Optical fiber sensing device with fault monitoring and positioning functions

Abstract

The utility model relates to the technical field of optical fiber sensor manufacturing, in particular to an optical fiber sensing device with fault monitoring and positioning functions, which is provided with an optical fiber sensing mechanism which is internally provided with an upper computer, a first laser, a first circulator, an optical cable and a data acquisition card. Wherein the output end of the first laser is sent into the optical cable through the first circulator, an optical signal returned from the optical cable is sent into the data acquisition card through the first circulator, and the upper computer is connected with the data acquisition card. The fault monitoring and positioning mechanism is provided with a second laser, a 1 * 2 optical coupler, a semiconductor optical amplifier SOA, an erbium-doped optical fiber amplifier EDFA, a second circulator, a 2 * 2 optical coupler and an optical switch, and compared with the prior art, the device is reasonable in structure, easy and convenient to operate and high in sensitivity.

Description

Technical Field

[0001] The utility model relates to the technical field of optical fiber sensor manufacturing, in particular to an optical fiber sensing device with a fault monitoring and positioning function, which has a reasonable structure, is easy to operate, can monitor the operation state of buried underground optical cables, locate fault points, and thus can significantly improve the maintenance efficiency of the optical fiber sensing system. Background Art

[0002] In modern information society, underground optical cables play a crucial role in the "information superhighway". Once the optical cable is damaged, the communication in the corresponding area will be greatly affected. Therefore, how to quickly locate the fault location of the optical cable is of great importance. Traditionally, OTDR is generally used to locate the fault point of the optical cable. However, OTDR can only locate the meters along the optical cable, roughly estimate the geographical location, and then judge the distance between the fault point and the attenuation point by artificially creating attenuation to gradually find the fault point. However, most communication optical cables are buried underground, making the operation difficult. Therefore, this method is time-consuming and laborious, and the maintenance cost is high. In addition, there is also a method of combining φ-OTDR and OTDR to locate the fault point of the optical cable. This method has a limited detection distance and low sensitivity, and is not effective for optical cables buried deep and with a long distance. Summary of the Invention

[0003] The utility model aims at the defects and deficiencies existing in the prior art, and provides an optical fiber sensing device with a fault monitoring and positioning function, which has a reasonable structure, is easy to operate, can monitor the operation state of buried underground optical cables, locate fault points, and thus can significantly improve the maintenance efficiency of the optical fiber sensing system.

[0004] The utility model is achieved by the following measures:

[0005] An optical fiber sensing device with a fault monitoring and positioning function

[0006] A fiber optic sensing mechanism is provided. In the fiber optic sensing mechanism, there are a host computer, a first laser, a first circulator, an optical cable, and a data acquisition card. The output end of the first laser is sent into the optical cable through the first circulator, and the optical signal returned in the optical cable is sent into the data acquisition card through the first circulator. The host computer is connected to the data acquisition card. It is characterized in that a fault monitoring and positioning mechanism is further provided. The fault monitoring and positioning mechanism is provided with a second laser, a 1*2 optical coupler, a semiconductor optical amplifier SOA, an erbium-doped fiber amplifier EDFA, a second circulator, a 2*2 optical coupler, and an optical switch. The output end of the second laser is connected to the signal input end of the 1*2 optical coupler. One output of the 1*2 optical coupler is connected to the semiconductor optical amplifier SOA, and the other output end of the 1*2 optical coupler is connected to one input end of the 2*2 optical coupler. The output end of the semiconductor optical amplifier SOA is connected to the input end of the erbium-doped fiber amplifier EDFA. The output end of the erbium-doped fiber amplifier EDFA is connected to the input end of the second circulator. The output end of the second circulator is connected to the optical cable through the optical switch. One output end of the second circulator is connected to the second input end of the 2*2 optical coupler. The two output ends of the 2*2 optical coupler are respectively connected to the data acquisition card.

[0007] In the present utility model, the optical switch is connected between the optical cable and the circulator. The circulator includes a first circulator and a second circulator, and is used to switch the on-off of the optical path of the fiber optic sensor mechanism and the on-off of the optical path of the fault monitoring and positioning mechanism.

[0008] In the present utility model, the line width of the first laser is greater than 1 MHz, and it emits pulsed optical signals; the line width of the second laser is < 3 kHz, and it emits continuous optical signals. The optical signal wavelengths of the first laser and the second laser are both 1550 nm.

[0009] The 1*2 coupler in the present utility model is used to divide the light of the second laser into two beams for propagation. The splitting ratio of the 2*2 coupler is 50:50, and it is used to make the scattered light returned from the optical cable interfere with the light output from the 1*2 coupler and input it into the data acquisition card.

