Submarine cable detection method and device based on quantum magnetometer

Abstract

The invention discloses a submarine cable detection method and device based on quantum magnetometers, the device comprises a multi-frequency signal generating device and a quantum magnetic field sensing device, and the quantum magnetic field sensing device comprises a first quantum magnetometer, a second quantum magnetometer and a signal processing module; according to the method, two quantum magnetometers which are horizontally installed are used for detecting the ratio of amplitude values of alternating magnetic fields generated by two equal-amplitude alternating currents with different frequencies in a submarine cable, and the distance relation between the two quantum magnetometers and the submarine cable is judged by comparing the ratio values detected by the two quantum magnetometers. And when the ratios detected by the two quantum magnetometers are equal, the position of the motion platform is the position of the submarine cable. The quantum magnetometer is used as a core sensor, so that the influence of posture change of the motion platform on detection data jitter is reduced, and the detection precision is improved; and a multi-frequency signal detection mode is adopted, so that the difficulty of extracting the characteristic magnetic field signal generated by the submarine cable to be detected from the total magnetic field is reduced.

Description

Technical Field

[0001] The present invention belongs to the field of submarine cable operation and maintenance, and relates to a submarine cable detection method and device based on a quantum magnetometer, which are used for detecting the position of a submarine cable in a moving state. Background Art

[0002] Submarine cables (referred to as submarine cables) are important infrastructure in modern communications, power transmission and marine engineering. The reliability of their operation directly affects the stability of the communication network and the efficiency of energy transmission. In the operation, maintenance and overhaul of submarine cables, submarine cable detection technology is an important means to ensure their safety and work efficiency. By quickly and accurately locating submarine cables, not only can the overhaul efficiency be significantly improved, but also the maintenance cost can be effectively reduced. However, traditional submarine cable detection technology still has many shortcomings in practical applications and is difficult to meet the increasingly complex application requirements.

[0003] Traditional submarine cable detection technology mainly detects submarine cables by detecting the alternating magnetic field generated by the alternating current in the submarine cable. Vector magnetic sensors are usually used to measure the magnetic field in a specific direction or multiple specific directions, and then compare or calculate the position of the submarine cable. When the vector magnetic sensor is mounted on a moving platform such as a surface ship, a towed body or an underwater robot, the posture change of the moving platform will cause changes in the magnetic field sensitive axis of the vector magnetic sensor, which will cause jitter in the measurement data. When the sea conditions are high, this impact will directly cause the magnetic field signal generated by the submarine cable to be submerged in the jitter noise, making it impossible to detect the submarine cable. In addition, the traditional submarine cable detection technology uses S-type scanning to detect submarine cables, which has problems such as low detection efficiency and discontinuous detection information. Summary of the invention

[0004] The purpose of the present invention is to solve the problem that the traditional submarine cable detection method is greatly affected by the posture in the moving state and requires S-shaped scanning, resulting in low detection efficiency. A submarine cable detection method and device based on a quantum magnetometer are provided.

[0005] In a first aspect, the present invention provides a submarine cable detection device based on a quantum magnetometer, comprising a multi-frequency signal generating device and a quantum magnetic field sensing device;

[0006] The multi-frequency signal generating device is used to output two continuous sinusoidal current signals of equal amplitude and different frequencies. The signal output positive electrode of the multi-frequency signal generating device is connected to one end of the central conductor of the submarine cable to be tested through a cable, and the signal output negative electrode is grounded through the cable; the other end of the central conductor of the submarine cable to be tested is grounded;

[0007] The quantum magnetic field sensing device comprises a first quantum magnetometer, a second quantum magnetometer and a signal processing module; the first quantum magnetometer and the second quantum magnetometer are located on the same horizontal line, respectively detecting the total magnetic field amplitude at their respective locations, the first quantum magnetometer and the second quantum magnetometer are respectively connected to the signal processing module via cables; the signal processing module is used to receive and process the total magnetic field amplitude, and then determine the location of the submarine cable to be measured.

