Rydberg electric field meter electromagnetic induction method, submarine underground cable detection method and system

Abstract

The present application relates to the technical field of electromagnetic detection, in particular to a Rydberg electric field meter electromagnetic induction method and system for submarine underground cable detection, wherein the direct measurement of radio frequency electric field is introduced into the detection process, the atomic energy level displacement is used to sensitively perceive the weak electric field, and the weak electric field is converted into an optical signal for transmission and demodulation, thereby effectively overcoming the problems of serious signal attenuation and noise interference of the traditional electromagnetic induction equipment under deep water or complex geological conditions, and the submarine cable buried deeper or with weaker current signal can be detected, meanwhile, the electric field response amplitude and phase information obtained through heterodyne demodulation, combined with the spatial position information, constructs the electric field response data containing multi-dimensional physical characteristics, changes the single criterion mode of only relying on the signal strength peak value for positioning, and the multi-dimensional data is introduced into the neural network model for electric field image reconstruction, so that the more detailed electric field spatial distribution around the cable can be restored.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electromagnetic detection, in particular to a Rydberg electric field meter electromagnetic induction method for submarine underground cable detection and a system thereof. BACKGROUND

[0002] The technical field of electromagnetic detection refers to the related technology of detecting underground or underwater targets by utilizing the generation, propagation and response characteristics of electromagnetic fields, including identifying the distribution of underground structures and the presence state of metals or dielectric bodies through the interaction of electric and magnetic fields.

[0003] Among them, the submarine underground cable detection method refers to obtaining the electric field or magnetic field signal generated by the cable in the seawater environment by means of electromagnetic induction to determine its position. Common methods include detecting the magnetic field distribution formed by the transmission current through coil induction method and capturing the electric field signal formed by the cable current in seawater by electrode measurement method.

[0004] The prior art mainly relies on coil induction method to measure the magnetic field or electrode measurement method to capture the potential difference. In the coil induction method, the sensor is easily disturbed by other electromagnetic sources in the environment. When the target cable is buried deep or the external shielding layer is thick, the magnetic field signal generated by the cable is very weak when it propagates to the surface of the seabed, and is often overwhelmed by environmental background noise, causing the detector to be unable to effectively identify. In the electrode measurement method, the electrode contact surface with seawater will produce electrochemical noise, and the conductivity of seawater will be locally uneven due to temperature and salinity changes. These factors will introduce measurement errors, making the measurement results of the electric field signal unstable. In addition, both methods usually rely on finding the maximum value of signal strength to determine the cable position. When there are multiple parallel cables or other metal conductors nearby causing electromagnetic field distortion, the position of the signal peak may deviate from the top of the cable, and the positioning method based on field strength amplitude will produce positioning deviation or even incorrect judgment. SUMMARY

[0005] The purpose of the present application is to solve the shortcomings in the prior art and to provide a Rydberg electric field meter electromagnetic induction method for submarine underground cable detection and a system thereof.

[0006] In order to achieve the above purpose, the present application adopts the following technical scheme: a Rydberg electric field meter electromagnetic induction method for submarine underground cable detection, comprising the following steps:

[0007] S1: applying an alternating electric signal to the target pipeline through a transmitting source to generate electromagnetic radiation signals in the metal pipeline under the seabed, pairing the amplitude of the radiated electromagnetic field signal with the corresponding applied excitation signal frequency to construct a target excitation parameter set;

[0008] S2: excite the induced current of the seabed underground target detection area by the target excitation parameter set, measure the atomic energy level change caused by the alternating electric field, and form a transmission electric signal sequence;

[0009] S3: irradiate the alkali metal vapor cell in the underwater probe with the optical excitation signal group, excite the Rydberg state atom to perceive the energy level displacement change caused by the radio frequency electric field, and output a perturbation phase data set;

[0010] S4: heterodyne conversion and demodulation processing are performed on the transmission electric signal sequence and the perturbation phase data set, the three-dimensional spatial position of the underwater probe after heterodyne conversion and demodulation processing and the transmission parameter are bound, and an electric field response spatial data table is formed;

[0011] S5: according to the three-dimensional spatial position of each underwater probe in the electric field response spatial data table, the amplitude, phase and angle of arrival of the position where the underwater probe is located are sequentially collected in the order of position, introduced into a neural network model to reconstruct an electric field image, and a sequence of metal pipeline direction coordinates is output.

[0012] As a further scheme of the present application, the target excitation parameter set includes the radiation electromagnetic field signal amplitude and the excitation signal frequency, the transmission electric signal sequence specifically is atomic energy level change data, electric field induction characteristic quantity and signal transmission amplitude, the perturbation phase data set includes transmission phase change caused by energy level displacement, phase drift characteristic and interference fringe position information, the electric field response spatial data table specifically is underwater probe spatial coordinates, electric field response amplitude, electric field response phase and electric field response frequency, and the sequence of metal pipeline direction coordinates specifically is the spatial path of the metal pipeline.

[0013] As a further scheme of the present application, the acquisition step of the target excitation parameter set specifically includes:

[0014] S111: a frequency alternating electric signal with a frequency range of 10 kHz to 10 MHz is applied to the target pipeline by a transmitting source, a sequence of instantaneous power waveforms generated after the metal pipeline is excited is collected, the radiation electromagnetic field signal amplitude corresponding to the sequence of instantaneous power waveforms is calculated, and the excitation frequency response signal amplitude is obtained by combining the excitation signal frequency currently applied;

[0015] S112: a frequency adjustment step is set in the frequency range of 10 kHz to 10 MHz, the excitation signal frequency output by the transmitting source is cyclically adjusted, and the signal application and amplitude calculation are repeatedly performed, a plurality of excitation frequency response signal amplitudes obtained under each excitation frequency are integrated, and a multi-frequency point electromagnetic radiation sequence is established;

[0016] S113: all excitation signal frequencies and corresponding radiation electromagnetic field signal amplitudes in the multi-frequency point electromagnetic radiation sequence are called, arranged in the numerical order of the excitation signal frequency, and a target excitation parameter set is formed.

