the water medium.

[0020] In traditional technical architectures, underwater acoustic communication transmitters are mostly designed using discrete circuit schemes. The core architecture of this scheme consists of independent PWM modulation circuits, drive amplifier circuits, and power amplifier circuits. However, this multi-stage discrete design exposes significant technical shortcomings in the signal processing flow. Specifically, the signal must sequentially flow through multiple discrete components and traverse long and complex transmission lines. At each processing node, the signal inevitably experiences additional attenuation. Furthermore, various non-ideal factors such as circuit thermal noise and electromagnetic interference are constantly added during this process, acting like impurities in the water flow and severely impacting signal quality.

[0021] In stark contrast, this disclosure employs a highly integrated power amplifier chip solution, integrating the PWM modulation circuit, drive amplifier circuit, and power amplifier circuit into a single chip. This optimizes the signal path, allowing for smoother and more efficient signal transmission. Simultaneously, this integrated design significantly reduces power consumption, minimizing unnecessary energy loss.

[0022] Example 2 Based on Example 1, this example extends the system.

[0023] like Figure 2 As shown, the system also includes a receiving circuit module 500 and a transceiver switching module 600.

[0024] The underwater acoustic transducer 300 is also used to convert the received underwater acoustic signal into an analog underwater acoustic signal. In addition to its transmitting function, the underwater acoustic transducer 300 also converts the received underwater acoustic signal into an analog underwater acoustic signal. Due to the reversible effect of the piezoelectric material, the underwater acoustic transducer 300 generates an electrical signal proportional to the sound pressure when receiving sound waves. In this embodiment, the underwater acoustic transducer 300 adopts a transmit-receive design, that is, it acts as an electro-acoustic converter in the transmitting state and as an acoustic-electric converter in the receiving state. This design simplifies the system structure and reduces size and cost.

[0025] The receiving circuit module 500 amplifies and filters the underwater acoustic analog signal before outputting it to the digital signal processing platform 100. The digital signal processing platform 100 then performs analog-to-digital conversion and digital demodulation on the underwater acoustic analog signal to recover the original information. The specific structure of the receiving circuit module 500 will be described in detail in subsequent embodiments.

[0026] The transceiver switching module 600 is connected to the transmitting circuit module, the receiving circuit module and the underwater acoustic transducer, respectively, and is used to switch the system between transmitting and receiving states; the transceiver switching module adopts a digital-analog switch.

[0027] In the transmitting mode, the high-power signal output from the power amplifier circuit 213 is directed to the underwater acoustic transducer 300, while the receiving path is blocked to prevent the high-power signal from damaging sensitive components such as the low-noise amplifier. In the receiving mode, the weak signal received by the underwater acoustic transducer 300 is directed to the receiving circuit module 500, while the transmitting path is blocked to avoid noise interference from the transmitting end with the received signal.

[0028] For example, the transmit / receive switching module 600 can adopt the following... Figure 3 The SN74LVC1G3157DBVR shown has the following connection method for the transceiver switching module 600: its common terminal (COM) is connected to the underwater acoustic transducer 300, its normally open terminal (NO) is connected to the output terminal of the transmitting circuit module 200, and its normally closed terminal (NC) is connected to the input terminal of the receiving circuit module 500. By controlling the high and low levels of the logic signals, the transducer is selected to be connected to the transmitting path or the receiving path.

[0029] In the past design practice of underwater acoustic communication devices, diodes were mostly used to construct the transceiver conversion module. The reason why this traditional solution was widely used was mainly due to its low cost, which had a significant advantage in material procurement and overall cost. Moreover, it was simple to operate, easy to learn, and did not require high technical skills, playing an important role in the early stages of technology development and application promotion.

[0030] However, as underwater acoustic communication technology continues to develop towards higher power and higher reliability, the drawbacks of diode solutions are becoming increasingly apparent. When the transmission voltage increases significantly, once it exceeds the breakdown voltage threshold set by the diode itself, the transceiver will suffer irreversible damage and will be unable to continue to operate normally. This failure will further cause unexpected conduction at both ends of the transmitter and receiver, allowing a large amount of current to flow into the relevant components without obstruction, resulting in serious consequences such as overheating, short circuits, or even burnout of the relevant components, posing a great threat to the stable operation of the equipment.

[0031] To address the aforementioned technical challenges, this disclosure employs a digital-analog switch to achieve transmit / receive switching in the underwater acoustic communication device. The digital-analog switch not only retains the advantages of traditional solutions—low cost and ease of integration—while maintaining its strengths in cost control and system setup, but also possesses numerous outstanding benefits. It boasts excellent high-voltage resistance, easily handling high-transmit voltage scenarios and effectively preventing device damage due to excessive voltage, thus providing reliable assurance for transmit / receive switching. Simultaneously, it utilizes extremely low on-resistance, significantly reducing energy loss during signal transmission, greatly improving signal transmission efficiency, and minimizing energy waste. Furthermore, the digital-analog switch offers extremely fast switching speed and high control precision, enabling precise and rapid switching between transmit and receive states, ensuring the underwater acoustic communication device maintains stable and reliable operation in complex, variable, and frequently interfered underwater environments.

[0032] Example 3 Based on Embodiment 2, this embodiment further defines the specific structure of the transceiver switching module 600. The transceiver switching module 600 includes a first switch, a second switch, and a controller.

[0033] The first switch is connected between the output of the transmitting circuit module and the underwater acoustic transducer; The second switch is connected between the underwater acoustic transducer and the input terminal of the receiving circuit module; The controller is connected to the first switch and the second switch respectively; the controller is used to turn on the first switch and turn off the second switch when the system needs to transmit a signal, and to turn off the first switch and turn on the second switch when the system needs to receive a signal.

[0034] Specifically, a first switch has its first terminal connected to the output terminal of the transmitting circuit module 200 and its second terminal connected to the underwater acoustic transducer 300. The first switch, when in the ON state, transmits the amplified target signal output by the transmitting circuit module 200 to the underwater acoustic transducer 300. A second switch has its first terminal connected to the underwater acoustic transducer 300 and its second terminal connected to the input terminal of the receiving circuit module 500. The second switch, when in the ON state, transmits the underwater acoustic analog signal converted by the underwater acoustic transducer 300 to the receiving circuit module 500. A controller has its first control terminal connected to the control terminal of the first switch and its second control terminal connected to the control terminal of the second switch. The controller outputs corresponding control signals according to the system's operating mode.

[0035] Specifically, when the system needs to transmit a signal, the controller outputs an on signal to the control terminal of the first switch and an off signal to the control terminal of the second switch. At this time, the first switch is on and the second switch is off, forming a path between the transmitting circuit module 200 and the underwater acoustic transducer 300, while the receiving path is blocked.

[0036] When the system needs to receive a signal, the controller outputs a shutdown signal to the control terminal of the first switch and a conduction signal to the control terminal of the second switch. At this time, the first switch is off, the second switch is on, a path is formed between the underwater acoustic transducer 300 and the receiving circuit module 500, and the transmission path is blocked.

[0037] In this embodiment, both the first and second switches employ digital-analog switching devices. By way of example and not limitation, the digital-analog switching devices can be selected from analog switch chips with a withstand voltage range of ±60V to ±100V and an on-resistance of less than 10Ω, such as ADG5412 or MAX14778. These switching devices feature low on-resistance, fast switching speed, and low turn-off leakage current, making them suitable for switching high-pressure underwater acoustic signals.

[0038] The controller can be implemented using a microcontroller (MCU), digital signal processor (DSP), field-programmable gate array (FPGA), or complex programmable logic device (CPLD). As an example, the controller uses a low-power microcontroller, such as the STM32L0 series chip, whose internal control program executes corresponding switching actions according to the instructions sent by the digital signal processing platform 100.

[0039] To prevent simultaneous conduction in both transmit and receive states, the controller performs a timing control that first turns off and then on when switching operating modes. Specifically, when switching from transmit mode to receive mode, the controller first outputs a turn-off signal to the first switch, and after a first preset delay, outputs an on signal to the second switch; when switching from receive mode to transmit mode, the controller first outputs a turn-off signal to the second switch, and after a second preset delay, outputs an on signal to the first switch. Both the first and second preset delays are greater than the maximum turn-off time of the switching devices, ensuring that the previous switch is completely turned off before the next switch is turned on.

[0040] This embodiment achieves active switching of the transmission and reception paths through the coordinated operation of the first switch, the second switch, and the controller, avoiding the risk of breakdown due to excessive voltage in traditional diode switching schemes, while reducing insertion loss during signal transmission.

