CN111947765A - Fully-distributed underwater acoustic sensing system based on micro-structure optical fiber hydrophone towing cable - Google Patents
Fully-distributed underwater acoustic sensing system based on micro-structure optical fiber hydrophone towing cable Download PDFInfo
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- G01H—MEASUREMENT OF MECHANICAL VIBRATIONS OR ULTRASONIC, SONIC OR INFRASONIC WAVES
- G01H9/00—Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves by using radiation-sensitive means, e.g. optical means
- G01H9/004—Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves by using radiation-sensitive means, e.g. optical means using fibre optic sensors
Abstract
The invention discloses a fully-distributed underwater acoustic sensing system based on a micro-structure optical fiber underwater acoustic towing cable, and relates to the field of underwater acoustic sensing. The invention adopts the optical time domain reflection technology to realize the full distribution demodulation of the hydrophone towing cable. The micro-structure optical fibers in the towing cable can be spirally wound in two modes of uniform spacing or local density, the uniform winding mode can realize full-distributed sound wave collection along the hydrophone cable, and no sensing blind area exists; the underwater acoustic sensing units with high sensitivity and small size can be obtained by local dense winding, and an underwater acoustic sensing unit array with small track pitch and high sensitivity is realized; meanwhile, the towing cable structurally realizes the integration of all solid state and light weight, can be rapidly deployed during application, has simpler manufacturing process compared with the traditional towing cable, and can realize batch industrial processing production. Generally, the invention can realize high-sensitivity and fully-distributed marine underwater acoustic sensing, greatly reduces the volume and the weight of the towing cable and reduces the laying cost of the optical cable.
Description
Technical Field
The invention belongs to the field of underwater sound sensing, and particularly relates to a fully-distributed underwater sound sensing system based on a micro-structure optical fiber underwater sound towing cable.
Background
In recent years, the importance of ocean exploration has become more prominent and has become the focus of research. However, the propagation attenuation of light waves, radio waves and the like in water is very large, and the requirements of human sea activities (such as underwater target detection and underwater communication) and the like cannot be met. Therefore, the monitoring of the acoustic characteristics of underwater targets by using sound waves as information carriers has a very important position not only in underwater military communication, navigation and anti-submarine operation, but also has become an important means for people to know, develop and utilize marine resources in peace time.
At present, the optical fiber hydrophone has the characteristics of high sensitivity, electromagnetic interference resistance, severe environment resistance, underwater no electricity and the like, wherein the point type optical fiber hydrophone based on the optical fiber interferometer principle is developed rapidly in recent years. The multipoint hydrophone towed cable array based on the optical interferometer structure mainly adopts various high-sensitivity optical structures as underwater sound sensing units, such as a Fabry-Perot (F-P) interferometer, a Mach-Zehnder (MZ) interferometer, a Michelson (MI) interferometer and the like. The interferometer structure can effectively convert external vibration into the change of resonance wavelength in the interferometer, and the real-time detection capability of underwater sound waves is realized by various wavelength demodulation methods or intensity demodulation methods.
However, the fiber optic hydrophone of the fiber optic interferometer structure is complex in structure and high in manufacturing cost. Meanwhile, in order to realize a multipoint sensing array, the cabling mode of the point type optical fiber hydrophone mainly utilizes time division, space division and wavelength division multiplexing technologies, however, since the multiplexing capacity of the multipoint multiplexing technology is limited, crosstalk noise is easily generated among sensors in a sensing network, and it is difficult to realize a large-capacity sensing array, a relationship of mutual restriction exists between the detection distance of the single-point type networking hydrophone sensing array and the sound wave detection spatial density. Meanwhile, in a sensor network based on a point-mode interferometer hydrophone networking, an optical transmission area between sensors cannot respond to a sound wave signal, so that the problems of measurement blind areas that the measured position is not changed and the changed position is not measured exist. Moreover, the structure of the sensing unit of the interferometer-based towing cable is generally relatively complex, and precise underwater packaging is required to resist the water pressure and corrosion of the ocean, so that the size and the weight of the underwater towed cable are often large, and rapid deployment is not facilitated during use.
Disclosure of Invention
In view of the above defects or improvement needs in the prior art, the present invention provides a fully distributed underwater acoustic sensing system based on a micro-structured optical fiber underwater acoustic towing cable, and aims to provide a lightweight long-distance highly sensitive fully distributed underwater acoustic towing cable for underwater detection.
