Time channel extraction method for underwater transient electromagnetic detection and FPGA implementation system

Abstract

The application provides a time channel extraction method for underwater transient electromagnetic detection, comprising the following steps: a parameter configuration step: obtaining detection configuration parameter information; a signal generation step: generating a first control signal and a second control signal based on the detection configuration parameter information; a pulse excitation step: emitting a bipolar pulse wave according to the first control signal; a signal collection step: collecting signals within a preset time window after the bipolar pulse wave is turned off according to the second control signal, and obtaining initial coupled field signal data; a signal extraction step: extracting sampling data located on a target time channel from the initial coupled field signal data to obtain target response signal data; and a data processing and identification step: analyzing and identifying the target response signal data to obtain underwater target detection results.

Description

Technical Field

[0001] This invention relates to the field of magnetic anomaly detection technology, and more specifically, to a time channel extraction method and FPGA implementation system for underwater transient electromagnetic detection. Background Technology

[0002] Currently, underwater detection technology mainly relies on acoustic, optical, and magnetic methods. During seabed exploration, sediment disturbance caused by moving platforms severely affects the detection effectiveness of optical and acoustic methods, both of which are limited by the inherent limitations of water visibility and cross-medium propagation. In contrast, magnetic detection possesses excellent cross-medium propagation capabilities and can directly obtain the electromagnetic response of buried metallic targets.

[0003] Existing magnetic detection technologies mainly include two categories: electromagnetic induction (EMI) and magnetic anomaly detection (MAD). However, MAD technology has insufficient detection capability for non-ferromagnetic metal targets with near-zero magnetic susceptibility; while frequency domain electromagnetic method (FEM) in EMI technology, although simple to operate, is prone to false alarms in complex underwater environments, resulting in low reliability. Transient electromagnetic method (TEM) excites strong transient eddy currents within the target, exhibiting higher detection sensitivity for shallowly buried non-ferromagnetic metal targets. However, its traditional systems mostly employ fixed-point static detection modes, using single-pulse attenuation observation or continuous pulse superposition to improve the signal-to-noise ratio, which is difficult to adapt to the real-time, high-efficiency detection requirements of underwater mobile platforms.

[0004] In recent years, although some studies have attempted to introduce data-driven methods to improve the adaptability of TEM systems, the prevailing approach is still to use a full-time data transmission and processing mode. This results in a huge data storage and computational burden on the system, making it difficult to achieve effective real-time processing and severely limiting its applicability in long-term, dynamic underwater detection scenarios. Therefore, how to achieve a miniaturized, low-power, and highly real-time dynamic platform TEM detection system while ensuring detection accuracy has become a key technical problem that urgently needs to be solved in this field.

[0005] Therefore, there is an urgent need to develop a time channel extraction method and FPGA implementation system for underwater transient electromagnetic detection that overcomes the above-mentioned defects. Summary of the Invention

[0006] This invention provides a time channel extraction method and FPGA implementation system for underwater transient electromagnetic detection, which at least solves the problems of poor real-time performance, large data storage burden, and difficulty in adapting to the continuous and efficient detection requirements of underwater mobile platforms caused by the fixed-point static working mode and all-time data transmission mechanism of traditional transient electromagnetic detection systems.

[0007] To achieve the above objectives, the present invention provides a time channel extraction method for underwater transient electromagnetic detection, comprising:

[0008] Parameter configuration steps: Obtain detection configuration parameter information;

[0009] Signal generation steps: Generate a first control signal and a second control signal based on the detection configuration parameter information;

[0010] Pulse excitation step: Emit a bipolar pulse wave according to the first control signal;

[0011] Signal acquisition steps: According to the second control signal, signal acquisition is performed within a preset time window after the bipolar pulse wave is turned off to obtain initial coupled field signal data;

[0012] Signal extraction step: Based on the initial coupled field signal data, extract the sampled data located in the target time channel to obtain the target response signal data;

[0013] Data processing and identification steps: The target response signal data is analyzed and the target is identified to obtain the underwater target detection results.

[0014] Furthermore, the signal extraction step includes:

[0015] Based on the initial coupled field signal data, sampled data located on the same target time channel within multiple pulse cycles are extracted, and sampled data other than the target time channel within the preset time window are discarded;

[0016] The extracted sampled data is subjected to coherent integration processing to obtain the target response signal data.

