A system combining optical time domain reflectometry and optical fiber vibration sensor

Abstract

The present invention provides a system combining an optical time domain reflectometer and an optical fiber vibration sensor, which is applied to the field of optical cable line operation and maintenance technology, and comprises: an Arm processing core, a light source and an optical switch driving circuit, a narrow line width pulse light source, a first broadband light source, a second broadband light source, a first optical fiber amplifier, a first optical switch, a wavelength division multiplexer, a three-terminal optical ring type device, an optical interface, a communication optical fiber, a second optical switch, a second optical fiber amplifier, a photoelectric detector, an analog switch, a first amplifier circuit, a second amplifier circuit, a high-speed data acquisition module and a touch display module, so as to realize the combination of a DVS system and an OTDR system in the underlying hardware optical path and control, and comprises the same optical interface, the same photoelectric detector, and the switching of OTDR and DVS functions through the unified control of two optical switches, so as to realize the functional integration and convenient controllability of a single system device.

Description

Technical Field

[0001] The present invention relates to the field of optical cable line operation and maintenance technology, and in particular to a system combining an optical time domain reflectometer and an optical fiber vibration sensor. Background Art

[0002] The optical time domain reflectometer is an instrument that analyzes the measurement curve to understand the uniformity, defects, fractures, joint coupling and other properties of optical fibers. It is made based on the backscattering and Fresnel reverse principles of light, and uses the backscattered light generated when light propagates in the optical fiber to obtain attenuation information. It can be used to measure optical fiber attenuation, joint loss, optical fiber fault point location, and understand the loss distribution along the length of the optical fiber. It is an indispensable tool in optical cable construction, maintenance and monitoring.

[0003] There are many technical solutions for fiber optic vibration sensing. Among them, the distributed fiber optic vibration sensing system based on phase-sensitive optical time domain reflectometry (Φ-OTDR) technology has the advantages of single-ended, distributed high-precision positioning that only requires access to a single-core optical fiber. It is increasingly used in intrusion detection based on communication optical fiber, perimeter security, and infrastructure security monitoring.

[0004] For the above two types of technologies, the former OTDR is generally used as the most commonly used detection and operation and maintenance instrument for optical communications; the latter, due to the high technical research and development and cost threshold, is generally made into a rack-type system host for online security monitoring and external damage threat location and warning of optical communication lines, oil and gas pipelines, and power communication pipelines. The two technologies are generally not organically combined in the same system or equipment.

[0005] From the perspective of industry applications, in the operation and maintenance scenarios of optical fiber communication lines, in addition to OTDR, there is also a type of commonly used "optical cable surveyor" equipment. It is based on the vibration sensing technology of the Mach-Zehnder interference principle. After connecting to one end of the optical fiber, it can identify the knocking signal on the optical fiber body, which can be used to identify and distinguish multiple optical cables on site. However, since this technology cannot locate, it is impossible to detect the specific location of the line fault.

[0006] In the field of operation and maintenance of optical transmission lines, OTDR is the most commonly used instrument equipment, but it can only detect the current loss and breakage status of optical fibers. The location data of each loss, reflection, and breakpoint event is the length of the optical fiber from that location to the optical fiber end point in the machine room, that is, the fiber length. It is difficult to quickly match the fiber length "meter mark" with the actual line site location using OTDR, so as to find the location and target optical fiber that needs to be repaired very quickly and efficiently; another device used in operation and maintenance is the optical cable survey instrument, which is based on the MZ interference principle and can determine whether it is the target optical fiber by knocking on the optical fiber on site, but it cannot locate and still cannot solve the problem of accurately finding the fault location. At present, there is a lack of an instrument that combines OTDR optical fiber status detection and precise positioning vibration sensing to solve the problems of optical transmission line status detection, fault detection, accurate positioning, target cable identification, etc.

[0007] Therefore, the present invention proposes a system combining an optical time domain reflectometer and an optical fiber vibration sensor. Summary of the invention

[0008] The present invention aims to solve the current problem of lack of an instrument that combines OTDR optical fiber status detection and precise positioning vibration sensing, so as to solve the problems of optical transmission line status detection, fault discovery, accurate positioning, target cable identification, etc., and provide a system combining optical time domain reflectometer and optical fiber vibration sensor.

[0009] The present invention adopts the following technical means to solve the technical problem:

[0010] The present invention provides a system combining an optical time domain reflectometer and an optical fiber vibration sensor, comprising: an Arm processing core, a light source and an optical switch driving circuit, a narrow line width pulse light source, a first broadband light source, a second broadband light source, a first optical fiber amplifier, a first optical switch, a wavelength division multiplexer, a three-terminal optical ring type device, an optical interface, a communication optical fiber, a second optical switch, a second optical fiber amplifier, a photodetector, an analog switch, a first amplifying circuit, a second amplifying circuit, a high-speed data acquisition module and a touch display module;