[0008] Preferably, the first quantum magnetometer and the second quantum magnetometer are connected via a rigid support rod.

[0009] Preferably, the rigid support rod is made of non-magnetic material.

[0010] Preferably, the first quantum magnetometer and the second quantum magnetometer are both scalar magnetometers.

[0011] The working mechanism of the present invention is: using two quantum magnetometers installed horizontally on a moving platform to detect the ratio of the amplitudes of the alternating magnetic field generated by two alternating currents of equal amplitude and different frequencies in the submarine cable, and by comparing the magnitudes of the ratios detected by the two quantum magnetometers, the distance relationship between the two quantum magnetometers and the submarine cable is determined. By continuously adjusting the position of the moving platform, when the ratios detected by the two quantum magnetometers are equal, the position of the moving platform is the position of the submarine cable.

[0012] In a second aspect, the present invention provides a submarine cable detection method based on a quantum magnetometer based on the above device, which specifically includes the following steps:

[0013] Step (1), adjustment of the multi-frequency signal generating device:

[0014] The positive electrode of the signal output of the multi-frequency signal generating device is connected to one end of the central conductor of the submarine cable to be tested through a cable, the negative electrode of the signal output is grounded, and the other end of the central conductor of the submarine cable to be tested is grounded; then the multi-frequency signal generating device is adjusted so that the output current signal I(t) satisfies formula (1):

[0015] I(t)=I0[sin(2πf1t)+sin(2πf2t)] (1)

[0016] Among them, I0 is the alternating current amplitude, f1 and f2 are two different frequencies and f1<f2, and t is time.

[0017] Step (2), quantum magnetic field sensor device adjustment:

[0018] The first quantum magnetometer and the second quantum magnetometer are installed on the moving platform, and the first quantum magnetometer and the second quantum magnetometer are leveled by a rigid support rod so that the position connection direction of the first quantum magnetometer and the second quantum magnetometer is perpendicular to the moving direction of the moving platform; the first quantum magnetometer measures the total magnetic field amplitude at the position in real time The total magnetic field amplitude at the location is measured in real time by the second quantum magnetometer The measured total magnetic field amplitude and Satisfying formulas (2)-(5):

[0019]

[0020]

[0021] Where B0 is the ambient magnetic field amplitude, is the unit vector of the ambient magnetic field direction, μ0 is the vacuum magnetic permeability, γ1 and γ2 are the propagation constants at frequencies f1 and f2, μ is the seawater magnetic permeability, σ is the seawater electrical conductivity, L1 and L2 are the distances from the submarine cable to be tested to the first quantum magnetometer and the second quantum magnetometer, respectively. and are the unit vectors of the magnetic field generated by the submarine cable to be tested at the first quantum magnetometer position and the second quantum magnetometer position, respectively. K1 is the second-kind first-order modified Bessel function, and i represents the imaginary part.

[0022] The signal processing module extracts the total magnetic field amplitude measured by the first quantum magnetometer The amplitude components B1(f1) and B1(f2) with intermediate frequencies f1 and f2 are calculated, and their ratio B1(f1) / B1(f2) is calculated, which satisfies formulas (6)-(8):

[0023]

[0024] The signal processing module extracts the total magnetic field amplitude measured by the second quantum magnetometer The amplitude components B2(f1) and B2(f2) with intermediate frequencies f1 and f2 are calculated, and their ratio B2(f1) / B2(f2) is calculated, satisfying formulas (9)-(11):

[0025]

[0026] The method for extracting the amplitude component can be a conventional method, such as Fourier transform.