[0010] When the utility model is working, after connecting the optical cable to be measured, the upper computer will first automatically run in the monitoring function state. At this time, the second laser is turned off, the optical switch remains in the channel where the first laser is located, and the pulsed light emitted by the first laser is finally sent into the optical cable. The scattered light returned by the optical cable is processed by the data acquisition card and then enters the upper computer. The upper computer displays the attenuation information of the entire optical cable according to the received optical signal and automatically monitors whether there is a fault point. When a fault point appears, the upper computer will issue an alarm and display the cable meter number of the fault point; after a fault alarm occurs, manually control the upper computer to switch to the positioning function state. At this time, the first laser is turned off, the optical switch remains in the channel where the second laser is located, and the light emitted by the second laser becomes pulsed light after passing through subsequent devices and is injected into the optical cable. The scattered light returned by the optical cable interferes with the light output by the 1*2 coupler in the 2*2 coupler. The interfered light is processed by the data acquisition card and then enters the upper computer. The upper computer will display the vibration information of the entire optical cable in real time in the form of a curve. When a certain position of the optical cable is vibrated, the curve will show obvious undulating changes at the corresponding position; the optical cable maintenance personnel first reach the approximate location of the optical cable site according to the fault meter number reported by the monitoring function, and then accurately locate the cable meter number of the knocking point by knocking on the ground. In this way, it is possible to know how far the knocking point is from the fault point. Move forward along the optical cable and knock until the knocking point shown by the vibration curve is exactly at the fault point, and then it is possible to dig and find and repair the fault point.

[0011] Compared with the prior art, the utility model has a reasonable structure and is easy to operate. It points out the cable meter number of the fault point through the monitoring function, roughly determines the range of the fault point area, and then can basically determine the position of the fault point by observing the vibration signal caused by the optical cable maintenance personnel knocking on the ground at the optical cable site. Only 1-2 working pits need to be dug to find the fault point, the detection distance is up to 50 km, and the sensitivity is high. Brief Description of the Drawings

[0012] Attached Figure 1 is the principle block diagram of the utility model.

[0013] Reference numerals: first laser 1, first circulator 2, optical switch 3, second laser 4, 1*2 optical coupler 5, semiconductor optical amplifier SOA 6, erbium-doped fiber amplifier EDFA 7, second circulator 8, 2*2 optical coupler 9, data acquisition card 10, upper computer 11, optical cable 12. Detailed Embodiments

[0014] The following will further describe the utility model with reference to the drawings and embodiments. Embodiment

[0015] As attached Figure 1As shown in the figure, this example provides an optical cable fault monitoring and positioning system, which is provided with an optical fiber sensing mechanism. In the optical fiber sensing mechanism, there are a host computer 11, a first laser 1, a first circulator 2, an optical cable 12, and a data acquisition card 10. The output end of the first laser 1 is sent into the optical cable 12 through the first circulator 2. The optical signal returned in the optical cable 12 is sent into the data acquisition card 10 through the first circulator. The host computer 11 is connected to the data acquisition card 10. There is also a fault monitoring and positioning mechanism, which is provided with a second laser 4, a 1*2 optical coupler 5, a semiconductor optical amplifier SOA6, an erbium-doped fiber amplifier EDFA7, a second circulator 8, a 2*2 optical coupler 9, and an optical switch 3. The output end of the second laser 4 is connected to the signal input end of the 1*2 optical coupler. One output of the 1*2 optical coupler 5 is connected to the semiconductor optical amplifier SOA6. The other output end of the 1*2 optical coupler is connected to one input end of the 2*2 optical coupler 9. The output end of the semiconductor optical amplifier SOA6 is connected to the input end of the erbium-doped fiber amplifier EDFA7. The output end of the erbium-doped fiber amplifier EDFA7 is connected to the input end of the second circulator 8. The output end of the second circulator 8 is connected to the optical cable through the optical switch. One output end of the second circulator 8 is connected to the second input end of the 2*2 optical coupler 9. The two output ends of the 2*2 optical coupler 9 are respectively connected to the data acquisition card 10.

[0016] In this example, the line width of the first laser 1 is 150 MHz, and it emits pulsed light; the line width of the second laser 4 is 2 kHz, and it emits continuous light, and the wavelength of both is 1550 nm. When the device in this example is connected to the optical cable 12 and works normally, the second laser 4 is turned off, the first laser 1 is turned on, and the optical switch 3 is kept in the channel where the first laser 1 is located. The pulsed light emitted by the first laser 1 is injected into the optical cable 12 after passing through the first circulator 2 and the optical switch 3. The backward Rayleigh scattered light in the optical cable 12 travels back, enters the data acquisition card for preliminary processing after passing through the circulator, and then enters the host computer. The host computer 11 will display the OTDR curve of the entire optical cable after analyzing the data, including information such as attenuation and length. When a fault occurs at a certain point of the optical cable, the host computer 11 monitors that there is a large attenuation point in the OTDR curve, and will immediately issue an audible and visual alarm, and at the same time display the alarm meters.

