Perimeter warning monitoring device and method using fiber grating

Abstract

The present invention discloses a perimeter warning monitoring device and method using fiber Bragg gratings, which relates to the field of fiber Bragg grating warning devices and includes a cable core, encapsulation rings are provided at both ends of the cable core, a cladding is provided on the outside of the cable core, a metal ring is fixedly installed on the outer end of the encapsulation ring, the cable core extends into the interior of the metal ring, a connecting ring is threadedly installed on the outside of the metal ring, a cable core is provided on the inside of the connecting ring, and when the metal ring and the connecting ring are installed together, the ends of the two sections of the cable core are in close contact. The present invention provides a metal ring, a connecting ring, and a connecting core, and the metal ring and the connecting ring can be separated to replace different optical fibers or fiber Bragg grating vibration sensors. There is no need to cut the optical fiber, and there is no need to weld the optical fibers together during installation, so the operation is very convenient. The connecting core can ensure the stability of the connection between different sections of optical fiber and ensure the normal transmission of the signal.

Description

Technical Field

[0001] The present invention relates to the field of fiber grating warning devices, in particular to a perimeter warning monitoring device and method using fiber grating. Background Art

[0002] A fiber Bragg grating (FBG) sensor uses an ultraviolet laser to inscribe a grating on the core of an optical fiber. When continuous broadband light from the source is transmitted through the transmission fiber, a narrowband light is selectively reflected back from the grating. The remaining broadband light continues to transmit and is reflected from the next grating with a different central wavelength. An array of multiple gratings forms a fiber Bragg grating (FBG) sensing network. FBG sensors are immune to electromagnetic interference and have excellent stability and reliability.

[0003] Fiber Bragg gratings (FBGs) also have important applications in border surveillance and perimeter security. Existing underground surveillance systems involve directly burying the FBG vibration detector in the soil during construction. The FBG vibration detector and the optical fiber are typically welded together, creating a fixed connection that is inconvenient during installation, especially when inspecting and repairing the optical fiber. Replacing the fiber requires cutting the welded portion, which is inconvenient. Several cold-splice techniques exist, but these are relatively expensive, require specialized operation, and require extensive training.

[0004] More importantly, the losses caused by existing fusion welding and cold welding technologies will affect the accuracy of the grating sensor, and there is currently no way to adjust it well. If the signal recognition model is retrained, the cost will be very high. Summary of the Invention

[0005] The object of the present invention is to provide a perimeter security monitoring device using fiber gratings to solve the problems raised in the above background technology.

[0006] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0007] Perimeter security monitoring device using fiber optic Bragg grating, including:

[0008] The cable core comprises a first core and a second core, each having a predetermined length, wherein an optical fiber having an end face reflectivity within a predetermined range is installed; a fiber Bragg grating is formed in at least a portion of the length of the optical fiber in the first core; and a cladding is provided on the outer side of the cable core;

[0009] At least two packaging rings are fixed to both ends of the first core, and a metal ring is fixedly mounted on the outer end of each packaging ring;

[0010] a connecting ring, threadedly connected to the metal ring;

[0011] Ends of the first core and the second core extend into the interior of the metal ring and the connecting ring and are fixed;

[0012] When the metal ring and the connecting ring are screwed and fixed, the ends of the first core and the second core are in contact with each other and have a predetermined longitudinal pressure.

[0013] According to one aspect of the present application, an annular limiting ring is fixedly installed at the end of the cable core;

[0014] In the installed state, when the limiting ring extends to the inside of the connecting ring, the connecting ring can rotate around the axis.

[0015] According to one aspect of the present application, at least one connecting core having a predetermined elastic coefficient is installed on the inner side of the metal ring and is sleeved on the connection between the first core and the second core.

[0016] According to one aspect of the present application, a mounting seat is further provided at the bottom of the cable core, and the elastic coefficient of the mounting seat is greater than the elastic coefficient of the optical fiber.

[0017] According to one aspect of the present application, the mounting base comprises:

[0018] A support rod with a base fixedly mounted at the bottom;

[0019] The mounting block is mounted on the top of the support rod. The mounting block is an open structure with a top opening and closed all around. Two side walls of the mounting block are provided with sliding grooves matching the connecting ring, and the packaging ring can be accommodated in the opening structure.