[0041] Example 4 Based on the above embodiments, this embodiment further optimizes the transmit / receive switching module 600. The transmit / receive switching module 600 also includes a timing control circuit and a discharge circuit.

[0042] I. The specific structure of the bleeder circuit.

[0043] The discharge circuit includes a discharge switch and a discharge resistor.

[0044] A discharge switch has its first terminal connected to the underwater acoustic transducer 300 and its second terminal connected to system ground via a discharge resistor. The discharge switch is used to release residual charge stored in the underwater acoustic transducer 300 to ground via the discharge resistor when it is in the ON state.

[0045] The underwater acoustic transducer 300 is a capacitive load, and its equivalent capacitance C0 is typically in the nanofarad to microfarad range. At the end of the transmitting state, the underwater acoustic transducer 300 stores residual charge due to the applied high-voltage signal, and the voltage across its terminals is close to the peak value of the transmitting voltage (approximately ±90V in this embodiment). If the receiver is switched directly to the receiving state without discharge, this residual high voltage will be applied to the input of the receiving circuit module 500 via the second switch, potentially damaging the receiving circuit module 500. The function of the discharge circuit is to discharge the residual high voltage to a safe level before switching to the receiving state.

[0046] The connection between the two discharge switches forms an RC discharge circuit, with a discharge time constant τ = R × C0, where R represents the resistance of the discharge resistor and C0 represents the equivalent capacitance of the underwater acoustic transducer. Assuming the equivalent capacitance of the underwater acoustic transducer is C0 = 0.1μF, τ = 100Ω × 0.1μF = 10μs. The residual voltage V(t) after time t is V0 × e (-t / τ) V0 represents the initial residual voltage across the underwater acoustic transducer at the end of transmission. After 10 μs (one time constant), the voltage drops to 37% of the initial value (approximately 33V); after 30 μs (three time constants), the voltage drops to below 5% (<4.5V), reaching the safe voltage range of the receiving circuit.

[0047] II. The specific structure of the timing control circuit.

[0048] The timing control circuit has its first input terminal connected to the transmission status indicator terminal of the transmitting circuit module 200, its first output terminal connected to the control terminal of the first switch, its second output terminal connected to the control terminal of the second switch, and its third output terminal connected to the control terminal of the bleeder switch. The timing control circuit is used to automatically control the on / off states of the first switch, the second switch, and the bleeder switch according to a preset timing sequence after the transmission status is detected to have ended.

[0049] The timing control circuit can be implemented using independent hardware timing circuitry without the need for a controller. As an example, in this embodiment, the timing control circuit is implemented using a combination of a monostable multivibrator and an RC delay network, including: a trigger signal detection unit, a first delay unit, and a logic control unit.

[0050] The trigger signal detection unit is connected to the output of the transmitting circuit module 200 and detects the falling edge of the transmitting signal through a voltage comparator. When the transmitting voltage is lower than a set threshold (e.g., 10V), the transmitting state is determined to be over, and a trigger pulse is output.

[0051] The first delay unit is composed of an RC delay circuit and a Schmitt trigger, with a set delay of 30μs, used to control the conduction time of the discharge switch.

[0052] The logic control unit consists of basic logic gates such as AND gates and OR gates, and generates the control timing of each switch based on the trigger signal and the delay signal.

[0053] When implemented using a CPLD or FPGA, the timing control circuit can be further integrated, and its internal hardware logic directly implements the above timing control functions without the need to run software programs.

[0054] III. Timing control logic.

[0055] The timing control circuit is configured to execute the following timing control logic: Step S401: The timing control circuit monitors the operating status of the transmitting circuit module 200 in real time. When a transmitting state end signal is detected (e.g., the output voltage of the power amplifier unit 210 drops below a preset threshold, or the transmitting enable signal changes from high level to low level), the timing control process is triggered.

[0056] Step S402: At the instant t0 when the end of the transmission state is detected, the timing control circuit immediately outputs a conduction signal to the control terminal of the discharge switch, causing the discharge switch to conduct. At this time, the first switch remains in the conducting state, and the second switch remains in the off state. The residual high voltage stored in the underwater acoustic transducer 300 forms a discharge circuit through the discharge resistor, and the charge begins to be released.

[0057] Step S403: The internal delay unit of the timing control circuit starts timing, delaying for a first preset duration Δt1.

[0058] Step S404: After the first preset duration Δt1 ends, the timing control circuit simultaneously performs three actions: Output a shutdown signal to the control terminal of the discharge switch to shut off the discharge switch; Output a shutdown signal to the control terminal of the first switch to shut off the first switch; Output a conduction signal to the control terminal of the second switch to turn on the second switch.

[0059] The three actions mentioned above are executed synchronously, and their timing deviation is determined by the propagation delay of the hardware logic gates, which is usually less than 10ns.

[0060] Step S405: The timing control circuit may optionally output a state switching completion signal to the digital signal processing platform 100, indicating that the system has entered the receiving mode.

[0061] The value of the first preset duration Δt1 must simultaneously meet the requirements of sufficient discharge and the safety requirements of the receiving circuit.

[0062] According to the basic principle of RC discharge circuit, the residual voltage V(t) on the equivalent capacitance C0 of the underwater acoustic transducer decays exponentially with time t: ; Where V0 is the initial residual voltage across the underwater acoustic transducer at the end of the transmission, τ = R·C0 ​​is the discharge time constant, R is the resistance of the discharge resistor, and C0 is the equivalent capacitance of the underwater acoustic transducer.

[0063] From the perspective of sufficient discharge, after n times the time constant, the residual voltage decays to e of the initial value. -nWhen n=3, the residual voltage decays to less than 5% of its initial value. At this point, it can be considered that the residual charge has been basically discharged, and the voltage across the transducer has dropped to a safe range. Therefore, to ensure sufficient discharge, the first preset duration should satisfy: ; From the perspective of receiver circuit safety, the residual voltage V across the transducer after discharge is considered. res It must be lower than the maximum safe voltage V that the input terminal of the receiving circuit module can withstand. max The preamplifier circuit of the receiver module typically uses a low-voltage operational amplifier, which has a limited input common-mode voltage range. Excessive input voltage may damage the device. From the bleeder formula, we can obtain: ; Taking the natural logarithm of both sides of the above inequality, we get: ; Based on the above two conditions, the value of the first preset duration Δt1 should simultaneously satisfy: ; Those skilled in the art will understand that the discharge resistor R in the above parameters can be selected according to the discharge speed and power consumption requirements, the equivalent capacitance C0 of the transducer is determined by the transducer itself, the initial residual voltage V0 is related to the operating voltage of the transmitting circuit, and the maximum safe voltage V of the receiving circuit is... max The value of the first preset duration Δt1 is determined by the selected preamplifier. In practical applications, the specific value can be calculated and determined according to the parameters of the specific device and the above design principles.

[0064] This embodiment achieves automatic discharge of residual high voltage after transmission and precise transmit / receive switching timing through the coordinated design of independently operating timing control circuits and discharge circuits, effectively protecting the receiving front-end circuit and improving the system's reliability and response speed.

[0065] Example 5 Based on the above embodiments, this embodiment further defines the transmitting circuit module 200. For example... Figure 4 As shown, the transmitting circuit module 200 also includes a single-ended to differential circuit 220, a transformer 230, and an impedance matching circuit 240.

[0066] The single-ended to differential circuit 220 serves as a crucial bridge connecting the DAC and the power amplifier in the transmitting circuit. Its task is to convert single-ended analog signals into differential signals. The main purpose of the single-ended to differential circuit is to convert single-ended signals into differential signals to meet the differential input requirements of the power amplifier circuit, such as... Figure 5As shown, the signal in the single-ended to differential converter is input from Vout. It first passes through the first JRC4580N, outputting a non-inverting signal. Then it enters the second JRC4580N, outputting an inverting signal, thus forming a differential signal. This signal is then input to the power amplifier circuit. The two operational amplifiers (often integrated on the same chip) ensure impedance matching at the output. Their common-mode rejection ratio (CMRR) depends primarily on the characteristics of the operational amplifiers themselves, and the resistor matching requirements are relatively relaxed, allowing for a stable CMRR level of over 100dB.