[0017] As a further scheme of the present application, the acquisition step of the transmission electric signal sequence is specifically:

[0018] S211: Call the target excitation parameter set to excite the induced current of the seabed underground target detection area, use the underwater probe containing a sealed alkali metal vapor cell and an optical window arranged in the target detection area, measure the atomic energy level change caused by the alternating electric field, quantify the transmission light signal output by the atomic transition behavior at the vapor cell window, and obtain the atomic transition response light intensity;

[0019] S212: Output the atomic transition response light intensity from the optical window of the underwater probe to the photoelectric detection end through the optical fiber path, continuously monitor the light signal in the transmission process, record all signal forms of the light signal at the photoelectric detection end, and acquire the optical fiber backhaul light signal spectrum;

[0020] S213: Based on the optical fiber backhaul light signal spectrum, perform photoelectric conversion processing at the photoelectric detection end, convert the change relationship of the received light signal intensity with time into the amplitude sequence of the electric signal, and obtain the transmission electric signal sequence.

[0021] As a further scheme of the present application, the underwater probe is filled with rubidium atoms or cesium atoms.

[0022] As a further scheme of the present application, the acquisition step of the perturbation phase data set is specifically:

[0023] S311: Use the light excitation signal group to irradiate the alkali metal vapor cell in the underwater probe with pump light and probe light, sequentially excite the alkali metal atoms from the ground state to the excited state and then to the Rydberg state, and form a transmission spectrum;

[0024] S312: Transmit the transmission spectrum to the photoelectric detector and sample, acquire a plurality of time-series transmission spectrum data, extract the electromagnetic induction transparent window position, peak shift, Autler-Townes splitting width multiple feature parameters in the spectrum, and establish a spectrum response sequence;

[0025] S313: Analyze the mapping relationship between each feature parameter in the spectrum response sequence and the atomic energy level displacement, calculate the intensity and phase of the external electric field, and construct a perturbation phase data set.

[0026] As a further scheme of the present application, the acquisition step of the electric field response space data table is specifically:

[0027] S411: call the transmission electric signal sequence and the perturbation phase data set, adopt a local reference signal source to mix the transmission electric signal sequence to construct a heterodyne detection channel, and demodulate the processed signal and the perturbation phase data set to extract the electric field response amplitude and the electric field response phase of each underwater probe at the excitation frequency, and obtain a demodulation transmission component;

[0028] S412: obtain the three-dimensional spatial position information of each underwater probe, and according to the demodulation transmission component, pair the position information of each probe with the corresponding transmission electric signal amplitude response value and instantaneous phase value, bind the position information with the transmission parameter, and generate position-bound transmission parameters;

[0029] S413: according to the position-bound transmission parameters of all underwater probes, bind the three-dimensional spatial position of the underwater probe after heterodyne conversion and demodulation processing with the transmission parameter to form an electric field response spatial data table.

[0030] As a further scheme of the present application, the obtaining step of the metal pipeline trend coordinate sequence is specifically:

[0031] S511: collect the amplitude, phase and angle of arrival between the electromagnetic wave incident direction and the internal reference direction of the sensor of each underwater probe in the electric field response spatial data table, combine the amplitude, phase and angle of arrival corresponding to each probe to construct an input sample vector set;

[0032] S512: import the data in the input sample vector set into a neural network model to reconstruct an electric field image, and perform image interpolation on the spatial region with a sampling interval greater than 10 cm in the image to complete the signal between sparse measurement points and obtain a complete reconstructed electric field image;

[0033] S513: identify a response region of a metal pipeline continuous region in the complete reconstructed electric field image with an electric field intensity higher than a preset discrimination threshold, aggregate the coordinates of all spatial reconstruction data in the response region, arrange the aggregated coordinate points in order, and output the trend coordinate sequence of the metal pipeline.

[0034] As a further scheme of the present application, the process of aggregating the coordinates of all spatial reconstruction data in the response region is specifically that the geometric center points of the response region on multiple cross sections are calculated, and the coordinates of all geometric center points are connected to form the trend coordinate sequence of the metal pipeline.

[0035] The Rydberg electric field meter electromagnetic induction method submarine underground cable detection system is used to execute the above-mentioned Rydberg electric field meter electromagnetic induction method submarine underground cable detection method, and the system comprises:

[0036] An alternating excitation parameter construction module applies an alternating electric signal to the target pipeline through a transmitting source to generate an electromagnetic radiation signal in the metal pipeline under the seabed, pairs the amplitude of the radiation electromagnetic field signal with the corresponding applied excitation signal frequency, and constructs a target excitation parameter set;

[0037] A transmission electric signal acquisition module excites an induced current in a target detection area under the seabed through the target excitation parameter set, and measures atomic energy level changes caused by an alternating electric field by using an underwater probe arranged in the target detection area to form a transmission electric signal sequence;

[0038] An atomic energy level sensing module irradiates an alkali metal vapor cell in the underwater probe with a light excitation signal group to excite a Rydberg state atom to sense energy level displacement changes caused by a radio frequency electric field, and outputs a perturbation phase data set;

[0039] An electric field response data processing module performs heterodyne conversion and demodulation processing on the transmission electric signal sequence and the perturbation phase data set, binds the three-dimensional spatial position of the underwater probe after heterodyne conversion and demodulation processing with transmission parameters, and forms an electric field response spatial data table;

[0040] An electric field image reconstruction module obtains the amplitude, phase and angle of arrival of the spatial position of each underwater probe in the electric field response spatial data table as an input sample vector, imports a neural network model to reconstruct an electric field image, and outputs a sequence of metal pipeline direction coordinates.

[0041] Compared with the prior art, the advantages and positive effects of the present application are as follows:

[0042] In the present application, the direct measurement of the radio frequency electric field is introduced into the detection process, the atomic energy level displacement is used to sense the weak electric field with high sensitivity, and the light signal is converted for transmission and demodulation, which effectively overcomes the problems of serious signal attenuation and noise interference of traditional electromagnetic induction equipment under deep water or complex geological conditions, and can detect deeper buried or weaker current signal submarine cables. At the same time, the electric field response amplitude and phase information obtained through heterodyne demodulation, combined with the spatial position information, constructs the electric field response data containing multi-dimensional physical characteristics, changes the single criterion mode of relying only on the signal strength peak value for positioning, and by importing the multi-dimensional data into the neural network model for electric field image reconstruction, a more detailed electric field spatial distribution around the cable can be restored, even for sparse measurement points, a continuous pipeline direction can be generated, which significantly improves the accuracy of cable positioning and the continuity of path tracking. BRIEF DESCRIPTION OF DRAWINGS

[0043] Figure 1 The figure is a workflow schematic diagram of the present application;

[0044] Figure 2 The figure is a flowchart of step S1 of the present application;

[0045] Figure 3 Flow chart for step S2 of the present application;

[0046] Figure 4 Flow chart for step S3 of the present application;

[0047] Figure 5 Flow chart for step S4 of the present application;

[0048] Figure 6 Flow chart for step S5 of the present application. DETAILED DESCRIPTION

[0049] In order to make the objects, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and do not limit the present application.