[0020] According to one aspect of the present application, the mounting seat is a rectangular box with an open top and a plurality of divided areas, and the two packaging rings and the cable core are installed inside the rectangular box.

[0021] According to one aspect of the present application, at least two partitions are installed on the inner side of the rectangular box, and a placement groove for placing the packaging ring is formed between the partition and the inner wall of the rectangular box; the first core has freedom along the direction of the central axis in the rectangular box and is constrained in the direction perpendicular to the central axis.

[0022] According to one aspect of the present application, the partition and the two side walls parallel to the rectangular box and the partition are provided with a slot for placing the connecting ring, and the bottom of the rectangular box between the two partitions is set to be open;

[0023] An upper cover is also installed at the upper end of the rectangular box body, and a plurality of snap-in plates are fixedly installed at the bottom of the upper cover. A snap-in groove is provided at the bottom of the snap-in plate. When the upper cover and the rectangular box body are snapped together, the snap-in groove of the partition plate and the snap-in groove of the snap-in plate form an installation ring for installing the connecting ring. The two side edges of the packaging ring do not contact the inner side of the placement groove, and the packaging ring can slide inside the placement groove.

[0024] According to one aspect of the present application, an opening cavity is provided in the middle of the upper cover. When the upper cover is snapped together with the rectangular box body, the opening cavity and the opening overlap to form an opening that passes through from top to bottom.

[0025] A fiber Bragg grating-based perimeter security monitoring method is further provided, which is implemented using the fiber Bragg grating-based perimeter security monitoring device, comprising the following steps:

[0026] When in use, first open a groove in the ground where it needs to be buried, bury the mounting seat, and then place the packaging ring on the mounting seat;

[0027] Then the connecting ring of the cable core and the metal ring are installed together through threads. Different connecting cores will produce different degrees of deformation under the extrusion of the connecting ring and the metal ring, so that the contact surface of the connecting core and the contact surface of the connecting core and the cable core are tightly fitted together;

[0028] By connecting the cable core to a signal transceiver, the environment is monitored based on the transmitted and received signals.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] The present invention utilizes a metal ring, a connecting ring, and a connecting core. The metal ring and connecting ring can be separated to replace different optical fibers or fiber Bragg grating vibration sensors. This eliminates the need to cut the optical fibers or weld them together during installation, making operation very convenient. Furthermore, by controlling the end face reflectivity, signal loss can be reduced, improving the quality of the detection signal, reducing signal loss caused by welding, and lowering the cost of existing cold-joining technology. The connecting core ensures the stability of the connection between different sections of optical fiber, ensuring normal signal transmission. Furthermore, the provision of a mounting base further enhances the sensitivity of the fiber Bragg grating response. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a cross-sectional view of the packaging ring and cable core of the present invention.

[0032] Figure 2 It is a cross-sectional view of the packaging ring, cable core and connecting core of the present invention.

[0033] Figure 3 This is a structural diagram of the connecting ring and the limiting ring of the present invention.

[0034] Figure 4 This is a structural diagram of the packaging ring, cable core and connecting core of the present invention.

[0035] Figure 5 This is a structural diagram of the cable core, mounting block and support rod of the present invention.

[0036] Figure 6 This is a structural diagram of the mounting block, support rod and base of the present invention.

[0037] Figure 7 It is a cross-sectional view of the mounting block, cover plate and pressing sheet of the present invention.

[0038] Figure 8 This is a structural diagram of the rectangular box and cable core of the present invention.

[0039] Figure 9 This is a structural cross-sectional view of the outer rectangular box and the cable core of the present invention.

[0040] Figure 10 This is a structural diagram of the rectangular box and upper cover of the present invention.

[0041] Figure 11 This is another structural diagram of the rectangular box and upper cover of the present invention.

[0042] Figure 12 This is a third structural diagram of the rectangular box and upper cover of the present invention.

[0043] Figure 13 It is a cross-sectional view of the rectangular box, packaging ring and upper cover of the present invention.

[0044] Figure 14 It is a top view of the rectangular box, packaging ring and cable core of the present invention.