[0067] The power amplifier circuit 210 is used to sequentially perform PWM modulation, drive amplification, and power amplification on the differential analog signal, outputting a first-stage amplified signal. For example... Figure 6 As shown, the differential signal is input from pins 5 and 6 of the TPA3255, amplified by the TPA3255 into a 48V PWM signal, then restored to the original signal by an LC filter circuit composed of L1 and C3, and finally enters the transformer. Specifically, the core task of a power amplifier circuit (referred to as a "power amplifier") is to amplify weak input signals (voltage or current) to drive loads such as speakers and motors with sufficient power. It is essentially an energy converter that converts the energy from a DC power supply into AC energy controlled by the input signal and delivers it to the load. The input analog audio signal enters the chip and is fed into the core Delta-Sigma modulator. Here, the signal is compared with a high-frequency triangular wave carrier, and pulse width modulation (PWM) technology instantly converts the continuous analog voltage into a series of digital pulse sequences whose width varies with the signal amplitude. Subsequently, these PWM signals drive the internal H-bridge power output stage (composed of four N-channel MOSFETs). The H-bridge rapidly switches the main power supply (PVDD) connection according to the pulse duty cycle, chopping the DC power into a high-energy pulse current and delivering it to the output. Finally, the high-frequency PWM square wave output by the H-bridge passes through an external LC low-pass filter to filter out the high-frequency switching carrier component, restoring a smooth analog audio current, thereby driving the speaker to produce sound efficiently and with low distortion.

[0068] The transformer 230 is used to boost the voltage of the first-stage amplified signal to obtain a voltage boosted signal, which meets the voltage level required to drive the underwater acoustic transducer to transmit. The impedance matching circuit 240 is used to perform impedance transformation on the voltage-boosted signal, so that the transformed signal impedance forms a conjugate match with the capacitive impedance of the underwater acoustic transducer, thereby canceling the capacitive reactance of the underwater acoustic transducer. The voltage-boosted signal after impedance transformation is the target amplified signal. Given that the underwater acoustic transducer exhibits extremely high impedance characteristics near its resonant frequency (typically hundreds to thousands of ohms of capacitive impedance), while the output stage of the power amplifier circuit 210 is typically designed with low impedance, the impedance matching objective is to achieve maximum power transfer and suppress reflected waves. Through impedance matching and a transformer, the high impedance of the transducer is transformed to the optimal load impedance of the amplifier, improving the electroacoustic conversion efficiency. Figure 7 The diagram shows an impedance matching circuit 240. In the impedance matching circuit, L3 is used to cancel the capacitive reactance generated by the transducer at the resonant frequency.

[0069] In this disclosure, the initial signal generated by the digital signal processing platform of the underwater acoustic communication hardware system is weak and cannot drive the underwater acoustic transducer to work normally. Therefore, a power amplification unit is selected to amplify the original signal to obtain the required driving current and voltage, enabling the load to enter the working state. Impedance matching refers to the technical means of optimizing signal transmission performance by adjusting the impedance of the signal source, transmission line, or load to achieve an equal or conjugate matched state.

[0070] In one embodiment, such as Figure 4 The transmitting circuit module 200 also includes a protection circuit 250. Since the underwater acoustic transducer will generate an extremely high back electromotive force at the moment of transmission, the protection circuit 250 ensures that the protection circuit is in a high-resistance state and does not introduce losses within the normal communication signal range. It only responds when an abnormal high voltage occurs, clamping the voltage of the subsequent circuit within a safe range.

[0071] Example 6 Based on the above embodiments, this embodiment describes the specific structure of the receiving circuit module 500. The environment in an underwater acoustic channel is very complex, containing various interferences that cause sound waves to attenuate to varying degrees during transmission, resulting in large amplitude variations in the signal output from the transmitting end. This necessitates a flexible and controllable receiving circuit to buffer these variations. First, the input signal at the receiving end is amplified and restored to a certain extent, restoring the amplitude of the significantly attenuated signal. Then, the mixed noise is filtered out to facilitate signal processing by the digital processing module, such as... Figure 8 As shown, the receiving circuit module 500 includes a preamplifier circuit 510, a filter circuit 520, and a variable gain amplifier circuit 530 connected in sequence.

[0072] The preamplifier circuit 510 has its input connected to the output of the second switch of the transceiver switching module 600, and its output connected to the input of the filter circuit 520. The preamplifier circuit 510 is used to initially amplify the underwater acoustic analog signal converted by the underwater acoustic transducer 300 and transmitted through the transceiver switching module 600, obtaining a pre-amplified signal. In other words, the function of the preamplifier circuit is to initially amplify signals with significant attenuation, maximally suppressing interference from external environmental noise on weak input signals.

[0073] A filtering circuit is used to filter out noise in the initially amplified signal to obtain a filtered signal. A variable gain amplifier circuit is used to adjust the gain of the filtered signal according to the gain control voltage so that the amplitude of the output signal meets the input requirements of the digital signal processing platform.

[0074] The following is a detailed introduction to each module.

[0075] Preamplifier Circuit: As the first processing unit in the receiving circuit, the preamplifier low-noise amplifier circuit undertakes the crucial signal preprocessing task. Its core design goal is to minimize the interference of external environmental noise on weak input signals while achieving linear signal amplification. This circuit uses an ultra-low noise operational amplifier and a precision-matched resistor network. By optimizing the feedback coefficient and input impedance, it provides a stable 20dB gain for the received signal while ensuring an extremely low equivalent input noise voltage density. In addition, the circuit design specifically considers the overload protection mechanism of the input stage to effectively prevent device damage caused by strong interference signals, providing a high-fidelity, high signal-to-noise ratio intermediate signal for subsequent processing modules.

[0076] like Figure 9As shown, the signal is input from pin 2 (OPA2140 ADR 2) of the OPA2140 and output from pin 1 (OPA2140 ADR 1) to the bandpass filter circuit. Through R54 and R57, an inverting amplifier circuit with a gain of 20dB is formed. Specifically, the inverting preamplifier circuit with OPA2140 as the core works on the principle of the "virtual short" and "virtual open" characteristics of the operational amplifier: since the non-inverting input is grounded, the inverting input forms a "virtual ground" under the action of negative feedback, and the potential is approximately 0V. At the same time, the extremely high input impedance of the op-amp makes it so that almost no current flows into its input terminal. Therefore, the input voltage V`i acts on the input resistor Rin, generating a current Iin = V`i / Rin. This current has only one path: it flows entirely to the feedback resistor Rf, resulting in a voltage drop across Rf. The final output voltage V`o = -If × Rf = -(Rf / Rin) × V`i, achieving inverting amplification of the input signal. Its closed-loop gain is determined solely by the ratio of Rf to Rin. The OPA2140, with its ultra-low noise, high input impedance, and low offset voltage, ensures high-precision, low-distortion amplification when processing weak signals.

[0077] Filtering Circuit: The unique multipath effect and time-varying characteristics of underwater acoustic channels inevitably result in the superimposed broadband background noise, narrowband interference, and out-of-band harmonic components in the received signal. The filtering circuit employs a multi-order Butterworth filter structure, maintaining a flat amplitude-frequency response characteristic in the passband while achieving attenuation suppression of over 40dB in the stopband region.

[0078] like Figure 10 As shown, the signal is input from the preamplifier circuit (OPA2140 ADR 1), flows into the bandpass filter circuit to filter out noise outside the desired passband, and maintains a flat signal within the passband. After exiting the bandpass filter circuit, the signal enters the automatic gain amplifier circuit. A bandpass filter circuit can be used because the received signal inevitably contains broadband background noise, narrowband interference, and out-of-band harmonic components. The function of the bandpass filter circuit is to filter out noise outside the passband and improve the signal-to-noise ratio.

[0079] This circuit achieves a bandpass response by cascading high-pass and low-pass filter stages. The sixth-order design consists of three cascaded second-order stages to achieve the maximum passband flatness and good phase characteristics characteristic of the Butterworth response. The OP282, with its 4MHz bandwidth, high-input-impedance JFET input stage, and low power consumption, provides precise gain and isolation for each active filter stage, ensuring that the overall transfer function after cascading meets the design requirements. During operation, each second-order stage utilizes feedback from the op-amp and the external RC network to selectively attenuate the frequency, collectively synthesizing a filter characteristic that allows signals to pass smoothly within the specified passband and rapidly roll off signals outside the passband.

[0080] Variable gain amplifier circuit: Because the analog input of the ADC has a fixed voltage range, an excessively large voltage range can damage the chip. Therefore, a variable gain amplifier circuit is needed to adjust the voltage to ensure that the analog signal voltage received by the ADC is within a stable range.

