Acoustic-magnetic sensing optical fiber composite system

Abstract

The utility model belongs to the technical field of optical fiber detection, and particularly relates to an acoustic-magnetic sensing optical fiber composite system which comprises a plurality of acoustic-magnetic sensing nodes, an optical fiber, a signal processing module and a light energy input module. The light energy input module is coupled with the optical fiber and is used for inputting light energy and transmitting the light energy to each acoustic-magnetic sensing node; each node comprises an optical splitter, an acoustic sensor, a magnetic sensor or an acoustic-magnetic simultaneous measurement sensor, a photocell connected with an optical fiber, a wavelength division multiplexer and a circuit. The optical splitter splits part of light energy from the optical fiber, and the photocell converts the light energy into electric energy for power supply; the acoustic sensor and the magnetic sensor or the acoustic-magnetic simultaneous measurement sensor are connected with the wavelength division multiplexer through a circuit, and the wavelength division multiplexer converts acoustic signals and magnetic signals into optical signals with different wavelengths and transmits the optical signals to the signal processing module through optical fibers. According to the invention, problems of limited detection capability, complex deployment and insufficient sensitivity and anti-interference capability are solved, integration of signal transmission and electric energy supply is realized, and detection precision and long-distance transmission stability are improved.

Description

TECHNICAL FIELD

[0001] The utility model relates to the field of optical fiber detection technology, more particularly to a kind of acoustic-magnetic sensing optical fiber composite system. BACKGROUND

[0002] In the field of underwater detection, acoustic characteristics are still widely considered as the main means of target detection due to their long propagation distance and good stability in seawater. Traditional underwater detection systems usually use a single type of sensor, such as acoustic sensors, magnetic sensors (e.g. Hall effect sensors, magnetoresistive sensors) or fluxgate sensors, which are used to receive acoustic signals or magnetic field signals respectively.

[0003] Although acoustic sensors and magnetic sensors each have unique detection capabilities, in practical applications, traditional systems relying on a single sensor still have the following main defects:

[0004] 1. Limited sensor detection capability: Traditional single sensor systems are difficult to comprehensively obtain multiple physical signals. Acoustic sensors mainly receive acoustic wave signals, while magnetic sensors are mainly used to detect changes in the magnetic field. This single detection method makes it difficult for the system to accurately locate and identify targets in complex underwater environments. For example, in complex seabed terrain with high background noise, the reflection and attenuation of acoustic signals often affect detection accuracy; while the magnetic signal is limited by sensor sensitivity and background magnetic field noise interference, making it difficult to detect weak magnetic field changes.

[0005] 2. Complex system deployment: In traditional systems, sensor nodes often require multiple components to work together, such as power systems, communication cables and optical fibers, etc. This multi-component integration mode makes the deployment of equipment in water extremely complex, especially in seabed environments, where the laying and maintenance of cables is costly and the failure rate increases. For example, in deep sea environments, cables are easily affected by ocean currents and terrain, and the laying process requires a lot of manpower and resources, and later maintenance is extremely difficult.

[0006] 3. Insufficient sensitivity and anti-interference ability: In the case of long-distance target detection or low signal strength, the sensitivity of traditional sensors (such as fluxgate sensors) is insufficient, making it difficult to accurately detect weak target signals. In addition, such sensors are easily affected by noise and electromagnetic interference in complex underwater environments, making it difficult to ensure the accuracy of the detection results.

[0007] 4. Low signal transmission efficiency: Traditional detection systems usually rely on electrical signals for signal transmission. In complex underwater environments, electrical signal transmission is easily affected by factors such as water flow, electromagnetic noise, etc., resulting in low signal transmission efficiency and reliability, limiting the overall detection performance of the system. For example, due to the high conductivity of seawater, electromagnetic signals are easily absorbed and attenuated by seawater during long-distance transmission, resulting in unsatisfactory transmission results.

[0008] 5. Difficulty in multi-sensor fusion: In existing technologies, although some multi-sensor combination systems have been proposed, due to differences in sensor types, signal processing methods and transmission methods, the efficiency and accuracy of data fusion are still low, and the accuracy of the fusion results is difficult to guarantee.

