CN107389106A - A kind of φ OTDR quadrature phase demodulations system and phase demodulating method - Google Patents
A kind of φ OTDR quadrature phase demodulations system and phase demodulating method Download PDFInfo
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- CN107389106A CN107389106A CN201710764241.7A CN201710764241A CN107389106A CN 107389106 A CN107389106 A CN 107389106A CN 201710764241 A CN201710764241 A CN 201710764241A CN 107389106 A CN107389106 A CN 107389106A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
- G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
- G01D5/26—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light
- G01D5/32—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light
- G01D5/34—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells
- G01D5/353—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells influencing the transmission properties of an optical fibre
- G01D5/35338—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells influencing the transmission properties of an optical fibre using other arrangements than interferometer arrangements
- G01D5/35354—Sensor working in reflection
- G01D5/35358—Sensor working in reflection using backscattering to detect the measured quantity
- G01D5/35361—Sensor working in reflection using backscattering to detect the measured quantity using elastic backscattering to detect the measured quantity, e.g. using Rayleigh backscattering
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Abstract
The present invention is a kind of φ OTDR quadrature phase demodulations system and phase demodulating method, the laser of narrow linewidth laser is through fiber coupler beam splitting, larger Shu Zuowei senses soft exchange acousto-optic modulator, modulate shift frequency fc and be sent into sensor fibre, compared with tuftlet as reference light, with the sense light that is returned through circulator 2 × 2 fiber couplers carry out heterodyne it is relevant after, it is further divided into two equal beam flashlights and is converted to electric signal through balanced detector, two-way is divided into by power splitter after bandpass filtering, all the way after electric adjustable delay chip enters line delay, the sinusoidal signal that the frequency that two path signal is sent in frequency mixer and signal generating module respectively is fc is mixed, each low-pass filtered device and analog-to-digital conversion module are sent into control centre again, obtain the phase information of sensing optical signal.The present invention need not introduce interferometer, will not introduce extra ambient noise；Also without the high-speed data acquisition and processing of complexity, system is relatively easy, cheap, is more suitable for engineer applied.
Description
Technical field
The present invention relates to a kind of optical fiber sensing system, specifically relates to a kind of φ-OTDR based on balanced detector and electricity delay
(phase sensitive optical time domain reflectometer) quadrature phase demodulation system and phase demodulating method.
Background technology
Phase sensitive optical time domain reflectometer φ-OTDR are a kind of Distributed Optical Fiber Sensing Techniques.It is anti-with conventional optical time domain
Penetrate meter OTDR to compare, identical is to work as light pulse to inject from one end of optical fiber, detects backward Rayleigh scattering light by detector.
Unlike, injection fibre one end is just relevant by force in Φ-OTDR.Therefore the output of φ-OTDR systems is exactly that pulse is wide
The result of back scattering Reyleith scanttering light interference in the range of degree.It is corresponding to be disturbed opening position when fibre circuit is by external interference
Optical fibre refractivity will change, so as to cause the change of the opening position light phase.By measuring input pulse with receiving
The time delay of signal is that can determine whether the position of noise spot.The method can just have been applied since coming out by extensive concern φ-OTDR
In multiple fields such as border, oil-gas pipeline, oil well well logging, Traffic monitoring and key area intrusion detections.
Research is mostly the intensity of direct detection rear orientation light earlier, can not obtain the phase information of scattering light, therefore
The wave character and frequency information of extraneous vibration can not accurately be obtained.Ground so φ-OTDR Phase Demodulation Method of Optic just becomes
Study carefully focus, there are three kinds of main φ-OTDR phase demodulating modes at present；3 × 3 coupler demodulation methods, phase produce carrier wave (PGC)
Demodulation method and digital coherent demodulation method.First two needs to introduce an interferometer structure, is easily influenceed by environment, and by
This introduces extra noise.Digital coherent demodulation method needs complicated high-speed data acquisition and processing mechanism, so price is held high
It is expensive, realize difficulty, and measurement in real time relatively difficult to achieve.