In order to achieve the above object, the present invention provides a fully distributed underwater acoustic sensing system based on a microstructure fiber hydrophone towing cable, comprising:
the light source module is used for generating probe light and local oscillator light;
the optical pulse modulation module is used for modulating the probe light into ultra-narrow optical pulses and amplifying the ultra-narrow optical pulses;
the circulator is used for injecting the ultra-narrow light pulse into the micro-structure optical fiber in the lightweight fully-distributed hydrophone towing cable and returning backward Rayleigh scattered light which is back-scattered by the micro-structure optical fiber to the coherent receiving module;
the lightweight fully-distributed hydrophone towing cable comprises a towing cable body and a microstructure optical fiber wound on the towing cable body; the micro-structure optical fiber is used for performing back scattering on the ultra-narrow optical pulse to form backward Rayleigh scattering light, and full-distributed underwater acoustic wave sensing is realized;
the coherent receiving module is used for carrying out interference frequency mixing on the backward Rayleigh scattering light and the local oscillator light to obtain a scattering beat frequency signal and converting the scattering beat frequency signal into an electric beat frequency signal;
and the data processing module is used for carrying out phase demodulation on the electric beat frequency signal to obtain blind-spot-free sound wave information distributed along the lightweight fully-distributed hydrophone towing cable.
Further, the lightweight fully-distributed hydrophone towing cable is of a round straight cable structure, wherein the towing cable body comprises a rigid mandrel layer and an elastic sensitization layer which are sequentially distributed from inside to outside;
the rigid mandrel layer is used for resisting axial stretching deformation of the towing cable in the towing process and simultaneously ensuring the towing cable to be suspended in the sea; the elastic sensitization layer is wrapped on the rigid mandrel layer and is used for contracting or expanding under the action of underwater sound pressure signals to realize transverse sound wave sensing of the towing cable;
the microstructure optical fiber is spirally and tightly wound on the elastic sensitization layer, the length of the microstructure optical fiber changes along with the contraction or expansion of the elastic sensitization layer, so that the phase at each position correspondingly changes, and the transverse deformation of the elastic sensitization layer is converted into the axial strain of the microstructure optical fiber.
Optionally, the microstructure optical fiber is spirally wound on the elastic sensitization layer in an equidistant and uniform mode, and the transverse deformation of the elastic sensitization layer is converted into the axial strain of the microstructure optical fiber, so that the full-distributed underwater acoustic sensing sensitization is realized.
Further, the space resolution of the towing cable to underwater sound waves is adjusted by changing the winding intercept of the microstructure optical fiber and the surface perimeter of the elastic sensitivity enhancing layer.
Optionally, the microstructure optical fiber is spirally wound on the elastic sensitization layer in a local dense mode to form a high-sensitivity small-size underwater acoustic sensing unit, so that a small-track-pitch high-sensitivity underwater acoustic sensing unit array is realized.
Further, the space resolution of the towing cable to underwater sound waves is adjusted by changing the spacing between adjacent densely wound areas.
Preferably, the lightweight fully-distributed hydrophone towing cable further comprises an acoustic transmission waterproof layer wrapped on the microstructure optical fiber and the elastic sensitization layer; the sound-transmitting waterproof layer is used for providing transverse hydrostatic pressure protection for the microstructure optical fiber and transmitting a hydroacoustic signal to the elastic sensitization layer.
Preferably, the lightweight fully distributed hydrophone towing cable further comprises a protective sheath encapsulated at the outermost part of the towing cable for protecting the internal structure of the towing cable.
Optionally, the rigid mandrel layer is formed by wrapping Kevlar fibers on the surface of a duralumin alloy cable or a steel cable; the hard aluminum alloy cable or the steel cable has a larger Young modulus and is used for resisting tensile deformation in the dragging process of the dragging cable; the low-density Kevlar fiber also has a large Young modulus and strong tensile property, and meanwhile, the overall density of the hydrophone towing cable can be adjusted, so that the density of the towing cable is close to that of seawater, and the towing cable is guaranteed to be suspended in the sea.
Furthermore, the elastic sensitization layer adopts silicon rubber, fluorine rubber and the like with larger elasticity.
Furthermore, the sound-transmitting waterproof layer adopts an elastomer with high hardness, such as polyurethane rubber TPU, thermoplastic elastomer TPE, thermoplastic rubber TPR and the like.