[0027] Step (3), moving the motion platform, comparing the size of B1(f1) / B1(f2) and B2(f1) / B2(f2), when B1(f1) / B1(f2) is equal to B2(f1) / B2(f2), that is, L1=L2, it means that the plane position of the submarine cable to be tested is at the midpoint of the line connecting the position of the first quantum magnetometer and the position of the second quantum magnetometer, that is, directly below the quantum magnetic field sensor device; when B1(f1) / B1(f2) is greater than B2(f1) / B2(f2), that is, L1>L2, it means that the plane position of the submarine cable to be tested is on the side close to the position of the second quantum magnetometer; when B1(f1) / B1(f2) is less than B2(f1) / B2(f2), that is, L1<L2, it means that the plane position of the submarine cable to be tested is on the side close to the position of the first quantum magnetometer. In this way, the plane position detection of the submarine cable to be tested is achieved.

[0028] Preferably, the submarine cable to be tested is a three-core cable or a single-core cable and is in an out-of-service state.

[0029] Preferably, the motion platform is a ship, a towed vehicle or an underwater robot.

[0030] Preferably, the frequency values ​​of f1 and f2 differ by more than 100 times.

[0031] Preferably, the response bandwidth ranges of the first quantum magnetometer and the second quantum magnetometer cover f1 and f2.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] 1. The quantum magnetometer is used to measure the total magnetic field and is insensitive to attitude, eliminating the impact of the motion platform's attitude changes on the measurement data and improving the accuracy of submarine cable detection.

[0034] Second, the method of using two quantum magnetometers to simultaneously detect multi-frequency current signals and measuring the ratio of the alternating magnetic field amplitudes generated by the current signals of two different frequencies eliminates the problem that the angle between the alternating magnetic field direction vector generated by the submarine cable to be tested and the ambient magnetic field direction vector changes with the spatial position, that is, eliminates the and The influence of the two quantum magnetometers can be used to simultaneously measure the submarine cable to be tested, and by comparing the ratios, the planar position detection of the submarine cable to be tested is realized without measuring the magnetic field angle information, which reduces the difficulty of extracting the characteristic magnetic field signal generated by the submarine cable to be tested from the total magnetic field.

[0035] 3. The device of the present invention is simple, easy to operate, and applicable to various sports platforms. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is a schematic diagram of the device of the present invention.

[0037] Figure 2 It is a cross-sectional schematic diagram of the quantum magnetic field sensor device of the present invention near the submarine cable to be tested.

[0038] Figure 3 This is a graph showing the variation of the magnetic field ratio generated by the multi-frequency current obtained by the present invention with the distance from the quantum magnetometer to the submarine cable to be measured.

[0039] Figure 4 The experimental results of the influence of the motion platform posture change on the jitter noise of the traditional vector magnetic sensor and the quantum sensor obtained by the present invention, wherein (a) is the measured jitter noise of the traditional vector magnetic sensor caused by the motion platform posture change, and (b) is the measured jitter noise of the quantum magnetic sensor caused by the motion platform posture change.

[0040] Markings in the figure: 1. Multi-frequency signal generating device; 2. First quantum magnetometer; 3. Second quantum magnetometer; 4. Signal processing module. DETAILED DESCRIPTION

[0041] The present invention will be further analyzed below in conjunction with the accompanying drawings.

[0042] like Figure 1 As shown, the present invention provides a submarine cable detection device based on quantum magnetometer, comprising a multi-frequency signal generating device 1 and a quantum magnetic field sensing device, wherein the quantum magnetic field sensing device comprises a first quantum magnetometer 2, a second quantum magnetometer 3 and a signal processing module 4; wherein the signal output positive pole of the multi-frequency signal generating device 1 is connected to the central conductor at one end of the submarine cable to be tested through a cable, and the signal output negative pole is connected to the grounding wire through a cable; the central conductor at the other end of the submarine cable to be tested is grounded through a cable; the quantum magnetic field sensing device consists of a first quantum magnetometer 2, a second quantum magnetometer 3 and a signal processing module 4; wherein the first quantum magnetometer 2 and the second quantum magnetometer 3 are connected through a rigid support rod and are on the same horizontal line; the first quantum magnetometer 2 and the second quantum magnetometer 3 are respectively connected to the signal processing module 4 through a cable.