[0011] The touch-switch display module is electrically connected to the Arm processing core, the Arm processing core is electrically connected to the light source and the optical switch driving circuit and the high-speed data acquisition module, the light source and the optical switch driving circuit are respectively electrically connected to the narrow line width pulse light source, the first broadband light source, the second broadband light source, the first optical fiber amplifier, the first optical switch, the second optical switch, the second optical fiber amplifier and the analog switch, the narrow line width pulse light source signal is connected to the first optical fiber amplifier, the first optical fiber amplifier signal is connected to the second port of the first optical switch, the first broadband light source signal is connected to the first port of the first optical switch, the third port of the first optical switch signal is connected to the wavelength division multiplexer, the second broadband light source signal is connected to the wavelength division multiplexer, the wavelength division multiplexer signal is connected to the first port of the three-terminal optical circulator, the second port and the third port of the three-terminal optical circulator are respectively signal-connected to the first port and the optical interface of the second optical switch, the second port and the fourth port of the second optical switch are signal-connected to the second optical fiber amplifier, the third port of the second optical switch is also signal-connected to a photodetector, the photodetector signal is connected to the analog switch, and the analog switch is signal-connected to the high-speed data acquisition module through the first amplification circuit and the second amplification circuit respectively;

[0012] The system combining the optical time domain reflectometer and the optical fiber vibration sensor includes two working modes, which are: OTDR mode and DVS mode;

[0013] The communication optical fiber realizes OTDR detection and vibration sensor detection of the optical fiber by accessing the optical interface.

[0014] Furthermore, the first broadband light source and the second broadband light source have different wavelengths. When the wavelength of the second broadband light source is activated, the light source and the optical switch driving circuit only drive the second broadband light source to emit a light pulse and turn off the power supply of the second broadband light source; when the wavelength of the first broadband light source is activated, the light source and the optical switch driving circuit only drive the first broadband light source to emit a light pulse and turn off the power supply of the second broadband light source; the touch-switch display module allows the user to select the wavelength length.

[0015] Furthermore, the OTDR mode includes: the light source and optical switch driving circuit shuts down the power supply of the narrow linewidth pulse light source, the first optical fiber amplifier and the second optical fiber amplifier, switches the first optical switch to 1-through-3, switches the second optical switch to 1-through-3 and 2-through-4, and controls the analog switch to switch the path of the detector output signal to the first amplifier circuit; according to the wavelength, detection distance, pulse width and other parameters selected by the user in the interface, the light pulse emitted by the first broadband light source or the second broadband light source of the corresponding wavelength enters the first port of the three-terminal optical ring device through the wavelength division multiplexer, is output from the second port, enters the communication optical fiber through the optical interface, and the pulse light and the optical fiber material undergo Rayleigh scattering effect, wherein the back Rayleigh scattered light returns to the optical interface to enter the second port of the three-terminal optical ring device, and enters the first port of the second optical switch from the third port and is output from the third port, is converted into an electrical signal by the detector and then enters the first amplifier circuit through the analog switch, the amplified electrical signal enters the high-speed data acquisition module, is converted into a digital signal and enters the Arm processing core, and is demodulated and calculated to obtain the OTDR data and events of the optical fiber, data, events and curves.

[0016] Furthermore, the DVS mode includes: the light source and the optical switch driving circuit turn off the first broadband light source and the second broadband light source, turn on the power supply of the first optical fiber amplifier and the second optical fiber amplifier, control the first optical switch to switch to 2-through-3, control the second optical switch to switch to 1-through-4 and 2-through-3, and control the analog switch to switch the path of the detector output signal to the second amplification circuit; after the user sets the pulse width, detection length, detection threshold and other parameters, the light source and the optical switch driving circuit drive the narrow linewidth pulse light source to emit a laser pulse, which is amplified by the first optical fiber amplifier and enters the wavelength division multiplexer through the second port and the third port of the first optical switch, and then enters the first port of the three-terminal optical ring type device, and is output from the second port through the optical interface to enter the communication optical fiber, and the laser pulse is combined with the optical fiber material. The material undergoes Rayleigh scattering, and the scattered light of the narrow linewidth laser will also become coherent and carry the phase information of the optical signal; the back Rayleigh scattering returns to the second port of the three-terminal optical ring device through the optical interface, and enters the first port of the second optical switch through the third port, and then enters the second optical fiber amplifier through the fourth port. The scattered light is amplified and enters the second port of the second optical switch, and then enters the photodetector through the third port. After being converted into an electrical signal, it is output to the second amplifier circuit for amplification through the analog switch, enters the high-speed data acquisition module, and is converted into a digital signal and enters the Arm processing core. After the phase information is demodulated and calculated, the vibration signal and position information of the entire optical fiber are obtained and compared with the set domain value. The relevant results are displayed and output on the touch display module to complete the optical fiber vibration measurement.

[0017] Furthermore, the pulse modulation method of the narrow linewidth pulse light source may be direct modulation of the laser, or may be modulation of the continuous light signal output by the laser into a pulse signal using an acousto-optic modulator or an electro-optic modulator.

[0018] Furthermore, the light source and optical switch driving circuit switches and multiplexes two light sources of the OTDR and DVS of the same wavelength band, namely the narrow linewidth pulse light source and the first broadband light source, by controlling the path state of the first optical switch, so that they can share the input end of the wavelength division multiplexer.

