Water body dynamics information detection system and method based on laser intensity modulation

Abstract

This invention discloses a system and method for detecting water dynamics information based on laser intensity modulation, comprising: a signal sensing and modulation transmission module, an optical signal receiving and conversion module, and a data acquisition and processing module connected in sequence; the signal sensing and modulation transmission module is used to sense water dynamic parameters and generate corresponding electrical signals, thereby modulating the output light intensity of the laser transmitter so that the intensity of the output laser carries water dynamics information; the optical signal receiving and conversion module is used to receive the modulated laser signal and restore it to an electrical signal; the data acquisition and processing module is used to acquire, process, and analyze the electrical signal to extract the water dynamics information. This invention, by adopting a simplified technical approach of laser intensity modulation and direct detection, replaces the traditional complex frequency modulation system, successfully solving the long-standing core problems in the field of water dynamics detection: high equipment cost, system complexity, and difficulty in widespread adoption.

Description

Technical Field

[0001] This invention belongs to the field of fluid measurement technology, and in particular relates to a system and method for detecting water dynamics information based on laser intensity modulation. Background Technology

[0002] Accurate detection of hydrodynamic information is crucial for hydrological monitoring, water resource management, safe operation of water conservancy projects, environmental science research, and flood disaster early warning. This hydrodynamic information mainly includes key parameters such as flow velocity, flow rate, and water level. Real-time, accurate, and low-cost acquisition of this information is fundamental for scientific analysis, engineering design, and intelligent decision-making.

[0003] Currently, the technologies applied to the detection of hydrodynamic information can be mainly divided into the following categories: Contact-type mechanical measurement methods, such as propeller flow meters and rotor flow meters, require the sensor probe to be directly placed in the water body being measured. These methods are susceptible to entanglement or corrosion by aquatic organisms, debris, and other contaminants, resulting in high long-term operation and maintenance costs. Furthermore, they can disturb the water flow, affecting measurement accuracy.

[0004] Acoustic and ultrasonic methods, such as ultrasonic Doppler current profilers (ADCP), can achieve non-contact or minimally disturbed measurements, but the equipment is expensive, signal processing is complex, and the measurement accuracy and stability decrease significantly in water bodies with high gas content or under complex boundary conditions.

[0005] Optical velocimetry – Laser Doppler velocimetry (LDV): This technology utilizes the Doppler frequency shift generated by the scattering of laser light by moving particles to invert flow velocity, offering significant advantages such as high measurement accuracy, good spatial resolution, and fast dynamic response. However, LDV systems integrate precision optical components, high-sensitivity detectors, and complex signal processing units, resulting in a complex system structure, high technological integration, and extremely high manufacturing costs (often exceeding one million yuan), greatly limiting its widespread application in routine hydrological monitoring and general use.

[0006] On the other hand, laser intensity modulation (LIMM) technology, as a mature information loading method, has been widely used in optical communication, medical imaging, and precision measurement. Its principle is to directly or indirectly control the output intensity of a laser source through the electrical signal to be transmitted, thereby loading information onto an optical carrier. This technology has advantages such as intuitive principles, high modulation efficiency, and ease of implementation. However, the innovative application of LIMM technology to the specific scenario of water dynamics information detection, especially the construction of a technical solution aimed at replacing high-cost LDV systems and achieving low-cost and reliable detection, remains a gap in existing technologies.

[0007] In summary, existing low-cost traditional detection methods are insufficient in terms of accuracy, stability, or anti-interference capabilities; while high-precision laser Doppler velocimetry technology is difficult to popularize due to its high cost and system complexity.

[0008] Therefore, the industry urgently needs a new hydrodynamic information detection technology that combines low cost, high measurement accuracy, simple system structure, and ease of implementation and maintenance to fill the aforementioned technological gap. Summary of the Invention

[0009] To address the aforementioned technical problems, this invention provides a water dynamics information detection system based on laser intensity modulation, comprising: The signal sensing and modulation transmission module, the optical signal receiving and conversion module, and the data acquisition and processing module are connected in sequence. The signal sensing and modulation transmission module is used to sense water dynamic parameters and generate corresponding electrical signals, thereby modulating the output light intensity of the laser transmitter so that the intensity of the output laser carries water dynamic information. The optical signal receiving and conversion module is used to receive the modulated laser signal and convert it back into an electrical signal; The data acquisition and processing module is used to acquire, process, and analyze the electrical signals to extract water dynamics information.

[0010] Optionally, the signal sensing and modulation transmission module includes a hydrodynamic sensor, a signal amplification circuit, and a laser transmitter; The hydrodynamic sensor is used to sense hydrodynamic parameters and output raw electrical signals; The input terminal of the signal amplification circuit is connected to the output terminal of the hydrodynamic sensor to amplify the original electrical signal; The driving end of the laser emitter is connected to the output end of the signal amplification circuit, and its output light intensity is controlled by the amplified electrical signal.

[0011] Optionally, in the signal sensing and modulation transmission module, the water dynamics sensor is a Hall effect flow velocity sensor.

[0012] Optionally, in the signal sensing and modulation transmission module, the signal amplification circuit includes a first amplification unit and a second control unit; The first amplification unit is used to receive and initially amplify the electrical signal from the sensor; The second control unit controls the magnitude of the current flowing through the laser emitter based on the output signal of the first amplification unit.

[0013] Optionally, the optical signal receiving and conversion module includes a silicon-based photoelectric conversion unit and a signal conditioning unit; The silicon-based photoelectric conversion unit is used to convert received light intensity changes into current or voltage changes. The signal conditioning unit is connected to the silicon-based photoelectric conversion unit and is used to amplify and condition the converted electrical signal.

[0014] Optionally, in the optical signal receiving and conversion module, the signal conditioning unit is a digital power amplifier board based on a Class D amplifier chip.