In general, the above technical solutions contemplated by the present invention can achieve the following advantageous effects compared to the prior art.
(1) Compared with the traditional optical fiber hydrophone towing cable, the underwater sound sensing system provided by the invention realizes the full-distribution demodulation of the hydrophone towing cable by adopting the optical time domain reflection technology instead of the multiplexing technology to connect the traditional point-type hydrophones in series. The micro-structure optical fibers in the towing cable can be spirally wound in two modes of uniform spacing or local density, the uniform winding mode can realize full-distributed sound wave collection along the hydrophone cable, and no sensing blind area exists; the underwater acoustic sensing units with high sensitivity and small size can be obtained by local dense winding, and an underwater acoustic sensing unit array with small track pitch and high sensitivity is realized; compared with the existing piezoelectric ceramic hydrophone and the existing optical fiber interferometer hydrophone, the towing cable can realize high-sensitivity and fully-distributed underwater acoustic sensing.
(2) The whole dragging cable provided by the invention is a round straight cable, the integration of all solid state and light weight is realized on the structure, the volume and the weight of the hydrophone dragging cable are greatly reduced, the laying cost of the optical cable is reduced, the optical cable can be rapidly deployed in practical application, the manufacturing process is simpler compared with the traditional dragging cable, and the batch industrial processing production can be realized. Meanwhile, the system has the advantages of strong environment adaptability, long service life, no need of power supply and the like, can be deployed rapidly, and meets the requirements of modern naval counter-diving operations and ocean resource exploration.
(3) The transverse sensitivity enhancing design is carried out on the underwater acoustic towing cable by arranging the elastic sensitivity enhancing layer, so that the transverse underwater acoustic sensing sensitivity of the underwater acoustic towing cable is improved; and the adjustment of the spatial resolution of the underwater sound wave by the towing cable can be realized by changing the winding mode and specific parameters of the microstructure optical fiber on the elastic sensitization layer.
Drawings
FIG. 1 is a schematic diagram of an embodiment of a fully-distributed underwater acoustic sensing system based on a micro-structured fiber hydrophone towing cable provided by the invention;
FIG. 2 is a schematic illustration of a trailing cable configuration according to an embodiment of the present invention;
FIG. 3 is a drawing of a configuration for uniform tow cable wrapping in an embodiment of the present invention;
FIG. 4 is a drawing of a closely wound configuration of trailing cables according to an embodiment of the present invention;
FIG. 5 is a drawing illustrating a structure of a vertical tight winding of a trailing cable according to an embodiment of the present invention;
the optical fiber cable comprises a light source module 1, an optical pulse modulation module 2, a circulator 3, a lightweight fully-distributed hydrophone towing cable 4, a coherent receiving module 5 and a data processing module 6.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.
As shown in fig. 1, an embodiment of the present invention provides a fully distributed underwater acoustic sensing system based on a micro-structured fiber underwater acoustic towing cable, including: the light source module 1 is used for generating probe light and local oscillator light; the optical pulse modulation module 2 is used for modulating the probe light into ultra-narrow optical pulses, so that the width of the optical pulses is smaller than the flight time of the light between two adjacent microstructure points, and then the light amplification is carried out; the circulator 3 is used for injecting the ultra-narrow light pulse into the microstructure optical fiber on the lightweight fully-distributed hydrophone towing cable 4 through the first port a and the second port b; backward Rayleigh scattered light which is backscattered and returned by the microstructure optical fiber returns to the coherent receiving module 5 through the third port c; the micro-structure optical fiber is wound inside the dragging cable in a spiral mode, and full-distributed underwater acoustic wave sensing is achieved; the coherent receiving module 5 is configured to perform interference frequency mixing on the backward rayleigh scattering light and the local oscillation light to obtain a scattering beat signal, and convert the scattering beat signal into an electrical beat signal; and the data processing module 6 is used for carrying out phase demodulation on the electric beat frequency signal to obtain sound wave information distributed along the lightweight fully-distributed hydrophone towing cable.
