Distributed sound wave sensing system for deep sea environment

Abstract

The distributed sound wave sensing system comprises a sensing device, a laying device and an optical cable, the sensing device comprises a supporting frame, a pressure-resistant cabin and a DAS demodulator arranged in the pressure-resistant cabin in a sealed mode, the pressure-resistant cabin is fixed to the supporting frame, the DAS demodulator comprises an optical phase demodulation module and a dry-wet connection module, and the optical phase demodulation module is connected with the laying device. The dry-wet connection module comprises an elastic bearing shaft and an optical fiber pressure-resistant cabin penetrating piece connected with the elastic bearing shaft, one end of the dry-wet connection module is connected with the optical phase demodulation module, the other end of the dry-wet connection module is connected with an optical cable, a damping control shaft is arranged on the laying device, the laying device is arranged on the sensing device, and the damping control shaft is used for controlling damping of the optical cable. The sensing device is enabled to complete multi-sea-area mobile detection or monitoring, a pressure-resistant cabin and a dry-wet connection module are utilized to seal a DAS demodulator to be matched with a laying device to carry out retraction and release, deep sea entering can be completed, and deep sea seabed environment distributed sound wave sensing observation is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of deep-sea equipment, and in particular to a distributed acoustic wave sensing system for deep-sea environments. Background Art

[0002] Currently, marine technology mainly uses single-point or multi-point sensors to achieve deep-sea environment observation and earthquake detection. The amount of data they obtain is proportional to the deployment location and sensor density, which makes it difficult to achieve high-density spatial sampling observation in some key areas.

[0003] Currently, distributed sensing DAS is used to complete data collection and transmission. Distributed sensing technology has advantages such as a large observation range and a wide range of applications. However, it currently has significant disadvantages. For example, distributed sensing technology consumes a lot of power, is large in size, and can only be accessed on land through optical cables for observation. These shortcomings make DAS difficult to apply in the marine field and can only be deployed on land.

[0004] In view of this, the present invention proposes a distributed acoustic wave sensor device that can be used in the deep sea. Summary of the Invention

[0005] In order to solve the problem that the current DAS demodulator cannot enter the deep sea to carry out deep sea exploration, the present invention proposes a distributed acoustic wave sensing system for deep sea environment.

[0006] The present invention is achieved through the following technical solutions:

[0007] The present invention proposes a distributed acoustic wave sensing system for deep-sea environments, comprising a sensing device, a deployment device, and an optical cable, wherein:

[0008] The sensing device includes a supporting frame, a pressure-resistant cabin, and a DAS demodulator sealed inside the pressure-resistant cabin. The pressure-resistant cabin is fixed to the supporting frame. The DAS demodulator includes an optical phase demodulation module and a dry-wet connection module. The dry-wet connection module includes an elastic load-bearing shaft and an optical fiber pressure-resistant cabin penetration part connected thereto. One end of the dry-wet connection module is connected to the optical phase demodulation module, and the other end is connected to the optical cable.

[0009] The laying device is provided with a damping control shaft, and the laying device is provided on the sensing device. The damping control shaft is used to control the damping of the optical cable and enable the sensing device to complete multi-area detection and monitoring.

[0010] Furthermore, the optical cable comprises an optical fiber and tension-bearing Kevlar fiber, a water-permeable aromatic wheel, a pressure-bearing stainless steel wire and a water-permeable outer sheath wrapped in sequence from the inside to the outside.

[0011] Furthermore, the DAS demodulator further includes a GPS module, a heat dissipation module, a power management module, a control communication module and a switch, and an oven-controlled crystal oscillator is embedded in the GPS module.

[0012] Furthermore, the optical phase demodulation module includes a photoelectric adjustment unit and a data processing unit. The photoelectric adjustment unit includes a line width laser, a first modulator, an isolator, an erbium-doped fiber amplifier and a circulator connected in sequence, and one end of the circulator is connected to a fiber grating.

[0013] Furthermore, the optical phase demodulation module also includes a phase modulator and a 3dB coupler, the 3dB coupler is connected to a Faraday rotator, a photodetector and a circulator respectively, and the phase modulator, the first modulator and the photodetector are connected to the data processing unit.

[0014] Furthermore, the data processing unit includes a conversion module connected to the phase modulator, the first modulator and the photodetector, and a programming module connected to the conversion module.