The content of the invention
The purpose of the present invention is that a kind of φ-OTDR quadrature phase demodulations system of design and phase demodulating method, narrow linewidth swash
The strong coherent laser that light device is sent is divided into two beams through fiber coupler, it is larger it is a branch of be allocated as sense light, after modulated shift frequency fc
Sensor fibre is sent into, smaller light beam is as reference light, with the sense light rear orientation light that is returned through circulator outside coupler
Difference is relevant, is further divided into two equal beam flashlights, electric signal is converted to through balanced detector, by 1 × 2 work(point after bandpass filtering
Device is divided into two-way, enters line delay by electric adjustable delay chip all the way, and in frequency mixer and signal mould occurs for two path signal respectively
The sinusoidal signal that the frequency that block is sent is fc is mixed, then each low-pass filtered device and analog-to-digital conversion module are sent into control centre, enter
Row differential multiplication cross, which subtracts each other (DCM) operation or carries out arctangent cp cp operation, conciliates the phase letter that winding algorithm obtains sensing optical signal
Breath.
A kind of φ-OTDR phase demodulatings system designed by the present invention includes LASER Light Source, acousto-optic modulator and sense light
Fibre connects through optical fiber successively, and the sinusoidal signal that the frequency that signal generating module is sent is fc accesses acousto-optic modulator；The present invention's
LASER Light Source is narrow linewidth laser, and narrow linewidth laser connects fiber coupler, and laser beam is divided into two beams by fiber coupler, greatly
Part light is sensing soft exchange acousto-optic modulator, and acousto-optic modulator is modulated to it and after shift frequency fc through circulator and sense light
The connection of fine or sensing optic cable.Fiber coupler using fraction light as referring to soft exchange Polarization Controller, Polarization Controller it is defeated
Going out termination 2 × 2 fiber coupler, one input, the other end of circulator accesses 2 × 2 fiber couplers another inputs,
It is divided into two equal beam signal soft exchange balance detections after two beams input optical heterodyne is relevant in 2 × 2 fiber couplers
Device, balanced detector change gained electric signal be filtered into centre frequency into fc bandpass filter, then access 1 ×
Filtered electric signal is divided into two-way by 2 power splitters, 1 × 2 power splitter, wherein electric signal access No.1 electricity frequency mixer all the way, separately
Electric signal first accesses electric adjustable delay chip delay 1/4fc time all the way, then accesses No. two electric frequency mixers, and the signal occurs
The frequency that module is sent is that fc sinusoidal signal is also respectively connected to No.1, No. two electric frequency mixers, is mixed with two path signal；
The output of No.1 electricity frequency mixer is through No.1 low pass filter and No.1 analog-to-digital conversion module Access Control center, No. two
The output of electric frequency mixer is through No. two low pass filters and No. two analog-to-digital conversion module Access Control centers；The No.1, No. two electricity
The specifications parameter of frequency mixer is identical, No.1, the specifications parameter of No. two low pass filters are identical, No.1, No. two analog-to-digital conversion modules
Specifications parameter is identical.
The splitting ratio of the fiber coupler is (9:1)~(7:3).
The narrow linewidth laser accesses the fiber coupler again through continuous image intensifer and preposition optical fiber filter.
The acousto-optic modulator is followed by pulse image intensifer and rearmounted optical fiber filter accesses circulator again.
The balanced detector is PIN pipes or avalanche diode.
The balanced detector is followed by accessing the bandpass filter after amplifying circuit is amplified again.
The control centre is computer, digital signal processor, in field programmable gate array (FPGA) and industrial computer
It is any.