[0081] like Figure 11 As shown, the signal flows from the bandpass filter into the automatic gain amplifier circuit and is finally output to the digital processing platform. The nominal output voltage of the automatic gain amplifier circuit is 1.5V. The variable gain amplifier circuit, based on the AD603, operates by precisely adjusting the amplifier's gain through an external control voltage. It is particularly suitable for automatic gain control (AGC) or programmable gain systems requiring a wide dynamic range. The AD603 internally consists of a passive input attenuator, a gain control interface, and a fixed gain amplifier. The input signal is attenuated and output by the subsequent amplifier. Its gain control voltage is uniquely determined by the differential control voltage (VG) applied to pins 1 and 2 of the two AD603 chips. The gain in decibels is linearly related to the control voltage. When shorted, it achieves a gain of -10dB to 30dB and a bandwidth of 90MHz; when open, it provides a gain of 10dB to 50dB and a bandwidth of 9MHz. With its low noise, high input impedance and wide bandwidth characteristics, the AD603 can accurately amplify weak signals in front-end signal processing and achieve dynamic gain adjustment through feedback loop or digital control, thereby maintaining the stability of the output signal amplitude in communication receivers, instruments and other systems.

[0082] Example 7 Based on the above embodiments, this embodiment further optimizes the receiving circuit module 500 by introducing a closed-loop feedback control structure. For example... Figure 12 As shown, the receiving circuit module 500 further includes a peak detection circuit 540, a comparison circuit 550, and a control voltage generation circuit 560.

[0083] A peak detection circuit 540 has its input connected to the output of a variable gain amplifier circuit 530, and its output connected to the input of a comparator circuit 550. The peak detection circuit 540 is used to detect the peak amplitude of the output signal R_out of the variable gain amplifier circuit 530 in real time, and outputs a DC voltage V_peak proportional to the peak amplitude. By way of example and not limitation, in this embodiment, the peak detection circuit 540 is implemented using a combination of a precision rectifier and a low-pass filter. The precision rectifier consists of a high-speed operational amplifier (such as an OPA820) and a Schottky diode (such as a BAT54), which can convert a bipolar input signal into a unipolar signal. The low-pass filter is a first-order RC filter with a time constant of 1ms, which can filter out high-frequency ripples while tracking the envelope change rate of the underwater acoustic signal. The working principle of the peak detection circuit 540 is as follows: the output signal R_out of the variable gain amplifier circuit 530 is converted into a full-wave rectified signal by the precision rectifier, and then smoothed by the low-pass filter to obtain a DC voltage V_peak proportional to the peak amplitude of R_out. V_peak changes slowly over time, reflecting the fluctuations in the signal envelope.

[0084] The comparator circuit 550 has its first input connected to the output of the peak detection circuit 540, its second and third inputs connected to preset upper limit reference voltage V_ref_H and lower limit reference voltage V_ref_L, respectively, and its first and second outputs connected to the input of the control voltage generation circuit 560. The comparator circuit 550 compares the V_peak output by the peak detection circuit 540 with a preset ADC input voltage range [V_ref_L, V_ref_H] and outputs the comparison result. The preset ADC input voltage range is determined based on the characteristics of the ADC inside the digital signal processing platform 100. In this embodiment, the digital signal processing platform 100 uses an ADC input range of ±5V. To ensure the ADC operates in the linear region and fully utilizes its dynamic range, the upper limit reference voltage V_ref_H is set to 4.5V (leaving a 10% margin), and the lower limit reference voltage V_ref_L is set to 10mV (to ensure the signal amplitude is not lower than the minimum effective resolution of the ADC). The aforementioned reference voltage can be generated by voltage division from a bandgap reference source (such as LM4040) or provided by the DAC output of the digital signal processing platform 100.

[0085] By way of example and not limitation, the comparator circuit 550 in this embodiment adopts a window comparator structure, consisting of two independent comparators (such as LM393). Wherein: The first comparator is used to compare V_peak with V_ref_H. When V_peak > V_ref_H, it outputs a high level, indicating that the signal amplitude is too high. The second comparator is used to compare V_peak with V_ref_L. When V_peak < V_ref_L, it outputs a high level, indicating that the signal amplitude is too low.

[0086] When V_ref_L ≤ V_peak ≤ V_ref_H, both comparators output a low level, indicating that the signal amplitude is within the target range.

[0087] A control voltage generation circuit 560, whose first input terminal and second input terminal are respectively connected to the first output terminal and the second output terminal of the comparison circuit 550, and whose output terminal is connected to the gain control terminal of the variable gain amplifier circuit 530. The control voltage generation circuit 560 is used to dynamically adjust the gain control voltage V_ctrl of the variable gain amplifier circuit 530 according to the comparison result output by the comparison circuit 550, and further adjust the gain of the variable gain amplifier circuit 530.

[0088] By way of example and not limitation, in this embodiment, the control voltage generation circuit 560 is implemented using an integrator structure. The integrator consists of an operational amplifier (such as OPA2134), an integrating capacitor, and an input resistor. Its working principle is as follows: When the comparison circuit 550 outputs an indication that the signal amplitude is too high (V_peak > V_ref_H), the integrator integrates downward, V_ctrl decreases at a fixed rate, and the gain of the variable gain amplifier circuit 530 is reduced; When the comparison circuit 550 outputs an indication that the signal amplitude is too low (V_peak < V_ref_L), the integrator integrates upward, V_ctrl increases at a fixed rate, and the gain of the variable gain amplifier circuit 530 is increased; When the comparison circuit 550 has no output (V_ref_L ≤ V_peak ≤ V_ref_H), the integrator keeps the current V_ctrl value unchanged.

[0089] The integration rate of the integrator is determined by the integration resistor and the integration capacitor. In this embodiment, the integration rate is set to 10 mV / ms, which can complete the gain adjustment within a few milliseconds to adapt to the envelope change speed of the underwater acoustic signal.

[0090] The relationship between the gain G of the variable gain amplifier circuit 530 and the gain control voltage V_ctrl is determined by the characteristics of the selected chip. For example: in the 9 MHz bandwidth mode, the gain G (dB) = 40 × V_ctrl + 10, where the unit of V_ctrl is volts, and the range of -0.5V to +0.5V corresponds to a gain of 10 dB to 50 dB.

[0091] Among them, the peak detection circuit 540, the comparison circuit 550, and the control voltage generation circuit 560 form a closed-loop feedback control loop, so that the amplitude of the output signal of the variable gain amplifier circuit is always maintained within the preset ADC input voltage range. The working principle is as follows: 1. The peak detection circuit 540 monitors the output signal R_out of the variable gain amplifier circuit 530 in real time and outputs its peak voltage V_peak; 2. The comparison circuit 550 compares V_peak with the preset reference voltage range [V_ref_L, V_ref_H] to determine whether the current output amplitude is within the target range; 3. If V_peak > V_ref_H, the comparison circuit 550 outputs an indication that the signal amplitude is too high, and the control voltage generation circuit 560 reduces V_ctrl, thereby reducing the gain of the variable gain amplifier circuit 530 and causing the amplitude of R_out to decrease; 4. If V_peak < V_ref_L, the comparison circuit 550 outputs an indication that the signal amplitude is too low, and the control voltage generation circuit 560 increases V_ctrl, thereby increasing the gain of the variable gain amplifier circuit 530 and causing the amplitude of R_out to increase; 5. If V_ref_L ≤ V_peak ≤ V_ref_H, the control voltage generation circuit 560 keeps V_ctrl unchanged, and the system enters a steady state.

[0092] In this embodiment, through the closed-loop feedback control loop composed of the peak detection circuit, the comparison circuit, and the control voltage generation circuit, the automatic stable control of the received signal amplitude is realized, which provides guarantee for the reliable reception of the underwater acoustic communication system in a wide dynamic range channel.

[0093] Embodiment 8 Based on the above embodiment, this embodiment introduces a digital controller to implement a low-power consumption strategy for hierarchical power supply. The system further includes a power management module and a digital controller; The power management module is respectively connected to the digital controller, the transceiver switching module, and the receiving circuit module.

[0094] The power management module 400 adopts a multi-channel independent output design, and each output channel is controlled by the enable signal of the digital controller. Specifically, it includes: The first power supply output terminal V`1 (±5V): connected to the power supply terminal of the preamplifier circuit 510, controlled by the enable signal EN0, and this signal is enabled by default and always maintains power supply.