[0017] Furthermore, the signal acquisition step includes:

[0018] According to the second control signal, signal acquisition is performed within a preset time window after the bipolar pulse current is turned off;

[0019] The preset time window is set as the time interval during which the primary field-induced voltage decays to below the noise level but the secondary field-induced voltage has not yet fully decayed.

[0020] Furthermore, the second control signal is used to control the triggering time of the preset time window, and its triggering time... To configure control delay With inherent delay The sum is expressed as: .

[0021] Furthermore, the detection configuration parameters include: transmission pulse frequency, transmission pulse duty cycle, and acquisition control information.

[0022] This application provides an FPGA implementation system for underwater transient electromagnetic detection, used to implement the aforementioned time channel extraction method for underwater transient electromagnetic detection, including:

[0023] The power supply control module is configured to configure and send detection configuration parameters, and to receive and process target response signal data;

[0024] The FPGA main control module is electrically connected to the power supply control module and is configured to generate the first control signal and the second control signal based on the detection configuration parameters.

[0025] The pulse excitation module is electrically connected to the FPGA main control module and is configured to emit a bipolar pulse wave according to the first control signal;

[0026] The data acquisition module is electrically connected to the FPGA main control module and is configured to acquire initial coupling field signal data according to the second control signal and transmit it back to the FPGA main control module.

[0027] The FPGA main control module is also configured to extract sampled data located on the target time channel from the initial coupling field signal data to obtain target response signal data.

[0028] The power supply control module is also configured to receive target response signal data, analyze the target response signal data and identify the target, and obtain underwater target detection results.

[0029] Furthermore, the FPGA main control module includes:

[0030] The instruction input unit is configured to receive detection configuration parameter information from the power supply control module;

[0031] The instruction decoding unit is electrically connected to the instruction input unit and is configured to decode the detection configuration parameter information and generate a first control signal and a second control signal.

[0032] The acquisition unit, electrically connected to the instruction decoding unit, is configured to process the returned initial coupled field signal data, extract the target sampling data on a specific time channel and discard redundant data to obtain the target response signal data.

[0033] A communication protocol conversion unit, electrically connected to the acquisition unit, is configured to perform communication protocol conversion processing on the target response signal data;

[0034] The instruction feedback unit is electrically connected to the communication protocol conversion unit and is configured to send the target response signal data after protocol conversion back to the power supply control module.

[0035] Furthermore, the first control signal includes two PWM signals with a phase difference of 180°, used to drive the pulse excitation module to generate a bipolar pulse current.

[0036] Furthermore, the instruction input unit is configured to receive system clock signals, system reset signals, and host computer instruction signals, and to parse the host computer instruction signals based on the RS232 communication protocol to obtain the detection configuration parameter information.

[0037] Furthermore, the FPGA implementation system for underwater transient electromagnetic detection is mounted on an underwater mobile platform, which includes a transient electromagnetic detection watertight chamber, and the FPGA main control module is integrated in the transient electromagnetic detection watertight chamber.

[0038] Compared with the prior art, the advantages and positive effects of the present invention are as follows:

[0039] This invention proposes a time-channel extraction technique to accurately extract sampled data from the target time channel within a critical time window after the bipolar pulse is turned off, when the primary field-induced voltage decays below the noise level but the secondary field-induced voltage has not yet fully decayed. Redundant data is discarded, thus achieving efficient signal extraction and data compression at the hardware level. This method significantly reduces the system's data storage and transmission burden and improves real-time processing capabilities.

[0040] This invention leverages the highly parallel computing and precise timing control capabilities of FPGAs to construct a hardware system integrating instruction parsing, pulse transmission, signal acquisition, and real-time processing. This system precisely controls the sampling timing through configurable control signals, solving the problems of separation of acquisition and control and inconsistent timing in traditional detection systems, thus improving system integration and stability.

[0041] Furthermore, this invention designs a compact watertight chamber integration scheme to meet the dynamic detection needs of underwater mobile platforms, enabling the transient electromagnetic detection system to operate continuously and efficiently on the moving platform. This effectively overcomes the limitations of traditional fixed-point TEM systems in adapting to mobile detection scenarios, while also possessing good environmental robustness and detection efficiency. Attached Figure Description

[0042] Figure 1 This is a schematic flowchart of the time channel extraction method for underwater transient electromagnetic detection provided in an embodiment of the present invention;

[0043] Figure 2 This is a diagram of an FPGA system architecture for underwater transient electromagnetic detection provided in an embodiment of the present invention.