The phase demodulating method for the φ-OTDR quadrature phase demodulation systems that the present invention designs is as follows：Narrow linewidth laser is sent out
The laser beam gone out is divided into two parts by fiber coupler, and fraction light carries out Polarization Control as reference light through Polarization Controller,
Most of light is modulated by acousto-optic modulator and enters sensor fibre through circulator after shift frequency fc, is scattered back the sense light come
Signal accesses 2 × 2 fiber couplers through circulator, and the reference light after Polarization Control also accesses 2 × 2 fiber couplers, 2 × 2
The two is carried out being divided into two equal beam flashlights after heterodyne is relevant in fiber coupler, and telecommunications is converted into balanced detector
Number, two path signal is divided into by 1 × 2 power splitter again after bandpass filtering, wherein electric signal access No.1 electricity frequency mixer all the way, separately
Electric signal first accesses electric adjustable delay chip delay 1/4fc time all the way, then accesses No. two electric frequency mixers, two path signal point
The sinusoidal signal for not being fc with the frequency that signal generating module is sent in No.1, No. two frequency mixers is mixed, and obtained two-way is orthogonal
Electric signal filtered respectively by No.1, No. two low pass filters, filter out heterodyne frequency signal and its higher harmonic components, so
Data signal respectively is converted into through No.1, No. two modulus modules afterwards, is sent into the phase information that control centre obtains sensing optical signal.
The method that the control centre obtains the phase information of sensing optical signal is that two beam orthogonal electrical signals are carried out into differential
Multiplication cross subtracts each other (DCM) operation, obtains sensing the phase information of optical signal；Either two beam orthogonal electrical signals are carried out anyway
Computing is cut, then obtains sensing the phase information of optical signal around algorithm by phase unwrapping.
Compared with prior art, the advantages of a kind of φ-OTDR quadrature phase demodulations system and phase demodulating method of the invention
For：1st, an interferometer structure need not be introduced, extra ambient noise will not be introduced, coherent reception adds what balanced detector received
The signal to noise ratio that structure substantially increases sensing optical signal reaches more than 10dB, adds detection range；2nd, by the way of electricity is delayed
Two-way orthogonal electrical signal is produced, avoids the data acquisition for directly receiving 100,000,000 magnitudes required for being concerned with number and fortune
Calculate, system is relatively easy, is easily achieved, and reduces cost, is more suitable for engineer applied.
Brief description of the drawings
Fig. 1 is the structural representation of this φ-OTDR quadrature phase demodulations system embodiment 1；
Fig. 2 is the structural representation of this φ-OTDR quadrature phase demodulations system embodiment 2.
Figure internal label is：
1st, narrow linewidth laser, 2, fiber coupler, 3, acousto-optic modulator, 4, circulator, 5, balanced detector, 6, sensing
Optical fiber/optical cable, 7, signal generating module, 8, No.1 electricity frequency mixer, 9, No.1 low pass filter, 10, No.1 analog-to-digital conversion module,
11st, control centre, 12, No. two analog-to-digital conversion modules, 13, No. two low pass filters, 14, No. two electric frequency mixers, 15, electricity adjustable prolongs
When chip 16,1 × 2 power splitter, 17, bandpass filter, 18,2 × 2 fiber couplers, 19, Polarization Controller, 20, pulsed light puts
Big device, 21, rearmounted optical fiber filter, 22, amplifying circuit.
Embodiment
Present disclosure is described in further detail below in conjunction with the accompanying drawings.
φ-OTDR quadrature phase demodulations system embodiment 1
As shown in figure 1, figure inside solid line represents light path, dotted line connects this φ-OTDR quadrature phase demodulations system embodiment 1
Connect indication circuit.Wavelength connects fiber coupler 2 for the narrow linewidth laser 1 of C-band, and the splitting ratio of this example fiber coupler 2 is
90:10.Laser beam is divided into two beams by the fiber coupler 2, and 90% light is as sensing soft exchange acousto-optic modulator 3, signal hair
The sinusoidal signal that the frequency that raw module 7 is sent is fc accesses acousto-optic modulator 3；Acousto-optic modulator 3 is modulated simultaneously to sense light
After shift frequency fc sensor fibre 6 is accessed through circulator 4.