[0095] The second power supply output terminal V`2 (±5V): connected to the power supply terminal of the filter circuit 520, controlled by the enable signal EN1, and is turned off by default.

[0096] The third power supply output terminal V`3 (±5V): connected to the power supply terminal of the variable gain amplifier circuit 530, controlled by the enable signal EN2, and is off by default.

[0097] like Figure 16 and Figure 17 The circuit diagram shown is for voltage conversion, which converts 24V voltage to ±5V power supply.

[0098] The power management module 400 internally employs an architecture combining a DC-DC converter and a low-dropout linear regulator (LDO). The DC-DC converter (such as the TPS62130) converts the 24V input voltage from the lithium battery into an intermediate voltage with high efficiency; the LDO (such as the TPS7A47) performs secondary regulation on the intermediate voltage, outputting a low-noise analog power supply voltage to provide clean power to the receiving circuit module 500.

[0099] 1. When the system is in standby monitoring mode, the digital controller is configured to perform the following operations: Step S801: The digital controller maintains power supply to the first power output terminal V`1 (±5V) through the enable signal EN0 of the power management module, enabling the preamplifier circuit 510 to operate, while maintaining power supply to the digital controller itself. All other enable signals (EN1, EN2) are turned off, putting the filter circuit 520, variable gain amplifier circuit 530, and transmitter circuit module 200 into a power-off state.

[0100] At this point, the system power consumption is only the sum of the static power consumption of the preamplifier circuit 510 and the digital controller. The preamplifier circuit 510 uses a low-noise operational amplifier OPA2140, with an operating current of approximately 2mA and a power consumption of 2mA × 10V = 20mW; the digital controller uses an ultra-low power micro-digital controller STM32L071C8T6, operating in low-power mode with an operating current of approximately 1mA and a power consumption of 3.3mW. The total standby power consumption is approximately 23.3mW.

[0101] Step S802: The preamplifier circuit 510 continuously amplifies the underwater acoustic analog signal converted by the underwater acoustic transducer 300, and outputs a preliminary amplified signal R1. This signal contains ambient background noise and possible useful signals.

[0102] Step S803: The on-chip ADC of the digital controller samples the preliminary amplified signal R1 output by the preamplifier circuit 510 at a low sampling rate (e.g., 1 kHz) and calculates the signal envelope value. To reduce power consumption, the ADC is only briefly awakened during sampling and immediately enters sleep mode after sampling is completed.

[0103] Step S804: The digital controller compares the sampled envelope value with a preset threshold V_th. The preset threshold V_th is set according to the ambient noise level; in this embodiment, it is set to 10mV, slightly higher than typical background noise (approximately 5mV), to avoid noise-induced false triggering.

[0104] 2. When the envelope value of the preliminary amplified signal R1 output by the current amplifier circuit 510 exceeds the preset threshold V_th, it indicates that a valid signal may have arrived. The digital controller is configured to execute the following wake-up confirmation procedure: Step S805: After the digital controller detects that the envelope exceeds the threshold for the first time, it does not immediately wake up all circuits, but instead initiates an acknowledgment mechanism. Specifically, the digital controller samples three times consecutively within the next 1ms. If at least two of the sampling results still exceed the threshold, it is determined that a valid signal has arrived, and the process proceeds to step S806; otherwise, it is determined to be a noise spike, and the process returns to standby monitoring mode.

[0105] 3. After determining that a valid signal has arrived, the digital controller is configured to execute the following reception state switching procedure: Step S806: The digital controller enables the power supply to the filter circuit 520 (second power supply output terminal V`2) via the enable signal EN1 of the power management module. The filter circuit 520 adopts a sixth-order Butterworth active filter, with a settling time of approximately 0.5ms. The digital controller delays for 1ms to wait for it to stabilize.

[0106] Step S807: The digital controller enables the power supply to the variable gain amplifier circuit 530 (third power supply output terminal V`3) via the enable signal EN2 of the power management module. The variable gain amplifier circuit 530 uses an AD603, whose settling time is approximately 0.1ms. The digital controller delays for 0.5ms to wait for it to stabilize.

[0107] Step S808: After the filter circuit 520 and the variable gain amplifier circuit 530 have stabilized, the digital controller controls the transceiver switching module 600 to switch to the receiving state (e.g., the transceiver switching module 600 turns off the first switch and turns on the second switch). At this time, the receiving circuit module 500 enters the full-power operating state, the filter circuit 520 filters the initially amplified signal R1, the variable gain amplifier circuit 530 adjusts the gain of the filtered signal, and outputs a stable received signal R_out to the digital signal processing platform 100.

[0108] Step S809: The digital controller sends a signal arrival notification to the digital signal processing platform 100 via the UART interface, and the digital signal processing platform 100 begins to perform analog-to-digital conversion and digital demodulation processing on the received signal R_out.

[0109] 4. After the digital signal processing platform 100 has finished receiving and processing the data, it sends a reception termination command to the digital controller. Upon receiving the command, the digital controller performs the following operations: Step S810: The digital controller shuts off the power supply to the variable gain amplifier circuit 530 (third power supply output terminal V`3) through the enable signal EN2 of the power management module.

[0110] Step S811: The digital controller shuts off the power supply to the filter circuit 520 (second power supply output terminal V`2) through the enable signal EN1 of the power management module 400.

[0111] Step S812: The digital controller controls the transceiver switching module 600 to switch to standby mode (e.g., to simultaneously turn off the first and second switches). At this time, the system returns to standby monitoring mode.

[0112] In another embodiment, the power management module includes: a lithium battery access module and a voltage conversion module; The input terminal of the lithium battery access module is connected to a lithium battery; The output terminal of the lithium battery access module is connected to the input terminal of the voltage conversion module; The control terminal of the lithium battery access module is connected to the digital controller; The voltage conversion module has multiple independently controlled power supply output terminals, which are respectively connected to the preamplifier circuit, filter circuit, variable gain amplifier circuit and transceiver switching module; Each power supply output terminal of the voltage conversion module has an enable control terminal, which is connected to the digital controller, and the digital controller independently controls the on / off state of each power supply output terminal.

[0113] In yet another embodiment, the power management module may include, for example, Figure 13 The lithium battery access module shown and such Figure 14 and Figure 15 The voltage conversion module shown Figure 14 and Figure 15 The core working principle is to use an integrated high-side MOSFET for high-frequency switching (TPS54560DDAR) to efficiently convert a 48V input voltage into 24V and 12V output voltages. It employs current-mode control, using a closed-loop circuit consisting of a precise internal voltage reference (0.8V) and an external feedback resistor to monitor the output voltage in real time and adjust the on-time (duty cycle) of the switching transistor, thereby maintaining output stability under load and input voltage variations.

[0114] This embodiment achieves refined hierarchical power supply control through the collaborative design of digital controller and power management module, which significantly reduces system standby power consumption while ensuring signal acquisition reliability, providing an effective energy-saving solution for long-term deployed underwater acoustic communication nodes.

[0115] Example 9 Based on the above embodiments, this embodiment further optimizes the impedance matching circuit 240 by introducing an adaptive impedance matching architecture based on the element fluid to solve the problem that the capacitive reactance of the underwater acoustic transducer 300 causes the fixed matching network to fail due to changes in the environment.

[0116] The impedance matching circuit 240 includes an adjustable fluid matching unit, an acoustic energy transmission enhancement module, and a capacitive reactance drift compensation unit.

[0117] The adjustable fluid matching unit is composed of at least two adjustable fluid matching layers connected in sequence. The input terminal of the first adjustable fluid matching layer serves as the overall input terminal of the adjustable fluid matching unit and is connected to the output terminal of the transformer. The output terminal of the last adjustable fluid matching layer serves as the overall output terminal of the adjustable fluid matching unit and is connected to the input terminal of the acoustic energy transmission enhancement module. In adjacent adjustable fluid matching layers, the output terminal of the preceding layer is connected to the input terminal of the following layer. Each adjustable fluid matching layer has an independent control terminal, which is connected to different output terminals of the digital signal processing platform. The adjustable fluid matching unit is used to perform impedance matching on the voltage boost signal to obtain a preliminary matching signal. The sound velocity parameter of each adjustable fluid matching layer is independently adjustable to form a gradient transition in acoustic impedance, achieving a smooth matching from the high impedance at the transformer output terminal to the low impedance of the water medium.