[0015] Optionally, the data acquisition and processing module includes a data acquisition unit and a data processing unit; The data acquisition unit is used to acquire electrical signals at a preset sampling rate; The data processing unit is used to display the waveforms and store the collected electrical signals, and to calculate the hydrodynamic parameters by analyzing the signal characteristics.

[0016] Optionally, in the data acquisition and processing module, the data processing unit is implemented by running a graphical programming software platform, which is configured to create data acquisition tasks, configure sampling parameters, and realize data visualization and storage.

[0017] This invention also provides a method for detecting water dynamics information based on laser intensity modulation, the system comprising: Hydrodynamic parameters are sensed by hydrodynamic sensors, and corresponding raw electrical signals are generated. The original electrical signal is amplified by a signal amplification circuit to obtain an amplified electrical signal, and the amplified electrical signal is used to modulate the driving current of the laser transmitter, so that the laser intensity output by the laser transmitter changes with the changes in the water dynamic parameters. A photoelectric converter is used to receive a modulated laser beam and convert it into a received electrical signal containing information about water dynamics. The received electrical signals are acquired through the data acquisition and processing module, and the water dynamic parameters are extracted by analyzing the modulation-related features in the received electrical signals.

[0018] Optionally, the step of extracting hydrodynamic parameters specifically includes: Identify and calculate the periodic pulse frequency or time interval in the received electrical signal; Based on the inherent linear proportional relationship between the pulse frequency and the water flow velocity of the Hall effect flow sensor, the calculated pulse frequency is substituted into the linear proportional relationship to calculate the corresponding water flow velocity value, thereby obtaining the hydrodynamic parameters.

[0019] Compared with the prior art, the present invention has the following advantages and technical effects: This invention simplifies the system structure and significantly reduces costs. The entire system consists of common electronic components, general-purpose sensors, and basic optoelectronic devices, eliminating the need for expensive optical lenses, precision mechanical structures, and complex coherent detection circuits. This allows the cost of the entire system to be reduced by several orders of magnitude compared to traditional high-end instruments, providing a realistic basis for large-scale deployment and widespread application.

[0020] This invention improves the system's reliability and environmental adaptability. The simplified optical path and circuit structure are more robust, reducing the risk of failure due to vibration or alignment misalignment. Meanwhile, the intensity modulation direct detection method has relatively relaxed requirements for optical path stability, ensuring accurate sensing of subtle changes in water dynamic parameters and enabling stable operation in complex field environments beyond the laboratory.

[0021] This invention ensures the intuitiveness and efficiency of information transmission and extraction. Since the information is directly reflected in changes in light intensity, the reception and demodulation processes become extremely straightforward, eliminating the need for complex spectral analysis. Combined with graphical programming software, a real-time data display, recording, and analysis platform can be quickly built, making data processing intuitive and easy to understand. This significantly lowers the technical barrier for operators and provides a more efficient solution for acquiring hydrodynamic information. Attached Figure Description

[0022] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings: Figure 1 This is a schematic diagram of the acousto-optic circuit according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the modulation circuit of the hydrodynamic sensor according to an embodiment of the present invention; Figure 3 This is a peak pulse signal diagram according to an embodiment of the present invention; Figure 4 This is a peak value diagram of the output pulse signal with a relatively high flow rate according to an embodiment of the present invention; Figure 5 This is a peak diagram of the output pulse signal with a slower flow rate according to an embodiment of the present invention; Figure 6 This is a schematic diagram of the system structure according to an embodiment of the present invention. Detailed Implementation

[0023] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0024] It should be noted that the steps shown in the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions, and although a logical order is shown in the flowchart, in some cases the steps shown or described may be executed in a different order than that shown here.

[0025] Example 1 like Figure 6 As shown, this embodiment provides a water dynamics information detection system based on laser intensity modulation, including: The signal sensing and modulation transmission module, the optical signal receiving and conversion module, and the data acquisition and processing module are connected in sequence. The signal sensing and modulation transmission module is used to sense water dynamic parameters and generate corresponding electrical signals, thereby modulating the output light intensity of the laser transmitter so that the intensity of the output laser carries water dynamic information. The optical signal receiving and conversion module is used to receive the modulated laser signal and convert it back into an electrical signal; The data acquisition and processing module is used to acquire, process, and analyze the electrical signals to extract water dynamics information.

[0026] The feasible signal sensing and modulation transmission module includes a hydrodynamic sensor, a signal amplification circuit, and a laser transmitter; the hydrodynamic sensor is used to sense hydrodynamic parameters and output raw electrical signals; the input terminal of the signal amplification circuit is connected to the output terminal of the hydrodynamic sensor and is used to amplify the raw electrical signals; the driving terminal of the laser transmitter is connected to the output terminal of the signal amplification circuit, and its output light intensity is controlled by the amplified electrical signals.

[0027] Furthermore, in the signal sensing and modulation transmission module, the water dynamics sensor is a Hall effect flow velocity sensor.

[0028] Furthermore, in the signal sensing and modulation transmission module, the signal amplification circuit includes a first amplification unit and a second control unit; the first amplification unit is used to receive and initially amplify the electrical signal from the sensor; the second control unit controls the magnitude of the current flowing through the laser transmitter according to the output signal of the first amplification unit.

[0029] In practice, the optical signal receiving and conversion module includes a silicon-based photoelectric conversion unit and a signal conditioning unit; the silicon-based photoelectric conversion unit is used to convert the received light intensity change into current or voltage change; the signal conditioning unit is connected to the silicon-based photoelectric conversion unit and is used to amplify and condition the converted electrical signal.

[0030] Furthermore, in the optical signal receiving and conversion module, the signal conditioning unit is a digital power amplifier board based on a Class D amplifier chip.

[0031] As a specific implementation method, the laser modulation in this embodiment adopts intensity modulation. Intensity modulation is essentially laser oscillation in which the intensity (light intensity) of the optical carrier changes according to the modulation signal. The electrical signal transmitted at the transmitting end is used to adjust the intensity of the optical signal to achieve information transmission. The advantage of using intensity modulation is that the receiver (detector) can directly respond to the received light intensity, thereby interpreting the original electrical signal more directly and efficiently.