[0050] Please refer to Figure 1 The present application provides a technical solution: a Rydberg electric field meter electromagnetic induction method for submarine underground cable detection, comprising the following steps:

[0051] S1: applying an alternating electric signal to the target pipeline through a transmitting source to generate an electromagnetic radiation signal in the submarine underground metal pipeline, pairing the amplitude of the radiated electromagnetic field signal with the corresponding applied excitation signal frequency to construct a target excitation parameter set;

[0052] S2: exciting the induced current of the submarine underground target detection area through the target excitation parameter set, and measuring the atomic energy level change caused by the alternating electric field to form a transmission electric signal sequence;

[0053] S3: using a light excitation signal group to irradiate an alkali metal vapor cell in the underwater probe to excite the Rydberg state atom to perceive the energy level shift change caused by the radio frequency electric field, and output a perturbation phase data set;

[0054] S4: performing heterodyne conversion and demodulation processing on the transmission electric signal sequence and the perturbation phase data set, binding the three-dimensional spatial position of the underwater probe after heterodyne conversion and demodulation processing with the transmission parameters to form an electric field response spatial data table;

[0055] S5: according to the three-dimensional spatial position of each underwater probe in the electric field response spatial data table, sequentially collecting the amplitude, phase and angle of arrival of the position where the underwater probe is located in the order of position, importing a neural network model to reconstruct an electric field image, and outputting a sequence of metal pipeline direction coordinates;

[0056] The target excitation parameter set includes the radiation electromagnetic field signal amplitude, the excitation signal frequency, the transmission electric signal sequence specifically the atomic energy level change data, the electric field induction characteristic quantity, the signal transmission amplitude, the perturbation phase data set includes the transmission phase change caused by the energy level displacement, the phase drift characteristic, the interference fringe position information, the electric field response space data table specifically the underwater probe spatial coordinates, the electric field response amplitude, the electric field response phase, the electric field response frequency, and the metal pipeline direction coordinate sequence specifically the spatial path of the metal pipeline.

[0057] Please refer to Figure 2 The target excitation parameter set is obtained by the following steps:

[0058] S111: An alternating electric signal with a frequency in the range of 10 kHz to 10 MHz is applied to the target pipeline through the emission source, the instantaneous power waveform sequence generated by the metal pipeline after excitation is collected, the radiation electromagnetic field signal amplitude corresponding to the instantaneous power waveform sequence is calculated, and the excitation frequency response signal amplitude is obtained by combining the calculated radiation electromagnetic field signal amplitude with the current excitation signal frequency.

[0059] The emission source applies a pure sinusoidal alternating electric signal to the target pipeline through a contact probe clamp. The initial signal frequency is 10 kHz. After the signal is applied, the magnetic field induction coil deployed at the predetermined monitoring position of the pipeline starts to collect the electromagnetic field radiated outward by the pipeline after excitation, and converts the sensed magnetic field strength change into a continuous voltage signal. The voltage signal is sampled by an analog-to-digital converter at a sampling rate much higher than the excitation signal frequency, ensuring that the complete form of the voltage waveform is captured without distortion, thereby generating a sequence composed of discrete voltage values arranged in chronological order. Then, the square operation is performed on each voltage value in the sequence to obtain a value sequence proportional to the instantaneous power, which is the instantaneous power waveform sequence. To calculate the radiation electromagnetic field signal amplitude corresponding to the instantaneous power waveform sequence, the part corresponding to at least one complete signal period in the sequence is intercepted, the sum of all instantaneous power proportional values in this part is calculated, and then the average value is obtained by dividing the total number of values. Finally, the square root operation is performed on the average value, and the result is the radiation electromagnetic field signal amplitude. Finally, the calculated radiation electromagnetic field signal amplitude and the current 10 kHz excitation frequency are combined into a data pair to obtain the excitation frequency response signal amplitude.

[0060] S112: Set the frequency adjustment step in the frequency range of 10 kHz to 10 MHz, cyclically adjust the excitation signal frequency output by the emission source, and repeatedly perform signal application and amplitude calculation. Integrate multiple excitation frequency response signal amplitudes obtained under each excitation frequency to establish a multi-frequency point electromagnetic radiation sequence.

[0061] The frequency adjustment step is set in the frequency interval of 10 kHz to 10 MHz. The setting of the step is based on the prior analysis of the pipeline material, diameter and the electromagnetic parameters of the soil medium, which is used to estimate the frequency band where the electromagnetic response peak may occur. In the vicinity of the estimated peak frequency band, a fine frequency adjustment step is set to accurately capture the response change. In the frequency band where the response is flat, a coarse step is set. If there is no prior analysis, a fast sweep with a large step is first performed to find the frequency band where the response amplitude change rate exceeds the preset change threshold. The change threshold is set based on the average fluctuation level higher than the measurement background noise to ensure that the identified change is a significant signal response rather than random noise. Then, a small step is used to perform a detailed scan of the identified frequency band. After setting the step, the frequency of the excitation signal output by the transmission source is adjusted and the signal application and amplitude calculation are repeatedly performed. Specifically, after completing the measurement of the 10 kHz frequency, the excitation frequency is increased by a step value, and the complete signal application, power waveform sequence collection and electromagnetic field signal amplitude calculation are performed again to obtain the new excitation frequency response signal amplitude. This cycle of operation is repeated until the excitation frequency reaches and completes the measurement of the 100 kHz frequency point. Then, the excitation frequency response signal amplitude data obtained at different excitation frequencies are collected to establish a multi-frequency point electromagnetic radiation sequence.

[0062] S113: Call all excitation signal frequencies and corresponding electromagnetic field signal amplitudes in the multi-frequency point electromagnetic radiation sequence, arrange them in numerical order of excitation signal frequencies to form a target excitation parameter set.