[0015] Furthermore, the data processing unit further includes an operating system and a peripheral device module, and the operating system is connected to the peripheral module and the programming module respectively.

[0016] Furthermore, the optical fiber pressure-resistant cabin component includes a cabin penetration component frame, a sealing ring, and a cabin penetration optical fiber. The sealing ring is connected to the cabin penetration component frame, and the cabin penetration optical fiber passes through the cabin penetration component frame. The cabin penetration optical fiber and the cabin penetration component frame are bonded by epoxy resin. One end of the cabin penetration optical fiber is connected to the optical cable, and the other end is connected to the circulator.

[0017] Furthermore, the laying device includes a load-bearing frame, a damping control shaft is provided on the load-bearing frame, the optical cable is wound around the damping control shaft, and limiting plates connected to the load-bearing frame are provided around the damping control shaft to limit the optical cable.

[0018] Furthermore, a T-shaped handle is provided on the top of the load-bearing frame.

[0019] Beneficial effects of the present invention:

[0020] (1) The distributed acoustic wave sensing system for deep-sea environments proposed in the present invention utilizes a pressure-resistant cabin and a dry-wet connection module to seal the DAS demodulator and cooperate with a deployment device for deployment and retraction, which can complete the detection and monitoring of multiple areas on the deep seabed, solving the problem that DAS cannot enter the deep sea for detection / monitoring.

[0021] (2) The DAS regulator of the distributed acoustic wave sensing system for deep-sea environment proposed in the present invention adopts a phase generation carrier demodulation algorithm to reduce the complexity of optical phase demodulation, exponentially reduce the number of operations, and reduce the requirements for high-performance, high-power chips and circuits; at the same time, it adopts a Kintex-7 FPGA chip that balances high performance and low power consumption, which has the advantages of small size and high-density computing resource allocation. In combination with the low-power and high-efficiency ARM architecture Linux operating system and Xilinx dual-core processor, it realizes low-power PGC real-time phase demodulation of large-capacity optical signals, solving the problems of high power consumption and large size of the DAS demodulator.

[0022] (3) The distributed acoustic wave sensing system for deep-sea environments proposed in the present invention utilizes a special optical cable structure, which has the characteristics of small diameter, light weight and low loss, and can better cooperate with the sensing device to complete deep-sea detection and monitoring. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 A connection diagram of a distributed acoustic wave sensing system for a deep-sea environment according to the present invention;

[0024] Figure 2 This is a structural diagram of the sensing device and deployment device of the distributed acoustic wave sensing system for deep-sea environments of the present invention;

[0025] Figure 3 This is a structural diagram of a DAS demodulator of a distributed acoustic wave sensing system for deep-sea environments according to the present invention;

[0026] Figure 4 A diagram showing the connection of DAS demodulator components of a distributed acoustic wave sensing system for deep-sea environments according to the present invention;

[0027] Figure 5 This is a structural diagram of the optical fiber pressure-resistant penetration component of the distributed acoustic wave sensing system for deep-sea environments of the present invention;

[0028] Figure 6 This is a diagram of the optical cable structure of the distributed acoustic wave sensing system for deep-sea environments of the present invention;

[0029] Figure 7 This is a structural diagram of a deployment device for a distributed acoustic wave sensing system for a deep-sea environment according to the present invention;

[0030] Figure: sensing device 1, optical cable 2, laying device 3, deep-sea universal carrier platform 4, support frame 5, pressure-resistant cabin 6, DAS demodulator 7, optical phase demodulation module 8, GPS module 9, heat dissipation module 10, power management module 11, control communication module 12, switch 13, dry and wet connection module 14, photoelectric demodulation unit 15, data processing unit 16, linewidth laser 17, first modulator 18, isolator 19, fiber amplifier 20, fiber Bragg grating 21, circulator 22, Faraday rotator 23, phase modulator 24, 3dB coupler 25, photodetector 26, fiber pressure-resistant cabin penetration part 27, elastic bearing shaft 28, Linux operating system 29, Xilinx dual-core processor 30, RAM memory 31, 28nm low-power Kintex-7 FPGA field programmable gate array chip 32, basic memory 33, low-power memory 34, analog-to-digital converter 35, digital-to-analog converter 36, peripheral device module 37, control computer 38, parameter setting and data display software 39, external network storage 40, ultra-large capacity internal hard disk 41, clock controller 42, high-precision trigger timer 43, cabin penetration frame 44, sealing ring 45, epoxy resin 46, optical fiber 47, water-permeable outer sheath 48, water-permeable aromatic wheel 49, pressure-bearing stainless steel wire 50, load-bearing frame 51, tensile Kevlar fiber 52, T-handle 53, limit plate 54, damping control shaft 55;