Further, the light source module 1 includes a narrow linewidth laser 11 and an optical coupler 12, and the embodiment of the present invention employs 9: 1; a beam of laser generated by the ultra-narrow linewidth laser 11 is split by the optical coupler 12 to generate a probe light beam with higher intensity and a local oscillator light beam with lower intensity respectively; the optical pulse modulation module 2 comprises an acousto-optic modulator 21 and an erbium-doped fiber amplifier 22; the probe light is input to the acousto-optic modulator 21, modulated into a narrow pulse sequence, and generates a 200MHZ shift frequency. The probe light after pulse modulation is input into an erbium-doped fiber amplifier 22 for pulse amplification; the coherent receiving module 5 comprises an optical coupler 51 and a balanced photoelectric detector 52, and the embodiment of the invention adopts a 2 × 2 optical coupler; the optical coupler 51 performs interference mixing on the backward rayleigh scattered light and the local oscillation light to obtain a scattered beat signal, and the scattered beat signal is received by the balanced photodetection 52 and converted into an electrical beat signal. The signal processing module 6 obtains phase changes at different positions on the microstructure optical fiber by utilizing quadrature phase demodulation, further obtains non-blind-spot phase information distributed along the towing cable 4, and finally extracts the non-blind-spot sound wave information distributed along the towing cable 4.
As shown in fig. 2, the lightweight fully-distributed hydrophone towing cable 4 is a circular straight cable structure, and includes, from inside to outside, sequentially distributed: a rigid mandrel layer 42 for resisting axial tensile deformation of the towing cable during towing; the elastic sensitization layer 43 is wrapped on the rigid mandrel layer 42 and used for contracting or expanding under the action of underwater sound pressure signals to enhance the transverse sound wave sensitivity of the towing cable; the microstructure optical fiber 41 is tightly wound on the elastic sensitization layer 43 in a screwing manner, and the length of the microstructure optical fiber is changed along with the contraction or expansion of the elastic sensitization layer, so that the phases at each position are correspondingly changed, and the transverse deformation of the sensitization layer is converted into the axial strain of the microstructure optical fiber; the sound-transmitting waterproof layer 44 is wrapped on the microstructure optical fiber 41 and the elastic sensitization layer 43 to prevent the internal structure of the towing cable and the microstructure optical fiber from being corroded by seawater; protective sheath 45, the encapsulation is outside at the cable of dragging for the inner structure of cable is dragged in the protection, improves the life who drags the cable.
Considering that the towing cable works in a deep water of 30m, the rigid mandrel layer is formed by wrapping Kevlar fibers on the surface of a hard aluminum alloy cable or a steel cable, and the hard aluminum alloy cable has a larger Young modulus and is used for resisting tensile deformation in the towing process of the towing cable; the low-density Kevlar fiber also has large Young modulus and strong tensile property, and can adjust the overall density of the hydrophone towing cable to make the density of the towing cable close to that of seawater. In this embodiment, the mandrel layer is made of a rigid material having a young's modulus of 7.03E +10Pa and a poisson's ratio of 0.345, and the diameter of the mandrel layer is 8mm in order to ensure the compression resistance and the acoustic pressure sensitivity of the trailing cable, which can be adjusted as required in practical application.
Considering that the optical fiber is not sensitive to transverse pressure, the invention wraps an elastic sensitization layer formed by sound pressure sensitive materials outside a rigid mandrel layer, the microstructure optical fiber is spirally and tightly wound on the elastic sensitization layer at a certain interval, when an underwater sound pressure signal acts on a towing cable, the elastic sensitization layer contracts or expands according to the sound pressure signal, the microstructure optical fiber tightly wound on the elastic sensitization layer correspondingly contracts or expands along with the elastic sensitization layer, the length of the microstructure optical fiber is changed, and further the phase of each position in the microstructure optical fiber is correspondingly changed. The elastic sensitization layer of the invention adopts silicon rubber, fluorine rubber and the like with larger elasticity. In the embodiment, the elastic sensitization layer is made of a silicon rubber material with Young modulus of 3.2E +7Pa and Poisson ratio of 0.465 and high elasticity, and the thickness of the sensitization layer is 23.5mm in order to increase the sound pressure sensitivity of the towing cable and facilitate use, and the thickness of the sensitization layer can be adjusted according to requirements in practical application. Meanwhile, in order to prevent the microstructure optical fiber and the sensitivity enhancing material from being eroded by seawater, a sound-transmitting waterproof layer made of polyurethane is wrapped outside the microstructure optical fiber and the elastic sensitivity enhancing layer. The sound-transmitting waterproof layer is made of elastomer with high hardness, such as polyurethane rubber TPU, thermoplastic elastomer TPE, thermoplastic rubber TPR and the like.