[0118] For example, the adjustable elemental fluid matching unit consists of three layers of elemental fluid material connected in series, and the sound velocity parameter of each adjustable elemental fluid matching layer is independently adjustable.

[0119] Metafluids are artificially designed acoustic metamaterials that, through the construction of specific microstructures (such as microchannel networks, hollow microsphere arrays, or periodic porous structures), possess acoustic parameters that are difficult to find in natural materials, such as negative equivalent density, negative equivalent modulus, or ultra-wide tunability of sound velocity. In this embodiment, the metafluid matching layer adopts a smart material system based on electrorheological fluids. The matrix material of the metafluid matching layer uses polyurethane elastomer as the matrix material, with a thickness ranging from 0.5 mm to 2 mm, exhibiting good acoustic transparency and mechanical flexibility. Periodically arranged microchannels, approximately 50 μm in diameter and 200 μm in spacing, are distributed within the matrix material and are fabricated using laser processing or micro / nano imprinting processes. The microchannels are filled with an electrorheological fluid, composed of silicone oil and nano-silica particles (approximately 100 nm in diameter) mixed in a certain proportion. Electrorheological fluids undergo rheological property changes under the influence of an electric field: when electric fields of different intensities are applied, suspended particles align into chain-like structures along the direction of the electric field, causing changes in the liquid's equivalent viscosity and elastic modulus, thereby altering the propagation speed of sound waves within it.

[0120] Each adjustable elemental fluid matching layer has transparent electrodes (such as ITO conductive film or mesh metal electrodes) on both sides, allowing independent adjustment of the equivalent sound velocity of that layer by applying different voltages. The voltage control circuit uses a high-voltage operational amplifier (such as APEX PA94) to amplify the 0-5V control voltage output from the digital signal processing platform 100 to 0-500V, which is then applied to the electrodes of each layer. The relationship between sound velocity and electric field strength can be obtained through experimental calibration. In this embodiment, within the 0-500V voltage range, the equivalent sound velocity of the elemental fluid can be continuously adjusted from 1500m / s to 2500m / s, covering various matching conditions required for underwater acoustic communication frequency bands.

[0121] Multiple tunable fluid matching layers are connected sequentially to form a tunable fluid matching unit. The signal enters from the input of the first tunable fluid matching layer, passes through each layer in sequence, and is output from the output of the last tunable fluid matching layer. The sound velocity of each tunable fluid matching layer can be adjusted independently, thereby changing the acoustic impedance of that layer. The signal is reflected and transmitted at the interfaces between adjacent layers. By adjusting the sound velocity of each layer, the reflection coefficient at each interface can be controlled, making the overall reflection coefficient approach zero, thus achieving impedance matching.

[0122] The configuration parameters output by the digital signal processing platform 100 are the target control voltage values ​​V1, V2, and V3 applied to the electrodes of each adjustable element fluid matching layer. These voltage values ​​correspond to the target sound velocities c1, c2, and c3 required for each layer. By adjusting these voltages, the sound velocity of each layer can be changed independently, thereby changing the acoustic impedance Zi = ρi · ci of each adjustable element fluid matching layer (ρi is the equivalent density, which is considered a constant in this embodiment).

[0123] The acoustic energy transmission enhancement module is connected between the overall output end of the adjustable fluid matching unit and the input end of the underwater acoustic transducer. It is used to enhance the acoustic energy penetration of the signal after impedance matching to obtain the target amplified signal.

[0124] In this embodiment, the acoustic energy transmission enhancement module employs an acoustic lens structure made of high-velocity acoustic materials, designed as a spherical focusing lens. The working principle of the acoustic lens is based on the law of sound wave refraction. When a plane sound wave enters a low-velocity water medium from a high-velocity lens material, it is deflected towards the normal direction. By designing the curved shape of the lens, the plane wavefront can be converged into a spherical wavefront, focusing the acoustic energy to the central region of the transducer's radiating surface, thereby increasing the radiated sound pressure.

[0125] The first input terminal of the capacitive drift compensation unit is connected to the electrode of the underwater acoustic transducer, the second input terminal of the capacitive drift compensation unit is connected to the environmental sensor, and the output terminal of the capacitive drift compensation unit is connected to the input terminal of the digital signal processing platform. The capacitive drift compensation unit is used to collect environmental parameters and capacitive drift data of the underwater acoustic transducer, calculate the acoustic impedance of the current water medium based on the environmental parameters, and transmit the capacitive drift data and the acoustic impedance to the digital signal processing platform.

[0126] The environmental sensors connected to the capacitive drift compensation unit include a temperature sensor and a salinity sensor. The temperature sensor is mounted on the surface of the housing of the underwater acoustic transducer 300 and communicates with the data acquisition unit via a single-bus interface. The salinity sensor is a conductivity sensor; it measures the conductivity of the water and calculates the salinity value after temperature compensation. The environmental parameters in the above embodiment include temperature parameters and salinity parameters.

[0127] The impedance measurement circuit of the capacitive drift compensation unit is connected to the electrodes of the underwater acoustic transducer 300. The circuit includes: an excitation signal source, an automatic balancing bridge, a quadrature demodulator, and an ADC sampler.

[0128] The excitation signal source can use a DDS chip to generate a sinusoidal excitation signal, with the frequency set to the center frequency of underwater acoustic communication (12kHz) and the amplitude 100mV (far below the transmission voltage, so it will not affect normal operation). An automatic balancing bridge uses a high-precision operational amplifier to form an IV-to-IV conversion circuit, converting the current flowing through the transducer into a voltage signal. A quadrature demodulator is used to quadrature demodulate the excitation and response signals, outputting the real part (resistive component Rt) and imaginary part (reactant component Xt) of the impedance. ADC sampling can use a 16-bit ADC to sample both the real and imaginary parts of the signal.

[0129] The velocity of sound c in the current water medium can be calculated using the Mackenzie formula based on the collected temperature parameter T and salinity parameter S. w : c w= 1448.96 + 4.591T - 5.304×10 -2 T 2 + 2.374×10 -4 T 3 + 1.340(S-35) +1.630×10 -2 D + 1.675×10 -7 D 2 - 1.025×10 -2 T(S-35) - 7.139×10 -13 TD 3 ; Where D represents depth, which is set to 100m in this embodiment. The density ρw of water is determined by temperature and salinity, and is calculated using the international seawater state equation. The characteristic impedance of the water medium is Zw = ρw · cw.

[0130] The imaginary part of the impedance Xt measured by the capacitive drift compensation unit can be used to deduce the current static capacitance C`0: C`0 = -1 / (2πf·Xt); Capacitive drift ΔC0 = C`0 - C 0ref C 0ref This is the factory nominal value (10nF) for the underwater acoustic transducer. The capacitive reactance drift data is ΔC0.

[0131] The equivalent impedance Z of the transducer under the current environment can be calculated based on ΔC0. trans The equivalent circuit of the underwater acoustic transducer can be represented as the static capacitor C`0 of the underwater acoustic transducer connected in parallel with the dynamic branch at the operating frequency f: Z trans = 1 / (j2πf·(C 0ref + ΔC0)) || Zdyn; Zdyn is the dynamic branch impedance, which can be measured and modeled in advance in the laboratory.

[0132] The equivalent impedance viewed from the overall output of the adjustable fluid matching unit towards the load is denoted as Z. L In this embodiment, the transmission characteristics of the acoustic energy transmission enhancement module can be pre-measured and compensated, therefore Z L Mainly composed of the equivalent impedance Z of the underwater acoustic transducer trans The decision is: ; The Z L It will be used as an important input parameter for the adaptive gradient adjustment algorithm to calculate the input impedance Z. in and reflection coefficient .

[0133] The digital signal processing platform has multiple output terminals connected to independent control terminals of the multiple tunable fluid matching layers. These terminals generate configuration parameters for each tunable fluid matching layer based on the capacitive drift data and acoustic impedance using an adaptive gradient adjustment algorithm, and then output these parameters to the respective tunable fluid matching layers. It is noteworthy that there is a one-to-one correspondence between the output terminals of the digital signal processing platform and the control terminals of the tunable fluid matching layers.

[0134] The goal of the adaptive gradient adjustment algorithm is to optimize the sound velocity parameters c1, c2, and c3 of each tunable fluid matching layer so that the input impedance Z seen from the overall input terminal of the tunable fluid matching unit is reduced. in The equivalent impedance Z of the underwater acoustic transducer 300 in the current environment trans To achieve conjugate matching, that is: Z in = Z trans ; Among them, Z trans For Z trans The conjugate complex number of . When the conjugate matching condition is met, the reflection coefficient of the signal at the interface between the matching layer and the underwater acoustic transducer is zero, and all energy is transferred to the underwater acoustic transducer, achieving maximum power transmission.