[0009] In order to solve these problems, a new detection system is needed that can detect acoustic and magnetic signals simultaneously, while improving sensitivity, signal processing capability and system deployment flexibility. Invention content

[0010] The utility model provides a kind of acoustic-magnetic sensing optical fiber composite system for the deficiency of prior art, realizes signal transmission and electrical energy supply by optical fiber, integrates multi-sensor, signal amplification, electro-optical conversion and wavelength division multiplexing, enhances detection accuracy and stability, ensures long-distance transmission and seamless coverage, improves target identification reliability.

[0011] To achieve the above technical purpose, the utility model will take the following technical scheme:

[0012] A kind of acoustic-magnetic sensing optical fiber composite system, including multiple acoustic-magnetic sensing nodes, optical fiber, signal processing module and light energy input module;The light energy input module is coupled with the optical fiber, for inputting light energy and transmitting to each acoustic-magnetic sensing node by optical fiber;Each acoustic-magnetic sensing node includes optical splitter, acoustic sensor and magnetic sensor or acoustic-magnetic simultaneous measurement sensor, photovoltaic cell connected with optical fiber, wavelength division multiplexer and corresponding circuit, optical splitter is used to at least split part of light energy from optical fiber, the photovoltaic cell receives the light energy and converts into electrical energy storage and provides power for each circuit in acoustic-magnetic sensing node;In each acoustic-magnetic sensing node, acoustic sensor and magnetic sensor or acoustic-magnetic simultaneous measurement sensor are connected with the wavelength division multiplexer by corresponding circuit, for obtaining external acoustic-magnetic signal;The wavelength division multiplexer is used to combine the light signals of different wavelengths generated by converting acoustic signal and magnetic signal and then transmit by optical fiber;The signal processing module is connected with the optical fiber, for receiving the light signal from the wavelength division multiplexer by optical fiber.

[0013] In a preferred implementation, the corresponding circuit within the acoustomagnetic sensing node further includes an amplification circuit and an electro-optical conversion circuit; the acoustic sensor and the magnetic sensor are connected to the wavelength division multiplexer in sequence through the amplification circuit and the electro-optical conversion circuit; the amplification circuit is used to perform impedance transformation and amplification on the acquired acoustomagnetic signal, and the electro-optical conversion circuit is used to perform electro-optical conversion on the acquired acoustomagnetic signal and convert the electrical signal into an optical signal.

[0014] In a preferred implementation, the acoustic sensor and the magnetic sensor are further embedded in optical fibers.

[0015] In a preferred implementation, the acousto-magnetic signal is further output as an optical signal through the electro-optical conversion circuit and the wavelength division multiplexer, and then transmitted through the optical fiber.

[0016] In a preferred implementation, the distance between two adjacent acoustic-magnetic sensing nodes further does not exceed the maximum detection distance of the acoustic sensor and the magnetic sensor.

[0017] In a preferred implementation, the signal processing module further includes a demultiplexer connected to an optical fiber, used to separate the acoustomagnetic input signal according to a selection signal.

[0018] In a preferred implementation, the signal processing module further includes a data processing center connected to the output of the demultiplexer for processing acousto-magnetic signal data.

[0019] In a preferred implementation, the optical energy input module further includes a high-power laser and an optical amplifier. The output end of the high-power laser is connected to the optical amplifier, and the output end of the optical amplifier is connected to the optical fiber. The high-power laser is used to provide power to the acoustomagnetic sensing node, and the optical amplifier is used to enhance the optical signal intensity.

[0020] In a preferred embodiment, the optical energy input module further includes an optical switch; the optical switch is disposed between the connection circuit of the high-power laser and the optical amplifier, and is used to control the input and output of optical energy.

[0021] In a preferred embodiment, the acoustic sensor is a piezoelectric underwater acoustic sensor, the magnetic sensor is a magnetoelectric weak magnetic sensor, and the amplification circuit is equipped with a charge amplifier.