When external underwater sound acts on the towing cable, backward Rayleigh scattered light carrying the sound wave information in the microstructure optical fiber is received by a detector in the DAS and converted into an electric signal, and the signal processing module performs phase demodulation to extract the sound wave information. The sound pressure sensitivity can be changed by the phase of the backward Rayleigh scattering light
The unit of the phase change is rad/Pa, the phase change caused by the Poisson effect and the elasto-optical effect is neglected, the phase change only caused by the change delta L of the length of the optical fiber is considered and can be expressed as 2nk delta L, wherein n is the refractive index of the micro-structural optical fiber, and k is the wave vector size of the light transmitted in the micro-structural optical fiber. The sound pressure sensitivity is calculated in a manner proportional to the microstructure point spacing of the microstructure fiber, but considering the spatial resolution of the system, the microstructure point spacing of the microstructure fiber is not too long, in this embodiment, the microstructure fiber uses the bending-resistant fiber to reduce the bending loss, and the microstructure point spacing is 5 meters, and can be vertically (the inclination angle of the fiber winding is small and tends to 0) tightly (the interval of the fiber winding is small and tends to 0) wound on the elastic sensitization layer for about 14 turns, as shown in fig. 4, when a sound wave signal acts on the drag cable, the radius change amplitude of the elastic sensitization enhanced outer surface is Δ DIf the fiber length between the microstructure points on the microstructure fiber is changed to 14 pi Δ D, the phase change of the backward rayleigh scattering light in the microstructure fiber caused by the fiber length change is 28nk pi Δ D, so the radius change amplitude Δ D of the sensitivity-enhanced outer surface can be increased by using the sound sensitive material in the elastic sensitivity-enhancing layer, and meanwhile, because the fiber is tightly wound on the outer surface of the sensitivity-enhancing layer, the length change of each circle of the fiber can be accumulated and superposed to achieve the effect of increasing the sound pressure sensitivity, in this embodiment, the sensitivity of the towing cable can reach-133 dBre: 1 rad/. mu.pa.
The winding structure can realize the sensitization effect and change the spatial resolution of the distributed hydrophone towing cable to underwater sound waves. The winding mode of the microstructure optical fiber can be as shown in fig. 3, and the microstructure optical fiber is uniformly and equidistantly wound on the elastic sensitization layer to realize the full-distributed underwater acoustic sensing sensitization. Wherein, the spatial resolution of the hydrophone towing cable is determined according to the following relation: the spatial resolution of the hydrophone towed cable (two-point spacing of scattering enhancement points in the micro-structured optical fiber. winding intercept)/(surface perimeter of the elastic sensitization layer + square of winding intercept). In this embodiment, according to the actual application requirement, the spatial resolution of the towing cable to the underwater sound wave is adjusted by adjusting the winding intercept of the microstructure optical fiber and the surface perimeter of the elastic sensitivity enhancing layer. Meanwhile, the winding mode of the microstructure fiber can also be locally and densely wound on the elastic sensitization layer as shown in fig. 4. Compared with a winding method with uniform spacing, the locally dense winding mode can form the high-sensitivity small-size underwater sound sensing unit, and the small-track-pitch high-sensitivity underwater sound sensing unit array is realized. In the local dense winding mode, the spatial resolution of the high-sensitivity underwater sound sensing array only depends on the distance between two dense winding areas, and the sensitivity of the underwater sound sensing unit depends on the length of the optical fiber of the dense winding areas. A schematic side cross-sectional view of the densely wound area is shown in fig. 5.
It will be understood by those skilled in the art that the foregoing is only a preferred embodiment of the present invention, and is not intended to limit the invention, and that any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the present invention.