[0135] For the i-th tunable fluid matching layer, its acoustic transfer matrix is: ; in, For phase delay, di is the thickness of the i-th tunable element fluid matching layer (fixed in this embodiment as d1=2mm, d2=2mm, d3=2mm), f is the operating frequency (e.g., 12kHz), and Z is the phase delay. i The acoustic impedance Z of the i-th tunable fluid matching layer i = ρi · ci, where ρi is the equivalent density of the i-th tunable element fluid matching layer, which is considered a constant in this embodiment (ρi = 1500kg / m³). 3 ), c i Let be the sound velocity of the i-th tunable fluid matching layer.

[0136] Multiplying the transfer matrix of each fluid matching layer by the load transfer matrix yields the total transfer matrix: ; Among them, M L For the correspondence of Z L The transfer matrix can be obtained through experimental measurement.

[0137] Let the total transfer matrix be: ; The input impedance Z seen from the overall input terminal of the adjustable fluid matching unit is... in for: ; The reflection coefficient is defined as the input impedance Z. in The degree of mismatch between the transducer and its equivalent impedance Ztrans. Since the goal is conjugate matching, the reflection coefficient formula should be: ; The objective function is defined as the square of the magnitude of the reflection coefficient: ; The goal of the algorithm is to find a set of sound speed parameters. To minimize the objective function: ; When the objective function approaches zero, that is, , satisfying the conjugate matching condition.

[0138] The gradient descent method is used to iteratively optimize the sound velocity parameters at each layer. The algorithm steps are as follows: Step S901: Initialize parameters. Set the initial speed of sound c1(0)=c2(0)=c3(0)=2000m / s.

[0139] Step S902: Calculate the reflection coefficient modulus |Γ(k)| based on the current sound speed parameters c1(k), c2(k), and c3(k).

[0140] Step S903: Calculate the partial derivatives of the objective function with respect to the sound velocity at each layer. |Γ| 2 / c i The numerical difference method is used for calculation: ; Where Δc is taken as 10 m / s.

[0141] Step S904: Update the speed of sound parameter: ; Where μ is the step size factor, and in this embodiment, μ = 0.01. This represents the squared value of the reflection coefficient modulus after changing the sound velocity of the i-th layer by ±Δc (keeping the sound velocities of other layers unchanged).

[0142] Step S905: Determine if the convergence condition is met. If |Γ(k)| 2 <0.01 (i.e., reflectance coefficient less than 0.1) or parameter change less than the threshold (|c i (k+1)-c iIf (k)|<1m / s), proceed to step S906; otherwise, return to step S902 to continue iterating.

[0143] Step S906: Calculate the optimized sound velocity parameter c i This is converted to the corresponding control voltage. Based on the pre-calibrated sound velocity-voltage relationship curve Vi = f(c i The required control voltage values ​​V1, V2, and V3 for each layer are obtained by looking up tables or interpolation.

[0144] Step S907: Output the control voltage values ​​V1, V2, and V3 to the independent control terminals of each adjustable element fluid matching layer through the digital-to-analog converter, and adjust the sound velocity of each adjustable element fluid matching layer.

[0145] Step S908: After a 1-second delay, return to step S901 and enter the next round of adaptive adjustment cycle to achieve real-time tracking calibration.

[0146] This embodiment achieves real-time adaptive compensation for the capacitive drift of the underwater acoustic transducer through the coordinated work of multiple adjustable fluid matching layers, capacitive drift compensation units, and acoustic energy transmission enhancement modules, combined with the adaptive gradient adjustment algorithm of the digital signal processing platform. This significantly improves the transmission efficiency and stability of the system in complex underwater environments.

[0147] The above analysis shows that although existing underwater acoustic communication equipment can achieve basic signal transmission, it still faces serious challenges when dealing with long-term deployed underwater nodes with limited energy resources. Low energy efficiency: Traditional transmitting circuits use discrete circuit structures, resulting in excessively long signal links and significant energy loss due to transmission line impedance.

[0148] High static power consumption of the receiver: To ensure that no communication commands are missed, the receiving circuit often needs to operate at full power for extended periods. Without efficient, low-noise conditioning circuitry and adaptive gain control (VGA), the equipment consumes a large amount of redundant energy, severely shortening the underwater platform's endurance.

[0149] Vulnerability of transmit / receive switching: During the frequent switching between ranging and communication, if there is a lack of efficient transmit / receive switching logic, the high-power signal at the transmitting end can easily remain and interfere with the receiving end, or even damage sensitive high-sensitivity analog devices, leading to system failure or performance degradation.

[0150] With the development of global ocean observation networks and underwater navigation technologies, underwater equipment is evolving towards miniaturization, longer endurance, and clustering. As a core energy-consuming component, the power consumption of the underwater acoustic communication unit directly determines the continuous operation capability of the navigation system. Therefore, constructing a hardware system integrating a high-efficiency, low-power underwater acoustic communication unit is not only a key means to solve the "endurance anxiety" of underwater equipment, but also a core path to improve underwater positioning accuracy and communication robustness.

[0151] In summary, this disclosure aims to provide a low-power, high-efficiency underwater acoustic communication transceiver hardware system to address the technical pain points of high power consumption, large size, severe signal path loss, and low circuit security during the navigation and ranging process of underwater vehicles (AUVs) and underwater sensor networks. By optimizing the traditional discrete circuit scheme of the transmitter and adopting a digital transceiver conversion device, the system power consumption is reduced while improving signal conversion efficiency and the security of the front-end circuit.

[0152] The underwater acoustic communication system provided in this application can not only realize low-power, high-reliability communication between underwater devices, but can also be further used for navigation and ranging of underwater vehicles (AUVs), underwater robots (ROVs), and underwater sensor network nodes.

[0153] In a typical navigation and ranging application scenario, multiple underwater nodes (such as beacons, buoys, or ships) constitute a positioning array, employing long baseline (LBL), short baseline (SBL), or ultra-short baseline (USBL) positioning principles. The underwater acoustic communication system, as the core transceiver unit for each node, performs the following operations: The ranging signal is transmitted by a digital signal processing platform that generates a ranging request signal (such as a linear frequency modulated pulse or coded pulse). After processing by the power amplification unit, transformer, and impedance matching circuit of the transmitting circuit module, the signal drives the underwater acoustic transducer to transmit the signal into the water medium. The ranging signal has high time resolution and good multipath resistance.

[0154] The response signal reception and time delay measurement process involves the target node receiving the ranging request signal and switching to receiving mode via a transceiver switching module. The weak response signal is conditioned by the preamplifier, filter, and variable gain amplifier circuits of the receiving circuit module. The digital signal processing platform uses matched filtering or correlation detection algorithms to accurately estimate the time of arrival (TOA) or round-trip time delay (RTT). Combined with known sound velocity profile data, the slant distance between nodes is calculated.

[0155] Multi-node collaborative positioning involves deploying the system across multiple fixed beacon nodes. Mobile nodes sequentially perform bidirectional ranging with each beacon, and the digital signal processing platform uses trilateration or least squares algorithms to calculate its own 3D coordinates in real time. Ranging accuracy can reach the centimeter level, while the positioning update rate is limited by the underwater acoustic propagation delay (typically several times per second).

[0156] During navigation, the system can simultaneously carry communication data and ranging sequences within the same frame. The digital signal processing platform embeds a wideband ranging code while transmitting communication data, and the receiver extracts the arrival time of the ranging code while demodulating the data, thus achieving the fusion of communication and ranging. This mode significantly reduces the additional power consumption and time overhead required for independent ranging.

[0157] An adaptive ranging strategy is employed, where the digital signal processing platform adaptively selects the bandwidth, pulse width, and encoding method of the ranging signal based on the current signal-to-noise ratio (SNR) and multipath environment. Under low SNR conditions, long pulses and spreading codes are used to improve detection probability; under high SNR conditions, short pulses and wideband signals are used to improve ranging accuracy. The tiered power supply strategy of the power amplifier unit and the rapid switching capability of the transceiver switching module ensure low-latency conversion between ranging and communication modes.

