A method for spatial position calibration of underwater optical cables based on distributed optical fiber sensing

Abstract

The present invention discloses a method for calibrating the spatial position of an underwater optical cable based on distributed optical fiber sensing, comprising: driving a calibration vessel into a water area to be measured to carry out activities, using a satellite positioning system to record the vessel's travel trajectory, and simultaneously using distributed optical fiber sensing equipment to obtain acoustic wave signals at various positions along the underwater optical cable; obtaining a spatiotemporal information distribution map containing time domain information; extracting specific frequency acoustic wave signals generated by the vessel's activities; obtaining a spatiotemporal spectrum energy integral map containing frequency domain information; combining water depth and calibration vessel information to achieve a relationship mapping between energy value and the distance between the vessel and the underwater optical cable, performing vessel trajectory correspondence at various positions along the underwater optical cable, and achieving spatial position calibration of the underwater optical cable. The method can achieve spatial position calibration of the underwater optical cable, has high efficiency, high positioning accuracy, low cost, and can perform real-time monitoring and analysis.

Description

Technical Field

[0001] The present invention belongs to the field of optical fiber sensing technology, and specifically relates to a method for calibrating the spatial position of an underwater optical cable based on distributed optical fiber sensing, thereby realizing the monitoring of the underwater optical cable laying status and ships in nearby waters. Background Art

[0002] With the development of the global internet, countries are increasingly demanding higher efficiency and speed in information transmission. To meet this demand, underwater optical cables have become ubiquitous in oceans and waterways worldwide. Despite their advantages, such as high bandwidth, reliability, and durability, the shifting position of underwater optical cables due to ocean currents and geological activity is a major concern for monitoring their condition. Three primary factors influence the shifting position of underwater optical cables: natural factors such as geological activity and ocean currents, human factors such as drag from fishing vessels, and biological factors such as the activity of fish on the seabed. Although the seabed environment is relatively stable, these factors are frequent and unpredictable, making the calibration of underwater optical cable positions difficult and complex.

[0003] Overcoming calibration difficulties requires on-site surveys by professionals, which is costly and challenging. Currently, the main methods for calibrating the location of underwater optical cables include side-scan sonar and magnetometry. Side-scan sonar emits sideways sound waves to detect the acoustic structure and dielectric properties of the seabed. It is suitable for detecting optical cables or pipelines laid on the seabed surface, and can select specific frequencies to avoid interference from other structures or signal sources. However, due to the limited propagation of sound waves, it cannot be used to detect optical cables buried in the seabed where the trench structure has been eroded and difficult to identify. Magnetometry, a detection method that uses the magnetic differences between rock and minerals, detects the magnetic difference between the submarine optical cable and the surrounding seabed environment, which can be visualized as magnetic anomalies, thereby calibrating the cable's location. Magnetic measurement technology is unaffected by trench structures and can detect buried optical cables. However, interference from metal objects such as anchor chains and fishing gear can produce erroneous peaks. Furthermore, the cost of currently used magnetometers is relatively high, requiring specialized techniques such as differential positioning and underwater real-time positioning to ensure measurement accuracy.

[0004] In summary, due to the randomness of external influences and the complexity of the underwater environment, the existing underwater optical cable spatial calibration methods have problems such as high cost, complex methods, and susceptibility to environmental influences. New solutions are needed to improve calibration efficiency and accuracy. Summary of the Invention

[0005] Technical problem solved: The present invention discloses a method for calibrating the spatial position of an underwater optical cable based on distributed optical fiber sensing. The method realizes the spatial position calibration of the underwater optical cable through the cooperation of a vessel and distributed optical fiber sensing equipment. The method solves the technical problems of the existing underwater optical cable spatial calibration method, such as high cost, complex method, and susceptibility to environmental influences.