[0063] Call the multi-frequency point electromagnetic radiation sequence, which contains unordered data pairs composed of excitation frequencies and corresponding electromagnetic field signal amplitudes. To form the target excitation parameter set, all data pairs in the sequence need to be arranged in numerical order of excitation signal frequencies. The arrangement process is as follows: first, search for the data pair with the lowest frequency value in the sequence and place it as the first element of the new sequence; then, continue to search for the data pair with the lowest frequency value in the remaining data pairs and place it as the second element of the new sequence; repeat the searching and placing process until all data pairs in the original sequence are placed in the new sequence in order of frequency value from low to high. The final ordered data set with monotonically increasing frequency is the target excitation parameter set.

[0064] Please refer to Figure 3 The acquisition step of the transmission electromagnetic signal sequence is as follows:

[0065] S211: Call the target excitation parameter set to excite the induced current of the seabed underground target detection area, use the underwater probe containing sealed alkali metal vapor cell and optical window laid in the target detection area, measure the atomic energy level change caused by alternating electric field, and quantify the transmission light signal output by the atomic transition behavior at the vapor cell window, obtain the atomic transition response light intensity, wherein the underwater probe is filled with rubidium atoms or cesium atoms inside;

[0066] Call the target excitation parameter set, and drive the emission source to apply excitation to the pipeline of the seabed underground target detection area according to the frequency order in the parameter set, and the induced current generated around the pipeline forms an alternating electric field with the same excitation frequency. At this time, the underwater probe starts to work, and the rubidium atoms or cesium atoms filled in the underwater probe will experience the displacement of the inherent atomic energy level when they feel the effect of the external alternating electric field. At the same time, a probe light with a frequency accurately locked on a specific atomic transition spectrum line passes through the vapor cell (the spectrum line is pre-selected according to the type of alkali metal atom used, and the corresponding transition has high sensitivity to external electric field and is easy to realize by a commercial laser). The displacement of the atomic energy level changes the absorption probability of the atomic transition to the probe light, and further changes the transmission light intensity after passing through the vapor cell. The transmission light carrying the atomic transition information, i.e. the atomic transition response light intensity, will be output from the optical window of the underwater probe.

[0067] S212: The atomic transition response light intensity is output from the optical window of the underwater probe, transmitted to the photoelectric detection end through the optical fiber path, the optical signal in the transmission process is continuously monitored, the whole signal form of the optical signal at the photoelectric detection end is recorded, and the optical fiber backhaul optical signal spectrum is obtained;

[0068] The atomic transition response light intensity carrying the atomic transition information is guided out of the optical window of the underwater probe and coupled into an optical fiber connected thereto. The optical signal is transmitted from the seabed to the photoelectric detection end on the sea surface along the optical fiber path. In the photoelectric detection end, a high-sensitivity photodiode detector continuously monitors the optical signal transmitted thereto, and converts the number of received photons into a specific current or voltage value in real time. The data acquisition device records the instantaneous value of the electrical signal output by the photoelectric detector at a fixed high-frequency time interval (the setting standard of the time interval is much smaller than one tenth of the fastest changing period in the measured signal, to ensure that the signal dynamic process is fully sampled). All the signal values recorded in time sequence are collected to depict the complete waveform and spectral characteristics of the signal intensity change with time, so as to obtain the optical fiber backhaul signal spectrum.

[0069] S213: Based on the optical fiber backhaul optical signal spectrum, perform photoelectric conversion processing at the photoelectric detection end to convert the change relationship of the received optical signal intensity with time into the amplitude sequence of the electrical signal, and obtain the transmission electrical signal sequence;

[0070] The process accurately converts the change of light signal intensity over time into the amplitude sequence of the electrical signal, and the specific execution actions are as follows: the light signal in the fiber backhaul optical signal spectrum is first irradiated on the light-sensitive surface of a photomultiplier tube or an avalanche photodiode, the photoelectric device linearly converts the light intensity value at each moment into a current signal with a larger amplitude range through internal multiplication amplification process, then a high-speed analog-to-digital converter samples the continuously changing current signal at equal intervals, converts the current analog quantity at each sampling moment into a binary number with a specific bit width, the bit width of the binary number is determined according to the expected dynamic range of the signal and the required signal-to-noise ratio, so as to maximize the quantization precision without signal clipping, and all the binary numbers arranged in time sequence together constitute the final transmission electrical signal sequence.

[0071] Please refer to Figure 4 The acquisition step of the perturbation phase data set is specifically as follows:

[0072] S311: using the optical excitation signal group, the pump light and the probe light irradiate the alkali metal vapor cell in the underwater probe in turn to excite the alkali metal atoms from the ground state to the excited state and then to the Rydberg state, and form a transmission spectrum;

[0073] Using the optical excitation signal group, the process starts with precisely locking the frequency of the probe laser, and through the saturated absorption spectrum technology, a laser with a wavelength of 780.24 nm is stabilized at the resonance frequency of the transition from the ground state 5S1 / 2 to the intermediate excited state 5P3 / 2 of rubidium (Rb) atom, the intensity of the probe light is maintained at a low level to avoid saturation effect, then the frequency of another strong coupling laser with a wavelength of 480.15 nm is locked at the transition from the intermediate excited state 5P3 / 2 to the target high excited Rydberg state 50D5 / 2, the two lasers are transmitted to the underwater probe through the same polarization maintaining optical fiber, in the alkali metal vapor cell inside the probe, the probe light and the coupling light are accurately spatially overlapped in a counter-propagating manner, forming a three-level ladder atomic system, under the action of the strong coupling light field, quantum interference occurs between the ground state and the Rydberg state, resulting in a narrow-width transmission window, i.e. electromagnetically induced transparency window, in the center of the absorption peak corresponding to the transition from the ground state to the excited state in the absorption spectrum of the probe light, at this time, the atoms are effectively prepared in the coherent dark state, and the absorption of the probe light is suppressed, and the intensity of the probe light passing through the atomic vapor is the transmission spectrum.