[0031] The purpose, features and advantages of the present invention will be further described with reference to the accompanying drawings and in conjunction with the embodiments. DETAILED DESCRIPTION

[0032] In order to more clearly and completely illustrate the technical solution of the present invention, the present invention will be further described below with reference to the accompanying drawings.

[0033] Please refer to Figure 1-Figure 7 The present invention proposes a distributed acoustic wave sensing system for deep-sea environments, comprising a sensing device 1, a deployment device 3, and an optical cable 2, wherein:

[0034] The sensing device 1 includes a supporting frame 5, a pressure-resistant cabin 6 and a DAS demodulator 7 sealed inside the pressure-resistant cabin 6. The pressure-resistant cabin 6 is fixed to the supporting frame 5. The DAS demodulator 7 includes an optical phase demodulation module 8 and a dry-wet connection module 14. The dry-wet connection module 14 includes an elastic load-bearing shaft 28 and an optical fiber 47 connected thereto and a pressure-resistant cabin penetration part 27. One end of the dry-wet connection module 14 is connected to the optical phase demodulation module 8 and the other end is connected to the optical cable 2.

[0035] A damping control shaft 55 is provided on the laying device 3 , which is arranged on the sensing device 1 . The damping control shaft 55 is used to control the damping of the optical cable 2 and enable the sensing device 1 to complete multi-region detection and monitoring.

[0036] In a specific embodiment, the elastic load-bearing shaft 28 can enable the optical cable 2 to have unidirectional load-bearing and rotational force functions when coiled, preventing the optical cable 2 from being subjected to excessive force and breaking or excessive bending and causing excessive loss. The pressure cabin 6 and the support frame 5 are made of titanium alloy material to reduce weight while preventing seawater corrosion. Both sides of the pressure cabin 6 are sealed, and the DAS demodulator 7 is arranged inside the pressure cabin 6. It has functions such as demodulation of optical phase changes caused by deep-sea disturbances, data storage, and communication control. During operation, the entire sensing device 1 is fixed on the deep-sea universal carrier platform 4, and then the deep-sea universal carrier platform 4 is used to deploy the entire sensing device 1 together with the deployment device 3 underwater, and the sensing device 1 is used to complete detection and monitoring in the deep sea. After completing the detection and monitoring, the deployment device is fixed to the seabed, and the deep-sea universal carrier platform 4 is moved to deploy the optical cable 2, and finally the deployment device 3 and the sensing device 1 are salvaged and recovered.

[0037] Furthermore, the optical cable 2 includes an optical fiber 47 and a tension-bearing Kevlar fiber 52, a water-permeable aromatic wheel 49, a pressure-bearing stainless steel wire 50 and a water-permeable outer sheath 48 wrapped in sequence from the inside to the outside.

[0038] In a specific embodiment, the optical cable 2 has a diameter of 2-4 mm and a weight of 18-20 kg / km. The optical cable 2 uses gradient enhanced scattering optical fiber 47 inside, which has the effect of suppressing low-frequency noise and transmission loss. The optical cable 2 has the characteristics of small diameter, light weight and low loss.

[0039] Furthermore, the DAS demodulator 7 further includes a GPS module 9, a heat dissipation module 10, a power management module 11, a control and communication module 12 and a switch 13. An oven-controlled crystal oscillator is embedded in the GPS module 9.

[0040] In a specific embodiment, the power management module 11 regulates the current and voltage of the entire system. The GPS module 9 has functions such as positioning, timing, and timekeeping. The control communication module 12 communicates with the host computer through the TCP / IP protocol, can set the current system time, set the working time of the optical phase demodulation module 8, and transmit the collected system voltage, current, temperature, water leakage, power insulation status and other data to the host computer, and store them in the SD card at the same time. The switch 13 provides network connection for the optical phase demodulation module 8, the control communication module 12 and the host computer. The GPS module 9 is connected to the clock controller 42 to realize the clock synchronization of the internal modules of the DAS demodulator 7, and the underwater cumulative drift error is less than 5 milliseconds.