[0045] In the figure: 1. Cable core; 2. Metal ring; 3. Connecting ring; 4. Encapsulating ring; 5. Cladding; 6. Limiting ring; 7. Connecting core; 8. Mounting block; 9. Support rod; 10. Base; 11. Slide; 12. Rectangular box; 13. Placement slot; 14. Opening; 15. Upper cover; 16. Opening cavity; 17. Snap-in plate; 18. Slot; 19. Cover; 20. Pressing piece. DETAILED DESCRIPTION

[0046] In order to solve the above problems, the applicant has conducted intensive research.

[0047] Fiber Bragg gratings are affected by a relatively large number of factors, including the material properties of the fiber itself, such as elastic modulus, thermal expansion coefficient, elongation coefficient, and compression coefficient, as well as external factors such as temperature and stress. During light propagation, signal loss is also caused by various conditions, such as welding. Therefore, the question of how to implement it more simply and accurately is currently in need of resolution. Furthermore, since thermal expansion and force stretching exhibit similar signal performance, distinguishing between these two conditions, reducing the impact of background factors on the detection results, and minimizing signal noise are also issues that need to be addressed.

[0048] See also Figures 1 to 3This embodiment provides a perimeter surveillance monitoring device using fiber Bragg gratings (FBGs). The device comprises a cable core 1, with encapsulation rings 4 disposed at both ends of the cable core 1. A cladding 5 is disposed on the outer side of the cable core 1. The encapsulation rings 4 are made of stainless steel. A Bragg grating (FBG) is disposed in the cable core 1 between the two encapsulation rings 4, forming a fiber Bragg grating (FBG). A metal ring 2 is fixedly mounted on the outer ends of the encapsulation rings 4. The end of the cable core 1 extends into the interior of the metal ring 2. A connecting ring 3 is threadedly mounted on the outer side of the metal ring 2. The cable core 1 is disposed inside the connecting ring 3. When the metal rings 2 and connecting rings 3 are installed together, the ends of the two sections of the cable core 1 are in close contact, and a slight amount of compression is generated at the contact point, thereby ensuring the tightness of the connection between the connecting ring 3 and the metal ring 2. In other words, longitudinal pressure is applied to the ends of the first and second cores to maintain their abutment. Because the ends of the first core are fixedly connected to the encapsulation rings, stress or temperature changes applied to the first core can be applied to the grating within the optical fiber of the first core. Stress or temperature changes in the second core cannot be applied to the fiber Bragg grating in the first core. This prevents the non-operating area from being affected by related factors, which could cause signal changes and distortion in the operating area. This approach significantly speeds up installation and deployment, improving deployment efficiency. Furthermore, signal loss is controllable. Using an end-face reflectivity tester, the approximate signal loss can be determined. Subsequent compression of the end faces to ensure a tight connection can reduce signal loss.

[0049] For ease of description, the cable core equipped with the fiber Bragg grating (FBG) is referred to as the first core, and the adjacent cores on either side of the first core are referred to as the second cable core. The first and second cores are each of predetermined lengths and each contains an optical fiber with an end-face reflectivity within a predetermined range. In practice, reflectivity can be measured using a micro-nano fiber reflectance measurement device to ensure that the desired reflectivity is achieved.

[0050] During installation, multiple fiber Bragg gratings (ie, fiber Bragg grating vibration sensors) can be connected in series on one optical fiber.

[0051] When replacing or repairing an optical fiber or fiber Bragg grating vibration sensor, the metal ring 2 and the connecting ring 3 can be directly separated to replace a different optical fiber or fiber Bragg grating vibration sensor. There is no need to cut the optical fiber, and there is no need to weld the optical fibers together during installation, making the operation very convenient. If welding technology is used, the loss of the optical signal cannot be adjusted secondary, and it is necessary to optimize the software algorithm or use a neural network to train the loss under various conditions to obtain a better processing model. However, such a model is generally only applicable to specific situations and needs to be retrained after the working conditions change, resulting in poor generalization performance.

[0052] In this embodiment, a limiting ring 6 is fixedly installed at the end of the cable core 1. When a connecting ring 3 is provided at the end of the cable core 1, the limiting ring 6 is located inside the connecting ring 3. The connecting ring 3 can rotate outside the limiting ring 6 and the cable core 1. When installing the connecting ring 3 and the metal ring 2, the connecting ring 3 can be directly rotated to cause relative rotation between the metal ring 2 and the connecting ring 3, thereby facilitating the installation of the connecting ring 3. Moreover, after the two are installed together, the connecting ring 3 will provide a force pointing to the metal ring 2 on the end of the cable core 1, so that the cable core in the connecting ring 3 is in close contact with the cable core in the metal ring 2.