[0019] Furthermore, the optical path structure of the second optical switch and the second optical fiber amplifier can switch the input and output paths, so that the OTDR or DVS scattered light returned from the third port of the three-terminal optical annulator can select different paths to enter the detector.

[0020] Furthermore, after the scattered light is converted into an electrical signal by the detector, the switching of the analog switch determines the subsequent amplification circuit it enters.

[0021] Furthermore, the first amplifier circuit and the second amplifier circuit have different parameters such as amplification factor and signal bandwidth, which can respectively meet the different requirements of OTDR scattered light and DVS scattered light in terms of amplification factor, bandwidth and dynamic range during signal detection and demodulation.

[0022] Furthermore, the system combining the optical time domain reflectometer and the optical fiber vibration sensor realizes that the OTDR and DVS systems share the same external optical interface and the same detector through the combination and switching control of modules such as the first optical switch, the first optical fiber amplifier, the wavelength division multiplexer, the three-terminal optical ring type device, the second optical switch, the second optical fiber amplifier, the analog switch, the first amplifying circuit, and the second amplifying circuit.

[0023] The present invention provides a system combining an optical time domain reflectometer and an optical fiber vibration sensor, which has the following beneficial effects:

[0024] 1. The present invention combines the OTDR and DVS systems to form a unified system. When performing optical transmission line operation and maintenance, the OTDR function is first used to measure the optical fiber loss and fiber length information of the event, and then the DVS is switched to perform vibration disturbance on the same line site, so that the actual geographical location of the event can be quickly confirmed, and efficient repair of various faults can be achieved.

[0025] 2. The present invention uses the same set of Arm processing cores and touch display modules to perform signal calculations and input and output operations, which is conducive to calling OTDR and DVS functions under the same software process, and can even connect the two on the interface, making it more efficient and convenient to use.

[0026] 3. The present invention realizes flexible control of different modules and optical channels through modules such as the first optical switch, the second optical switch, the optical ring device, the switchable detector amplifier circuit, and unified control and switching of EDFA and multiple light sources, and is compatible with the different requirements of OTDR and DVS in terms of signal source, detection dynamic range, data demodulation and analysis, and ultimately achieves the effect that the composite system only uses a single external optical interface, a single detector and a single input and output interface, bringing great convenience to daily use. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is an overall structural diagram of an embodiment of a system combining an optical time domain reflectometer and an optical fiber vibration sensor of the present invention;

[0028] In the figure, an Arm processing core 1, a light source and an optical switch driving circuit 2, a narrow linewidth pulse light source 3, a first broadband light source 4, a second broadband light source 5, a first optical fiber amplifier 6, a first optical switch 7, a wavelength division multiplexer 8, a three-terminal optical ring type device 9, an optical interface 10, a communication optical fiber 11, a second optical switch 12, a second optical fiber amplifier 13, a photodetector 14, an analog switch 15, a first amplifying circuit 16, a second amplifying circuit 17, a high-speed data acquisition module 18 and a touch-switch display module 19.

[0029] The purpose, features and advantages of the present invention will be further described with reference to the accompanying drawings in conjunction with the embodiments. DETAILED DESCRIPTION

[0030] It should be understood that the specific embodiments described herein are only used to explain the present invention, and are not used to limit the present invention.

[0031] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0032] Reference Figure 1 , is a schematic diagram of a flow chart of a system combining an optical time domain reflectometer and an optical fiber vibration sensor in one embodiment of the present invention;

[0033] In one embodiment, the present invention provides a system combining an optical time domain reflectometer and an optical fiber vibration sensor, comprising: an Arm processing core 1, a light source and an optical switch driving circuit 2, a narrow linewidth pulse light source 3, a first broadband light source 4, a second broadband light source 5, a first optical fiber amplifier 6, a first optical switch 7, a wavelength division multiplexer 8, a three-terminal optical circulator 9, an optical interface 10, a communication optical fiber 11, a second optical switch 12, a second optical fiber amplifier 13, a photodetector 14, an analog switch 15, a first amplifier circuit 16, a second amplifier circuit 17, a high-speed data acquisition module 18, and a touch display module 19;

[0034] The touch display module 19 is electrically connected to the Arm processing core 1, the Arm processing core 1 is electrically connected to the light source and optical switch driving circuit 2 and the high-speed data acquisition module 18, the light source and optical switch driving circuit 2 are electrically connected to the narrow line width pulse light source 3, the first broadband light source 4, the second broadband light source 5, the first optical fiber amplifier 6, the first optical switch 7, the second optical switch 12, the second optical fiber amplifier 13 and the analog switch 15, the narrow line width pulse light source 3 signal is connected to the first optical fiber amplifier 6, the first optical fiber amplifier 6 signal is connected to the second port of the first optical switch 7, the first broadband light source 4 signal is connected to the first port of the first optical switch 7, and the third port of the first optical switch The signal is connected to the wavelength division multiplexer 8, the second broadband light source 5 is signal connected to the wavelength division multiplexer 8, the wavelength division multiplexer 8 is signal connected to the first port of the three-terminal optical circulator 9, the second port and the third port of the three-terminal optical circulator 9 are respectively signal connected to the first port of the second optical switch 12 and the optical interface 10, the second port and the port 4 of the second optical switch 12 are signal connected to the second optical fiber amplifier 13, the port 3 of the second optical switch 12 is also signal connected to the photodetector 14, the photodetector 14 is signal connected to the analog switch 15, and the analog switch 15 is signal connected to the high-speed data acquisition module 18 through the first amplifier circuit 16 and the second amplifier circuit 17 respectively;