[0041] Furthermore, the optical phase demodulation module 8 includes a photoelectric adjustment unit and a data processing unit 16. The photoelectric adjustment unit includes a line width laser 17, a first modulator 18, an isolator 19, an erbium-doped fiber 47 amplifier 20 and a circulator 22 connected in sequence. One end of the circulator 22 is connected to the optical fiber 47 grating 21.

[0042] In a specific embodiment, the optoelectronic demodulation unit 15 adopts a phase-generated carrier PGC demodulation algorithm to reduce the complexity of optical phase demodulation, exponentially reduce the number of operations, and reduce the requirements for high-performance, high-power chips and circuits. The data processing unit 16 adopts a Kintex-7 FPGA chip with low power consumption, small size, and high-density computing resources, an ARM architecture Linux operating system with high-efficiency computing, and a Xilinx dual-core processor, realizing real-time demodulation of the optical phase by low-power hardware operation of the PGC algorithm.

[0043] Furthermore, the optical phase demodulation module 8 also includes a phase modulator 24 and a 3dB coupler 25. The 3dB coupler 25 is respectively connected to the Faraday rotator 23, the photodetector 26 and the circulator 22. The phase modulator 24, the first modulator 18 and the photodetector 26 are connected to the data processing unit 16.

[0044] In a specific embodiment, a Faraday rotator mirror 23, a phase modulator 24, a coupler and a photodetector 26 constitute a Michelson interferometer, and the data processing unit 1616 is mainly composed of a Linux operating system 29, a Xilinx dual-core processor 30, a RAM memory 31, a 28nm low-power Kintex-7 FPGA field programmable gate array chip 32, a basic memory 33, a low-power memory 34, an analog-to-digital converter 35, a digital-to-analog converter 36, and a peripheral device module 37.

[0045] Furthermore, the data processing unit 16 includes a conversion module connected to the phase modulator 24 , the first modulator 18 and the photodetector 26 , and a programming module connected to the conversion module.

[0046] In a specific embodiment, the conversion module includes an analog-to-digital converter 35 and a digital-to-analog converter 36 , and the programming module includes a 28nm low-power Kintex-7 FPGA field programmable gate array chip 32 , a basic memory 33 , and a low-power memory 34 .

[0047] Furthermore, the data processing unit 16 also includes an operating system and a peripheral device module, and the operating system is connected to the peripheral module and the programming module respectively.

[0048] In a specific embodiment, the operating system includes a Linux operating system 29, a Xilinx dual-core processor 30, and a RAM memory 31. The peripheral module 37 includes a control computer 38, parameter setting and data display software 39, an external network storage 40, an ultra-large capacity built-in hard disk 41, a clock controller 42, and a high-precision trigger timer 43, which has the function of assisting the system to complete data storage and communication control functions.

[0049] Furthermore, the pressure-resistant cabin component of the optical fiber 47 includes a cabin penetration component frame 44, a sealing ring 45, and a cabin penetration optical fiber 47. The sealing ring 45 is connected to the cabin penetration component frame 44. The cabin penetration optical fiber 47 passes through the cabin penetration component frame 44. The cabin penetration optical fiber 47 and the cabin penetration component frame 44 are bonded by epoxy resin 46. One end of the cabin penetration optical fiber 47 is connected to the optical cable 2, and the other end is connected to the circulator 22.

[0050] In a specific embodiment, the cabin penetration piece frame 44 is made of titanium alloy, and the sealing ring 45 is sleeved on the cabin penetration piece frame 44. A space for passing the cabin penetration optical fiber 47 is provided inside the cabin penetration piece frame 44. The cabin penetration optical fiber 47 passes through the interior of the cabin penetration piece frame 44 and is sealed and bonded to the cabin penetration piece frame 44 by epoxy resin 46.

[0051] Furthermore, the laying device 3 includes a load-bearing frame 51, on which a damping control shaft 55 is provided, and the optical cable 2 is wound around the damping control shaft 55. The damping control shaft 55 is surrounded by limiting plates 54 connected to the load-bearing frame 51 to limit the optical cable 2.