[0022] The beneficial effects of this utility model are:

[0023] First, this invention introduces acoustomagnetic sensing nodes into an acoustomagnetic sensing fiber optic composite system. Combined with the collaborative design of an optical energy input module, a beam splitter, a photovoltaic cell, an acoustic sensor, a magnetic sensor or a simultaneous acoustomagnetic sensor, and a wavelength division multiplexer, it achieves synchronous detection and transmission of acoustic and magnetic signals. The system utilizes optical energy transmitted through optical fiber to power each node, avoiding the limitations of traditional power supply and improving the system's flexibility and durability. Furthermore, the combination of acoustic and magnetic sensors enables the system to integrate and sense multiple physical signals, and the wavelength division multiplexing technology combines optical signals of different wavelengths, reducing interference and loss during signal transmission and enhancing transmission efficiency and signal quality.

[0024] Secondly, in the preferred implementation, this utility model sets up an amplification circuit and an electro-optic conversion circuit in the acoustomagnetic sensing node, so that the signals acquired by the acoustic sensor and the magnetic sensor can be efficiently converted into electro-optic signals after impedance transformation and amplification, and the electrical signals are converted into optical signals and transmitted to the wavelength division multiplexer. This design not only improves the stability and efficiency of signal transmission, but also effectively reduces the signal attenuation and interference problems during transmission, thereby improving the detection accuracy and reliability of the system.

[0025] Third, in the preferred implementation, this utility model achieves efficient acquisition and direct conversion of acoustic and magnetic signals by embedding the acoustic sensor and magnetic sensor into the optical fiber respectively, avoiding the complex layout of multiple cables in traditional wiring, simplifying the wiring structure of the system. After converting the acoustic and magnetic signals into optical signals through the electro-optical conversion circuit and wavelength division multiplexer, they are transmitted uniformly through optical fiber, further optimizing the wiring scheme for signal transmission, extending the transmission distance, and reducing signal transmission loss and interference.

[0026] Fourth, in the preferred implementation, this utility model sets the distance between two adjacent acoustic and magnetic sensing nodes to not exceed the maximum detection distance of the acoustic and magnetic sensors, which can ensure seamless coverage of the entire system within the detection range, avoid blind spots in signal reception and data omissions, thereby improving the detection accuracy and continuity of underwater targets and ensuring comprehensive monitoring of the detection area.

[0027] Fifth, in the preferred implementation, the signal processing module of this utility model effectively separates the acoustic and magnetic input signals according to different wavelengths through a demultiplexer, ensuring independent transmission and processing of acoustic and magnetic signals, thereby avoiding signal interference and cross-influence; the data processing center further performs comprehensive analysis and processing on the separated signals, which can accurately extract target features, realize multi-dimensional information fusion, and improve the target recognition accuracy and detection reliability of the system.

[0028] Sixth, in the preferred implementation, the optical energy input module of this utility model provides stable power to the acoustomagnetic sensing node through a high-power laser, and combines it with an optical switch to achieve precise control of energy input and output, avoiding overload or failure. At the same time, it uses an optical amplifier to enhance the intensity of the optical signal, ensuring signal stability and reliability in long-distance transmission, thereby improving the system's energy supply efficiency and detection performance. Attached Figure Description

[0029] Fig. 1 This is a schematic diagram of an acoustomagnetic sensing fiber optic composite system according to an embodiment of this utility model.

[0030] Fig. 2 This is a schematic diagram of an acoustomagnetic sensing node according to an embodiment of the present invention. Detailed Implementation

[0031] To enable those skilled in the art to better understand the technical solutions of this application, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0032] The directional terms such as above, below, left, right, front, and back used in this application are based on the positional relationships shown in the attached drawings. Different attached drawings may result in different positional relationships, therefore they should not be interpreted as limitations on the scope of protection.

[0033] In this application, the terms "installation," "connection," "interlocking," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, an integral connection, a mechanical connection, an electrical connection, or a connection that allows communication between components. They can also refer to a direct connection or an indirect connection through an intermediate medium. They can refer to the internal connection of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in this application can be understood according to the specific circumstances.