[0044] Figure 3 This is a schematic diagram of the signal timing principle of the time channel extraction technology provided in this embodiment of the invention;

[0045] Figure 4 This is a schematic diagram of the FPGA control signal timing and sampling effect of the time channel extraction technology provided in this embodiment of the invention;

[0046] Figure 5 This is a schematic diagram of an FPGA system architecture for underwater transient electromagnetic detection provided in an embodiment of the present invention.

[0047] Figure 6 This is a schematic diagram of the logic of each unit of the FPGA main control module in an embodiment of the present invention;

[0048] Figure 7 This is a schematic diagram of the transient electromagnetic detection watertight chamber structure in an embodiment of the present invention.

[0049] In the above image:

[0050] 100. Power supply control module; 200. FPGA main control module; 300. Pulse excitation module; 400. Data acquisition module. Detailed Implementation

[0051] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0052] In the description of this application, it should be understood that the terms "center," "upper," "lower," "front," "rear," "left," "right," "vertical," "level," "top," "bottom," "inner," and "outer," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, unless otherwise stated, "a plurality of" means two or more.

[0053] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0054] The Transient Electromagnetic Method (TEM) is a time-domain geophysical exploration technique based on the principle of electromagnetic induction. Its basic principle is to emit a pulsed primary electromagnetic field into the subsurface, and then, during the intervals between pulses, measure the decay of the secondary electromagnetic field generated by eddy currents induced by subsurface conductors over time.

[0055] By analyzing the attenuation characteristics of the secondary field, such as attenuation rate and amplitude, the electrical structure and geological features of the subsurface medium can be inferred. The TEM method is sensitive to highly conductive materials, such as metallic ore bodies, groundwater, and graphitized strata, and is a very important geophysical method in resource exploration, hydrogeological, and engineering geological surveys.

[0056] However, traditional systems using transient electromagnetic methods mostly employ a fixed-point static detection mode, which improves the signal-to-noise ratio through single-pulse attenuation observation or continuous pulse superposition, making it difficult to meet the real-time and efficient detection requirements of underwater mobile platforms.

[0057] Therefore, this application provides a time channel extraction method and FPGA implementation system for underwater transient electromagnetic detection based on an underwater mobile platform, so as to at least solve the problems of poor real-time performance, large data storage burden, and difficulty in adapting to the continuous and efficient detection requirements of underwater mobile platforms caused by the fixed-point static working mode and all-time data transmission mechanism of traditional transient electromagnetic detection systems.

[0058] like Figures 1-7 As shown, this invention provides a time channel extraction method for underwater transient electromagnetic detection and its FPGA implementation system. The following is a detailed explanation. Figures 1-7 This section provides a detailed explanation of the time channel extraction method for underwater transient electromagnetic detection.

[0059] like Figure 1 and Figure 2 As shown, this invention provides a time channel extraction method for underwater transient electromagnetic detection, comprising:

[0060] Parameter configuration step S100: Obtain detection configuration parameter information.

[0061] In some embodiments, the detection configuration parameter information includes, but is not limited to, the transmit pulse frequency, the transmit pulse duty cycle, and acquisition control information. The detection configuration parameter information is issued by the power supply control module (PC).

[0062] Signal generation step S200: Generate a first control signal and a second control signal based on the detection configuration parameter information.

[0063] In some embodiments, the Field-Programmable Gate Array (FPGA) control module receives and analyzes the probe configuration parameter information, then generates two signals: a first control signal and a second control signal. The first control signal consists of two PWM waves, and the second control signal is a data acquisition control signal.

[0064] Pulse excitation step S300: Emit a bipolar pulse wave according to the first control signal.

[0065] In some embodiments, the pulse excitation module (transmitter) is provided with an excitation coil, and the first control signal, namely two PWM signals, can control the generation of bipolar pulse waves in the excitation coil.

[0066] Signal acquisition step S400: According to the second control signal, signal acquisition is performed within a preset time window after the bipolar pulse wave is turned off to obtain the initial coupling field signal data.

[0067] In some embodiments, a second control signal is sent to a signal acquisition module (receiving end), and the signal acquisition module performs signal acquisition according to the second control signal to obtain initial coupling field signal data.