[0053] If only the connecting ring 3 is used, the cable core in the connecting ring 3 is in direct contact with the cable core in the metal ring 2. Since the cables at both ends are integral, it is easy to encounter insufficient compression margin between the contact parts during installation. In addition, the compression margin between the two contact parts is the largest, and the compression margin decreases as it moves towards the middle of the cable. This leads to unstable installation, gaps in the joints, and unstable signal transmission. After long-term use, the ends of the cable core may deform.

[0054] In order to improve the stability and tightness of the connection between the cable cores 1, Figure 2 and Figure 4 As shown, a plurality of connecting cores 7 are installed on the inner side of the metal ring 2. The connecting cores 7 are multiple pie-shaped structures. The connecting cores are located between the cable core in the connecting ring 3 and the cable core in the metal ring 2. When the connecting core 7 is squeezed, since the connecting core 7 is relatively short, the two ends of the connecting core 7 are subjected to the same force when squeezed, so the compression margin of the entire connecting core 7 remains almost consistent. Moreover, compared with the squeeze contact with the ends of the two sections of cable, the connecting core 7 is more easily deformed when squeezed, thereby making the connection between the two sections of cable more stable. Moreover, when multiple connecting cores 7 are squeezed, there will be more compression margins. On the one hand, it can protect the ends of the cable cores. On the other hand, it is also beneficial to the stability of the connection part and avoids the occurrence of gaps. When the connecting core 7 is squeezed, it provides a reaction force outward, so that the connection between the connecting ring 3 and the metal ring 2 is also relatively stable.

[0055] In other words, by connecting the cores, a certain stress is maintained at the joints, so that the joints can be connected more tightly, avoiding gaps that cause signal loss.

[0056] Based on the sensing principle of fiber Bragg grating, it can be known that the signal of fiber Bragg grating is a wavelength-encoded signal. However, in practical applications, fiber Bragg grating sensors are mainly used to measure physical quantities such as temperature and stress, and these physical quantities need to be converted into wavelength signals.

[0057] According to the coupled mode theory, when the phase matching condition is met, the resonant wavelength of the grating is:

[0058] Where: B =2n eff Λ;

[0059] λ B is the resonant wavelength of the fiber Bragg grating; n eff is the effective refractive index of the fiber Bragg grating propagation mode; Λ is the grating period;

[0060] Any change in any of these parameters will cause the fiber Bragg grating resonant wavelength to shift. From this, the shift Δλ of the fiber Bragg grating resonant wavelength can be obtained. B for:

[0061]

[0062] Therefore, the change in displacement wavelength is related to factors such as strain ε, temperature change ΔT, photoelastic coefficient P, Poisson's ratio v, and optical fiber thermal expansion coefficient α.

[0063] The wavelength shift caused by stress or temperature can be given by the following formula:

[0064] Δλ B =2Δn eff Λ+2n eff In order to improve accuracy, the transverse stress should generally be eliminated so that the optical fiber is subjected to only axial stress as much as possible.

[0065] When the fiber Bragg grating is subjected to external stress or the ambient temperature changes, it causes n eff The stress changes, through the photoelastic effect, cause a shift in the fiber Bragg grating's resonant wavelength. By detecting the shift in the resonant wavelength using a spectrometer or photoelectric detection system, it's possible to determine if an object has passed. The magnitude of the shift can also be used to determine the size of the object. Generally, larger objects produce larger vibrations.

[0066] In a further embodiment, since the existing fiber gratings are directly installed in the soil, when there is a sudden vibration, the fiber grating can easily follow the soil vibration and produce resonance, resulting in insensitive detection. In order to improve the detection sensitivity of the cable core 1, a mounting seat is also provided at the bottom of the cable core 1. When burying the cable, the mounting seat can be pre-installed in the excavated trench through concrete. The depth of the mounting seat is buried greater than the depth of the trench, so that the cable core is installed more stably, and the vibration force of the ground during vibration can be better transmitted to the cable core, making the cable core more sensitive to reaction.