[0034] As per the instruction manual Figs. 1-2This utility model describes an acoustomagnetic sensing fiber optic composite system, comprising multiple acoustomagnetic sensing nodes, optical fibers, a signal processing module, and a light energy input module. The light energy input module is connected to the optical fibers and amplifies the light energy, transmitting it through the fibers to each acoustomagnetic sensing node. Each acoustomagnetic sensing node is connected in parallel to the optical fibers. Each acoustomagnetic sensing node includes a beam splitter, an acoustic sensor and a magnetic sensor or an acoustomagnetic-magnetic co-sensor, a photovoltaic cell connected to the optical fiber, a wavelength division multiplexer, and corresponding circuitry. The beam splitter separates at least a portion of the light energy from the optical fiber. The photovoltaic cell receives the light energy, converts it into electrical energy for storage, and provides power to the circuitry within the acoustomagnetic sensing node. In each acoustomagnetic sensing node, the acoustic sensor and the magnetic sensor or the acoustomagnetic-magnetic co-sensor are connected to the wavelength division multiplexer through corresponding circuitry to acquire external acoustomagnetic signals. The wavelength division multiplexer combines the optical signals of different wavelengths generated by the acoustic and magnetic signals and transmits them through the optical fiber. The signal processing module is connected to the optical fibers and receives the optical signals from the wavelength division multiplexer through the optical fiber, performing signal decomposition and data processing. This system transmits optical signals and electrical energy simultaneously via optical fiber, achieving the integration of detection, transmission, and power supply of acousto-magnetic signals.

[0035] Specifically, the corresponding circuits within each acoustomagnetic sensing node include an amplifier circuit and an electro-optical conversion circuit. The acoustic and magnetic sensors are connected to the wavelength division multiplexer sequentially through the amplifier and electro-optical conversion circuits. The amplifier circuit performs impedance transformation and amplification on the acquired acoustomagnetic signals, while the electro-optical conversion circuit performs electro-optical conversion on the acquired acoustomagnetic signals, converting the electrical signals into optical signals. Photovoltaic cells are installed within each acoustomagnetic sensing node, positioned close to the amplifier and electro-optical conversion circuits to directly power these circuits, reducing transmission loss and ensuring circuit stability.

[0036] In traditional optoelectronic sensing systems, energy supply is often a bottleneck, especially in underwater environments requiring long-term continuous operation. To address this issue, the optical energy input module of this system includes a high-power laser, an optical switch, and an optical amplifier. The output of the high-power laser is connected to the optical amplifier via the optical switch, and the optical amplifier is connected to the optical fiber. The high-power laser provides sufficient optical energy to each acoustomagnetic sensing node. This energy is stored in photovoltaic cells within each node through photoelectric conversion, thus providing a stable power supply to the amplification circuit and electro-optical conversion circuit. This approach significantly improves the system's reliability in long-term operating environments. It should be noted that different types of lasers or light sources can be selected to provide energy in different application scenarios; for example, continuous wave lasers or pulsed lasers can be selected based on transmission distance and power requirements. The optical switch controls the input and output of optical energy, ensuring that the optical energy supply is adjusted as needed and providing emergency power-off protection in case of system overload or failure, improving system safety and the accuracy of energy management. The optical amplifier enhances the intensity of the optical signal transmitted from the optical fiber, ensuring signal stability during long-distance transmission. The optical energy transmitted through the optical fiber is amplified by the optical amplifier and then enters the photocells in each acoustomagnetic sensing node through the beam splitter. The photocells store the energy and output electrical energy stably to maintain the normal operation of each acoustomagnetic sensing node.

[0037] Traditional underwater detection systems typically rely on a single type of sensor (such as acoustic sensors, magnetic sensors, or fluxgate sensors). Acoustic sensors primarily rely on the propagation of sound waves in water; however, in actual detection, due to the complexity of the underwater environment, sound waves are easily interfered with by factors such as water flow, noise, and temperature changes, leading to signal attenuation and reduced accuracy. Magnetic sensors rely on changes in external magnetic fields for detection. While they can respond to ferromagnetic targets, their recognition capability is limited when the signal is weak or the magnetic field disturbance is large. Although fluxgate sensors have high sensitivity to weak magnetic field changes, their disadvantage is that they are easily affected by strong external magnetic fields or electromagnetic interference, leading to false alarms or reduced accuracy, and they are difficult to use alone to deal with complex targets in the underwater environment. This application proposes to combine acoustic and magnetic sensors to form a multi-sensor fusion node that simultaneously measures acoustic and magnetic information. Through joint detection and complementarity of acoustic and magnetic information, each sensor can leverage its own advantages: the acoustic sensor is used to capture the acoustic wave characteristics of underwater targets, such as rotational and vibration frequencies, while the magnetic sensor is used to sense the magnetic field characteristics of the target, such as metallic composition and magnetic features. The deployment of multiple acoustomagnetic sensing nodes, with flexible adjustments to sensor types and numbers based on detection needs, helps enhance adaptability and detection capabilities in complex underwater environments. The acoustomagnetic fusion detection method effectively reduces detection errors that may occur with a single sensor, improving the accuracy and detection range for underwater targets.