[0035] The system combining the optical time domain reflectometer and the optical fiber vibration sensor includes two working modes, namely: OTDR mode and DVS mode;

[0036] The pulse modulation method of the narrow linewidth pulse light source 3 can be direct modulation of the laser, or it can be to modulate the continuous optical signal output by the laser into a pulse signal using an acousto-optic modulator or an electro-optic modulator; the light source and optical switch driving circuit 2 switches and multiplexes the two light sources of the OTDR and DVS of the same band, namely the narrow linewidth pulse light source 3 and the first broadband light source 4, by controlling the path state of the first optical switch 7, and can share the input end of the wavelength division multiplexer 8; the first amplifier circuit 16 and the second amplifier circuit 17 have different parameters such as amplification factor and signal bandwidth, which can respectively meet the different requirements of OTDR scattered light and DVS scattered light in terms of amplification factor, bandwidth and dynamic range during signal detection and demodulation.

[0037] The communication optical fiber 11 is connected to the optical interface 10 to realize OTDR detection and vibration sensor detection of the optical fiber.

[0038] In this embodiment, the Arm processing core 1 is responsible for the control logic and data calculation of other parts of the system, the light source and optical switch driving circuit 2 is used to power and directly control the light sources and optical switches of the system, the narrow linewidth pulse light source 3 is a light source for optical fiber vibration sensing, the first broadband light source 4 is one of the light sources used by OTDR, and the second broadband light source 5 is also one of the light sources used by OTDR. The first broadband light source 4 and the second broadband light source 5 are different in wavelength. In this embodiment, the first broadband light source 4 is a 1550nm broadband light source, and the second broadband light source 5 is a 1310nm broadband light source; the first optical fiber amplifier 6 adopts a pulse EDFA to amplify the pulse signal light output by the 1550nm narrow linewidth pulse light source 3. The first optical switch 7 has three ports 1-3. Through the driving circuit, its optical path can be switched between two modes: 1 through 3 and 2 through 3; the wavelength division multiplexer 8 adopts 1310nm / 1550nm WDM can connect the two wavelengths of 1310nm and 1550nm to the common end through wavelength division multiplexing; the three-terminal optical ring type device 9 has three ports 1-3, and the optical signal can only be transmitted in the directions of 1 in 2 out, 2 in 3 out, and 3 in 1 out; the optical interface 10 is the adapter flange between the internal optical path of the system and the communication optical fiber 11 for external detection, and various types such as FC, SC, LC, and ST can be used according to needs; the communication optical fiber 11 can be the communication optical fiber 11 that actually needs to be detected, or the optical fiber for laboratory testing, in which the inner core is connected to the system through the 10-optical interface 10; the second optical switch 12 has four ports 1 to 4, and the optical path can be switched between two modes: 1 through 3 and 2 through 4, and 1 through 4 and 2 through 3; the second optical fiber amplifier 13 uses a continuous light EDFA to amplify the system The photoelectric detector 14 is used to convert the optical signal into an electrical signal, and a PIN (photodiode) detector or an APD (avalanche diode) detector can be used; the analog switch 15 is composed of a high-speed analog switch 15 chip and corresponding circuits, and is used to switch the subsequent amplification circuit through which the detector output signal passes; the first amplification circuit 16 is used to amplify the electrical signal converted from the Rayleigh scattered light of the OTDR system; the second amplification circuit 17 is used to amplify the electrical signal converted from the Rayleigh scattered light of the DVS system; the high-speed data acquisition module 18 includes FPGA, AD chip, etc., and is used to convert the electrical signal into a digital signal; the touch display module 19 is composed of a touch screen, a plurality of buttons and corresponding drive circuits, and is used for inputting and outputting information for interaction between the system and people.

[0039] In specific implementation, when performing OTDR detection, an instruction is input through the touch display module to call the OTDR mode to the Arm processing core 1, the light source and optical switch driving circuit 2 turns off the power supply of the narrow linewidth pulse light source 3, the first optical fiber amplifier 6 and the second optical fiber amplifier 13, the first optical switch 7 is switched to 1 on 3, the second optical switch 12 is switched to 1 on 3 and 2 on 4, and the analog switch 15 is controlled to switch the path of the detector output signal to the first amplifier circuit 16; when the 1310nm wavelength is activated, the light source and the optical switch driving circuit 2 only drives the second broadband light source 5 to emit a light pulse, and turns off the power supply of the first broadband light source 4; when the 1550nm wavelength is activated, the light source and the optical switch driving circuit 2 only drives the first broadband light source 4 to emit a light pulse, and turns off the power supply of the second broadband light source 5; when the 1310nm of the OTDR is selected through the touch display module and the pulse width, detection length, detection threshold and other parameters are set, the light pulse emitted by the second broadband light source 5 is transmitted through the wavelength division The multiplexer 8 enters the first port of the three-terminal optical ring type device 9, outputs from the second port, and is connected to the communication optical fiber 11 through the optical interface 10. The pulse light and the optical fiber material undergo Rayleigh scattering effect, wherein the back Rayleigh scattered light returns to the optical interface 10 and enters the second port of the three-terminal optical ring type device 9, and enters the first port of the second optical switch 12 from the third port and is output from the third port. After being converted into an electrical signal by the detector, it enters the first amplifier circuit 16 through the analog switch 15. The amplified electrical signal enters the high-speed data acquisition module 18, is converted into a digital signal and enters the Arm processing core 1. After being demodulated and calculated, the OTDR data and events of the optical fiber are obtained. The data, events, curves and other results are displayed and output on the touch display module to complete the optical fiber status measurement. When the OTDR selects a wavelength of 1550nm, the optical pulse emitted by the first broadband light source 4 will first enter the first port of the first optical switch 7 and be output from the third port, and then enter the wavelength division multiplexer 8. The subsequent process is consistent with when the 1310nm wavelength is activated.