[0074] S312: transmitting the transmission spectrum to a photodetector and sampling, acquiring a plurality of time-sequenced transmission spectrum data, extracting a plurality of characteristic parameters of the electromagnetically induced transparency window position, peak shift and Autler-Townes splitting width in the spectrum, and establishing a spectrum response sequence;

[0075] The transmission spectrum signal carrying atomic response information is returned to a photodetector, and is discretely sampled by photoelectric conversion and an analog-to-digital converter at a sampling rate of 1 MS / s to obtain a series of discrete voltage values representing transmission light intensity, i.e. time-series transmission spectrum data, for extracting spectral feature parameters. First, a reference transmission spectrum is obtained by scanning the detection laser frequency under the condition of no external radio frequency electric field, and a Lorentz linear fitting algorithm is applied to the spectrum data to determine the center frequency of the fitted peak as the initial position of the electromagnetically induced transparency window and is stored. When the to-be-detected radio frequency electric field is applied, the transmission spectrum is re-acquired at each sampling time , and the Lorentz linear fitting algorithm is again used to determine the new peak center position , and the peak shift is calculated as At the same time, multi-peak detection is performed on the spectrum data at the current time, specifically, the first derivative and the second derivative of the spectrum data are calculated, the number of peaks is determined according to the correspondence between the zero points of the second derivative and the extreme points of the first derivative, if a single peak is detected, the Autler-Townes splitting width is assigned a value of zero, and if two peaks are detected, a double Lorentz peak fitting function is used to fit the data to analyze the center frequencies of the two sub-peaks and , and the Autler-Townes splitting width is calculated as The electromagnetically induced transparency window position, peak shift, and Autler-Townes splitting width obtained at each time are integrated into a feature vector, and arranged in time sequence to establish a spectrum response sequence.

[0076] S313: Analyze the mapping relationship between each feature parameter in the spectrum response sequence and the atomic energy level shift, calculate the strength and phase of the external electric field, and construct a perturbation phase data set;

[0077] By analyzing the close relationship between the feature parameters and the atomic energy level position at each time point in the optical harmonic response sequence, the internal correlation of the electric field action item is obtained, the peak shift of the electromagnetically induced transparency window is converted into a delta-level quantitative quantity, which is positively correlated with the average value of the external electric field, and the index phase position generated by the external electric field is explained by frequency detection technology. The phase information of the to-be-detected microwave signal is obtained by referring to the local oscillator signal. The optical signal (microwave band) given by the local oscillator is mixed with the to-be-detected microwave signal at a near same frequency. The intensity of the mixed microwave signal carries the phase difference of the to-be-detected signal (compared to the local signal). The signal carrying the phase difference information is converted into an electrical signal by a photodetector, and then subjected to subsequent processing. According to the in-phase component and the quadrature component The following phase analysis function is called to calculate the value of the perturbation phase change: ,in, To be at the sampling time Radiated electric field of submarine cables The perturbation phase caused by this perturbation, demodulated in the atomic ensemble response, is the core parameter to be solved. (The letter is...) Represents the phase angle, subscript This indicates that the phase is induced by an external electric field, as specified in parentheses. This indicates that the phase is time. The function corresponds to each discrete sampling time point in step S312 when the time-series spectral data is acquired. The amplitude of the in-phase component signal is represented by the letter. Represents signal, subscript Representing in-phase, it is obtained by directly mixing the electrical signal output from the photodetector with the reference local oscillator signal, and then passing it through a low-pass filter to obtain a DC or slowly varying voltage signal. The amplitude of the quadrature component signal is indicated by the subscript. The orthogonality is represented by the following method: the electrical signal output from the photodetector is mixed with a reference local oscillator signal that has undergone a 90-degree phase shift, and then the result is a voltage signal obtained by passing it through a low-pass filter. The arctangent function is calculated based on the x-coordinate of a point in a rectangular coordinate system. ) and ordinate ( Calculate the angle between the line connecting this point and the origin along the positive horizontal axis. This angle is used here to recover the phase information of the original signal from two mutually orthogonal signal components, at a given sampling time. For example, after mixing and low-pass filtering, the actual measured amplitude of the in-phase component signal... The amplitude of the quadrature component signal is 0.351V. The value is 0.192V. Substituting the measured value into the phase analysis function, the calculation is performed first. and The ratio: Then, an arctangent operation is performed on this ratio to solve for the phase angle: The advantage of the rad formula is that by performing orthogonal demodulation in classical signal processing on the optical readout signal of the atomic quantum state, the direct measurement of the phase of the weak electric field is transformed into the measurement of two DC voltage components. This phase analysis function is repeatedly executed on the spectral response sequence data at each sampling time point to generate a series of discrete perturbation phase change values ​​and construct a perturbation phase dataset.

[0078] Please see Figure 5 The specific steps for obtaining the electric field response spatial data table are as follows:

[0079] S411: Call the transmission electric signal sequence and the perturbation phase data set, mix the transmission electric signal sequence with a local reference signal source to construct a heterodyne detection channel, and demodulate the processed signal and the perturbation phase data set to extract the electric field response amplitude and the electric field response phase of each underwater probe at the excitation frequency, and obtain the demodulation transmission component;

[0080] First, a local reference signal source is enabled, and the signal source generates a sinusoidal electric signal with a fixed difference higher than the current excitation signal frequency. The fixed difference is selected according to the need to move the signal to a low-noise frequency band, and the frequency needs to be low enough for subsequent digital filtering processing, and high enough to avoid the zero-frequency drift area of the sensor, for example, one kilohertz

[0081] Then, heterodyne conversion and demodulation processing are performed. The processing process is as follows: first, the transmission electric signal sequence from the photoelectric conversion module and the sinusoidal electric signal from the local reference signal source are simultaneously input to two ports of an electronic mixer. The electronic mixer multiplies the instantaneous voltage values of the two input signals. According to the product rule of trigonometric functions, the output signal will contain two new frequency components: one is the sum of the input signal frequency and the local reference signal frequency (sum frequency), and the other is the difference between the two frequencies (difference frequency), and the frequency of the difference frequency is one kilohertz. Thus, the heterodyne conversion is completed. Then, demodulation is performed. The output signal of the mixer is sent to a low-pass filter, and the cutoff frequency of the filter is set to a value slightly higher than one kilohertz, for example, one thousand one hundred hertz. This setting ensures that the difference frequency signal with a frequency of one kilohertz can pass without attenuation, while the sum frequency component and other high-frequency noise with a frequency much higher than this are effectively filtered out. After filtering, only the difference frequency signal with a frequency of one kilohertz carrying the original signal amplitude information is retained. Finally, the pure difference frequency signal is envelope detected. The envelope detector extracts the slow change profile of the difference frequency signal amplitude through a fast-response rectifier circuit and a slow-response smoothing filter circuit. This profile is the transmission electric signal amplitude response value at the excitation frequency. At the same time, the instantaneous phase value completely matched with the current demodulation time point is found and extracted from the perturbation phase data set. Finally, the transmission electric signal amplitude response value and the instantaneous phase value are combined as a data pair to obtain the demodulation transmission component.