[0038] Furthermore, traditional signal transmission typically requires multiple optical fibers to transmit different types of signals separately. This increases the complexity of the transmission system and makes it susceptible to external interference, affecting signal quality. To address this issue, this application employs wavelength division multiplexing (WDM) technology, modulating acoustic and magnetic signals onto different optical wavelengths to achieve synchronous transmission of multiple signals within a single optical fiber. This method not only significantly reduces the number of optical fibers used and lowers the system's structural complexity but also mitigates interference and attenuation during signal transmission, ensuring the stability and reliability of long-distance transmission. Through this multi-sensor information fusion and optimized signal transmission scheme, the overall performance of the underwater detection system is effectively improved.

[0039] In this application, the acoustic and magnetic sensors are embedded in optical fibers, which more effectively utilizes the protection and transmission functions of the optical fibers and reduces external interference and losses. Different sensor installation positions can also be selected according to actual application requirements. For example, when high flexibility of the optical fiber is required, the sensors can be installed on the outer sheath of the fiber instead of being completely embedded within it. Furthermore, the type and number of acoustic and magnetic sensors can be adjusted according to the characteristics of the target being detected, such as using a high-precision microphone array to detect complex sound fields. The distance between two adjacent acoustic-magnetic sensing nodes does not exceed the maximum detection distance of the acoustic and magnetic sensors to ensure the detection coverage and sensitivity of the entire system and avoid signal reception blind spots and data loss. The amplifier circuit and electro-optic conversion circuit are powered by photovoltaic cells. The acoustic-magnetic signals are output as optical signals through the electro-optic conversion circuit and wavelength division multiplexer, and then transmitted through optical fibers.

[0040] Acoustic and magnetic sensors achieve joint detection through complementary signal timing, frequency, and characteristics. Specifically, the complementarity in signal timing and frequency manifests in the different response times of the acoustic and magnetic sensors. Acoustic sensors can quickly capture changes in the sound waves of underwater targets, while magnetic sensors can monitor continuous changes in the magnetic field generated by the target over a longer period. This temporal complementarity allows the system to effectively detect targets under different conditions, including rapid passage and slow movement. Acoustic sensors primarily detect low-frequency sound wave signals from 20Hz to 2kHz, while magnetic sensors primarily detect low-frequency magnetic field changes from 0.1Hz to 100Hz. By combining their frequency ranges, the system can more comprehensively capture the motion information of the detected object. The complementarity in signal characteristics is manifested in the fact that the sound wave signals detected by the acoustic sensor can reflect information such as the rotational frequency and vibration frequency of moving objects (e.g., the rotational frequency of a submarine propeller, the vibration frequency of a ship's hull). The magnetic field changes detected by the magnetic sensor can reflect the metallic composition and magnetic characteristics of the object (e.g., the metallic composition and magnetic characteristics of a submarine). By using acoustic and magnetic sensors, different information about the target's motion state and physical characteristics can be provided simultaneously. By comprehensively analyzing acoustic and magnetic field data, the data processing center can more accurately identify the target's type, location, and trajectory.

[0041] In this application, the acoustic sensor is a piezoelectric underwater acoustic sensor, and the magnetic sensor is a magnetoelectric weak magnetic sensor. The amplification circuit includes a charge amplifier, which can effectively process the low-intensity signals output by the acoustic and magnetic sensors, exhibiting high input impedance and low output impedance characteristics to ensure stable signal transmission. Different types of sensors can also be selected according to specific application requirements. For example, a high-sensitivity piezoelectric acoustic sensor or a Hall effect magnetic sensor can be used to improve detection performance. Furthermore, the wavelength division multiplexer design can be adjusted according to system scale and signal type to support a wider range of signal transmissions. For the photovoltaic power supply, other types of energy harvesting equipment, such as solar panels or thermoelectric converters, can be selected based on environmental conditions.