[0040] When performing a vibration sensing test, the optical fiber inputs instructions to the Arm processing core 1 through the touch display module to call the DVS mode, the light source and optical switch driving circuit 2 turns off the first broadband light source 4 and the second broadband light source 5, turns on the first optical fiber amplifier 6 and the second optical fiber amplifier 13 for power supply, controls the first optical switch 7 to switch to 2-through 3, controls the second optical switch 12 to switch to 1-through 4 and 2-through 3, and controls the analog switch 15 to switch the path of the detector output signal to the second amplifier circuit 17; when the DVS mode is selected through the touch display module and the parameters such as the pulse width, detection length, and detection threshold are set, the light source and optical switch driving circuit 2 drives the 1550nm narrow linewidth pulse light to emit a laser pulse, which is amplified by the first optical fiber amplifier 6 and enters the wavelength division multiplexer 8 through the second port and 3 of the first optical switch 7, and then enters the first port of the three-terminal optical ring type device 9, and is output from the second port through the optical interface 10 to enter the communication optical fiber 11, and the laser pulse is Rayleigh scattered with the optical fiber material, and the scattered light of the narrow linewidth laser will also be coherent and carry the phase information of the optical signal. Backward Rayleigh scattering returns to the second port of the three-terminal optical ring device 9 through the optical interface 10, enters the first port of the second optical switch 12 through the third port, and then enters the second optical fiber amplifier 13 through the fourth port. The scattered light is amplified and enters the second port of the second optical switch 12, and then enters the detector through the third port. After being converted into an electrical signal, it is output to the second amplifier circuit 17 for amplification through the analog switch 15, enters the high-speed data acquisition module 18, and is converted into a digital signal and enters the Arm processing core 1. After the phase information is demodulated and calculated, the vibration signal and position information of the entire optical fiber are obtained and compared with the set domain value. The relevant results are displayed and output on the touch display module to complete the optical fiber vibration measurement.

[0041] In one embodiment, the first broadband light source 4 and the second broadband light source 5 have different wavelengths. When the wavelength of the second broadband light source 5 is activated, the light source and the optical switch driving circuit 2 only drive the second broadband light source 5 to emit a light pulse, and turn off the power supply of the second broadband light source 5; when the wavelength of the first broadband light source 4 is activated, the light source and the optical switch driving circuit 2 only drive the first broadband light source 4 to emit a light pulse, and turn off the power supply of the second broadband light source 5; the touch-switch display module 19 allows the user to select the wavelength length;

[0042] The OTDR mode includes: the light source and optical switch driving circuit 2 turns off the power supply of the narrow line width pulse light source 3, the first optical fiber amplifier 6 and the second optical fiber amplifier 13, switches the first optical switch 7 to 1 on 3, switches the second optical switch 12 to 1 on 3 and 2 on 4, controls the analog switch 15 to switch the path of the detector output signal to the first amplifier circuit 16; according to the wavelength, detection distance, pulse width and other parameters selected by the user in the interface, the optical pulse emitted by the first broadband light source 4 or the second broadband light source 5 of the corresponding wavelength enters the first port of the three-terminal optical circulator 9 through the wavelength division multiplexer 8, and is transmitted from the second optical circulator 9 to the first port of the three-terminal optical circulator 9. The output of the optical port enters the communication optical fiber 11 through the optical interface 10, and the pulse light undergoes Rayleigh scattering effect with the optical fiber material, wherein the back Rayleigh scattered light returns to the optical interface 10 and enters the second port of the three-terminal optical ring device 9, and enters the first port of the second optical switch 12 from the third port and is output from the third port. After being converted into an electrical signal by the detector, it enters the first amplifying circuit 16 through the analog switch 15. The amplified electrical signal enters the high-speed data acquisition module 18, and is converted into a digital signal and enters the Arm processing core 1. After being demodulated and calculated, the OTDR data and events of the optical fiber, data, events and curves are obtained.