[0068] Signal extraction step S500: Based on the initial coupled field signal data, extract the sampled data located on the target time channel to obtain the target response signal data.

[0069] In some embodiments, the acquisition module transmits the acquired initial coupling field signal data back to the FPGA control module via the SPI communication protocol. After filtering and eliminating the initial coupling field signal data, the FPGA control module transmits the valid data containing the secondary field signal, i.e. the target response signal data, back to the power supply control module (PC) of the remotely operated vehicle (ROV).

[0070] Data processing and identification step S600: Analyze the target response signal data and identify the target to obtain the underwater target detection results.

[0071] In some embodiments, the power supply control module (PC) backs up and processes the data and visualizes it as a response voltage signal to observe the presence of the target and obtain the underwater target detection results.

[0072] Preferably, the signal acquisition step includes:

[0073] According to the second control signal, signal acquisition is performed within a preset time window after the bipolar pulse current is turned off.

[0074] The preset time window is set as the time interval between the primary field induced voltage decaying to below the noise level and the secondary field induced voltage not yet fully decaying.

[0075] Preferably, the signal extraction step includes:

[0076] Based on the initial coupled field signal data, sampled data located on the same target time channel within multiple pulse cycles are extracted, and sampled data other than the target time channel within a preset time window are discarded.

[0077] The extracted sampled data is subjected to coherent integration processing to obtain the target response signal data.

[0078] In some embodiments, a typical TEM detection system consists of a transmitting coil and a receiving coil forming its core sensing unit. The transmitting coil is driven by a bipolar pulsed current, generating a primary magnetic field. This primary field induces eddy currents in a nearby conductive target, which in turn generate a secondary magnetic field. Finally, the receiving coil captures the coupled signal.

[0079] Figure 3 This is a schematic diagram of the signal timing principle of the time channel extraction technology provided in the embodiments of the present invention, such as... Figure 3 As shown, in the initial stage of applying the excitation coil current I... At this time, the environmental field signal is the primary field induced voltage. and secondary field induced voltage The coupling signal.

[0080] In the actual signal extraction stage, i.e. after I is turned off In the initial stage, the primary field-induced voltage It still exists. And... Figure 3 middle During this phase, the excitation coil current I is turned off, and the primary field induced voltage... Completely disappeared, secondary field induced voltage It gradually diminishes over time.

[0081] During the aforementioned stages, from multiple Extract signals from the same time channel within each sampling period. That is, within each sampling period... Extract the fixed-time channel within the window. Voltage value And maintain the same relative phase. These sampling points The coherent integral in the time domain is Used for target-induced capture Signal.

[0082] exist The sampled signal has a coherent integral in the time domain as follows: Its calculation expression is as follows:

[0083]

[0084] Where k is the sampling point index and N is the total number of sampling points. The target response can then be obtained:

[0085]

[0086] Preferably, the second control signal is used to control the triggering time of the preset time window, and its triggering time... To configure control delay With inherent delay The sum is expressed as: .

[0087] In some embodiments, Figure 4 This is a schematic diagram of the FPGA control signal timing and sampling effect of the time channel extraction technology provided in this embodiment of the invention, as shown below. Figure 4 As shown, the time channel extraction technique is explained in detail.

[0088] like Figure 4 As shown in (a), the FPGA control module generates control signals while outputting PWM excitation pulses. The control signal is configured by the power supply control module (PC) and triggered by the falling edge of a single PWM pulse. The 50MHz system clock system has a minimum delay resolution of 20ns, ensuring accurate extraction at the ideal sampling time of the target signal, thereby improving detection reliability and system performance.

[0089] Among them, parameters This indicates the user-defined control delay, or additional delay. The system delay arises from the AD conversion module packaging 24-bit data. To compensate for these two delay periods, the actual control signal trigger time... It is expressed as follows:

[0090]

[0091] The above formula clearly defines the precise triggering time of the real-time control signal. This strategy improves the accuracy of time channel extraction technology. By discarding redundant sampled data outside the selected time channel, unnecessary data storage space is significantly reduced. Therefore, the system achieves significant improvements in both response speed and memory efficiency.

[0092] like Figure 4 As shown in (b), the time channel extraction technique selects the sampling time channel according to the above formula, where channels (i) and (ii) are located in the window. In addition, channel (iii–v) is located Inside the window.