[0067] like Figure 5 and Figure 6As shown, the mounting base includes a support rod 9, and a base 10 is fixedly installed at the bottom of the support rod 9. The base 10 is made of metal or a concrete structure. During installation, an installation groove for placing the base 10 is excavated in the opened groove, and the base 10 and the support rod 9 are placed in the installation groove, so that the mounting base is installed more stably. When the ground vibrates, it is ensured that the base 10 and the support rod 9 will not move significantly with the ground, avoiding large displacement of the optical fiber core and causing deformation and displacement of the optical fiber. When an object moves nearby, the movement of the soil drives the cable core to stretch or compress, thereby generating displacement, which can be identified from the signal detection process. If the temperature changes, it also causes changes in the fiber grating, which is reflected in the signal detection.

[0068] A mounting block 8 is fixedly mounted on the top of the support rod 9. The mounting block 8 is a cavity structure with an open top. One of the encapsulation rings 4 is directly installed into the inner cavity of the mounting block 8 through the top opening. Slots 11 are provided on both side walls of the mounting block 8. The connecting ring 3 is directly stuck in the slots 11. This allows the encapsulation ring 4 to be installed, and thus the cable core 1 (i.e., the fiber Bragg grating) is also installed. The cable core 1 can then be buried in the soil, with the cable core 1 (i.e., the fiber Bragg grating) in direct contact with the soil.

[0069] The mounting block 8 supports the cable core 1. The vibration of the ground is relatively large, and the vibration force is directly transmitted to the cable core 1 (ie, the fiber Bragg grating), making the cable core 1 more sensitive.

[0070] like Figures 6 and 7 As shown, a cover plate 19 is also installed on the top of the mounting block 8 through a rotating shaft, and a pressing plate 20 is fixedly installed on the bottom of the cover plate 19. The pressing plate 20 is made of spring steel and has a W-shaped structure. After the packaging ring 4 is placed inside the mounting block 8, the cover plate 19 is closed, and the bottom of the pressing plate 20 contacts the top two sides of the packaging ring 4, so that the packaging ring 4 is installed more stably. In addition, the pressing plate 20 also has a protective effect on the packaging ring 4 to avoid the deformation of the packaging ring 4 due to excessive pressure. In addition to the protective effect, it also has a limiting effect, so that the optical fiber can detect signals in the axial direction more accurately. Reduce the interference of stress in other directions.

[0071] In addition to the above structure, the mounting base Figures 8 to 14 As shown, it can also be set as a rectangular box 12 with an open top. The two packaging rings 4 and the cable core 1 are installed inside the rectangular box 12. The rectangular box 12 also has a supporting function. When the ground vibrates, the vibration force can also be transmitted to the cable core.

[0072] Moreover, the rectangular box 12 supports both packaging rings 4 of the cable core 1 (ie, the fiber Bragg grating), which provides a better installation effect for the cable core 1 (ie, the fiber Bragg grating).

[0073] At least two partitions are fixedly installed on the inner side of the rectangular box 12. Figures 8 and 9 As shown, a placement groove 13 for accommodating the encapsulation ring 4 is formed between the partition plate and the inner side wall of the rectangular box 12. When installing the cable core 1 (i.e., the fiber Bragg grating), the encapsulation ring 4 can be directly placed in the placement groove 13. It can then be directly buried in the soil. The cladding 5 is in contact with the soil. When the soil is subjected to force and vibration, the vibration force can be directly transmitted to the fiber Bragg grating, causing the fiber Bragg grating to deform or vibrate, resulting in a shift in the resonant wavelength of the fiber Bragg grating.

[0074] In a further embodiment, the partition and the two side walls parallel to the rectangular box 12 are provided with a slot 18 for placing the connecting ring 3. When the fiber Bragg grating is placed inside the rectangular box 12, the encapsulation ring 4 is located in the rectangular box. The bottom of the rectangular box 12 between the two partitions is set as an opening 14. When buried in the soil, the soil can fall from the opening 14 to the bottom of the trench, completely wrapping the fiber Bragg grating inside the soil. When the soil layer vibrates, the fiber Bragg grating can be better vibrated, and the vibration force is directly transmitted to the fiber Bragg grating, making the fiber Bragg grating more sensitive.