[0032] Lasers can be classified in many ways, including solid-state, gas, liquid, semiconductor, dye, and fiber lasers. Semiconductor lasers use semiconductor materials as the working medium. Electrons and holes are injected into the active region by a forward current. During injection, electrons and holes recombine, releasing energy as photons. Amplification and enhancement of the laser beam are achieved through a resonant cavity and optical feedback mechanism. In this way, semiconductor lasers can generate high-brightness, high-monochromaticity, and highly directional laser beams. Furthermore, these lasers are small in size, lightweight, long-life, and simple in structure, and are widely used in optical communication, optical storage, laser printing, and other fields. This embodiment uses such a semiconductor laser head, which consists of a light-emitting diode, a focusing lens, and an adjustable sleeve. Its relevant operating parameters are shown in Table 1.

[0033] Table 1 Laser modulation uses a laser as a transmission carrier (i.e., a carrier signal). By controlling one or more parameters (such as amplitude, frequency, or phase) of the carrier signal (laser), the information of the input signal (also called the baseband signal) is loaded onto the carrier signal, forming a modulated signal for transmission. Because laser light has excellent directionality, high brightness, and monochromaticity, it possesses excellent temporal and spatial coherence, similar to radio waves, making it easy to modulate. Furthermore, due to its extremely high frequency, laser light can carry a large amount of information during transmission. In addition, the small divergence angle of the laser beam allows for highly concentrated light energy, enabling signal stability over long distances and facilitating secure transmission due to its high focus. Demodulation, on the other hand, is the reverse process of modulation and a crucial step at the receiving end. In the receiving section, the demodulator's main task is to accurately recover the original information from the modulated laser signal. Modulation and demodulation are inseparable concepts. Modulation allows information to be transmitted through the channel, while demodulation ensures that the receiving end can correctly recover the original information.

[0034] Furthermore, based on the relative relationship between the modulator and the laser, laser modulation can generally be classified into internal modulation and external modulation.

[0035] Internal modulation: Internal modulation occurs during laser formation, meaning modulation is achieved within the laser itself. This is accomplished by adjusting a key parameter of the laser oscillation to influence the laser's output characteristics, thus achieving modulation. There are two main methods: (1) Directly control the pump source of the laser and achieve precise modulation of the laser output intensity and presence or absence by precisely controlling the power supply.

[0036] A modulation element is placed inside the resonant cavity, and the physical characteristics of the modulation element are controlled by a signal to change the parameters of the resonant cavity, thereby precisely affecting the output characteristics of the laser.

[0037] External modulation: External modulation is a technique that separates the laser generation and modulation processes. Specifically, the modulation process does not occur during the laser generation stage, but rather after laser generation, a modulator is placed in the optical path outside the laser resonant cavity. When a modulation signal is applied to the modulator, certain physical characteristics of the modulator change accordingly. As the laser passes through it, the laser's optical parameters (such as intensity and frequency) change according to the characteristics of the modulation signal, thus carrying the information to be transmitted. Based on the modulator's working mechanism, external modulation can be classified into electro-optic modulation, acousto-optic modulation, magneto-optic modulation, and direct modulation. This embodiment uses intensity modulation, a specific application of the direct modulation principle within external modulation. In direct modulation, this embodiment directly uses the changing electrical signal sensed by the sensor to modulate the driving current of the semiconductor laser or light-emitting diode. In this way, the intensity of the output light changes accordingly with the change in the electrical signal, thereby achieving optical signal modulation. Depending on the modulation signal, direct modulation is also divided into the following two methods: (1) TTL modulation in direct modulation: By adding a TTL digital signal to the laser power supply, the on / off state of the laser drive current can be controlled, thereby controlling the laser output frequency.

[0038] (2) Analog modulation in direct modulation: The laser's drive current is directly adjusted based on changes in the analog signal. When the voltage or amplitude of the analog signal changes, the laser's drive current also changes accordingly, resulting in a change in the output optical power. This embodiment uses a sensor to generate analog signals, and these signals can be easily transmitted and processed through analog modulation. Furthermore, because of its relatively simple structure, ease of implementation, direct and efficient modulation process, and low cost, this modulation method is chosen for this embodiment.

[0039] The main function of a feasible signal amplification circuit is to enhance the weak electrical signals generated by the acoustic signals in the acousto-optic circuit or the hydrodynamic information sensed by the hydrodynamic sensor, increasing the signal amplitude or power for easier transmission. The amplified signal is then transmitted to the laser, modulated, and emitted. To achieve this, the circuit typically employs several key components, including: BC547 transistor: The BC547 transistor is an NPN bipolar junction transistor (BJT). It consists of three terminals: emitter (E), collector (C), and base (B). Current flows from the emitter terminal, through the base to control the transistor's bias, and then to the collector terminal. It can be used in various circuits, including amplifier circuits. In amplifier circuits, the BC547 transistor can be used as a signal amplifier or a switch. Its operating principle is that when an input voltage is applied to the base terminal, a certain amount of current begins to flow from the base terminal to the emitter terminal, controlling the current at the collector terminal. The voltage between the base and emitter terminals (…) The voltage is negative at the emitter terminal and positive at the base terminal, used in its NPN structure. The voltage between the collector and base (…) The base is negative, and the collector terminal is positive. The voltage between the collector and emitter is ( ) The emitter terminal is negative, and the collector terminal is positive.

[0040] A basic amplifier circuit can be built using the BC547 transistor, where the signal input is to the base and the output is taken from the collector. Due to its relatively small gain, it is usually cascaded with other amplifiers. The typical gain of the BC547 is 200, meaning that a 1 mA change in base current will result in a 200 mA change in collector current. However, this value may vary depending on circuit conditions. When using the BC547 for amplification, it is important to maintain circuit stability. This can be achieved by adding negative feedback circuitry or using a stable bias circuit.