[0042] The signal processing module includes a demultiplexer connected to an optical fiber and a data processing center connected to the demultiplexer. The demultiplexer receives the optical signal multiplexed by the wavelength division multiplexer and separates it into individual acoustic and magnetic signals based on wavelength, ensuring that each signal can be processed and analyzed independently. The output of the demultiplexer is connected to the data processing center, where the separated signals are transmitted. The data processing center receives the acoustic and magnetic signals separated by the demultiplexer, performs signal analysis using data processing algorithms, and ultimately outputs the target detection results. Through multi-dimensional comprehensive analysis of these two signals via data processing, the location, type, and state of the target can be determined more accurately. Compared to traditional single-sensor detection, this application reduces environmental interference and improves detection reliability.

[0043] It should be noted that different types of demultiplexing techniques can be used in different application scenarios, such as frequency division, time division, or code division demultiplexing, to adapt to different signal processing needs. Furthermore, different processors and storage devices can be configured according to different data processing requirements to ensure the computing power and response speed of the processing center.

[0044] After the demultiplexer separates the acoustic and magnetic signals, data processing at the data processing center involves target identification based on these signals. Taking a submarine as an example, acoustic signal analysis extracts information such as the submarine's propeller spectral characteristics and noise patterns to determine the submarine's type and speed. Analysis of magnetic signal intensity variations and magnetic field disturbance patterns estimates the submarine's position and heading. By fusing and analyzing the acoustic and magnetic field signals and integrating the detection results from different sensors, errors that might arise from a single signal are eliminated, improving the accuracy and reliability of the identification process.

[0045] The working process of the acoustomagnetic sensing fiber optic composite system of this application is as follows:

[0046] The high-power laser in the optical energy input module controls the output of optical energy via an optical switch. The output of the optical amplifier is connected to an optical fiber, and the optical energy is transmitted to each acoustomagnetic sensing node through the optical fiber. Within each acoustomagnetic sensing node, the acoustic and magnetic sensors collect external acoustomagnetic signals. These weak signals undergo impedance transformation and signal amplification through an amplification circuit. The amplified acoustic and magnetic signals then enter an electro-optical conversion circuit, where they are modulated into optical signals of different wavelengths. The converted multiplexed optical signals are then multiplexed into a single optical fiber by a wavelength division multiplexer, forming a multiplexed optical signal, which is then transmitted over long distances through the optical fiber. The multiplexed optical signal is transmitted through the optical fiber to a demultiplexer in the signal processing module. The demultiplexer receives the optical signal from the optical fiber and separates the acoustic and magnetic signals into individual signals based on their wavelengths. The separated signals are then transmitted to the data processing center. The data processing center performs comprehensive analysis and processing on the acoustic and magnetic signals output from the demultiplexer, uses data algorithms to calculate the target type, location, and status, and outputs the target detection results.

[0047] Example 1

[0048] In underwater detection, the acoustomagnetic sensing fiber optic composite system of this application is used to monitor the position and activity of underwater targets such as submarines, unmanned underwater vehicles, and schools of fish. Taking submarine detection as an example, the acoustomagnetic sensing fiber optic composite system is used to detect the activity of submarines in the water. Through the joint detection of acoustomagnetic signals, the accuracy of identifying the submarine's position, course, and motion status is improved.

[0049] First, the configuration of the acoustic-magnetic sensing fiber optic composite system is determined: the acoustic sensor is a piezoelectric underwater acoustic sensor with a sensitivity of -160dB re 1V / μPa and an operating frequency range of 20Hz to 2kHz. The acoustic sensor can detect low-frequency acoustic signals generated by the submarine, such as those produced by propeller rotation and hull vibration. The magnetic sensor is a magnetoelectric type weak magnetic sensor with a sensitivity of 100μV / nT and an operating frequency range of 0.1Hz to 100Hz. The magnetic sensor can detect minute disturbances in the magnetic field during submarine navigation, especially the influence of the submarine's metallic hull on the Earth's magnetic field. The amplification circuit includes a charge amplifier with a voltage gain of 40dB and a bandwidth range of 20Hz to 5kHz, effectively amplifying the low-intensity signals from both the acoustic and magnetic sensors.