[0043] In this embodiment, the wavelengths of the first broadband light source 4 and the second broadband light source 5 are 1550nm and 1310nm respectively; in specific implementation, the OTDR mode is called by inputting instructions to the Arm processing core 1 through the touch display module, the light source and optical switch driving circuit 2 turns off the power supply of the narrow linewidth pulse light source 3, the first optical fiber amplifier 6 and the second optical fiber amplifier 13, switches the first optical switch 7 to 1 on 3, switches the second optical switch 12 to 1 on 3 and 2 on 4, and controls the analog switch 15 to switch the path of the detector output signal to the first amplifier circuit 16; when the 1310nm wavelength is activated, the light source and optical switch driving circuit 2 only drives the second broadband light source 5 to emit optical pulses, and turns off the power supply of the first broadband light source 4; when the 1550nm wavelength is activated, the light source and optical switch driving circuit 2 only drives the first broadband light source 4 to emit optical pulses, and turns off the power supply of the second broadband light source 5; after selecting 1310nm of the OTDR through the touch display module and setting the pulse width, detection length, detection threshold and other parameters, the second broadband The optical pulse emitted by the light source 5 enters the first port of the three-terminal optical ring device 9 through the wavelength division multiplexer 8, is output from the second port, and is connected to the communication optical fiber 11 through the optical interface 10. The pulse light and the optical fiber material undergo Rayleigh scattering effect, wherein the back Rayleigh scattered light returns to the optical interface 10 and enters the second port of the three-terminal optical ring device 9, and enters the first port of the second optical switch 12 from the third port and is output from the third port. After being converted into an electrical signal by the detector, it enters the first amplifier circuit 16 through the analog switch 15. The amplified electrical signal enters the high-speed data acquisition module 18, is converted into a digital signal and enters the Arm processing core 1. After being demodulated and calculated, the OTDR data and events of the optical fiber are obtained. The data, events, curves and other results are displayed and output on the touch display module to complete the optical fiber state measurement. When the OTDR selects a wavelength of 1550nm, the optical pulse emitted by the first broadband light source 4 will first enter the first port of the first optical switch 7 and be output from the third port, and then enter the wavelength division multiplexer 8. The subsequent process is consistent with when the 1310nm wavelength is activated.

[0044] In one embodiment, the DVS mode includes: the light source and optical switch driving circuit 2 turns off the first broadband light source 4 and the second broadband light source 5, turns on the power supply of the first optical fiber amplifier 6 and the second optical fiber amplifier 13, controls the first optical switch 7 to switch to 2-on-3, controls the second optical switch 12 to switch to 1-on-4 and 2-on-3, and controls the analog switch 15 to switch the path of the detector output signal to the second amplifier circuit 17; after the user sets the pulse width, detection length, detection threshold and other parameters, the light source and optical switch driving circuit 2 drives the narrow linewidth pulse light source 3 to emit a laser pulse, which is amplified by the first optical fiber amplifier 6 and enters the wavelength division multiplexer 8 through the second port and 3 of the first optical switch 7, and then enters the first port of the three-terminal optical ring type device 9, and is output from the second port through the optical interface 10 to enter the communication optical fiber 11, and the laser pulse and the optical The fiber material undergoes Rayleigh scattering, and the scattered light of the narrow linewidth laser will also coherently carry the phase information of the optical signal; the back Rayleigh scattering returns to the second port of the three-terminal optical ring type device 9 through the optical interface 10, and enters the first port of the second optical switch 12 through the third port, and then enters the second optical fiber amplifier 13 through the fourth port. The scattered light is amplified and enters the second port of the second optical switch 12, and then enters the photodetector 14 through the third port. After being converted into an electrical signal, it is output to the second amplifier circuit 17 for amplification through the analog switch 15, enters the high-speed data acquisition module 18, and is converted into a digital signal and enters the Arm processing core 1. After the phase information is demodulated and calculated, the vibration signal and position information of the entire optical fiber are obtained, and compared with the set domain value, the relevant results are displayed and output on the touch display module to complete the optical fiber vibration measurement.

[0045] In this embodiment, the narrow linewidth pulse light source 3 is a 1550nm narrow linewidth pulse light source 3; in specific implementation, the DVS mode is called to the Arm processing core 1 by inputting instructions through the touch display module, the light source and optical switch driving circuit 2 turns off the first broadband light source 4 and the second broadband light source 5, turns on the first optical fiber amplifier 6 and the second optical fiber amplifier 13 for power supply, controls the first optical switch 7 to switch to 2-through 3, controls the second optical switch 12 to switch to 1-through 4 and 2-through 3, and controls the analog switch 15 to switch the path of the detector output signal to the second amplifier circuit 17; when the DVS mode is selected through the touch display module and the parameters such as pulse width, detection length, and detection threshold are set, the light source and optical switch driving circuit 2 drives the 1550nm narrow linewidth pulse light to emit a laser pulse, which is amplified by the first optical fiber amplifier 6 and enters the wavelength division multiplexer 8 through the second port and 3 of the first optical switch 7, and then enters the first port of the three-terminal optical ring type device 9, and is output from the second port through the optical interface 10 to enter the communication optical fiber 11, and the laser pulse is Rayleigh scattered with the optical fiber material, and the scattered light of the narrow linewidth laser will also be coherent and carry the phase information of the optical signal. Backward Rayleigh scattering returns to the second port of the three-terminal optical ring device 9 through the optical interface 10, enters the first port of the second optical switch 12 through the third port, and then enters the second optical fiber amplifier 13 through the fourth port. The scattered light is amplified and enters the second port of the second optical switch 12, and then enters the detector through the third port. After being converted into an electrical signal, it is output to the second amplifier circuit 17 for amplification through the analog switch 15, enters the high-speed data acquisition module 18, and is converted into a digital signal and enters the Arm processing core 1. After the phase information is demodulated and calculated, the vibration signal and position information of the entire optical fiber are obtained and compared with the set domain value. The relevant results are displayed and output on the touch display module to complete the optical fiber vibration measurement.