[0082] S412: Obtain the three-dimensional spatial position information of each underwater probe, and according to the demodulation transmission component, pair the position information of each probe with the corresponding transmission electric signal amplitude response value and instantaneous phase value, bind the position information with the transmission parameters, and generate position-bound transmission parameters.

[0083] The acoustic positioning base station network deployed in the detection area transmits acoustic inquiry signals to each underwater probe and receives its response signals, calculates the three-dimensional spatial position information of each underwater probe relative to the preset seabed coordinate system origin according to the signal propagation time difference, and achieves a high precision sufficient to analyze the small changes in the pipeline path. According to the demodulated transmission component obtained in the previous step, the three-dimensional spatial position information of each probe is paired with the amplitude response value and instantaneous phase value of the transmission electric signal demodulated from the probe signal. The specific pairing operation is to create a data record containing five fields: three fields for storing the x, y, z coordinate values of the probe, and the other two fields for storing the corresponding transmission electric signal amplitude response value and instantaneous phase value. By generating such a data record for each probe, the position information and transmission parameters are bound, and the position-bound transmission parameters are generated.

[0084] S413: According to the position-bound transmission parameters of all underwater probes, the three-dimensional spatial position and transmission parameters of the underwater probes after frequency conversion and demodulation processing are bound to form an electric field response spatial data table.

[0085] According to the position-bound transmission parameters of all underwater probes, these scattered data records are summarized and arranged. The specific operation is to initialize a structured data collection through a data processing program. The logical structure of the collection is a two-dimensional table, and the column headers are predefined as: probe ID, X coordinate, Y coordinate, Z coordinate, amplitude response, and phase response. The program then iterates through all the position-bound transmission parameter records generated in the previous step. For each probe record, the program reads the five core data (x, y, z coordinates, amplitude, and phase) it contains and creates a new row in the table, filling these data into the corresponding columns one by one. This process is executed in a loop until all probe data is added. In this way, the originally scattered data records, which are based on individual probes, are integrated into a single, structured data table. Each row in the table completely describes the full information of a spatial detection point. This collection closely associates the geometric position information of all probes with the measured electric field response physical quantities, forming an electric field response spatial data table that comprehensively describes the distribution characteristics of the electric field in space.

[0086] Please refer to Figure 6 The steps for obtaining the coordinate sequence of the metal pipeline are as follows:

[0087] S511: Collect the amplitude, phase, and arrival angle between the electromagnetic wave incident direction and the internal reference direction of the sensor at the spatial position of each underwater probe in the electric field response spatial data table. Combine the amplitude, phase, and arrival angle corresponding to each probe to construct an input sample vector set.

[0088] The acquisition of the angle of arrival is achieved by setting a miniaturized three-axis orthogonal magnetic field antenna array inside each probe, by comparing the amplitudes and phase differences of the signals received by different axial antennas, and by analyzing the azimuth and elevation angles between the incident direction of the electromagnetic wave and the preset reference coordinate axis inside the probe. The four values of amplitude, phase, azimuth and elevation corresponding to each probe are combined to form a four-dimensional vector. The four-dimensional vectors generated by all the probes are collected together to form an input sample vector set for subsequent processing.

[0089] S512: importing the data in the input sample vector set into a neural network model to reconstruct an electric field image, and performing image interpolation on the spatial regions in the image with a sampling interval greater than 10 cm to complete the signals between the sparse measurement points and obtain a complete reconstructed electric field image;

[0090] The data in the input sample vector set is imported into a pre-trained deep neural network model to reconstruct an electric field image. The neural network model adopts an encoder-decoder structure, and its training data set is a preset library generated by a large number of finite element simulation calculations on the electromagnetic field distribution of various possible pipeline routes, depths and materials in a simulated seabed environment. On the model structure, the encoder is composed of a series of convolutional layers and pooling layers, which are used to compress and extract deep spatial feature maps from the input sparse probe data vector. The decoder is composed of a series of deconvolutional layers (or transpose convolutional layers) and up-sampling layers, which gradually enlarge the feature maps output by the encoder and restore them to the complete grid resolution of the target three-dimensional space. A skip connection is provided between the encoder and the decoder to pass the feature maps of the shallow layers of the encoder directly to the corresponding layers of the decoder to preserve fine electric field details. When the model is executed, the input sample vector set is fed into the encoder for forward propagation, and then the decoder performs up-sampling and feature fusion after feature extraction and compression. Finally, a complete reconstructed electric field image is output, in which each point on the fine three-dimensional grid has a predicted electric field strength value. Subsequently, image interpolation is performed on the regions between any two adjacent valid data points in the image with a distance greater than the preset target spatial resolution. The interpolation process is based on the physical laws of electromagnetic fields, and the Laplace equation or the Helmholtz equation between the measurement points is solved to complete the signals between the sparse measurement points, thereby obtaining a complete reconstructed electric field image.

[0091] S513: identifying a response region in the complete reconstructed electric field image where the electric field strength is higher than a preset discrimination threshold, aggregating the coordinates of all the spatial reconstruction data in the response region, arranging the aggregated coordinate points in order, and outputting the coordinate sequence of the pipeline route, wherein the process of aggregating the coordinates of all the spatial reconstruction data in the response region is specifically to calculate the geometric center points of the response region on multiple cross sections, and connect the coordinates of all the geometric center points to form the coordinate sequence of the pipeline route;