Fiber coupler 2 is using 10% light as referring to soft exchange Polarization Controller 19, the output end of Polarization Controller 19
2 × 2 fiber coupler, 18 1 inputs are connect, sensor fibre 6 is scattered back the sensing optical signal come and accesses 2 × 2 light through circulator 4
Fine another input of coupler 18.The sense light that 2 × 2 fiber couplers 18 return to the reference light after Polarization Control and scattering
Signal carries out being divided into two equal beam signal soft exchange balanced detectors 5 after heterodyne is relevant, the electricity of the conversion gained of balanced detector 5
Signal enters the bandpass filter 17 that centre frequency is fc and is filtered, and electric signal then is divided into two by 1 × 2 power splitter 16
Road, wherein electric signal access No.1 electricity frequency mixer 8 all the way, another way electric signal first passes through the electric delay of adjustable delay chip 15 1/
4fc time, then No. two electric frequency mixers 14 are accessed, the frequency that signal generating module 7 is sent is that fc sinusoidal signal also connects respectively
Enter two electric frequency mixers 8,14, be mixed with two path signal, No.1, No. two electric frequency mixers 8,14 are respectively through No.1, No. two low pass filtereds
Ripple device 9,13 and No.1, No. two analog-to-digital conversion modules 10,12 are converted into data signal Access Control center 11, this example No.1, two
The specifications parameter of number electric frequency mixer 8,14 is identical, No.1, the specifications parameter of No. two low pass filters 9,13 are identical, No.1, No. two
The specifications parameter of analog-to-digital conversion module 10,12 is identical.
This example control centre 11 is computer.
φ-OTDR quadrature phase demodulations system embodiment 2
This φ-OTDR quadrature phase demodulations system embodiment 2 is as shown in Fig. 2 the narrow linewidth laser 1, optical fiber coupling of this example
Clutch 2, acousto-optic modulator 3, signal generating module 7, circulator 4, sensor fibre 6, Polarization Controller 19,2 × 2 fiber couplers
18th, balanced detector 5, bandpass filter 17,1 × 2 power splitter 16, No.1 electricity frequency mixer 8, No.1 low pass filter 9, No.1 mould
Number modular converter 10, the analog-to-digital conversion mould of low pass filter 13, two of electric frequency mixer 14, two of electric adjustable delay chip 15, two
Block 12 and control centre 11 and connected mode are same as Example 1, and this example acousto-optic modulator 3 is followed by the He of pulse image intensifer 20
Rearmounted optical fiber filter 21 accesses circulator 4 again.
Continuous image intensifer and preposition optical fiber filter can be connected in this example after narrow linewidth laser 1, and incoming fiber optic couples again
Device 2.
This example balanced detector 5 is managed for PIN, and it is followed by accessing bandpass filter 17 again after amplifying circuit 22 is amplified.
The phase demodulating embodiment of the method one of φ-OTDR quadrature phase demodulation systems
The phase demodulating embodiment of the method one of this φ-OTDR quadrature phase demodulation systems is in above-mentioned φ-OTDR quadrature phases
Carried out in demodulating system embodiment 1.
The laser beam that narrow linewidth laser 1 is sent is divided into two parts by fiber coupler 2, and fraction light passes through as reference light
Polarization Controller 19 carries out Polarization Control, most of to be modulated by acousto-optic modulator 3 and enter after shift frequency fc through circulator 4
Sensor fibre 6, it is scattered back the sensing optical signal come and accesses 2 × 2 fiber couplers 18 through circulator 4, the reference after Polarization Control
Light also accesses 2 × 2 fiber couplers 18, and the two carries out being divided into two equal beams after heterodyne is relevant in 2 × 2 fiber couplers 18
Signal soft exchange balanced detector 5, be converted to electric signal and be filtered into the bandpass filter 17 that centre frequency is fc, then
Two path signal is divided into by 1 × 2 power splitter 16, wherein electric signal access No.1 electricity frequency mixer 8 all the way, another way first accesses electricity
The delay of adjustable delay chip 15 1/4fc time, then No. two electric frequency mixers 14 are accessed, then two path signal respectively enters one
Number, No. two electric frequency mixers 8,14, the frequency that signal generating module 7 is sent be fc sinusoidal signal be respectively connected to two electric frequency mixers
8th, 14, it is mixed with two path signal, the orthogonal electric signal of obtained two-way is respectively by No.1, No. two low pass filters 9,13 and
No.1, No. two analog-to-digital conversion modules 10,12 are converted into the phase letter that data signal Access Control center 11 obtains sensing optical signal
Breath.