[0043] like Figure 2 As shown, when the quantum magnetic field sensor device is near the submarine cable to be tested, L1 is defined as the distance from the submarine cable to be tested to the first quantum magnetometer, and L2 is defined as the distance from the submarine cable to be tested to the second quantum magnetometer;

[0044] First, the signal output positive electrode of the multi-frequency signal generating device is connected to one end of the central conductor of the submarine cable to be tested through a cable, the signal output negative electrode is grounded, and the other end of the central conductor of the submarine cable to be tested is grounded; then the multi-frequency signal generating device is adjusted; then the first quantum magnetometer and the second quantum magnetometer are installed on the motion platform, and the first quantum magnetometer and the second quantum magnetometer are leveled by a rigid support rod so that the position connection direction of the first quantum magnetometer and the second quantum magnetometer is perpendicular to the motion direction of the motion platform; the first quantum magnetometer measures the total magnetic field amplitude at the position in real time The total magnetic field amplitude at the location is measured in real time by the second quantum magnetometer

[0045] The signal processing module extracts the total magnetic field amplitude measured by the first quantum magnetometer The amplitude components B1(f1) and B1(f2) with intermediate frequencies f1 and f2 are calculated, and their ratio B1(f1) / B1(f2) is calculated, which satisfies formulas (6)-(8):

[0046]

[0047]

[0048] The signal processing module extracts the total magnetic field amplitude measured by the second quantum magnetometer The amplitude components B2(f1) and B2(f2) with intermediate frequencies f1 and f2 are calculated, and their ratio B2(f1) / B2(f2) is calculated, satisfying formulas (9)-(11):

[0049]

[0050] From formula (8) and formula (11), it can be seen that comparing the size of B1(f1) / B1(f2) and B2(f1) / B2(f2) is equivalent to comparing the size of L1 and L2, and then the distance between the submarine cable to be tested and the first quantum magnetometer and the second quantum magnetometer can be determined;

[0051] When B1(f1) / B1(f2) is equal to B2(f1) / B2(f2), that is, L1=L2, it means that the plane position of the submarine cable to be tested is at the midpoint of the line connecting the positions of the first quantum magnetometer and the second quantum magnetometer, that is, directly below the quantum magnetic field sensor device; when B1(f1) / B1(f2) is greater than B2(f1) / B2(f2), that is, L1>L2, it means that the plane position of the submarine cable to be tested is on the side close to the position of the second quantum magnetometer; when B1(f1) / B1(f2) is less than B2(f1) / B2(f2), that is, L1<L2, it means that the plane position of the submarine cable to be tested is on the side close to the position of the first quantum magnetometer.

[0052] like Figure 3 As shown, when the multi-frequency signal generating device generates a current signal with parameters of I0=1A, f1=10Hz, f2=10000Hz, and the seawater conductivity σ=4S / m, Figure 3 It can represent the changing relationship between the magnetic field ratio B1(f1) / B1(f2) detected by the first quantum magnetometer 2 and the distance L1 between the first quantum magnetometer 2 and the submarine cable to be measured, and it can also represent the changing relationship between the magnetic field ratio B2(f1) / B2(f2) detected by the second quantum magnetometer 3 and the distance L2 between the second quantum magnetometer 3 and the submarine cable to be measured. Figure 3 It can be seen that the magnetic field ratio has a monotonically changing relationship with the distance, so the distance relationship between the two quantum magnetometers and the submarine cable to be tested can be obtained by the size of the magnetic field ratio.

[0053] like Figure 4 As shown in the figure, (a) is the measured jitter noise of the traditional vector magnetic sensor caused by the change of the motion platform posture, and (b) is the measured jitter noise of the quantum magnetic sensor caused by the change of the motion platform posture. It can be seen that the jitter noise caused by the traditional vector magnetic sensor with the change of the motion platform posture is much greater than the jitter noise caused by the quantum magnetic sensor with the change of the motion platform posture.