[0006] Technical solution:

[0007] A method for calibrating the spatial position of an underwater optical cable based on distributed optical fiber sensing, the method comprising the following steps:

[0008] S1, connect the distributed optical fiber sensing equipment to the underwater optical cable in the water area to be measured;

[0009] S2: The calibration vessel is driven into the waters to be measured, and the vessel's trajectory is recorded using a satellite positioning system. At the same time, distributed fiber optic sensing equipment is used to obtain acoustic wave signals at various locations along the underwater optical cable.

[0010] S3, performing phase demodulation on the original signal collected by the distributed optical fiber sensing device, restoring the time domain waveform information at each position along the underwater optical cable, and obtaining a spatiotemporal information distribution map containing the time domain information;

[0011] S4, performing spectrum feature analysis on the spatiotemporal information distribution map, comparing it with underwater background noise, extracting a specific frequency sound wave signal generated by the vessel activity, comparing the specific frequency sound wave signal with the vessel's trajectory, and determining whether the specific frequency sound wave signal is related to the vessel activity;

[0012] S5, performing short-time spectrum analysis on the signals at various locations on the underwater optical cable, performing noise suppression on the frequency domain of the extracted acoustic wave signals of specific frequencies generated by vessel activity, and performing frequency domain energy integration on the specific frequencies to obtain a spatiotemporal spectrum energy integral graph containing frequency domain information;

[0013] S6, the time-space spectrum energy integral map is matched with the ship's trajectory, the signal energy at each position of the underwater optical cable is used as a weight, and different energy value ranges are mapped into the same range to achieve energy value normalization;

[0014] S7, combining the water depth and calibration ship information, realizes the relationship mapping between the energy value and the distance between the ship and the underwater optical cable, and corresponds the ship trajectory at each position along the underwater optical cable to realize the spatial position calibration of the underwater optical cable.

[0015] Furthermore, in step S2, the calibration vessel performs calibration in a grid-like route in the underwater optical cable laying water area.

[0016] Furthermore, in step S2, for the water area where the approximate direction of the underwater optical cable is known, the calibration vessel repeatedly passes over the top to form weak-strong-weak changes at various positions of the underwater optical cable.

[0017] Furthermore, the calibration ship carries a transducer, and when the ship is moving, the transducer continuously outputs a sound wave signal with a single frequency and stable sound pressure amplitude as a standard detection signal.

[0018] Furthermore, the frequency and intensity of the sound wave signal continuously output by the transducer are related to the ecological environment of the water area to be measured and the low-frequency background noise of the ocean.

[0019] Furthermore, for an underwater optical cable having a length greater than a preset length threshold, the characteristic frequency of the transducer after folding is detected, and the characteristic frequency after folding is greater than a preset frequency threshold of background noise; the relationship between the specific high frequency of the transducer and the specific frequency after folding is:

[0020] f actual =f observed +mf k

[0021] Where, f actual is the characteristic signal frequency actually released by the transducer, f actual is the characteristic signal frequency detected by the distributed optical fiber sensing system, m is an integer not less than 0, f k is the sampling rate of the system.

[0022] Furthermore, in step S4, the specific frequency sound wave signal is compared with the ship's trajectory, and the sound wave signals at the same location and different times are compared to determine whether the specific frequency sound wave signal belongs to the ocean background noise.

[0023] Furthermore, in step S7, the relationship between the energy value and the distance between the ship and the underwater optical cable is mapped in combination with the water depth and the calibration ship information, and the ship trajectory is mapped to each position along the underwater optical cable. The process of achieving the spatial position calibration of the underwater optical cable includes the following steps:

[0024] The trajectory data is matched with the time-space spectrum energy integral diagram, and the turning points of the ship trajectory are mapped on the distance axis and time axis. The energy maximum position is located. When the calibration ship passes directly above the underwater optical cable, the energy value is the largest.

[0025] Obtain the calibration ship's trajectory and time information, and combine it with the water depth and energy maximum position information to achieve a mapping of the energy value and the distance between the ship and the underwater optical cable;

[0026] According to the energy-distance mapping relationship, the ship trajectory is matched at each position along the underwater optical cable, and the corresponding distance is calculated.