[0046] The existing DVS technology is used for long-term online early warning, so in terms of structure, it only needs to solve the distributed vibration sensing and analyze the vibration signal to give early warning information; the structure of the present invention is a brand-new design in the underlying optical path structure and circuit control, which truly combines the OTDR and DVS systems, including but not limited to: unified power supply control, unified external optical interface 10 (so that different functions can be used on the same line without changing the plug, completing the entire test process), unified photoelectric detector 14, and unified input interface, thereby forming a new complete system, rather than just cramming two independent structures into one device.

[0047] In one embodiment, the optical path structure of the second optical switch 12 and the second fiber amplifier 13 can switch the input and output paths, so that the OTDR or DVS scattered light returned from the third port of the three-terminal optical circulator 9 can select different paths to enter the detector.

[0048] In this embodiment, selecting different paths to enter the detector includes: entering the detector after optical signal amplification (DVS scattered light) through the second optical fiber amplifier 6, or directly entering the detector.

[0049] In one embodiment, after the scattered light signal is converted into an electrical signal by the detector, the switching of the analog switch 15 determines the subsequent amplification circuit it enters.

[0050] In this embodiment, the analog switch 15 converts the scattered light signal into an electrical signal through the detector and enters different circuits in different modes. In the OTDR mode, the returned scattered light enters the first amplifier circuit 16; in the DVS mode, the returned scattered light enters the second amplifier circuit 17.

[0051] In one embodiment, the system combining the optical time domain reflectometer and the optical fiber vibration sensor realizes that the OTDR and DVS systems share the same external optical interface 10 and the same detector through the combination and switching control of the first optical switch 7, the first optical fiber amplifier 6, the wavelength division multiplexer 8, the three-terminal optical ring type device 9, the second optical switch 12, the second optical fiber amplifier 13, the analog switch 15, the first amplifier circuit 16, the second amplifier circuit 17 and other modules.

[0052] In this embodiment, the DVS system and the OTDR system are combined in the underlying hardware optical path and control, including the same optical interface 10, the same photodetector 14, and the switching of OTDR and DVS functions through the unified control of two optical switches, thereby realizing the functional integration and convenient controllability of a single system device.