[0092] The identification process is to first count all the electric field intensity values in the complete reconstructed electric field map, calculate the mean and standard deviation, and set the electric field intensity threshold to the value of the mean plus three times the standard deviation. This setting is based on the 3-sigma principle of normal distribution, which can separate abnormal strong signal regions from background noise with high confidence. All continuous spatial voxels with electric field intensity values exceeding this threshold are aggregated to form a three-dimensional response region. Then, the coordinates of all spatial reconstruction data in the response region are aggregated. The aggregation process is as follows: first, determine the approximate extension direction of the response region as the main axis, then generate a series of two-dimensional cross sections at a fixed interval perpendicular to the main axis. The interval setting should be less than the minimum expected curvature radius of the pipeline path to ensure that no curved part of the pipeline is missed. For each cross section, calculate the geometric center point coordinates of all voxels in the intersection part of the response region and the cross section. The calculation is performed by the formula where represents the three-dimensional coordinates of the geometric center point on the th cross section, which is a point in the final pipeline orientation coordinate sequence; is the index counted for all cross sections, starting from 1 and increasing; represents the total number of voxels with field strength values higher than the preset field strength threshold in the th cross section; is the index counted for the th cross section; is the summation symbol, indicating the cumulative addition of the coordinate components of all high-field-strength voxels from the 1st to the th in the th cross section; , , , , , , After filtering by the field strength threshold, it was found that the field strength values ​​of 3 spatial voxels within this cross-section exceeded the threshold, therefore the total number of voxels was [not specified]. The value is 3. These three high-field-strength voxels completely reconstruct the electric field. Figure Three The coordinates in the 1D space grid are as follows: voxel 1 ( ):( , , ) = (25.2, 80.5, -15.4), voxel 2 ( ):( , , =(24.9, 80.5, -15.7), voxel 3 ( ):( , , = (25.5, 80.5, -15.6). Second step: Summate the x, y, and z coordinate components separately: Sum of x coordinates = The sum of the y-coordinates = The sum of the z coordinates = Step 3: Divide the sum of each component by the total number of voxels. Center point x-coordinate = The y-coordinate of the center point = The z-coordinate of the center point = Calculate the coordinates of the geometric center point of the 8th cross-section. The coordinates are (25.2, 80.5, -15.57). This coordinate point is considered as an estimate of the center position of the pipeline on the cross-section and is added to the coordinate sequence of the pipeline's orientation.

[0093] A Rydberg electric field meter electromagnetic induction method submarine underground cable detection system, used to perform the aforementioned Rydberg electric field meter electromagnetic induction method for submarine underground cable detection, the system includes:

[0094] The alternating excitation parameter construction module applies an alternating electrical signal to the target pipeline through a transmitter, causing electromagnetic radiation signals to be generated in the underground metal pipeline on the seabed. The amplitude of the radiated electromagnetic field signal is matched with the frequency of the corresponding applied excitation signal to construct the target excitation parameter set.

[0095] The transmission electrical signal acquisition module excites the induced current in the seabed subsurface target detection area through the target excitation parameter set, and uses underwater probes deployed in the target detection area to measure the changes in atomic energy levels caused by the alternating electric field, forming a transmission electrical signal sequence;

[0096] The atomic level sensing module irradiates the alkali metal vapor cell in the underwater probe with a light excitation signal group, excites the Rydberg state atom to sense the energy level displacement change caused by the radio frequency electric field, and outputs a perturbation phase data set;

[0097] The electric field response data processing module performs heterodyne conversion and demodulation processing on the transmission electric signal sequence and the perturbation phase data set, binds the three-dimensional spatial position of the underwater probe after heterodyne conversion and demodulation processing and the transmission parameter, and forms an electric field response spatial data table;

[0098] The electric field image reconstruction module obtains the amplitude, phase and angle of arrival of the spatial position of each underwater probe in the electric field response spatial data table as an input sample vector, imports a neural network model to reconstruct an electric field image, and outputs a sequence of metal pipeline direction coordinates.

[0099] The above is only a preferred embodiment of the present application, and is not intended to limit the present application in other forms. Any skilled person in the art can modify or change the above disclosed technical content to equivalent embodiments applied to other fields, but any simple modification, equivalent change and modification made on the basis of the technical essence of the present application to the above embodiments without departing from the technical solution content of the present application shall still fall within the protection scope of the present application.

Claims

1. A method for detecting submarine underground cables using electromagnetic induction with a Rydberg electric field meter, characterized in that... Includes the following steps: S1: By applying an alternating electrical signal to the target pipeline through the transmitter, electromagnetic radiation signals are generated in the underground metal pipeline on the seabed. The amplitude of the radiated electromagnetic field signal is matched with the frequency of the corresponding applied excitation signal to construct a target excitation parameter set. S2: The target excitation parameter set is used to excite the induced current in the seabed subsurface target detection area, and the changes in atomic energy levels caused by the alternating electric field are measured to form a transmission electrical signal sequence; S3: Use the optical excitation signal group to irradiate the alkali metal vapor pool in the underwater probe to excite the Rydberg state atoms to sense the energy level shift caused by the radio frequency electric field and output the perturbation phase data set. S4: Perform frequency conversion and demodulation processing on the transmitted electrical signal sequence and the disturbance phase dataset, and bind the three-dimensional spatial position of the underwater probe after frequency conversion and demodulation processing with the transmission parameters to form an electric field response spatial data table. S5: Based on the three-dimensional spatial position of each underwater probe in the electric field response spatial data table, the amplitude, phase and angle of arrival of the underwater probe are collected in sequence according to the position order, imported into the neural network model to reconstruct the electric field image, and output the direction coordinate sequence of the metal pipeline. The specific steps for obtaining the routing coordinate sequence of the metal pipeline are as follows: S511: Collect the amplitude, phase, and angle of arrival between the incident direction of the electromagnetic wave and the internal reference direction of the sensor for each underwater probe in the electric field response spatial data table; combine the amplitude, phase, and angle of arrival for each probe to construct an input sample vector set. S512: Import the data in the input sample vector set into the neural network model to reconstruct the electric field image, and perform image interpolation on the spatial region with a sampling interval greater than 10 cm in the image to complete the signal between sparse measurement points and obtain a complete reconstructed electric field image. S513: Identify the response region of the continuous metal pipeline where the electric field strength in the complete reconstructed electric field map is higher than the preset discrimination threshold, aggregate the coordinates of all spatial reconstruction data in the response region, arrange the aggregated coordinate points in order, and output the direction coordinate sequence of the metal pipeline. Specifically, the process of coordinate aggregation of all spatial reconstruction data within the response area involves calculating the geometric center points of the response area on multiple cross-sections and connecting the coordinates of all geometric center points to form the direction coordinate sequence of the metal pipeline. The specific calculation formula is as follows: ； In the formula, Representing the The three-dimensional coordinates of the geometric center point on each cross section; It is an index that counts all cross sections; Indicates the first Within a cross-section, the total number of voxels whose field strength values ​​are higher than the preset field strength discrimination threshold; It is in the Inside the cross-section, for this An index for counting individual units; Representing respectively in the The first cross-section Three-dimensional spatial coordinates of a high field strength voxel , , Quantity.