[0027] The present invention also discloses a ship position calibration method based on distributed optical fiber sensing, which includes the following steps:

[0028] Connecting a distributed optical fiber sensing device with a known underwater optical cable spatial position to the underwater optical cable in the water area to be measured;

[0029] The vessel to be tested is driven into the waters to be tested and distributed optical fiber sensing equipment is used to obtain acoustic wave signals at various locations along the underwater optical cable.

[0030] Phase demodulation is performed on the original signal collected by the distributed optical fiber sensing equipment to restore the time domain waveform information at each position along the underwater optical cable, and a time-space information distribution map containing time domain information is obtained;

[0031] Perform spectrum feature analysis on the spatiotemporal information distribution map, compare it with the underwater background noise, and extract the specific frequency sound wave signals generated by ship activities;

[0032] Perform short-time spectrum analysis on the signals at various locations on the underwater optical cable, extract the specific frequency acoustic signals generated by ship activity, perform noise suppression in the frequency domain, and perform frequency domain energy integration on the specific frequencies to obtain a time-space spectrum energy integral diagram containing frequency domain information.

[0033] The time-space spectrum energy integral diagram is matched with the spatial position of the underwater optical cable, and the signal energy at each position of the underwater optical cable is used as the weight to map different energy value ranges into the same range to achieve energy value normalization.

[0034] Combining the water depth and calibration ship information, the relationship between the energy value and the distance between the ship and the underwater optical cable is mapped, and the ship trajectory is matched according to the spatial position of the underwater optical cable to realize the ship position calibration.

[0035] Beneficial effects:

[0036] First, the method for calibrating the spatial position of an underwater optical cable based on distributed optical fiber sensing of the present invention uses distributed optical fiber sensing equipment as a monitoring device, an underwater optical cable as a sensing body, and a calibration ship as an excitation source, which can realize the spatial position calibration of the underwater optical cable, with high efficiency, high positioning accuracy, low cost, and real-time monitoring and analysis.

[0037] Second, the ship position calibration method based on distributed fiber optic sensing of the present invention can monitor the hydrological conditions near the underwater optical cable that has completed position calibration, and can also realize the rapid identification and positioning of surface ships in combination with distributed fiber optic sensing equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 A schematic diagram of a monitoring scenario according to an embodiment of the present invention;

[0039] Figure 2 A calibration vessel trajectory diagram according to an embodiment of the present invention;

[0040] Figure 3 This is a flow chart of a method for calibrating the spatial position of an underwater optical cable based on distributed optical fiber sensing according to an embodiment of the present invention;

[0041] Figure 4 2. It is a schematic diagram of the distribution of spatiotemporal information obtained by the underwater optical cable according to an embodiment of the present invention;

[0042] Figure 5 1 is a schematic diagram of the short-time spectrum at a position of 100 m of the underwater optical cable according to an embodiment of the present invention;

[0043] Figure 6 1 is a schematic diagram of the temporal and spatial information distribution of an underwater optical cable at a specific frequency according to an embodiment of the present invention;

[0044] Figure 7 7 is a diagram showing the time-space spectrum energy integration of an underwater optical cable according to an embodiment of the present invention;

[0045] Figure 8 2 is a schematic diagram of the spatial position calibration result of the underwater optical cable according to an embodiment of the present invention. DETAILED DESCRIPTION

[0046] The following examples may enable those skilled in the art to more fully understand the present invention, but are not intended to limit the present invention in any way.

[0047] This embodiment discloses a method for calibrating the spatial position of an underwater optical cable based on distributed optical fiber sensing, which includes the following steps:

[0048] S1, connect the distributed optical fiber sensing equipment to the underwater optical cable in the water area to be measured;

[0049] S2: The calibration vessel is driven into the waters to be measured, and the vessel's trajectory is recorded using a satellite positioning system. At the same time, distributed fiber optic sensing equipment is used to obtain acoustic wave signals at various locations along the underwater optical cable.