Claims (10)
1. A full distributed underwater acoustic sensing system based on a microstructure optical fiber hydrophone towing cable is characterized by comprising:
the light source module (1) is used for generating probe light and local oscillator light;
the optical pulse modulation module (2) is used for modulating the probe light into ultra-narrow optical pulses and carrying out optical amplification;
the circulator (3) is used for injecting the ultra-narrow light pulse into the microstructure optical fiber in the lightweight fully-distributed hydrophone towing cable (4) and returning backward Rayleigh scattering light which is back-scattered by the microstructure optical fiber to the coherent receiving module (5);
the lightweight fully-distributed hydrophone towing cable (4) comprises a towing cable body and a microstructure optical fiber wound on the towing cable body; the micro-structure optical fiber is used for performing back scattering on the ultra-narrow optical pulse to form backward Rayleigh scattering light, and full-distributed underwater acoustic wave sensing is realized;
the coherent receiving module (5) is used for carrying out interference frequency mixing on the backward Rayleigh scattering light and the local oscillator light to obtain a scattering beat frequency signal and converting the scattering beat frequency signal into an electric beat frequency signal;
and the data processing module (6) is used for carrying out phase demodulation on the electric beat frequency signal to obtain blind-spot-free sound wave information distributed along the lightweight fully-distributed hydrophone towing cable (4).
2. The fully-distributed underwater acoustic sensing system based on the micro-structured optical fiber underwater acoustic towing cable according to claim 1, wherein the light-weight fully-distributed underwater acoustic towing cable is a round straight cable structure, wherein the towing cable body comprises a rigid mandrel layer and an elastic sensitization layer which are sequentially distributed from inside to outside;
the rigid mandrel layer is used for resisting axial stretching deformation of the towing cable in the towing process and ensuring the towing cable to suspend in the ocean; the elastic sensitization layer is wrapped on the rigid mandrel layer and is used for contracting or expanding under the action of underwater sound pressure signals to realize transverse sound wave sensing of the towing cable;
the microstructure optical fiber is spirally and tightly wound on the elastic sensitization layer, the length of the microstructure optical fiber changes along with the contraction or expansion of the elastic sensitization layer, so that the phase at each position correspondingly changes, and the transverse deformation of the elastic sensitization layer is converted into the axial strain of the microstructure optical fiber.
3. The fully-distributed underwater acoustic sensing system based on the micro-structural optical fiber underwater acoustic towing cable according to claim 2, wherein the micro-structural optical fiber is spirally wound on the elastic sensitization layer in an equidistant and uniform manner, and the transverse deformation of the elastic sensitization layer is converted into the axial strain of the micro-structural optical fiber, so that fully-distributed underwater acoustic sensing sensitization is realized.
4. The fully distributed underwater acoustic sensing system based on the microstructured fiber hydrophone towing cable according to claim 3, wherein the spatial resolution of the towing cable to underwater acoustic waves is adjusted by changing the winding intercept of the microstructured fiber and the surface perimeter of the elastic sensitization layer.
5. The fully distributed underwater acoustic sensing system based on the micro-structured optical fiber underwater acoustic towing cable according to claim 2, wherein the micro-structured optical fibers are spirally wound on the elastic sensitization layer in a locally dense manner to form high-sensitivity small-size underwater acoustic sensing units, so as to realize a small track pitch and high-sensitivity underwater acoustic sensing unit array.
6. The fully distributed underwater acoustic sensing system based on the micro-structured fiber optic hydrophone towing cable according to claim 5, wherein the spatial resolution of the towing cable to underwater acoustic waves is adjusted by changing the spacing between adjacent densely wound areas.
7. The fully distributed underwater acoustic sensing system based on the micro-structured optical fiber underwater acoustic towing cable according to any one of claims 2 to 6, wherein the light-weight fully distributed underwater acoustic towing cable further comprises an acoustically transparent waterproof layer wrapped on the micro-structured optical fiber and the elastic sensitization layer; the sound-transmitting waterproof layer is used for providing transverse hydrostatic pressure protection for the microstructure optical fiber and transmitting a hydroacoustic signal to the elastic sensitization layer.
8. The fully distributed hydroacoustic sensing system based on a microstructured fiber hydrophone towing cable according to any one of claims 2-7, wherein the light-weight fully distributed hydroacoustic towing cable further comprises a protective jacket enclosing an outermost portion of the towing cable for protecting an inner structure of the towing cable.
9. The fully distributed hydroacoustic sensing system based on the microstructured fiber hydrophone towing cable of claim 2, wherein the rigid core layer is formed by wrapping Kevlar fibers on the surface of a duralumin alloy cable or a steel cable; the elastic sensitization layer adopts silicon rubber or fluorine rubber.
10. The fully distributed underwater acoustic sensing system based on the micro-structured optical fiber underwater acoustic towing cable according to claim 7, wherein the sound-transmitting and water-proof layer is made of polyurethane rubber TPU, thermoplastic elastomer TPE or thermoplastic rubber TPR.
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
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