[0017] The optical cable maintenance personnel manually switch the host computer 11 to the positioning function state. The first laser 1 is turned off, and the second laser 4 is turned on. The optical switch remains in the channel where the second laser is located. The second laser emits continuous light, which is divided into two beams after passing through the 1*2 coupler 5. One of the beams of light is used as the detection light, which is modulated into pulsed light after passing through the SOA, then amplified by the EDFA, and then injected into the optical cable after passing through the circulator. The backward Rayleigh scattered light in the optical cable travels back. The other beam of light is used as the local oscillator light, and enters the 2*2 coupler together with the Rayleigh scattered light returned by the circulator to generate interference. The interference light enters the data acquisition card 10 for preliminary processing, and then enters the host computer.

[0018] The host computer 11 further analyzes the data to obtain the vibration curve of the entire optical cable. When there is a vibration signal at a certain position of the optical cable, a large amplitude fluctuation will appear at the corresponding position of the vibration curve.

[0019] The optical cable maintenance personnel first reach the general area of the fault point according to the alarm meters of the monitoring function, and then tap the ground above the optical cable 12. At the same time, observe the vibration curve to obtain the number of meters difference between the tapping point and the fault point, and then move forward along the optical cable by the corresponding number of meters, and tap the ground again until the vibration curve shows that the number of meters just reaches the alarm meters of the fault point, and then the optical cable fault can be excavated and repaired.

[0020] Compared with the prior art, the utility model has a reasonable structure and is easy to operate. By the monitoring function, the number of meters of the optical cable at the fault point is pointed out, and the area range of the fault point is roughly determined. Then, by observing the vibration signal caused by the optical cable on-site maintenance personnel tapping the ground, the position of the fault point can be basically determined. Only 1-2 working pits need to be excavated to find the fault point. The detection distance is up to 50 km and the sensitivity is high.

Claims

1. An optical fiber sensing device with a fault monitoring and positioning function is provided with an optical fiber sensing mechanism. In the optical fiber sensing mechanism, there are a host computer, a first laser, a first circulator, an optical cable, and a data acquisition card. The output end of the first laser is sent into the optical cable through the first circulator, and the optical signal returned in the optical cable is sent into the data acquisition card through the first circulator. The host computer is connected to the data acquisition card. It is characterized in that, A fault monitoring and positioning mechanism is also provided. The fault monitoring and positioning mechanism is provided with a second laser, a 1*2 optical coupler, a semiconductor optical amplifier (SOA), an erbium-doped fiber amplifier (EDFA), a second circulator, a 2*2 optical coupler, and an optical switch. Among them, the output end of the second laser is connected to the signal input end of the 1*2 optical coupler. One output of the 1*2 optical coupler is connected to the semiconductor optical amplifier (SOA), and the other output end of the 1*2 optical coupler is connected to one input end of the 2*2 optical coupler. The output end of the semiconductor optical amplifier (SOA) is connected to the input end of the erbium-doped fiber amplifier (EDFA). The output end of the erbium-doped fiber amplifier (EDFA) is connected to the input end of the second circulator. The output end of the second circulator is connected to the optical cable through the optical switch. One output end of the second circulator is connected to the second input end of the 2*2 optical coupler. The two output ends of the 2*2 optical coupler are respectively connected to the data acquisition card.

2. The fiber optic sensing device with a fault monitoring and positioning function according to claim 1, characterized in that, The optical switch is connected between the optical cable and the circulator. The circulator includes a first circulator and a second circulator, and is used to switch the on / off of the optical path of the fiber optic sensor mechanism and the on / off of the optical path of the fault monitoring and positioning mechanism.

3. The fiber optic sensing device with a fault monitoring and positioning function according to claim 1, characterized in that, The line width of the first laser is greater than 1 MHz, and it emits pulsed optical signals; the line width of the second laser < 3 kHz, and it emits continuous optical signals. The optical signal wavelengths of the first laser and the second laser are both 1550 nm.

4. A fiber optic sensing device with a fault monitoring and positioning function according to claim 1, characterized in that, The 1*2 coupler is used to divide the light of the second laser into two beams for propagation. The splitting ratio of the 2*2 coupler is 50:50, and it is used to interfere the scattered light returned from the optical cable with the light output from the 1*2 coupler and input it into the data acquisition card.

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