[0050] Detection Process: When a submarine enters the detection range of the acoustic-magnetic sensing node (typical detection distance of 200 meters), the acoustic signals and magnetic field disturbances caused by the submarine's propulsion system, hull vibration, and navigation attitude are detected separately. The piezoelectric underwater acoustic sensor captures the acoustic signals generated by the submarine's propeller rotation and hull vibration, with a sensitivity of -160dB re 1V / μPa, capable of detecting low-frequency sound waves from 20Hz to 2kHz, with a minimum detectable acoustic signal intensity of 30μPa. The magnetoelectric weak magnetic sensor detects minute magnetic field disturbances caused by the submarine's navigation, with a sensitivity of 100μV / nT, capable of detecting magnetic field changes on the order of 10nT (nantes) generated when the submarine passes. The amplification circuit includes a charge amplifier with a voltage gain of 40dB (amplification factor of 100x) and a signal bandwidth ranging from 20Hz to 5kHz. After amplification, the acoustic and magnetic signals are increased in strength to a level sufficient for subsequent electro-optical conversion. The amplified acoustic and magnetic signals are modulated into optical signals of different wavelengths: the acoustic signal is modulated at 1310nm, and the magnetic signal at 1550nm. These optical signals (1310nm and 1550nm) are combined using a wavelength division multiplexer and transmitted to the signal processing module. The fiber optic transmission distance can reach 50km, with a signal attenuation rate of less than 0.2dB / km. A demultiplexer efficiently separates the 1310nm acoustic signal and the 1550nm magnetic signal, achieving a signal separation accuracy of 99%. The data processing center performs comprehensive analysis on the separated acoustic and magnetic signals to calculate the submarine's specific position, direction of travel, and speed. The algorithm in the data processing center has an error accuracy within 1m and can update target information at a rate of 10Hz. Throughout the process, the laser power is 5W, and through photoelectric conversion, a photovoltaic cell provides a continuous 5V voltage to the amplification and electro-optic conversion circuits at each node. In long-distance signal transmission, the optical signal gain is amplified by 10dB by an optical amplifier to ensure stable signal strength over a 50km transmission distance.

[0051] This embodiment demonstrates that the acoustomagnetic sensing fiber optic composite system can accurately detect the position, heading, and motion status of submarines in complex underwater environments. Multi-sensor joint detection effectively reduces noise interference and detection errors, while wavelength division multiplexing technology and efficient energy management ensure the reliability of long-distance signal transmission and node power supply, thereby improving the overall performance of underwater detection.

[0052] Advantages Comparison

[0053] Traditional underwater detection systems typically rely on a single type of sensor (such as an acoustic sensor, magnetic sensor, or fluxgate sensor) for detection. This embodiment compares a single-sensor detection system with an acousto-magnetic sensing fiber optic composite system to illustrate the advantages of the acousto-magnetic sensing fiber optic composite system.

[0054] Table 1

[0055]

[0056] In summary, the acoustomagnetic sensing fiber optic composite system of this application achieves a comprehensive improvement in underwater detection performance through multi-sensor fusion, wavelength division multiplexing technology, optical energy input, and efficient signal processing. Compared with traditional systems, this application demonstrates advantages in detection accuracy, transmission stability, energy supply, and multi-target identification.

[0057] This novel acoustomagnetic sensing fiber optic composite system utilizes optical fiber for both signal transmission and power supply. Multi-sensor joint detection enhances the comprehensiveness of signal acquisition. The system employs photovoltaic power generation, signal amplification circuitry, electro-optical conversion for synchronous transmission, and wavelength division multiplexing to improve transmission efficiency, simplifying wiring and enhancing the stability and efficiency of long-distance transmission. The embedded fiber optic design of the sensors enhances anti-interference capabilities, and optimized distances between adjacent nodes ensure seamless coverage, avoiding signal blind spots. The signal processing module independently separates acoustic and magnetic field signals, combining multi-dimensional data fusion to improve target recognition accuracy and system reliability.