[0075] like Figures 10 to 13 As shown, an upper cover 15 is further installed at the upper end of the rectangular box 12, and a plurality of snap-in plates 17 are fixedly installed at the bottom of the upper cover 15. A snap-in groove 18 is provided at the bottom of the snap-in plate 17. When the upper cover 15 is snapped together with the rectangular box 12, the snap-in groove 18 of the partition and the snap-in groove 18 of the snap-in plate 17 form a mounting ring for mounting the connecting ring 3. After the upper cover 15 is in contact with the rectangular box 12, the placement groove 13 is formed into a sealed space. When the encapsulation ring 4 is installed inside the placement groove, it does not contact the soil, which can avoid the encapsulation ring 4 vibrating with the soil and causing resonance. The fiber Bragg grating is in direct contact with the soil, and the vibration of the soil can be directly transmitted to the fiber Bragg grating, making the fiber Bragg grating more sensitive.

[0076] The two side edges of the packaging ring 4 do not contact the inner side of the placement groove 13, and the packaging ring 4 can slide inside the placement groove 13. The placement groove 13 also reserves space for horizontal movement for the packaging ring 4. When the vibration force is transmitted from a relatively distant part, such as when the human body or vehicle causes the ground to vibrate, longitudinal waves and a small amount of transverse waves will be generated. The longitudinal waves will cause the fiber Bragg grating to vibrate up and down, while a small amount of transverse waves will cause the fiber Bragg grating to shake slightly horizontally. These effects will form a certain stress, causing the state of the fiber Bragg grating to change. By setting the placement groove, the stress in one direction is limited, thereby making the signal detection more accurate and concentrating on detecting the axial stress.

[0077] An opening 16 is provided in the middle of the upper cover 15. When the upper cover 15 is engaged with the rectangular box 12, the opening 16 overlaps with the opening 14 to form an opening that passes through from top to bottom. When backfilling the soil, the soil can fall directly from the opening into the groove and contact the outer side of the fiber Bragg grating, thereby making the soil better able to wrap the fiber Bragg grating.

[0078] In this embodiment, the upper cover 15 may be a rectangular parallelepiped structure with an open bottom, such as Figure 10 As shown, four snap-on plates 17 are installed in the inner cavity of the upper cover 15. When the upper cover 15 is snapped together with the rectangular box 12, the two snap-on plates 17 in the middle are located inside the rectangular box 12, while the two snap-on plates on the outside contact the outside of the rectangular box 12. The upper cover 15 and the snap-on plates 17 cover the placement groove 13 inside, and the bottom edge of the upper cover 15 contacts the top of the rectangular box 12, forming a box structure. The placement groove 13 is a sealed structure that protects the packaging ring 4 placed therein.

[0079] In addition to the box structure, the upper cover 15 can also adopt a plate structure, such as Figure 11 As shown, when a plate-like structure is adopted, the height of the rectangular box 12 is slightly larger than the diameter of the packaging ring 4. Four snap-on plates 17 are fixedly mounted on the bottom of the upper cover 15. When the upper cover 15 and the rectangular box 12 are closed together, the two snap-on plates 17 in the middle snap into the rectangular box 12 and contact the two partitions, while the outer snap-on plates 17 contact the outer wall of the rectangular box 12, thereby forming a sealed space between the upper cover 15 and the snap-on plates 17 and the rectangular box 12. In addition, the upper cover 15 and the snap-on plates 17 cover the placement groove 13 inside. When water penetrates into the soil during rainy weather, the water can flow downward along the upper cover 15 and the snap-on plates 17 and will not flow into the placement groove 13. This provides better protection for the packaging ring 4 and prevents corrosion of the packaging ring.

[0080] The upper cover 15 can also be configured as a rectangular parallelepiped structure with two bottom openings, such as Figure 12As shown, the two upper covers 15 are directly stuck in the upper part of the placement groove 13, and the opening 14 of the rectangular box 12 is not covered. Therefore, when inspecting the cables, different upper covers 15 can be opened to inspect the connection parts of the cables separately. There is no need to dig too large grooves. The cable connection parts can be inspected by opening the upper cover alone, which is very convenient. Compared with the integral type, which requires digging a relatively large groove to remove the upper cover during inspection, inspection is easier.