[0050] S3, performing phase demodulation on the original signal collected by the distributed optical fiber sensing device, restoring the time domain waveform information at each position along the underwater optical cable, and obtaining a spatiotemporal information distribution map containing the time domain information;

[0051] S4, performing spectrum feature analysis on the spatiotemporal information distribution map, comparing it with underwater background noise, extracting a specific frequency sound wave signal generated by the vessel activity, comparing the specific frequency sound wave signal with the vessel's trajectory, and determining whether the specific frequency sound wave signal is related to the vessel activity;

[0052] S5, performing short-time spectrum analysis on the signals at various locations on the underwater optical cable, performing noise suppression on the frequency domain of the extracted acoustic wave signals of specific frequencies generated by vessel activity, and performing frequency domain energy integration on the specific frequencies to obtain a spatiotemporal spectrum energy integral graph containing frequency domain information;

[0053] S6, the time-space spectrum energy integral map is matched with the ship's trajectory, the signal energy at each position of the underwater optical cable is used as a weight, and different energy value ranges are mapped into the same range to achieve energy value normalization;

[0054] S7, combining the water depth and calibration ship information, realizes the relationship mapping between the energy value and the distance between the ship and the underwater optical cable, and corresponds the ship trajectory at each position along the underwater optical cable to realize the spatial position calibration of the underwater optical cable.

[0055] The following example illustrates the principle of the method for calibrating the spatial position of an underwater optical cable based on distributed optical fiber sensing. It should be understood that the data such as the underwater optical cable or the ship's acoustic wave signal in this example is not limited, as long as it meets the basic requirements of the method described in this embodiment.

[0056] The monitoring scenario and monitoring solution of this embodiment are as follows Figure 1 As shown in the figure, the distributed sensing equipment uses the DAS system and is installed in the shore-side machine room. The length of the underwater optical cable is 1 km. The calibration ship moves in the water area where the underwater optical cable is laid. The calibration movement trajectory is as follows: Figure 2 As shown by the solid line, the process of underwater optical cable spatial position calibration method is as follows: Figure 3 The specific process is as follows:

[0057] Step 1: Connect the DAS system to the underwater optical cable in the water area to be measured. The system pulse repetition frequency is set to 5km, the monitoring distance is 1km, and the spatial resolution is 10m; obtain the acoustic wave signal at each position along the underwater optical cable.

[0058] Step 2: A calibration vessel, capable of obtaining its own positioning coordinates in real time, is sailed into the waters to be tested. It primarily moves near the underwater optical cable, obtaining a satellite positioning system to record the vessel's trajectory. The calibration vessel can be calibrated using a grid-like route in the waters where the underwater optical cable is laid. For waters where the approximate direction of the underwater optical cable is known, the calibration vessel should repeatedly pass overhead, creating a variation of weak and strong signals at various locations on the underwater optical cable.

[0059] Calibration vessels are preferably equipped to carry transducers. These vessels continuously output a single-frequency, stable-amplitude signal as a standard detection signal, creating a distinct signal that is easily distinguishable from background noise. For example, a calibration vessel might carry a transducer that emits a single-tone signal with a constant intensity and a frequency of 1 kHz. The characteristic frequency emitted by this transducer should minimize overlap with low-frequency background ocean noise. The appropriate frequency and intensity should be selected based on the specific situation and ecological environment to minimize potential impacts on underwater life.

[0060] For underwater optical cables that require long-distance monitoring, the observable frequency band is limited. When the characteristic frequency of the transducer is too high, high-frequency folding may occur. A specific high frequency can be selected to detect its characteristic frequency after folding. The characteristic frequency after folding is greater than the frequency threshold of the preset background noise. The relationship between the specific high frequency of the transducer and the specific frequency after folding is calculated as follows:

[0061] f actual =f observed +mf k

[0062] where f actual is the characteristic signal frequency actually released by the transducer, f actual is the characteristic signal frequency detected by the distributed optical fiber sensing system, m is an integer not less than 0, f k is the sampling rate of the system.