[0054] The above relationship shows that the jitter noise caused by the traditional vector magnetic sensor with the change of the motion platform posture is large, resulting in low detection accuracy of the submarine cable, while the quantum magnetic sensor greatly reduces the jitter noise caused by the change of the motion platform posture by measuring the total magnetic field, thereby improving the detection accuracy. At the same time, by comparing the size of the magnetic field ratio generated by the multi-frequency current signal detected by the two quantum magnetometers, the distance between the two quantum magnetometers and the submarine cable to be tested can be judged, thereby realizing the detection of the submarine cable.

[0055] The specific adjustment method of submarine cable detection based on quantum magnetometer is:

[0056] In this embodiment, the multi-frequency signal generating device generates a current signal with parameters of I0=1A, f1=10Hz, f2=10000Hz; the seawater conductivity σ=4S / m; the underwater robot is used as a motion platform, and the first quantum magnetometer 2 and the second quantum magnetometer 3 both use optically pumped magnetometers, which are 2 meters apart, connected by a carbon fiber support rod, and horizontally fixed on the underwater robot, and the carbon fiber support rod is perpendicular to the forward direction of the underwater robot.

[0057] When the measurement starts, the underwater robot dives to a position near the submarine cable to be measured and 2 meters away from the seabed, and compares the magnetic field ratios B1(f1) / B1(f2) and B2(f1) / B2(f2) measured by the first quantum magnetometer 2 and the second quantum magnetometer 3 respectively. When B1(f1) / B1(f2) is greater than B2(f1) / B2(f2), the underwater robot moves to one side of the installation position of the second quantum magnetometer 3. When B1(f1) / B1(f2) is less than B2(f1) / B2(f2), the underwater robot moves to one side of the installation position of the first quantum magnetometer 2, until B1(f1) / B1(f2) is equal to B2(f1) / B2(f2), the submarine cable to be measured is directly below the underwater robot, thereby completing the submarine cable detection.

[0058] The above are only preferred embodiments of the present invention. It should be noted that the above preferred embodiments should not be regarded as limiting the present invention, and the protection scope of the present invention should be based on the scope defined by the claims. For ordinary technicians in this technical field, several improvements and modifications can be made without departing from the spirit and scope of the present invention, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A submarine cable detection device based on a quantum magnetometer, comprising a multi-frequency signal generating device and a quantum magnetic field sensing device; characterized in that: The multi-frequency signal generating device is used to output two continuous sinusoidal current signals of equal amplitude and different frequencies. The positive electrode of the signal output of the multi-frequency signal generating device is connected to one end of the central conductor of the submarine cable to be tested through a cable, and the negative electrode of the signal output is grounded; the other end of the central conductor of the submarine cable to be tested is grounded; The quantum magnetic field sensing device comprises a first quantum magnetometer, a second quantum magnetometer and a signal processing module; the first quantum magnetometer and the second quantum magnetometer are located on the same horizontal line, respectively detecting the total magnetic field amplitude at their respective locations, the first quantum magnetometer and the second quantum magnetometer are respectively connected to the signal processing module via cables; the signal processing module is used to receive and process the total magnetic field amplitude, and then determine the location of the submarine cable to be measured.

2. The submarine cable detection device based on quantum magnetometer according to claim 1 is characterized in that: The first quantum magnetometer and the second quantum magnetometer are connected via a rigid support rod.

3. The submarine cable detection device based on quantum magnetometer according to claim 2 is characterized in that: The rigid support rod is made of non-magnetic material.

4. The submarine cable detection device based on quantum magnetometer according to claim 1 is characterized in that: The first quantum magnetometer and the second quantum magnetometer are both scalar magnetometers.