[0041] C945 transistor: The C945 transistor is a low-power NPN transistor, a general-purpose transistor packaged in a TO-92 package. The C945 transistor can withstand a maximum voltage of 50V, a maximum current of 150mA, and a maximum power limit of 625mW. These parameters ensure stable and reliable operation in a variety of circuit applications. The C945 transistor operates by controlling the collector current through the base current. When the base current is zero, the transistor is off; when the base current is positive, the transistor is in an amplifying / conducting state. This operating principle allows the C945 transistor to be used as a current amplifier or switch. The C945 transistor has good DC current gain and low noise, making it ideal for use in audio preamplifiers and audio amplifier circuit stages, or for amplifying other signals in electronic circuits. Most transistors have a saturation voltage of 0.6V, but the C945 transistor only has 0.3V. Therefore, it performs well in low-voltage circuits or any circuit where a low base voltage is available and other transistors are not saturated. It can also be used in RF circuits below 200MHz. Moreover, due to its simple structure, stable performance, low price, good DC current gain, and low noise, the C945 can be used in various circuits, such as amplification, switching, and voltage regulation circuits.

[0042] Sound sensor: A sound sensor (also called a microphone, megaphone, or transducer) is an energy conversion device that converts sound signals into electrical signals. It is the opposite of a loudspeaker (which converts electrical signals into sound signals). The two are the two terminals of a sound device: the sound sensor is the input, and the loudspeaker is the output. Inside the sound sensor is a capacitor consisting of a diaphragm, spacers, and plates. When the diaphragm is subjected to sound pressure, it vibrates, changing the distance between the diaphragm and the plates. This changes the distance between the two plates of the capacitor, generating a voltage change, thus completing the conversion from sound signal to electrical signal.

[0043] Based on their working principle, sound sensors are currently mainly classified into four types on the market: dynamic, condenser, electret, and silicon microphones. This embodiment uses an electret sound sensor, which is characterized by its small size, simple structure, good electroacoustic performance, and low price. Electret microphones use electret materials that can retain a permanent charge, eliminating the need for power to the capacitor (unless the electret microphone has a built-in amplifier circuit, in which case power is required). They are widely used in wireless microphones and voice-controlled circuits, and are among the most frequently used types of condenser microphones.

[0044] Hall effect flow sensor: A Hall effect flow sensor is a widely used sensor for measuring flow rate and velocity. Its structure mainly includes a copper valve body, a water flow rotor assembly, a flow stabilizing assembly, and a Hall element. It utilizes the Hall effect to measure magnetic physical quantities. The Hall element plays a crucial role in the sensor's measurement of water flow velocity. When water flows through the sensor, it affects the magnetic field within the sensor, causing a change in the output voltage of the Hall element. This change is achieved through the Hall effect; that is, when current flows through the Hall element and is placed in a magnetic field, a potential difference is generated in a direction perpendicular to both the current and the magnetic field. This potential difference is the Hall voltage. By measuring and analyzing the output voltage of the Hall element, the corresponding water flow velocity value can be obtained.

[0045] In simple terms, the principle of a Hall effect flow sensor is to connect a load resistor in series with the positive terminal of the Hall element and apply a 5V DC voltage, ensuring that the direction of current flow is perpendicular to the direction of the magnetic field. When water flows into the turbine switch housing and drives the magnetic rotor to rotate, the rotor generates a rotating magnetic field with different magnetic poles. As the rotor rotates, different magnetic poles approach the Hall element, causing the Hall element to conduct. When the rotor moves away, the Hall element deactivates, cutting magnetic induction lines and generating high and low pulse levels. The Hall element outputs a corresponding pulse signal, which is fed back to the signal amplification circuit. After amplification, the signal is modulated and transmitted by a laser carrying the signal information. Since the frequency of the Hall element's output pulse signal is proportional to the speed of the magnetic rotor, and the rotor speed is proportional to the water flow, the corresponding water flow rate can be determined by collecting, processing, and analyzing the data at the receiving end.

[0046] The Hall effect flow sensor used in this embodiment has advantages such as rapid response, long service life, quick action, safety and reliability, and convenient connection. It requires a 5V to 18V DC power supply. Besides measuring water flow, the sensor can also detect the flow rate and volume of other liquids similar to water, such as measuring milk flow in the dairy industry.

[0047] Amplifier circuit: This embodiment first utilizes a sound sensor to build an acousto-optic amplification circuit to test whether the laser can be successfully modulated. Subsequently, following the same principle, an amplification circuit for modulating the laser signal using water flow velocity was built. The water flow velocity sensor detects the dynamic signal of the water body, thereby modulating the control circuit of the laser and thus modulating the power output of the laser.

[0048] The schematic diagram of the signal amplifier circuit is as follows: Figures 1-2This circuit is an amplifier circuit based on two transistors, BC547 and C945, primarily used to amplify signals acquired from a sound sensor / hydrodynamic sensor to modulate laser signals. The BC547 controls the switching state of the laser. The C945 amplifies the signal from the hydrodynamic sensor. A 100kΩ resistor R1 biases the BC547. A 1MΩ resistor R2 provides feedback and stabilizes the circuit. A 10kΩ resistor R3 biases the C945. A 10µF capacitor couples the signal and filters it. The hydrodynamic sensor and sound sensor sense the dynamic and acoustic signals of the water, respectively, and convert them into electrical signals input to the circuit. The laser, as the output device, has its output state controlled by the BC547.

[0049] The circuit operates by inputting the sensor's electrical signal to the base of C945. R3 provides bias current to the C945 base, ensuring it operates in the amplification region. C945 amplifies the sensor signal and outputs the amplified signal through its collector. The circuit consisting of a 10µF capacitor and R2 is used for signal filtering and stabilization, preventing high-frequency noise from affecting circuit stability. The amplified signal is transmitted to the base of BC547 through R1. BC547 acts as a switching device, controlling the laser's switching state based on the amplified signal input to its base. The magnitude of the BC547 base current determines the laser's intensity and on / off state, thus achieving a modulation effect. The overall circuit design ensures that the signal acquired from the hydrodynamic sensor / sound sensor can effectively control the laser's output, making it suitable for detecting changes in the corresponding signal.