[0063] When the system monitors over long distances, the upper frequency limit it can observe decreases. When monitoring over short distances, the upper frequency limit increases. If the applied vibration frequency exceeds the observable frequency, the above formula can be used to monitor the folded frequency value, thereby enabling high-frequency monitoring. The purpose of applying high frequency here is mainly to avoid low-frequency ocean background noise and prevent confusion. At the same time, the specific frequencies after folding should also avoid low-frequency background noise to prevent confusion and difficulty in distinguishing.

[0064] Step 3: Phase demodulate the original signal collected by the DAS system to restore the time domain waveform information at each position along the underwater optical cable, and obtain the time-space information distribution map containing time domain information, such as Figure 4 shown.

[0065] Step 4: Analyze the spectrum characteristics of the spatiotemporal information distribution map, compare it with the underwater background noise, and compare and analyze the signal at the 100m position to obtain Figure 5 ,Depend on Figure 5 It can be seen that the 1kHz signal generated by the calibration ship passing by is detected by the DAS system, so we choose to retain only the frequency near 1kHz, perform bandpass filtering, and filter out the non-calibration ship signal, and obtain the following Figure 6The temporal and spatial information distribution diagram of an underwater optical cable at a specific frequency is shown. Further comparison with the vessel's trajectory confirms that the acoustic signal at that frequency is associated with vessel activity, though the signal's signature is not readily apparent. For example, the characteristic frequency identification process is as follows: Since the real-time position and trajectory of the calibration vessel are known, the time-domain signal captured near the underwater cable will change as the calibration vessel passes by. Therefore, spectral analysis of the collected acoustic signal can be performed to identify the specific frequency. This is then compared with the calibration vessel's trajectory to confirm its association with vessel activity. Furthermore, acoustic signals at the same location but at different times can be compared to determine whether they represent ocean background noise, thus preventing misjudgments.

[0066] Step 6: Perform short-time spectrum analysis on the signals at each position of each underwater optical cable. Set the observation time to 1s, perform spectrum subtraction on the signals near the characteristic frequency of 1000Hz in the frequency domain, and then select a frequency band range of 1000Hz and a bandwidth of 10Hz for frequency domain energy integration to obtain a time-space spectrum energy integral diagram containing frequency domain information, as shown in the figure below: Figure 7 As shown in the figure, it can be considered that the darker the color, the closer the calibration ship is to the optical cable. By matching the ship movement time with the data, the response characteristics of the ship moving to each key position along the optical cable are obtained.

[0067] In step seven, the trajectory data is compared with the time-space spectrum energy integral graph. The energy value is found to be maximum when the ship is at point G, which means it passes directly above the underwater cable. The inflection points of the ship's trajectory are mapped on the distance and time axes. The energy values ​​at each point along the underwater cable are calculated, and the different energy value ranges are mapped to the same range to achieve energy normalization.

[0068] Step 8: Combine the water depth and the calibration ship information to realize the relationship mapping between the energy value and the distance between the ship and the underwater optical cable. According to the energy-distance mapping relationship, the ship trajectory is mapped to each position along the underwater optical cable to obtain Figure 8 The actual direction of the underwater optical cable is used to calibrate the spatial position of the underwater optical cable. For example, the process of calibrating the spatial position of the underwater optical cable is as follows:

[0069] (1) The trajectory data is matched with the space-time spectrum energy integral diagram, and the turning points of the ship trajectory are mapped on the distance axis and time axis:

[0070] (2) Calculate the energy value of each point along the underwater optical cable and map different energy value ranges into the same range to achieve energy value normalization. The larger the energy value, the closer the calibration vessel is to the underwater optical cable, and the smaller the energy value, the farther the calibration vessel is from the underwater optical cable.