5. A submarine cable detection method using the submarine cable detection device based on quantum magnetometer according to any one of claims 1 to 4, characterized in that: The following steps are involved: Step (1), adjustment of the multi-frequency signal generating device: The positive electrode of the signal output of the multi-frequency signal generating device is connected to one end of the central conductor of the submarine cable to be tested through a cable, the negative electrode of the signal output is grounded, and the other end of the central conductor of the submarine cable to be tested is grounded; then the multi-frequency signal generating device is adjusted so that the output current signal I(t) satisfies formula (1): I(t)=I0[sin(2πf1t)+sin(2πf2t)] (1) Where I0 is the alternating current amplitude, f1 and f2 are two different frequencies and f1<f2, t is time; Step (2), quantum magnetic field sensor device adjustment: The first quantum magnetometer and the second quantum magnetometer are installed on the moving platform, and the first quantum magnetometer and the second quantum magnetometer are leveled by a rigid support rod so that the position connection direction of the first quantum magnetometer and the second quantum magnetometer is perpendicular to the moving direction of the moving platform; the first quantum magnetometer measures the total magnetic field amplitude at the position in real time The total magnetic field amplitude at the location is measured in real time by the second quantum magnetometer The measured total magnetic field amplitude and Satisfying formulas (2)-(5): Where B0 is the ambient magnetic field amplitude, is the unit vector of the ambient magnetic field direction, μ0 is the vacuum magnetic permeability, γ1 and γ2 are the propagation constants at frequencies f1 and f2, μ is the seawater magnetic permeability, σ is the seawater electrical conductivity, L1 and L2 are the distances from the submarine cable to be tested to the first quantum magnetometer and the second quantum magnetometer, respectively. and are the unit vectors of the magnetic field generated by the submarine cable to be tested at the first quantum magnetometer position and the second quantum magnetometer position, respectively; K1 is the second kind of first-order modified Bessel function, and i represents the imaginary part; The signal processing module extracts the total magnetic field amplitude measured by the first quantum magnetometer The amplitude components B1(f1) and B1(f2) with intermediate frequencies f1 and f2 are calculated, and their ratio B1(f1) / B1(f2) is calculated, which satisfies formulas (6)-(8): The signal processing module extracts the total magnetic field amplitude measured by the second quantum magnetometer The amplitude components B2(f1) and B2(f2) with intermediate frequencies f1 and f2 are calculated, and their ratio B2(f1) / B2(f2) is calculated, satisfying formulas (9)-(11): Step (3), moving the motion platform, comparing the sizes of B1(f1) / B1(f2) and B2(f1) / B2(f2), when B1(f1) / B1(f2) is equal to B2(f1) / B2(f2), it indicates that the plane position of the submarine cable to be tested is at the midpoint of the line connecting the position of the first quantum magnetometer and the position of the second quantum magnetometer, that is, directly below the quantum magnetic field sensor device; when B1(f1) / B1(f2) is greater than B2(f1) / B2(f2), it indicates that the plane position of the submarine cable to be tested is on the side close to the position of the second quantum magnetometer, that is, L1>L2; when B1(f1) / B1(f2) is less than B2(f1) / B2(f2), it indicates that the plane position of the submarine cable to be tested is on the side close to the position of the first quantum magnetometer, that is, L1<L2.

6. The method according to claim 5, characterized in that The submarine cable to be tested is a three-core cable or a single-core cable and is in an out-of-service state.

7. The method according to claim 5, characterized in that The motion platform is a ship, a towed body or an underwater robot.

8. The method according to claim 5, characterized in that The frequency values ​​of f1 and f2 differ by more than 100 times.

9. The method according to claim 5, characterized in that The response bandwidth ranges of the first quantum magnetometer and the second quantum magnetometer cover f1 and f2.

10. The method according to claim 5, characterized in that The signal processing module uses Fourier transform to extract the amplitude component.

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