[0053] Although 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 the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A system combining an optical time domain reflectometer and an optical fiber vibration sensor, characterized in that: include: Arm processing core, light source and optical switch driving circuit, narrow line width pulse light source, first broadband light source, second broadband light source, first optical fiber amplifier, first optical switch, wavelength division multiplexer, three-terminal optical ring type device, optical interface, communication optical fiber, second optical switch, second optical fiber amplifier, photoelectric detector, analog switch, first amplifier circuit, second amplifier circuit, high-speed data acquisition module and touch display module; The touch-switch display module is electrically connected to the Arm processing core, the Arm processing core is electrically connected to the light source and the optical switch driving circuit and the high-speed data acquisition module, the light source and the optical switch driving circuit are electrically connected to the narrow line width pulse light source, the first broadband light source, the second broadband light source, the first optical fiber amplifier, the first optical switch, the second optical switch, the second optical fiber amplifier and the analog switch respectively, the narrow line width pulse light source signal is connected to the first optical fiber amplifier, the first optical fiber amplifier signal is connected to the second port of the first optical switch, the first broadband light source signal is connected to the first port of the first optical switch, the third port of the first optical switch signal is connected to the wavelength division multiplexer, the second broadband light source signal is connected to the wavelength division multiplexer, the wavelength division multiplexer signal is connected to the first port of the three-terminal optical circulator, the second port and the third port of the three-terminal optical circulator are respectively signal-connected to the first port and the optical interface of the second optical switch, the second port and the fourth port of the second optical switch are signal-connected to the second optical fiber amplifier, the third port of the second optical switch is also signal-connected to a photodetector, the photodetector signal is connected to the analog switch, and the analog switch is signal-connected to the high-speed data acquisition module through the first amplification circuit and the second amplification circuit respectively; The system combining the optical time domain reflectometer and the optical fiber vibration sensor includes two working modes, which are: OTDR mode and DVS mode; The communication optical fiber realizes OTDR detection and vibration sensor detection of the optical fiber by accessing the optical interface; The OTDR mode includes: the light source and optical switch driving circuit shuts down the power supply of the narrow line width pulse light source, the first optical fiber amplifier and the second optical fiber amplifier, switches the first optical switch to 1-through 3, switches the second optical switch to 1-through 3 and 2-through 4, and controls the analog switch to switch the path of the detector output signal to the first amplifier circuit; according to the wavelength, detection distance, pulse width and other parameters selected by the user in the interface, the light pulse emitted by the first broadband light source or the second broadband light source of the corresponding wavelength enters the first port of the three-terminal optical ring device through the wavelength division multiplexer, is output from the second port, enters the communication optical fiber through the optical interface, and the pulse light and the optical fiber material undergo Rayleigh scattering effect, wherein the back Rayleigh scattered light returns to the optical interface and enters the second port of the three-terminal optical ring device, and enters the first port of the second optical switch from the third port and is output from the third port, is converted into an electrical signal by the detector and then enters the first amplifier circuit through the analog switch, the amplified electrical signal enters the high-speed data acquisition module, is converted into a digital signal and enters the Arm processing core, and is demodulated and calculated to obtain the OTDR data and events of the optical fiber, data, events and curves; The DVS mode includes: the light source and the optical switch driving circuit turn off the first broadband light source and the second broadband light source, turn on the power supply of the first optical fiber amplifier and the second optical fiber amplifier, control the first optical switch to switch to 2-through-3, control the second optical switch to switch to 1-through-4 and 2-through-3, and control the analog switch to switch the path of the detector output signal to the second amplifier circuit; after the user sets the pulse width, detection length, detection threshold and other parameters, the light source and the optical switch driving circuit drive the narrow line width pulse light source to emit a laser pulse, which is amplified by the first optical fiber amplifier and enters the wavelength division multiplexer through the second port and the third port of the first optical switch, and then enters the first port of the three-terminal optical ring type device, and is output from the second port through the optical interface to enter the communication optical fiber, and the laser pulse reacts with the optical fiber material. Rayleigh scattering, the scattered light of the narrow linewidth laser will also be coherent and carry the phase information of the optical signal; the back Rayleigh scattering returns to the second port of the three-terminal optical ring device through the optical interface, and enters the first port of the second optical switch through the third port, and then enters the second optical fiber amplifier through the fourth port. The scattered light is amplified and enters the second port of the second optical switch, and then enters the photodetector through the third port. After being converted into an electrical signal, it is output to the second amplifier circuit for amplification through the analog switch, enters the high-speed data acquisition module, and is converted into a digital signal and enters the Arm processing core. After the phase information is demodulated and calculated, the vibration signal and position information of the entire optical fiber are obtained and compared with the set domain value. The relevant results are displayed and output on the touch display module to complete the optical fiber vibration measurement.

2. The system combining an optical time domain reflectometer and an optical fiber vibration sensor according to claim 1, characterized in that: The first broadband light source and the second broadband light source have different wavelengths. When the wavelength of the second broadband light source is activated, the light source and the optical switch driving circuit only drive the second broadband light source to emit light pulses and turn off the power supply of the second broadband light source; when the wavelength of the first broadband light source is activated, the light source and the optical switch driving circuit only drive the first broadband light source to emit light pulses and turn off the power supply of the second broadband light source; the touch-switch display module allows the user to select the wavelength length.

3. The system combining an optical time domain reflectometer and an optical fiber vibration sensor according to claim 1, characterized in that: The pulse modulation method of the narrow linewidth pulse light source can be direct modulation of the laser, or can be modulation of the continuous light signal output by the laser into a pulse signal using an acousto-optic modulator or an electro-optic modulator.

4. The system combining an optical time domain reflectometer and an optical fiber vibration sensor according to claim 1, characterized in that: The light source and optical switch driving circuit switches and multiplexes two light sources of the OTDR and DVS of the same wavelength band, namely the narrow linewidth pulse light source and the first broadband light source, by controlling the path state of the first optical switch, and can share the input end of the wavelength division multiplexer.

5. The system combining an optical time domain reflectometer and an optical fiber vibration sensor according to claim 1, characterized in that: The optical path structure of the second optical switch and the second optical fiber amplifier can switch the input and output paths, so that the OTDR or DVS scattered light returned from the third port of the three-terminal optical annulator can select different paths to enter the detector.

6. The system combining an optical time domain reflectometer and an optical fiber vibration sensor according to claim 5, characterized in that: After the scattered light is converted into an electrical signal by the detector, the switching of the analog switch determines the subsequent amplification circuit it enters.

7. The system combining an optical time domain reflectometer and an optical fiber vibration sensor according to claim 6, characterized in that: The first amplifier circuit and the second amplifier circuit have different parameters such as amplification factor and signal bandwidth, which can respectively meet the different requirements of OTDR scattered light and DVS scattered light on amplification factor, bandwidth and dynamic range during signal detection and demodulation.

8. The system combining an optical time domain reflectometer and an optical fiber vibration sensor according to claim 1, characterized in that: The system combining the optical time domain reflectometer and the optical fiber vibration sensor realizes that the OTDR and DVS systems share the same external optical interface and the same detector through the combination and switching control of modules such as the first optical switch, the first optical fiber amplifier, the wavelength division multiplexer, the three-terminal optical ring type device, the second optical switch, the second optical fiber amplifier, the analog switch, the first amplifying circuit, and the second amplifying circuit.

Images