[0093] like Figure 4 As shown in (c), the reconstructions obtained from different time channels (i–v) are illustrated. Response. The reconstructed responses of channels (i) and (ii) The amplitude is small because There are remnants outside the window right It produced an inhibitory effect. In contrast, in Reconstruction of channels (iii–v) within the window The signal exhibits a gradually decreasing amplitude due to time decay.

[0094] This timing strategy effectively improves detection accuracy. By discarding redundant sampling data outside the selected time channel, the strategy significantly reduces unnecessary data storage, thereby improving both the system's real-time response capability and storage efficiency.

[0095] like Figure 2 and Figure 5 As shown, this application provides an FPGA implementation system for underwater transient electromagnetic detection, used to implement the above-mentioned time channel extraction method for underwater transient electromagnetic detection, including: a power supply control module 100, an FPGA main control module 200, a pulse excitation module 300, and a data acquisition module 400.

[0096] The power supply control module 100 is configured to configure and send detection configuration parameters, and to receive and process target response signal data.

[0097] The FPGA main control module 200 is electrically connected to the power supply control module and is configured to generate a first control signal and a second control signal based on the detection configuration parameters.

[0098] The pulse excitation module 300 is electrically connected to the FPGA main control module and is configured to emit bipolar pulse waves according to the first control signal.

[0099] The data acquisition module 400 is electrically connected to the FPGA main control module and is configured to acquire initial coupling field signal data according to the second control signal and transmit it back to the FPGA main control module.

[0100] Among them, the FPGA main control module 200 is also configured to extract the sampled data located on the target time channel based on the initial coupling field signal data to obtain the target response signal data;

[0101] The power supply control module 100 is also configured to receive target response signal data, analyze the target response signal data and identify the target, and obtain underwater target detection results.

[0102] In some embodiments, the FPGA implementation system for underwater transient electromagnetic detection also includes an auxiliary function module. This module consists of a series of high-precision sensors used to sense the real-time status of the detection platform and information about the surrounding environment, providing key parameters for data interpretation, motion compensation, and navigation positioning.

[0103] Auxiliary function modules include, but are not limited to, positioning systems, attitude sensors, sonar systems, and altimeters.

[0104] The positioning system includes an ultra-short baseline positioning system (USBL) and a real-time dynamic differential positioning system (RTK). The USBL system determines the absolute geographical location of the underwater mobile platform relative to the surface mother ship using underwater acoustic signals; the RTK system provides a surface reference position with centimeter-level accuracy when the surface mother ship or platform can receive GPS / BeiDou signals. The combination of the two enables high-precision spatial positioning of the probe trajectory.

[0105] Attitude sensors, typically inertial measurement units (IMUs), are used to measure the three-axis acceleration and three-axis angular velocity of an underwater mobile platform in real time, and output the platform's roll, pitch, and yaw angles after calculation. This data is crucial for motion-induced noise compensation and for converting the data to a geodetic coordinate system.

[0106] The sonar system is used to detect terrain and obstacles in front of the underwater mobile platform to achieve obstacle avoidance. It can also provide side-scan sonar images, which can be cross-referenced with transient electromagnetic data for comprehensive geological interpretation.

[0107] Altimeters, typically acoustic altimeters, are used to continuously measure the vertical distance between an underwater mobile platform and the seabed. This distance information is crucial for inverting and interpreting transient electromagnetic data and calculating the depth of exploration.

[0108] Preferably, such as Figure 5 As shown, the FPGA main control module 200 includes: an instruction input unit, an instruction decoding unit, an acquisition unit, and an instruction feedback unit.

[0109] The instruction input unit is configured to receive detection configuration parameter information from the power supply control module.

[0110] The instruction decoding unit is electrically connected to the instruction input unit and is configured to decode the detection configuration parameter information and generate a first control signal and a second control signal.

[0111] The acquisition unit, electrically connected to the instruction decoding unit, is configured to process the returned initial coupled field signal data, extract the target sampling data on a specific time channel and discard redundant data to obtain the target response signal data.

[0112] The communication protocol conversion unit, electrically connected to the acquisition unit, is configured to perform communication protocol conversion processing on the target response signal data.