[0052] In a specific embodiment, the limit plate 54 blocks the optical cable 2 from rotating out of the rotating shaft to prevent the optical cable 2 from getting stuck during underwater operations. The damping control shaft 55 adjusts the damping required for underwater laying of the optical cable 2. The greater the damping, the greater the starting tension required, the greater the strength of the optical cable 2 in cutting sediments underwater, and the better the coupling of the optical cable 2. However, if the damping is set too large, there is also a risk of breaking the optical cable 2.

[0053] Furthermore, a T-shaped handle 53 is provided on the top of the load-bearing frame 51 .

[0054] In a specific embodiment, the design of the T-shaped handle 53 facilitates grasping by an underwater robot.

[0055] Of course, the present invention may have many other implementations. Based on this implementation, other implementations obtained by ordinary technicians in this field without any creative work are all within the scope of protection of the present invention.

Claims

1. A distributed acoustic wave sensing system for deep sea environments, characterized in that: It includes a sensing device, a laying device and an optical cable, wherein: The sensing device includes a supporting frame, a pressure-resistant cabin, and a DAS demodulator sealed inside the pressure-resistant cabin. The pressure-resistant cabin is fixed to the supporting frame. The DAS demodulator includes an optical phase demodulation module and a dry-wet connection module. The dry-wet connection module includes an elastic load-bearing shaft and an optical fiber pressure-resistant cabin penetration part connected thereto. One end of the dry-wet connection module is connected to the optical phase demodulation module, and the other end is connected to the optical cable. The laying device is provided with a damping control shaft, and the laying device is provided on the sensing device. The damping control shaft is used to control the damping of the optical cable and enable the sensing device to complete multi-area detection and monitoring.

2. The distributed acoustic wave sensing system for deep sea environment according to claim 1, characterized in that: The optical cable comprises an optical fiber and tension-bearing Kevlar fibers, a water-permeable aromatic wheel, a pressure-bearing stainless steel wire and a water-permeable outer sheath which are wrapped in sequence from the inside to the outside.

3. The distributed acoustic wave sensing system for deep sea environment according to claim 1, characterized in that: The DAS demodulator further comprises a GPS module, a heat dissipation module, a power management module, a control communication module and a switch. An oven-controlled crystal oscillator is embedded in the GPS module.

4. The distributed acoustic wave sensing system for deep sea environment according to claim 2, characterized in that: The optical phase demodulation module includes a photoelectric adjustment unit and a data processing unit. The photoelectric adjustment unit includes a line width laser, a first modulator, an isolator, an erbium-doped fiber amplifier and a circulator connected in sequence. One end of the circulator is connected to a fiber grating.

5. The distributed acoustic wave sensing system for deep sea environment according to claim 4, characterized in that: The optical phase demodulation module further includes a phase modulator and a 3dB coupler. The 3dB coupler is connected to a Faraday rotator, a photodetector and a circulator respectively. The phase modulator, the first modulator and the photodetector are connected to the data processing unit.

6. The distributed acoustic wave sensing system for deep sea environment according to claim 5, characterized in that: The data processing unit includes a conversion module connected to the phase modulator, the first modulator and the photodetector, and a programming module connected to the conversion module.

7. The distributed acoustic wave sensing system for deep sea environment according to claim 6, characterized in that: The data processing unit further comprises an operating system and a peripheral device module, wherein the operating system is connected to the peripheral module and the programming module respectively.

8. The distributed acoustic wave sensing system for deep sea environment according to claim 4, characterized in that: The optical fiber pressure-resistant cabin component includes a cabin penetration component frame, a sealing ring, and a cabin penetration optical fiber. The sealing ring is connected to the cabin penetration component frame, and the cabin penetration optical fiber passes through the cabin penetration component frame. The cabin penetration optical fiber and the cabin penetration component frame are bonded by epoxy resin. One end of the cabin penetration optical fiber is connected to the optical cable, and the other end is connected to the circulator.

9. The distributed acoustic wave sensing system for deep sea environment according to claim 1, characterized in that: The laying device includes a load-bearing frame, a damping control shaft is provided on the load-bearing frame, the optical cable is wound around the damping control shaft, and limiting plates connected to the load-bearing frame are provided around the damping control shaft to limit the optical cable.

10. The distributed acoustic wave sensing system for deep sea environment according to claim 1, characterized in that: A T-shaped handle is provided on the top of the load-bearing frame.

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