[0050] Signal receiving circuit: A silicon-based photovoltaic (PV) converter, also known as a silicon solar panel or photovoltaic panel, is a device that converts energy from solar energy or other light energy into electrical energy. It mainly consists of solar cells (also called photovoltaic cells), a glass cover layer, a backsheet, a frame, and a junction box. The solar cells are the core component of the silicon-based PV converter and are typically made of silicon, either monocrystalline or polycrystalline. Monocrystalline silicon cells are more efficient but also more expensive, while polycrystalline silicon cells are less expensive but slightly less efficient. This embodiment uses a silicon-based PV converter made of lower-cost polycrystalline silicon cells. The glass cover layer is transparent and durable glass that covers the solar cells, protecting them from environmental damage while allowing sunlight to pass through. The backsheet, located on the back of the solar cells, is typically made of weather-resistant material, providing additional protection and preventing moisture and dampness from penetrating. The junction box is used to connect cables to transmit the electrical energy generated by the silicon-based PV converter.

[0051] The working principle of a polycrystalline silicon-based photoelectric converter is primarily based on the photovoltaic effect, the phenomenon of directly converting light energy into electrical energy. First, when light shines on the converter, it is absorbed by the photosensitive material on the solar cell. The absorbed light energy excites electrons in the material to form electron-hole pairs. Under the influence of the electric field generated by the PN structure inside the converter, these electrons and holes begin to drift: electrons move towards the N-region, while holes move towards the P-region. This movement of electrons and holes generates a current inside the converter, which is the principle of photoelectric conversion. Finally, the current is collected through an internal metal wire mesh and output to an external circuit for transmission or storage. The entire process realizes the conversion of optical signals (such as laser signals carrying modulation information) into electrical signals. This electrical signal can then be received and processed by a signal receiving system for subsequent data processing and analysis.

[0052] Digital amplifier board: A digital power amplifier is an amplifier characterized by low distortion, low noise, and a wide dynamic range. The basic circuit of a digital power amplifier is the already existing Class D amplifier (also known as a Class D amplifier). The working principle of a digital power amplifier is to first convert the input analog signal into a digital signal, then process and amplify it through a digital signal processor (DSP) or specific digital processing circuitry. Finally, the amplified digital signal is converted back into an analog signal for output.

[0053] This embodiment uses the TPA3118 digital amplifier board, a high-efficiency digital audio amplifier module based on the Texas Instruments TPA3118 chip. The TPA3118 employs Class D amplifier technology, featuring high efficiency (greater than 90%) and low power consumption. It provides high-quality audio output while reducing overall system power consumption. This chip exhibits low distortion and low noise during audio processing, ensuring the purity and clarity of the audio signal, and supports a wide power supply voltage range (4.5V to 26V DC) to adapt to different power supply environments. It supports multiple audio input interfaces, including I2S, PCM, and TDM, providing flexible audio input options. It has comprehensive protection functions, including overheat protection, overload protection, and short-circuit protection, effectively protecting the chip and audio system from damage. The maximum output power is 8 watts per channel (4Ω load), and the maximum peak output current is 4A. At maximum output power, the distortion is less than 0.03%, ensuring signal accuracy. With a frequency response range of 20 Hz to 20 kHz and a response time of 0.01 seconds, it ensures signal integrity and dynamic range. A signal-to-noise ratio greater than 95 dB provides high-quality signal output. The operating temperature range is -40℃ to 85℃, enabling it to adapt to various working environments.

[0054] The signal receiving circuit, composed of a silicon-based photoelectric converter and a TPA3118 digital power amplifier board, has low cost, simple and clear structure, and is easy to build and maintain. The silicon photoelectric sensor has the characteristics of high sensitivity and fast response, which can accurately capture light signals and convert them into electrical signals, resulting in good signal reception.

[0055] In summary, this embodiment, based on the fundamental principle of laser intensity modulation, designs a signal amplification circuit to acquire signals from a sound sensor / hydrodynamic sensor and amplify them to modulate the laser signal, thereby improving the reliability and accuracy of signal transmission. Simultaneously, a matching simple signal receiving circuit is designed to receive the intensity-modulated laser signal and restore it to an electrical signal, realizing information transmission based on laser intensity modulation.

[0056] In practice, the data acquisition and processing module includes a data acquisition unit and a data processing unit; the data acquisition unit is used to acquire electrical signals at a preset sampling rate; the data processing unit is used to display the waveforms and store the acquired electrical signals, and to calculate the hydrodynamic parameters by analyzing the signal characteristics.

[0057] Furthermore, in the data acquisition and processing module, the data processing unit is implemented by running a graphical programming software platform, which is configured to create data acquisition tasks, configure sampling parameters, and realize data visualization and storage.

[0058] As a specific implementation method, this embodiment utilizes LabVIEW software and a data acquisition card in the data processing and analysis section. LabVIEW, as a standard data acquisition, processing, and instrument control software, can easily and quickly build functions such as data acquisition, data processing, and interface development. By acquiring data through the data acquisition card and combining it with LabVIEW to obtain and save the signal data, a curve showing the change of time with the laser pulse signal can be obtained. From this, the corresponding calculation formula can be derived, realizing the detection of water dynamics information.

[0059] LabVIEW is a graphical programming language and development environment developed by National Instruments (NI). It not only provides a graphical programming language but also builds a comprehensive and powerful development environment. Utilizing a dataflow programming model, it greatly simplifies operations in real-time data acquisition, analysis, control, and simulation. Through an intuitive graphical interface, users can easily perform various complex tasks. Furthermore, LabVIEW boasts excellent compatibility, supporting multiple hardware platforms and operating systems, ensuring seamless integration with various instruments and devices for efficient data exchange and communication.