[0113] The instruction feedback unit is electrically connected to the communication protocol conversion unit and is configured to send the target response signal data after protocol conversion back to the power supply control module.

[0114] Preferably, the first control signal includes two PWM signals with a phase difference of 180°, used to drive the pulse excitation module to generate a bipolar pulse current.

[0115] Preferably, the instruction input unit is configured to receive system clock signals, system reset signals, and host computer instruction signals, and to parse the host computer instruction signals based on the RS232 communication protocol to obtain detection configuration parameter information.

[0116] In some embodiments, Figure 6 Here are the logic diagrams of each unit in the FPGA main control module, such as... Figure 6 As shown, the units and logic of the FPGA main control module are as follows.

[0117] The instruction input unit receives the serial instruction signal rx from the power supply control module, i.e., the host computer. It completes initialization under the synchronization of the system clock sys_clk and the control of the system reset signal sys_rst_n. Based on the RS232 communication protocol, this unit decodes and converts the serial instruction data from serial to parallel, thereby parsing out the control instruction frame containing the transmit pulse frequency, duty cycle, and acquisition control delay parameters, and converting it into parallel data output. Its output is connected to the input of the instruction decoding unit.

[0118] In some embodiments, the instruction input module takes the system clock sys_clk, the system reset signal sys_rst_n, and the host computer instruction signal rx as inputs. Communication between the PC and the FPGA is implemented via the RS232 protocol, with the serial port baud rate set to 115200bps, and the transmitted data specified as 12 groups of hexadecimal data. The rx instruction includes a start bit, a flag bit, a stop bit, and the required duty cycle, frequency, and real-time acquisition control signal data.

[0119] Taking AB 00 50 AA 01 25 BA CA 00 05 00 CC as an example: AB is the start bit, the FPGA starts receiving duty cycle data; 00 50 is the duty cycle, which can be adjusted according to actual needs; AA is the flag bit; 01 25 is the frequency, which can be adjusted according to actual needs; BA is the flag bit; CA / DA are the judgment bits, CA is the delay backward from the moment the waveform falls, and DA is the delay forward from the moment the waveform falls; 00 05 00 is the delay unit, which can control the delay point to be selected within -20~20 ms, and this value is a delay of 500×20 ns = 10μs; CC is the stop bit, the FPGA completes data reception.

[0120] The instruction decoding unit parses the parallel data frames sent by the instruction input unit and extracts specific control parameters according to the preset frame format, such as start bit, flag bit, data bits, and stop bit. Subsequently, it uses these parameters to generate a first control signal and a second control signal. The first control signal is two PWM signals with a 180° phase difference, and the second control signal is the acquisition control signal spi_flag, which includes delay information. Their outputs are connected to the external transmitting module and the internal acquisition unit, respectively.

[0121] The acquisition unit generates a real-time capture signal to convert the acquired data returned by the acquisition card into voltage values, decodes and transmits the target acquisition data, and, based on the delay set by the control signal, captures only the valid data on the target time channel within a precise time window, discarding redundant sampled data from other times within the window in real time. DIN is the acquisition control signal, controlling the ADS127L01 to perform data acquisition. DOUT and DRDY pack the data into 24-bit groups. HR, start, and nCS are enable signals. SCLK is the SPI clock signal. reset is the acquisition reset signal.

[0122] The communication protocol conversion unit receives the 24-bit target response data preprocessed by the acquisition unit. Since the data acquisition module typically uses high-speed protocols such as SPI, and communication with the host computer uses the RS232 protocol, this unit is responsible for packaging the 24-bit data and converting it into an 8-bit data stream conforming to the RS232 transmission format. Its input is connected to the output of the acquisition unit.

[0123] The command feedback unit, acting as a data output, receives the 8-bit data prepared by the communication protocol conversion unit, performs parallel-to-serial conversion under RS232 protocol control, and transmits the final target response signal data back to the power supply control module via the transmit signal line tx. Its input is connected to the output of the communication protocol conversion unit.

[0124] Preferably, the FPGA implementation system for underwater transient electromagnetic detection is mounted on an underwater mobile platform, which includes a transient electromagnetic detection watertight chamber, and the FPGA main control module is integrated in the transient electromagnetic detection watertight chamber.