[0071] (3) When the calibration vessel passes directly above the underwater optical cable, the energy value is the maximum, and the position of the maximum energy value is located;

[0072] (4) Obtain the trajectory and time information of the calibration vessel, and combine it with the water depth and energy maximum position information to realize the relationship mapping between the energy value and the distance between the vessel and the underwater optical cable;

[0073] (5) Based on the energy-distance mapping relationship, the ship trajectory is mapped to each position along the underwater optical cable, and the corresponding distance is calculated.

[0074] The method for calibrating the spatial position of underwater optical cables based on distributed fiber optic sensing disclosed in this embodiment uses distributed fiber optic sensing equipment as a monitoring device, underwater optical cables as the sensing body, and a calibration vessel as an excitation source. This method can achieve spatial position calibration of underwater optical cables, with high efficiency, high positioning accuracy, low cost, and the ability to perform real-time monitoring and analysis. In addition, this method is not only applicable to the calibration of underwater optical cable positions, but also, for underwater optical cables that have already completed position calibration, combined with distributed fiber optic sensing equipment, can monitor the hydrological conditions near the underwater optical cables and can also achieve rapid identification and positioning of surface ships, providing a faster and more accurate determination method for the spatial position calibration of underwater optical cables.

[0075] The above is a further detailed description of the present invention in conjunction with specific preferred embodiments, and the specific implementation of the present invention should not be considered to be limited to these descriptions. For those skilled in the art to which the present invention belongs, several simple deductions or substitutions can be made without departing from the concept of the present invention, and all of these should be considered to fall within the scope of protection of the present invention.

Claims

1. A method for calibrating the spatial position of an underwater optical cable based on distributed optical fiber sensing, characterized in that: The underwater optical cable spatial position calibration method comprises the following steps: S1, connect the distributed optical fiber sensing equipment to the underwater optical cable in the water area to be measured; S2: The calibration vessel is driven into the waters to be measured, and the vessel's trajectory is recorded using a satellite positioning system. At the same time, distributed fiber optic sensing equipment is used to obtain acoustic wave signals at various locations along the underwater optical cable. S3, performing phase demodulation on the original signal collected by the distributed optical fiber sensing device, restoring the time domain waveform information at each position along the underwater optical cable, and obtaining a spatiotemporal information distribution map containing the time domain information; S4, performs spectrum feature analysis on the spatiotemporal information distribution map, compares it with the underwater background noise, and extracts the specific frequency sound wave signal generated by the ship activity; S5, performing short-time spectrum analysis on the signals at various locations on the underwater optical cable, performing noise suppression on the frequency domain of the extracted acoustic wave signals of specific frequencies generated by vessel activity, and performing frequency domain energy integration on the specific frequencies to obtain a spatiotemporal spectrum energy integral graph containing frequency domain information; S6, the time-space spectrum energy integral map is matched with the ship's trajectory, and the signal energy at each position of the underwater optical cable is used as the weight to map different energy value ranges into the same range to achieve energy value normalization processing; the larger the energy value, the closer the calibration ship is to the underwater optical cable, and the smaller the energy value, the farther the calibration ship is from the underwater optical cable; S7, combining the water depth and calibration ship information, realizes the relationship mapping between the energy value and the distance between the ship and the underwater optical cable, and corresponds the ship trajectory at each position along the underwater optical cable to realize the spatial position calibration of the underwater optical cable.

2. The method for calibrating the spatial position of an underwater optical cable based on distributed optical fiber sensing according to claim 1, characterized in that: In step S2, the calibration vessel performs calibration in a grid-like route in the underwater optical cable laying water area.

3. The method for calibrating the spatial position of an underwater optical cable based on distributed optical fiber sensing according to claim 2, characterized in that: In step S2, for the water area where the approximate direction of the underwater optical cable is known, the calibration vessel repeatedly passes over the top to form weak-strong-weak changes at various positions of the underwater optical cable.