[0058] The above descriptions are merely embodiments of this application, and common knowledge regarding specific structures and characteristics in the solutions is not described in detail here. It will be apparent to those skilled in the art that this application is not limited to the details of the above exemplary embodiments, and that this application can be implemented in other specific forms without departing from the spirit or essential characteristics of this application. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of this application is defined by the appended claims rather than the foregoing description. Therefore, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within this application. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. An acoustomagnetic sensing fiber optic composite system, characterized in that, The system includes multiple acoustomagnetic sensing nodes, optical fibers, a signal processing module, and a light energy input module. The light energy input module is coupled to the optical fibers and is used to input light energy and transmit it to each acoustomagnetic sensing node through the optical fibers. Each acoustomagnetic sensing node includes a beam splitter, an acoustic sensor and a magnetic sensor or an acoustomagnetic co-sensor, a photovoltaic cell connected to the optical fiber, a wavelength division multiplexer, and corresponding circuits. The beam splitter is used to separate at least a portion of the light energy from the optical fiber. The photovoltaic cell receives the light energy and converts it into electrical energy for storage and to provide power to the circuits within the acoustomagnetic sensing node. In each acoustomagnetic sensing node, the acoustic sensor and the magnetic sensor or the acoustomagnetic co-sensor are connected to the wavelength division multiplexer through corresponding circuits to acquire external acoustomagnetic signals. The wavelength division multiplexer is used to combine the optical signals of different wavelengths generated by the acoustic and magnetic signals and transmit them through the optical fiber. The signal processing module is connected to the optical fibers and is used to receive the optical signals from the wavelength division multiplexer through the optical fibers.

2. The optical fiber composite system for acousto-magnetic sensing according to claim 1, characterized in that, The corresponding circuit within the acoustomagnetic sensing node includes an amplification circuit and an electro-optical conversion circuit; the acoustic sensor and the magnetic sensor are connected to the wavelength division multiplexer in sequence through the amplification circuit and the electro-optical conversion circuit; the amplification circuit is used to perform impedance transformation and amplification on the acquired acoustomagnetic signal, and the electro-optical conversion circuit is used to perform electro-optical conversion on the acquired acoustomagnetic signal and convert the electrical signal into an optical signal.

3. The optical fiber composite system for acousto-magnetic sensing according to claim 1, characterized in that, The acoustic sensor and magnetic sensor are respectively embedded in optical fibers.

4. The optical fiber composite system for acousto-magnetic sensing according to claim 2, characterized in that, The acoustomagnetic signal is output as an optical signal through the electro-optical conversion circuit and the wavelength division multiplexer, and then transmitted through the optical fiber.

5. The optical fiber composite system for acousto-magnetic sensing according to claim 1, characterized in that, The distance between two adjacent acoustic-magnetic sensing nodes does not exceed the maximum detection distance of the acoustic sensor and the magnetic sensor.

6. The optical fiber composite system for acousto-magnetic sensing according to claim 1, characterized in that, The signal processing module includes a demultiplexer connected to an optical fiber, which is used to separate the acoustomagnetic input signal according to a selection signal.

7. The acoustomagnetic sensing fiber optic composite system according to claim 6, characterized in that, The signal processing module also includes a data processing center, which is connected to the output of the demultiplexer and is used to process the acoustic-magnetic signal data.

8. The acoustomagnetic sensing fiber optic composite system according to claim 1, characterized in that, The optical energy input module includes a high-power laser and an optical amplifier. The output end of the high-power laser is connected to the optical amplifier, and the output end of the optical amplifier is connected to the optical fiber. The high-power laser is used to provide power to the acoustomagnetic sensing node, and the optical amplifier is used to enhance the optical signal intensity.

9. The optical fiber composite system for acousto-magnetic sensing according to claim 8, characterized in that, The optical energy input module also includes an optical switch; the optical switch is disposed between the connection circuit of the high-power laser and the optical amplifier, and is used to control the input and output of optical energy.

10. The optical fiber composite system for acousto-magnetic sensing according to claim 1, characterized in that, The acoustic sensor is a piezoelectric underwater acoustic sensor, the magnetic sensor is a magnetoelectric weak magnetic sensor, and the amplification circuit is equipped with a charge amplifier.

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