2. The method for detecting submarine underground cables using the electromagnetic induction method with a Rydberg electric field meter according to claim 1, characterized in that, The target excitation parameter set includes the amplitude of the radiated electromagnetic field signal and the frequency of the excitation signal. The transmitted electrical signal sequence specifically includes atomic energy level change data, electric field induction characteristic quantities, and signal transmission amplitude. The perturbation phase dataset includes the transmission phase change caused by energy level displacement, phase drift characteristics, and interference fringe position information. The electric field response spatial data table specifically includes the underwater probe spatial coordinates, electric field response amplitude, electric field response phase, and electric field response frequency. The direction coordinate sequence of the metal pipeline specifically represents the spatial path of the metal pipeline.

3. The method for detecting submarine underground cables using electromagnetic induction with a Rydberg electric field meter according to claim 1, characterized in that, The specific steps for obtaining the target excitation parameter set are as follows: S111: Apply an alternating electrical signal with a frequency range of 10kHz to 10MHz to the target pipeline through the transmitter, collect the instantaneous power waveform sequence generated by the metal pipeline after excitation, calculate the amplitude of the radiated electromagnetic field signal corresponding to the instantaneous power waveform sequence, and combine it with the frequency of the currently applied excitation signal to obtain the amplitude of the excitation frequency response signal. S112: Set the frequency adjustment step size in the frequency range of 10kHz to 10MHz, cyclically adjust the frequency of the excitation signal output by the transmitter source and repeatedly perform signal application and amplitude calculation, integrate the amplitude values ​​of multiple excitation frequency response signals obtained at each excitation frequency, and establish a multi-frequency electromagnetic radiation sequence. S113: Call up all excitation signal frequencies and corresponding radiated electromagnetic field signal amplitudes in the multi-frequency electromagnetic radiation sequence, arrange them in numerical order according to the excitation signal frequencies, and form a target excitation parameter set.

4. The method for detecting submarine underground cables using electromagnetic induction with a Rydberg electric field meter according to claim 3, characterized in that, The specific steps for obtaining the transmitted electrical signal sequence are as follows: S211: The target excitation parameter set is called to excite the induced current in the seabed underground target detection area. The underwater probe with a sealed alkali metal steam pool and an optical window is deployed in the target detection area to measure the atomic energy level changes caused by the alternating electric field. The transmitted light signal output by the atomic transition behavior in the steam pool window is quantified to obtain the atomic transition response light intensity. S212: The intensity of the atomic transition response light is output from the optical window of the underwater probe and transmitted to the photoelectric detection end through the optical fiber path. The optical signal is continuously monitored during the transmission process, and all signal forms of the optical signal at the photoelectric detection end are recorded to obtain the optical fiber back-transmitted optical signal spectrum. S213: Based on the optical signal spectrum transmitted back through the optical fiber, photoelectric conversion processing is performed at the photoelectric detection end to convert the change relationship of the received optical signal intensity over time into an amplitude sequence of electrical signals, thereby obtaining a transmission electrical signal sequence.

5. The method for detecting submarine underground cables using the electromagnetic induction method with a Rydberg electric field meter according to claim 4, characterized in that, The underwater probe is filled with rubidium or cesium atoms.

6. The method for detecting submarine underground cables using the electromagnetic induction method with a Rydberg electric field meter according to claim 4, characterized in that, The specific steps for obtaining the perturbation phase dataset are as follows: S311: Using an optical excitation signal group, the pump light and the probe light are used to irradiate the alkali metal vapor cell in the underwater probe, which sequentially excites the alkali metal atoms to transition from the ground state to the excited state and then to the Rydberg state, forming a transmission spectrum; S312: The transmission spectrum is transmitted to the photodetector and sampled to obtain multiple time-series transmission spectrum data. Multiple characteristic parameters such as the position of the electromagnetic induction transparent window, peak shift, and Autler-Townes split width in the spectrum are extracted to establish a spectral response sequence. S313: Analyze the mapping relationship between each characteristic parameter in the spectral response sequence and the atomic energy level displacement, calculate the intensity and phase of the external electric field, and construct a perturbation phase dataset.

7. The method for detecting submarine underground cables using electromagnetic induction with a Rydberg electric field meter according to claim 6, characterized in that, The specific steps for obtaining the electric field response spatial data table are as follows: S411: Call the transmitted electrical signal sequence and the disturbance phase dataset, use a local reference signal source to perform frequency mixing processing on the transmitted electrical signal sequence to construct a different frequency detection path, and perform demodulation on the processed signal and the disturbance phase dataset to extract the electric field response amplitude and electric field response phase of each underwater probe at the excitation frequency to obtain the demodulated transmission component. S412: Acquire the three-dimensional spatial position information of each underwater probe, and according to the demodulated transmission components, pair the position information of each probe with the corresponding amplitude response value and instantaneous phase value of the transmission electrical signal, bind the position information with the transmission parameters, and generate position-bound transmission parameters. S413: Based on the positions of all underwater probes, bind the transmission parameters and the three-dimensional spatial positions of the underwater probes after frequency conversion and demodulation processing to form an electric field response spatial data table.

8. A Rydberg electric field meter electromagnetic induction method for detecting submarine underground cables, used to implement the Rydberg electric field meter electromagnetic induction method for detecting submarine underground cables as described in any one of claims 1-7, characterized in that, The system includes: The alternating excitation parameter construction module applies an alternating electrical signal to the target pipeline through a transmitter, causing electromagnetic radiation signals to be generated in the underground metal pipeline on the seabed. The amplitude of the radiated electromagnetic field signal is matched with the frequency of the corresponding applied excitation signal to construct the target excitation parameter set. The transmission electrical signal acquisition module excites the induced current in the seabed subsurface target detection area through the target excitation parameter set, and uses underwater probes deployed in the target detection area to measure the changes in atomic energy levels caused by the alternating electric field, forming a transmission electrical signal sequence. The atomic energy level sensing module uses a group of optical excitation signals to irradiate the alkali metal vapor pool in the underwater probe, which excites the energy level shift caused by the radio frequency electric field of the Rydberg state atoms and outputs a perturbation phase dataset. The electric field response data processing module performs frequency conversion and demodulation processing on the transmitted electrical signal sequence and the disturbance phase dataset, and binds the three-dimensional spatial position of the underwater probe after frequency conversion and demodulation processing with the transmission parameters to form an electric field response spatial data table. The electric field image reconstruction module obtains the amplitude, phase, and angle of arrival of each underwater probe in the electric field response spatial data table, and imports them as input sample vectors into the neural network model to reconstruct the electric field image, outputting the direction coordinate sequence of the metal pipeline.

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