[0060] LabVIEW is an integrated development environment (IDE) characterized by its unique graphical programming language (G language). Users can build programs by dragging and connecting graphical elements (called VIs, or virtual instruments). It is widely used in various fields such as automation control, testing, and measurement. Through the graphical interface, users can intuitively build and debug complex systems, thereby greatly improving work efficiency and accuracy.

[0061] LabVIEW, with its wide range of applications, has successfully spanned multiple fields, including automated testing, signal processing, machine vision, and data acquisition. To meet the needs of these diverse fields, LabVIEW includes a variety of powerful functions and toolboxes, providing robust support for users. Furthermore, LabVIEW integrates data storage and management, communication protocols, real-time operating systems, and web interaction, enabling it to perform powerfully in various complex application scenarios. At the same time, to help users better learn and use LabVIEW, NI provides abundant training resources and technical support, ensuring that users can fully utilize LabVIEW's functional advantages to achieve efficient project development and research.

[0062] In this embodiment, the LabVIEW version used is 2023 Q1 (32-bit), and the added toolkit is NI-DAQmx.

[0063] DAQmx: DAQmx is a core component of a data acquisition software and hardware solution developed by National Instruments (NI). DAQmx provides a set of APIs for controlling NI's data acquisition cards, facilitating the implementation of analog input / output, digital input / output, and counter input / output functions. It is used for measuring, controlling, and monitoring real-time data. The DAQmx API can be called in LabVIEW, LabVIEW SignalExpress, LabWindows / CVI, MeasurementStudio, .NET, and ANSI C, provided that the DAQmx driver is installed or imported first. The specific installation steps are as follows: Open NI Package Manager, select "Browse Products", and enter DAQmx in the search box.

[0064] Choose to install "NI-DAQmx", and the version should ideally match the LabVIEW version.

[0065] Open a VI, right-click in the block diagram, click Functions -> Measurement I / O. If you can see the "DAQmx Data Acquisition" control panel, the installation is successful.

[0066] DAQmx Control Panel: DAQmx primarily involves the hardware operation of data acquisition cards and the interaction between software and hardware. DAQmx channels are the interaction channels between the acquisition card and external signals; one channel represents one external signal. When no NI acquisition card is available, a virtual device can be created in DAQmx to complete programming tasks. When the NI acquisition card is connected to the computer, DAQmx detects the device, and the corresponding physical channels on the acquisition card can be used in the program. The hardware FIFO on the data acquisition card is used to store raw data received from the device or sensor. This FIFO is a hardware-level buffer, storing data in a first-in, first-out (FIFO) manner. Within the DAQmx data acquisition control, the DAQmx timing function determines the speed at which data is transmitted from the device or sensor to the hardware FIFO on the data acquisition card. It is a polymorphic VI used to control the amount and speed of data acquired from the device. The sampling rate determines the speed at which data is acquired and placed into the hardware FIFO; it must be a divisor of the time base, meaning the sampling rate is a division value of the time base signal. The PC buffer is an area in computer memory allocated for DAQmx tasks to store data transferred from the hardware FIFO. The DAQmx read function determines the data transfer from the PC buffer to the software application. Data transfer from the hardware FIFO to the PC buffer can be performed through different mechanisms, such as DMA (Direct Memory Access), interrupt requests, programmable I / O, or USB Bulk. These mechanisms determine how the PC buffer reads data from the hardware FIFO. DAQmx achieves accurate and efficient data acquisition from the device to the software application through components such as the hardware FIFO, DAQmx timer functions, the PC buffer, and DAQmx read functions, as well as data transfer and triggering mechanisms.

[0067] Data acquisition card: A data acquisition card is a computer expansion card used to implement data acquisition functions. It can connect to a computer via USB, PXI, PCI, Ethernet, various wireless networks, etc., to automatically acquire the analog or digital signals being measured from the device and send them to the host computer for analysis and processing. The basic principle of a data acquisition card is the conversion of analog signals into digital signals, mainly including signal acquisition, signal conversion, and data transmission. When an external signal enters the data acquisition card, it first undergoes preprocessing such as filtering, amplification, and impedance adjustment through an analog circuit. Then, it is sampled one by one to convert the analog signal into a digital signal. After conversion, the digital signal is stored in the data acquisition card's memory and can be read, processed, and analyzed by a computer. Based on the different signals processed, cards can be classified as analog input cards (A / D cards), analog output cards (D / A cards), digital input cards, digital output cards, pulse input cards, multi-function cards, etc.

[0068] This embodiment uses the NI USB-6009 data acquisition card, a low-cost, multi-functional DAQ device. It primarily consists of a Silicon Labs C8051F320 MCU (an enhanced 51-core), an ADC, and a DAC. The NI USB-6009 data acquisition card provides analog I / O, digital I / O, and a 32-bit counter. The USB-6009 meets the needs of various applications, from simple data logging to portable measurements and university laboratory experiments. Its lightweight mechanical casing design, combined with the convenience of bus power supply, makes the USB-6009 an easy-to-carry and use data acquisition tool. Sensor and signal connectivity is crucial for data acquisition, and the USB-6009 provides a simple and quick connection method via a screw-in terminal interface. Furthermore, the included NI-DAQmx driver and configuration utility further simplify the device configuration and measurement process, improving work efficiency. The data acquisition card features 8 AI channels (supporting synchronous scan mode), 2 AO channels, and 12 digital input / output (DIO) channels, providing users with flexible and diverse data acquisition options. Simultaneously, its built-in 32-bit counter with a full-speed USB interface ensures high-speed data transmission and processing. Regarding sampling resolution, the USB-6009 offers a choice between differential 14-bit and single-ended 13-bit to meet different precision requirements. Its high sampling rate of up to 48 kS / s guarantees real-time data accuracy.