[0081] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A perimeter surveillance and monitoring device using fiber optic Bragg gratings, characterized in that: include: The cable core (1) comprises a first core and a second core, each of which has a predetermined length and in which an optical fiber with an end face reflectivity within a predetermined range is installed; a fiber grating is formed in the optical fiber of at least a portion of the length in the first core; and a cladding (5) is provided on the outer side of the cable core (1); At least two packaging rings (4) are respectively fixed on two ends of the first core body, and a metal ring (2) is fixedly mounted on the outer end of each packaging ring (4); a connecting ring (3) threadedly connected to the metal ring; Ends of the first core and the second core extend into the interior of the metal ring and the connecting ring and are fixed; When the metal ring (2) and the connecting ring (3) are screwed and fixed, the ends of the first core and the second core abut against each other and have a predetermined longitudinal pressure; An annular limiting ring (6) is fixedly mounted on the end of the cable core (1); In the installed state, when the limiting ring (6) extends to the inside of the connecting ring (3), the connecting ring (3) can rotate around the axis direction; At least one connecting core (7) with a predetermined elastic coefficient is installed on the inner side of the metal ring (2) and is sleeved on the connection between the first core and the second core; Fiber Bragg Grating resonant wavelength offset Δλ B for: E is strain, ΔT is temperature change, P is the photoelastic coefficient, v is Poisson's ratio, and α is the thermal expansion coefficient of the optical fiber.

2. The perimeter security monitoring device using fiber Bragg grating according to claim 1, characterized in that: A mounting seat is also provided at the bottom of the cable core (1), and the elastic coefficient of the mounting seat is greater than the elastic coefficient of the optical fiber.

3. The perimeter security monitoring device using fiber Bragg grating according to claim 2, characterized in that: The mounting base comprises: A support rod (9) with a base (10) fixedly mounted at the bottom; The mounting block (8) is mounted on the top of the support rod (9). The mounting block is an open structure with a top opening and closed all around. Two side walls of the mounting block (8) are provided with sliding grooves (11) matching the connecting ring (3). The packaging ring can be accommodated in the opening structure.

4. The perimeter security monitoring device using fiber Bragg grating according to claim 3, characterized in that: The mounting seat is a rectangular box (12) with an open top and a plurality of divided areas. Two packaging rings (4) and a cable core (1) are mounted inside the rectangular box (12).

5. The perimeter security monitoring device using fiber Bragg grating according to claim 4, characterized in that: At least two partitions are installed on the inner side of the rectangular box (12), and a placement groove (13) for placing the packaging ring (4) is formed between the partition and the inner side wall of the rectangular box (12); the first core has freedom along the direction of the central axis in the rectangular box and is constrained in the direction perpendicular to the central axis.

6. The perimeter security monitoring device using fiber Bragg grating according to claim 5, characterized in that: The partition and two side walls parallel to the rectangular box (12) are provided with a slot (18) for placing the connecting ring (3), and the bottom of the rectangular box (12) between the two partitions is provided with an opening (14); An upper cover (15) is further installed at the upper end of the rectangular box (12), and a plurality of snap-in plates (17) are fixedly installed at the bottom of the upper cover (15). A snap-in groove (18) is provided at the bottom of the snap-in plate (17). When the upper cover (15) and the rectangular box (12) are snap-fitted together, the snap-in groove (18) of the partition plate and the snap-in groove (18) of the snap-in plate (17) form a mounting ring for mounting the connecting ring (3). The two side edges of the packaging ring (4) do not contact the inner side of the placement groove (13), and the packaging ring (4) can slide inside the placement groove (13).

7. The perimeter security monitoring device using fiber Bragg grating according to claim 6, characterized in that: An opening cavity (16) is provided in the middle of the upper cover (15). When the upper cover (15) and the rectangular box (12) are engaged together, the opening cavity (16) and the opening (14) are superimposed together to form an opening that penetrates from top to bottom.

8. A perimeter security monitoring method based on fiber Bragg grating, using the perimeter security monitoring device using fiber Bragg grating according to claim 7, characterized in that: The steps include: When in use, first a groove is opened in the ground where the device is to be buried, the mounting seat is buried, and then the packaging ring (4) is placed on the mounting seat; Then, the connecting ring (3) of the cable core (1) and the metal ring (2) are screwed together, and different connecting cores (7) will produce different degrees of deformation under the extrusion of the connecting ring (3) and the metal ring (2), so that the contact surface of the connecting core (7) and the contact surface of the connecting core (7) and the cable core are tightly fitted together; By connecting the cable core to a signal transceiver, the environment is monitored based on the transmitted and received signals.

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