[0158] Through the above operations, this system provides underwater nodes with high-precision, low-latency ranging and positioning capabilities while achieving low-power communication. It is suitable for applications such as underwater vehicle formation coordination, submarine pipeline inspection, underwater target tracking, and underwater sensor network node self-localization.

[0159] It is worth noting that in this disclosure Figure 3 , Figure 5 , Figure 6 , Figure 7 , Figure 9 , Figure 10 , Figure 11 , Figures 13-17 The detailed working principle of the circuit is similar to that in the related sections, and will not be repeated here.

[0160] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0161] This document uses specific examples to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the methods and core ideas of this application. Furthermore, those skilled in the art will recognize that, based on the ideas of this application, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A low-power underwater acoustic communication system for underwater navigation and ranging, characterized in that, include: A digital signal processing platform is used to preprocess the digital baseband signal to be transmitted to obtain a single-ended analog signal; The transmitting circuit module includes at least: a power amplification unit; the power amplification unit is a single chip integrating a PWM modulation circuit, a drive amplification circuit and a power amplification circuit, the power amplification unit is used to sequentially perform PWM modulation, drive amplification and power amplification on the single-ended analog signal, and output the target amplified signal; An underwater acoustic transducer is used to convert the amplified target signal into an acoustic signal and transmit it into the water medium.

2. The system according to claim 1, characterized in that, The system also includes: a receiving circuit module and a transceiver switching module; The underwater acoustic transducer is also used to convert the received underwater acoustic signal into an underwater acoustic analog signal; The receiving circuit module is used to amplify and filter the underwater acoustic analog signal and then output it to the digital signal processing platform. The transceiver switching module is connected to the transmitting circuit module, the receiving circuit module, and the underwater acoustic transducer, respectively, and is used to switch the system between transmitting and receiving states; the transceiver switching module adopts a digital-analog switch.

3. The system according to claim 2, characterized in that, The transceiver switching module includes: The first switch is connected between the output of the transmitting circuit module and the underwater acoustic transducer; The second switch is connected between the underwater acoustic transducer and the input terminal of the receiving circuit module; The controller is connected to the first switch and the second switch respectively; the controller is used to turn on the first switch and turn off the second switch when the system needs to transmit a signal, and to turn off the first switch and turn on the second switch when the system needs to receive a signal.

4. The system according to claim 3, characterized in that, The transceiver switching module further includes: a timing control circuit and a discharge circuit; the discharge circuit includes a discharge switch and a discharge resistor; One end of the discharge switch is connected to the underwater acoustic transducer, and the other end of the discharge switch is connected to one end of the discharge resistor, and the other end of the discharge resistor is grounded. The timing control circuit is connected to the first switch, the second switch and the discharge switch respectively; The timing control circuit is configured such that, at the instant the transmission state ends, the discharge switch is first turned on, so that the residual high voltage stored in the underwater acoustic transducer is released through the discharge resistor, and after a first preset time delay, the discharge switch is turned off, and at the same time the first switch is turned off and the second switch is turned on.

5. The system according to claim 1, characterized in that, The transmitting circuit module also includes: a single-ended to differential circuit, a transformer, and an impedance matching circuit; The single-ended to differential circuit is used to convert the single-ended analog signal into a differential analog signal; The power amplifier circuit is used to sequentially perform PWM modulation, drive amplification, and power amplification on the differential analog signal, and output a first-stage amplified signal. The transformer is used to boost the voltage of the first-stage amplified signal to obtain a boosted voltage signal, which satisfies the voltage level required to drive the underwater acoustic transducer to transmit. The impedance matching circuit is used to perform impedance transformation on the voltage boost signal, so that the transformed signal impedance forms a conjugate match with the capacitive impedance of the underwater acoustic transducer to counteract the capacitive reactance of the underwater acoustic transducer, wherein the voltage boost signal after impedance transformation is the target amplified signal.

6. The system according to claim 2, characterized in that, The receiving circuit module includes: A preamplifier circuit is used to initially amplify the underwater acoustic analog signal to obtain a preliminary amplified signal; A filtering circuit is used to filter out noise in the initially amplified signal to obtain a filtered signal. A variable gain amplifier circuit is used to adjust the gain of the filtered signal according to the gain control voltage so that the amplitude of the output signal meets the input requirements of the digital signal processing platform.

7. The system according to claim 6, characterized in that, The receiving circuit module further includes: A peak detection circuit is used to detect the peak amplitude of the output signal of the variable gain amplifier circuit. A comparator circuit is used to compare the peak amplitude with a preset ADC input voltage range; A control voltage generation circuit is used to dynamically adjust the gain control voltage of the variable gain amplifier circuit based on the comparison result; The peak detection circuit, the comparison circuit, and the control voltage generation circuit form a closed-loop feedback control loop, which keeps the output signal amplitude of the variable gain amplifier circuit within the preset ADC input voltage range.

8. The system according to claim 7, characterized in that, Also includes: Power management module and digital controller; The power management module is connected to the digital controller, the transceiver switching module, and the receiving circuit module, respectively. The digital controller is configured to: In standby monitoring mode, the power management module is controlled to enable power supply to the preamplifier circuit only, and to turn off power supply to the filter circuit and the variable gain amplifier circuit; at the same time, the envelope of the preamplifier circuit output is sampled at a preset sampling rate, and the sampled envelope value is compared with a preset threshold. When the envelope value is detected to exceed a preset threshold, multiple samples are taken continuously within a preset time window. If the sampling result exceeds the preset threshold after more than a preset number of samplings, it is determined that a valid signal has arrived. After determining that a valid signal has arrived, the power supply of the filter circuit and the power supply of the variable gain amplifier circuit are enabled in sequence, and a preset circuit stabilization time is waited after each enable. After the filtering circuit and the variable gain amplifier circuit have stabilized, control the transceiver switching module to switch to the receiving state; Upon receiving the end-of-reception command, the power supply to the variable gain amplifier circuit and the power supply to the filter circuit are sequentially turned off, and the transceiver switching module is controlled to switch to standby mode, so that the system returns to standby mode.

9. The system according to claim 8, characterized in that, The power management module includes: a lithium battery access module and a voltage conversion module; The input terminal of the lithium battery access module is connected to a lithium battery; The output terminal of the lithium battery access module is connected to the input terminal of the voltage conversion module; The control terminal of the lithium battery access module is connected to the digital controller; The voltage conversion module has multiple independently controlled power output terminals, which are respectively connected to the preamplifier circuit, the filter circuit, the variable gain amplifier circuit, and the transceiver switching module. Each power supply output terminal of the voltage conversion module has an enable control terminal, which is connected to the digital controller, and the digital controller independently controls the on / off state of each power supply output terminal.

10. The system according to claim 5, characterized in that, The impedance matching circuit includes: An adjustable fluid matching unit is provided, comprising at least two adjustable fluid matching layers connected sequentially. The input terminal of the first adjustable fluid matching layer serves as the overall input terminal of the adjustable fluid matching unit and is connected to the output terminal of the transformer. The output terminal of the last adjustable fluid matching layer serves as the overall output terminal of the adjustable fluid matching unit and is connected to the input terminal of the acoustic energy transmission enhancement module. In adjacent adjustable fluid matching layers, the output terminal of the preceding layer is connected to the input terminal of the following layer. Each adjustable fluid matching layer has an independent control terminal, which is connected to different output terminals of the digital signal processing platform. The adjustable fluid matching unit is used for impedance matching of the voltage boost signal, and the sound velocity parameter of each adjustable fluid matching layer is independently adjustable. The output of the acoustic energy transmission enhancement module is connected to the underwater acoustic transducer to enhance the acoustic energy penetration of the preliminary matching signal and obtain the target amplified signal; The first input terminal of the capacitive reactance drift compensation unit is connected to the electrode of the underwater acoustic transducer, the second input terminal of the capacitive reactance drift compensation unit is connected to the environmental sensor, and the output terminal of the capacitive reactance drift compensation unit is connected to the input terminal of the digital signal processing platform. It is used to collect environmental parameters and capacitive reactance drift data of the underwater acoustic transducer, calculate the acoustic impedance of the current water medium based on the environmental parameters, and transmit the capacitive reactance drift data and the acoustic impedance to the digital signal processing platform. The multiple output terminals of the digital signal processing platform are respectively connected to the independent control terminals of the multiple adjustable element fluid matching layers, and are used to generate configuration parameters of each adjustable element fluid matching layer according to the capacitive drift data and acoustic impedance through an adaptive gradient adjustment algorithm, and output them to each element fluid matching layer.

Images