[0125] In some embodiments, the underwater mobile platform may be a tethered remotely operated underwater vehicle (ROV). The ROV provides a mobile platform, power supply, and communication link with the surface mother ship for the underwater transient electromagnetic detection system of the present invention. The transient electromagnetic detection watertight compartment, as the core equipment compartment, is fixedly installed inside the ROV frame by a rigid bracket. The transient electromagnetic detection watertight compartment adopts a cylindrical pressure-resistant hull design, which is beneficial to the overall buoyancy balance and center of gravity stability of the ROV.

[0126] In some embodiments, such as Figure 7 As shown, the transient electromagnetic detection watertight chamber integrates, but is not limited to, a power supply module, an FPGA control module, a transient drive module, a fast recovery diode, and a data acquisition module.

[0127] The power supply module is responsible for providing a stable and isolated operating voltage to all modules inside the cabin. It includes a 12V power supply module and a 5V power supply module.

[0128] The FPGA control module, serving as the system's control hub, is integrated into the FPGA core circuit board within the cabin.

[0129] The transient drive module directly receives control signals from the FPGA control module and amplifies them into high-power current pulses that can drive the external transmitting coil.

[0130] Fast recovery diodes are used in protective circuits within the transmitting circuit to ensure system reliability during high-power pulse transmission. They effectively suppress transient high voltages such as reverse induced electromotive force generated by the interruption of the transmitting current, preventing damage to fragile semiconductor devices and providing crucial overvoltage protection.

[0131] The data acquisition module, using the ADS127L01 chip, is responsible for accurately sampling and digitizing the analog voltage signal representing the secondary attenuation field transmitted from the receiving coil, and transmitting the conversion result to the FPGA control module in real time in the form of a digital signal for processing.

[0132] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments for application in other fields. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the protection scope of the present invention.

Claims

1. An FPGA implementation system for underwater transient electromagnetic detection, characterized in that, include: The power supply control module is configured to configure and send detection configuration parameters, and to receive and process target response signal data; The FPGA main control module is electrically connected to the power supply control module and is configured to generate a first control signal and a second control signal based on the detection configuration parameters. The pulse excitation module is electrically connected to the FPGA main control module and is configured to emit a bipolar pulse wave according to the first control signal; The data acquisition module is electrically connected to the FPGA main control module and is configured to acquire initial coupling field signal data according to the second control signal and transmit it back to the FPGA main control module. The FPGA main control module is also configured to extract sampled data located on the target time channel from the initial coupling field signal data to obtain target response signal data. The power supply control module is also configured to receive target response signal data, analyze the target response signal data and identify the target, and obtain underwater target detection results. The FPGA main control module includes a data acquisition unit configured to process the returned initial coupling field signal data, extract target sampling data on a specific time channel and discard redundant data to obtain target response signal data; based on the initial coupling field signal data, extract sampling data located on the same target time channel within multiple pulse cycles and discard sampling data other than the target time channel within a preset time window; and perform coherent integration processing on the extracted sampling data to obtain the target response signal data.

2. The FPGA implementation system for underwater transient electromagnetic detection according to claim 1, wherein the FPGA main control module comprises: The instruction input unit is configured to receive detection configuration parameter information from the power supply control module; The instruction decoding unit is electrically connected to the instruction input unit and is configured to decode the detection configuration parameter information and generate a first control signal and a second control signal. The acquisition unit is electrically connected to the instruction decoding unit; A communication protocol conversion unit, electrically connected to the acquisition unit, is configured to perform communication protocol conversion processing on the target response signal data; The instruction feedback unit is electrically connected to the communication protocol conversion unit and is configured to send the target response signal data after protocol conversion back to the power supply control module.

3. The FPGA implementation system for underwater transient electromagnetic detection according to claim 1, characterized in that, The first control signal includes two PWM signals with a phase difference of 180°, which are used to drive the pulse excitation module to generate a bipolar pulse current.

4. The FPGA implementation system for underwater transient electromagnetic detection according to claim 2, characterized in that, The instruction input unit is configured to receive system clock signals, system reset signals, and host computer instruction signals, and to parse the host computer instruction signals based on the RS232 communication protocol to obtain the detection configuration parameter information.

5. The FPGA implementation system for underwater transient electromagnetic detection according to claim 2, characterized in that, It is mounted on an underwater mobile platform, which includes a transient electromagnetic detection watertight chamber, and the FPGA main control module is integrated in the transient electromagnetic detection watertight chamber.

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