4. The method for calibrating the spatial position of an underwater optical cable based on distributed optical fiber sensing according to claim 1, wherein: The calibration ship carries a transducer, and when the ship is moving, the transducer continuously outputs a sound wave signal with a single frequency and stable sound pressure amplitude as a standard detection signal.

5. The method for calibrating the spatial position of an underwater optical cable based on distributed optical fiber sensing according to claim 4, characterized in that: The frequency and intensity of the sound wave signal continuously output by the transducer are related to the ecological environment of the water area to be measured and the low-frequency background noise of the ocean.

6. The method for calibrating the spatial position of an underwater optical cable based on distributed optical fiber sensing according to claim 1, characterized in that: For underwater optical cables with a length greater than a preset length threshold, the characteristic frequency of the transducer after folding is detected, and the characteristic frequency after folding is greater than the frequency threshold of the preset background noise; the relationship between the specific high frequency of the transducer and the specific frequency after folding is: favorite actual =f observed +mf k Where, f actual is the characteristic signal frequency actually released by the transducer, f actual is the characteristic signal frequency detected by the distributed optical fiber sensing system, m is an integer not less than 0, f k is the sampling rate of the system.

7. The method for calibrating the spatial position of an underwater optical cable based on distributed optical fiber sensing according to claim 1, characterized in that: In step S4, the specific frequency sound wave signal is compared with the ship's trajectory, and the sound wave signals at the same location and different times are compared to determine whether the specific frequency sound wave signal belongs to the ocean background noise.

8. The method for calibrating the spatial position of an underwater optical cable based on distributed optical fiber sensing according to claim 1, characterized in that: In step S7, the relationship between the energy value and the distance between the ship and the underwater optical cable is mapped in combination with the water depth and the calibration ship information, and the ship trajectory is mapped to each position along the underwater optical cable. The process of calibrating the spatial position of the underwater optical cable includes the following steps: The trajectory data is matched with the time-space spectrum energy integral diagram, and the turning points of the ship trajectory are mapped on the distance axis and time axis. The energy maximum position is located. When the calibration ship passes directly above the underwater optical cable, the energy value is the largest. Obtain the calibration ship's trajectory and time information, and combine it with the water depth and energy maximum position information to achieve a mapping of the energy value and the distance between the ship and the underwater optical cable; According to the energy-distance mapping relationship, the ship trajectory is matched at each position along the underwater optical cable, and the corresponding distance is calculated.

9. A method for calibrating a ship's position based on distributed optical fiber sensing, characterized in that: The vessel position calibration method comprises the following steps: Connecting a distributed optical fiber sensing device with a known underwater optical cable spatial position to the underwater optical cable in the water area to be measured; The vessel to be tested is driven into the waters to be tested and distributed optical fiber sensing equipment is used to obtain acoustic wave signals at various locations along the underwater optical cable. Phase demodulation is performed on the original signal collected by the distributed optical fiber sensing equipment to restore the time domain waveform information at each position along the underwater optical cable, and a time-space information distribution map containing time domain information is obtained; Perform spectrum feature analysis on the spatiotemporal information distribution map, compare it with the underwater background noise, and extract the specific frequency sound wave signals generated by ship activities; Perform short-time spectrum analysis on the signals at various locations on the underwater optical cable, extract the specific frequency acoustic signals generated by ship activity, perform noise suppression in the frequency domain, and perform frequency domain energy integration on the specific frequencies to obtain a time-space spectrum energy integral diagram containing frequency domain information. The time-space spectrum energy integral diagram is matched with the spatial position of the underwater optical cable, and the signal energy at each position of the underwater optical cable is used as the weight to map different energy value ranges into the same range to achieve energy value normalization. Combining the water depth and calibration ship information, the relationship between the energy value and the distance between the ship and the underwater optical cable is mapped, and the ship trajectory is matched according to the spatial position of the underwater optical cable to realize the ship position calibration.

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