[0069] The LabVIEW and NI-DAQmx software used in this embodiment are commonly used data acquisition and processing tools in the prior art. They are merely exemplary means of implementing the present invention and are not essential components of the present invention. Those skilled in the art can also use other equivalent software or hardware platforms to achieve the same function.

[0070] The feasible process for testing flow rate sensor-modulated laser circuits includes: Under laboratory conditions, this embodiment connects a water flow velocity sensor to a simple water circulation machine consisting of a water pump and water pipes. Following the same principle as a laser-modulated sound information transmission system, the water flow velocity sensor detects the water flow velocity signal, which is then used to modulate the laser's control circuit, thereby modulating the laser's power output. On the other hand, a silicon-based photoelectric converter receives the laser light intensity, and data is acquired and processed using a data acquisition card and LabVIEW platform to obtain a curve showing the change in time over time with the laser pulse signal. This allows for the derivation of the corresponding calculation formula for the detected water dynamics information. The water pump has adjustable flow rates; in this experiment, the highest flow rate was used for signal transmission, reception, and acquisition. During operation, external light sources such as lights were turned off, curtains were drawn, and a dark environment was chosen to minimize interference from the external environment. Furthermore, to ensure data reliability and generalizability, after the water pump stabilized its output flow, this embodiment repeatedly collected three sets of data under the same conditions. Each set had 1000 samples per channel and a sampling rate of 1000, and 15 seconds of water flow velocity pulse signal data under the same conditions were saved for detailed analysis and processing. Subsequently, the saved data was imported into Origin, a software with powerful data processing and analysis capabilities, and the changes in the pulse signal were observed. It can be seen that as the water flows steadily at a certain flow rate, a regular pulse signal is output, which lays the theoretical foundation for the subsequent data processing and analysis in this embodiment.

[0071] Furthermore, this embodiment requires a reference for calibration, based on the flow pulse characteristic formula of the water flow velocity sensor. f = 6.6 Q ( f The pulse frequency, Q (The water flow rate is given by the laser pulse.) By calculating the ratio of the laser pulse to the flow rate pulse, the linear coefficient between the water flow rate and the laser pulse signal can be obtained, thus revealing the relationship between the laser pulse and the water flow rate. In this embodiment, a simple and convenient Arduino microcontroller development board connected to an LCD display is used to display the measured water flow rate data in real time as the standard for water flow rate. With all experimental conditions remaining constant, the water flow rate was measured to be approximately 11 L / min when the water flow from the water circulator stabilized.

[0072] Based on the laser pulse image modulated by the obtained water flow velocity signal, this embodiment uses Origin peak finding to locate the peak value of the pulse signal and analyzes the peak-to-peak value, such as... Figure 3As shown in the figure. Analysis revealed that the time intervals between the positive and negative peaks of the laser pulse signal are slightly different from those between the negative and positive peaks, which is speculated to be due to the influence of the output duty cycle. However, the time intervals between the positive and negative peaks are almost the same, indicating that the period and frequency of the output laser pulse signal are relatively stable, and the corresponding relationship can be calculated.

[0073] In this embodiment, three sets of 15-second pulse signal data were obtained. Since the time intervals between positive and negative peaks are almost the same, positive peaks are used for calculation in this embodiment. The average time interval between adjacent positive and negative peak signals in each set of data is calculated, and the corresponding pulse frequency is also calculated. Table 2 shows the analysis results of the positive and negative peak signals.

[0074] Table 2 After calculating the relevant data of the pulse signal, the flow pulse characteristic formula is used. f = 6.6 Q Substitute Q =11 (the measured true value of water velocity) can be used to calculate the frequency. f The average value of the three sets of frequencies in the table is then used to determine the linearity coefficient between the laser pulse signal and the water flow rate.

[0075] After obtaining the calculation formula, this embodiment directly connects the water pipe to the faucet and opens the faucet to its maximum to simulate a turbulent water flow environment. The water pump is then switched to a lower setting to simulate a gentle water flow environment. An Arduino microcontroller is used to measure the actual flow rate, which is then compared with the calculated result to verify the accuracy of the formula and analyze the error. Following the same procedure, in a dark environment, after the water pump has stabilized its output, this embodiment repeatedly collects three sets of data under both fast and slow flow rate conditions. Each set is configured with 1000 samples per channel and a sampling rate of 1000, and 15 seconds of water flow rate pulse signal data under the same conditions are saved. Using the above method, the positive and negative peak time intervals are calculated, and the frequency is derived and substituted into the obtained calculation formula. f = 0.25Q, to obtain the calculated flow velocity value, and then compare it with the actual flow velocity value. Wherein, Figure 4 The peak value diagram of the output pulse signal is for a faster flow rate. Figure 5 The peak value of the output pulse signal is shown for a slower flow rate.

[0076] According to the formula, when the water velocity is relatively high... f = 0.25Q, the calculated water velocity is 13L / min, the actual measured water velocity is 14.3L / min, the error is about 9%; when the water velocity is slower, the calculated water velocity is 8L / min, the actual measured water velocity is 6.8L / min, the error is about 17%.

[0077] This embodiment tests the laser modulation circuit of the flow velocity sensor. An Arduino microcontroller development board is used as a reference for calibration. Images of laser pulse signals changing over time are acquired, data analysis and calculation are performed, corresponding relationships are found, and experimental verification and error analysis are conducted, thus realizing the preliminary detection of water dynamic information.

[0078] This embodiment designs a laser modulation signal amplification and reception system, and also designs a signal acquisition system to collect the signal output from the receiving system. Specific work includes: Firstly, through research on the principle of laser modulation, a laser intensity modulation method—direct, efficient, and relatively simple to understand—is selected as the method for modulating the laser signal. Secondly, a sound signal modulated laser information transmission system is built, using sound signals to modulate the laser intensity. The modulated laser signal is received through a simple signal receiving circuit composed of a silicon-based photoelectric converter and a digital power amplifier board. The circuit is then tested and its feasibility analyzed. Thirdly, by deeply studying the working principle of a Hall effect water flow velocity sensor and combining it with laser intensity modulation technology, the water flow velocity sensor is used to sense water dynamics information, modulating the laser's control circuit, thereby modulating the laser's power output. The signal is received by the signal receiving circuit and collected using a data acquisition card. Utilizing the powerful data acquisition and processing capabilities of LabVIEW software, a corresponding program is written to display the collected data in the form of waveform charts, allowing for intuitive observation of changes in water flow velocity and enabling the acquisition and storage of relevant data. Finally, data processing and analysis yield an image of the laser pulse signal changing over time. By analyzing the characteristics of the flow pulse signal from the flow velocity sensor and obtaining its correspondence with the laser pulse, the characteristics of the laser pulse signal can be obtained, leading to relevant calculation formulas and enabling the detection of water dynamics information.

[0079] On the other hand, this embodiment also provides a method for detecting water dynamics information based on laser intensity modulation, which, based on the aforementioned system, includes: Hydrodynamic parameters are sensed by hydrodynamic sensors, and corresponding raw electrical signals are generated. The original electrical signal is amplified by a signal amplification circuit to obtain an amplified electrical signal, and the amplified electrical signal is used to modulate the driving current of the laser transmitter, so that the laser intensity output by the laser transmitter changes with the changes in the water dynamic parameters. A photoelectric converter is used to receive a modulated laser beam and convert it into a received electrical signal containing information about water dynamics. The received electrical signals are acquired through the data acquisition and processing module, and the water dynamic parameters are extracted by analyzing the modulation-related features in the received electrical signals.

[0080] Furthermore, the steps for extracting hydrodynamic parameters specifically include: Identify and calculate the periodic pulse frequency or time interval in the received electrical signal; Based on the inherent linear proportional relationship between the pulse frequency and the water flow velocity of the Hall effect flow sensor, the calculated pulse frequency is substituted into the linear proportional relationship to calculate the corresponding water flow velocity value, thereby obtaining the hydrodynamic parameters.

[0081] The above are merely preferred embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A water dynamics information detection system based on laser intensity modulation, characterized in that, include: The signal sensing and modulation transmission module, the optical signal receiving and conversion module, and the data acquisition and processing module are connected in sequence. The signal sensing and modulation transmission module is used to sense water dynamic parameters and generate corresponding electrical signals, thereby modulating the output light intensity of the laser transmitter so that the intensity of the output laser carries water dynamic information. The optical signal receiving and conversion module is used to receive the modulated laser signal and convert it back into an electrical signal; The data acquisition and processing module is used to acquire, process, and analyze the electrical signals to extract water dynamics information.

2. The system according to claim 1, characterized in that, The signal sensing and modulation transmission module includes a hydrodynamic sensor, a signal amplification circuit, and a laser transmitter. The hydrodynamic sensor is used to sense hydrodynamic parameters and output raw electrical signals; The input terminal of the signal amplification circuit is connected to the output terminal of the hydrodynamic sensor to amplify the original electrical signal; The driving end of the laser emitter is connected to the output end of the signal amplification circuit, and its output light intensity is controlled by the amplified electrical signal.

3. The system according to claim 2, characterized in that, In the signal sensing and modulation transmission module, the water dynamics sensor is a Hall effect flow velocity sensor.

4. The system according to claim 2, characterized in that, In the signal sensing and modulation transmission module, the signal amplification circuit includes a first amplification unit and a second control unit; The first amplification unit is used to receive and initially amplify the electrical signal from the sensor; The second control unit controls the magnitude of the current flowing through the laser emitter based on the output signal of the first amplification unit.

5. The system according to claim 1, characterized in that, The optical signal receiving and conversion module includes a silicon-based photoelectric conversion unit and a signal conditioning unit; The silicon-based photoelectric conversion unit is used to convert received light intensity changes into current or voltage changes. The signal conditioning unit is connected to the silicon-based photoelectric conversion unit and is used to amplify and condition the converted electrical signal.

6. The system according to claim 5, characterized in that, In the optical signal receiving and conversion module, the signal conditioning unit is a digital power amplifier board based on a Class D amplifier chip.

7. The system according to claim 1, characterized in that, The data acquisition and processing module includes a data acquisition unit and a data processing unit; The data acquisition unit is used to acquire electrical signals at a preset sampling rate; The data processing unit is used to display the waveforms and store the collected electrical signals, and to calculate the hydrodynamic parameters by analyzing the signal characteristics.

8. The system according to claim 7, characterized in that, In the data acquisition and processing module, the data processing unit is implemented by running a graphical programming software platform, which is configured to create data acquisition tasks, configure sampling parameters, and realize data visualization and storage.

9. A method for detecting hydrodynamic information based on laser intensity modulation, characterized in that, The system based on any one of claims 1-8 includes: Hydrodynamic parameters are sensed by hydrodynamic sensors, and corresponding raw electrical signals are generated. The original electrical signal is amplified by a signal amplification circuit to obtain an amplified electrical signal, and the amplified electrical signal is used to modulate the driving current of the laser emitter, so that the intensity of the laser light output by the laser emitter changes with the changes of the water dynamic parameters. A photoelectric converter is used to receive a modulated laser beam and convert it into a received electrical signal containing information about water dynamics. The received electrical signals are acquired through the data acquisition and processing module, and the water dynamic parameters are extracted by analyzing the modulation-related features in the received electrical signals.

10. The method according to claim 9, characterized in that, The steps for extracting hydrodynamic parameters specifically include: Identify and calculate the periodic pulse frequency or time interval in the received electrical signal; Based on the inherent linear proportional relationship between the pulse frequency and the water flow velocity of the Hall effect flow sensor, the calculated pulse frequency is substituted into the linear proportional relationship to calculate the corresponding water flow velocity value, thereby obtaining the hydrodynamic parameters.

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