This example No.1, the specifications parameter of No. two electric frequency mixers 8,14 are identical, No.1, the specification of No. two low pass filters 9,13
Parameter is identical, and No.1, the specifications parameter of No. two analog-to-digital conversion modules 10,12 are identical.
The signal to noise ratio of this example sensing optical signal at least improves more than 10dB.
The method that this example control centre 11 obtains sensing optical signal phase information has two kinds, and one is by the orthogonal telecommunications of two beams
Number carry out differential multiplication cross phase reducing, obtain sense optical signal phase information；Another is to enter two beam orthogonal electrical signals
Row arctangent cp cp operation, then the phase information of sensing optical signal is obtained around algorithm by phase unwrapping.
Above-described embodiment, only the purpose of the present invention, technical scheme and beneficial effect are further described specific
Individual example, the present invention are not limited to this.All any modifications made within the scope of disclosure of the invention, equivalent substitution, change
Enter, be all contained within protection scope of the present invention.
Claims (9)
1. a kind of φ-OTDR quadrature phase demodulation systems, including LASER Light Source, acousto-optic modulator and sensor fibre are successively through optical fiber
Connection, the sinusoidal signal that the frequency that signal generating module (7) is sent is fc access acousto-optic modulator (3)；The LASER Light Source is
Narrow linewidth laser (1), narrow linewidth laser (1) connect fiber coupler (2), and laser beam is divided into two by the fiber coupler (2)
Beam, most of light are modulated by acousto-optic modulator (3) and access sensor fibre (6) through circulator (4) after shift frequency fc or pass
Sensing optical cable；Fraction light terminates 2 × 2 optical fiber as soft exchange Polarization Controller (19), the output of Polarization Controller (19) is referred to
One input of coupler, sensor fibre (6) or sensing optic cable are scattered back the sensing optical signal come and access 2 × 2 through circulator (4)
Fiber coupler (18) another input, it is characterised in that：
The sensing optical signal that 2 × 2 fiber coupler returns to the reference light after Polarization Control and scattering carries out heterodyne and is concerned with
It is divided into two equal beam signal soft exchange balanced detectors (5) afterwards, the electric signal of balanced detector conversion gained enters center frequency
Rate is that fc bandpass filter (17) is filtered, and electric signal then is divided into two-way by 1 × 2 power splitter (16), wherein one
Road electric signal access No.1 electricity frequency mixer, another way electric signal first access electric adjustable delay chip (15) delay 1/4fc time,
Access No. two electric frequency mixers again, the sinusoidal signal that the frequency that signal generating module (7) is sent is fc be also respectively connected to No.1, No. two
Electric frequency mixer (8,14), it is mixed with two path signal；The output of No.1 electricity frequency mixer (8) is through No.1 low pass filter (9) and one
Number analog-to-digital conversion module (10) Access Control center, the output of No. two electric frequency mixers (14) is through No. two low pass filters (13) and two
Number analog-to-digital conversion module (12) Access Control center；The No.1, the specifications parameter of No. two electric frequency mixers (8,14) are identical, described
No.1, the specifications parameter of No. two low pass filters (9,13) are identical, the No.1, the rule of No. two analog-to-digital conversion modules (10,12)
Lattice parameter is identical.
2. φ-OTDR quadrature phase demodulation systems according to claim 1, it is characterised in that：
The splitting ratio of the fiber coupler (2) is (9:1)~(7:3).
3. φ-OTDR quadrature phase demodulation systems according to claim 1, it is characterised in that：
The narrow linewidth laser (1) continues image intensifer in succession and preposition optical fiber filter accesses the fiber coupler again
(2)。
4. φ-OTDR quadrature phase demodulation systems according to claim 1, it is characterised in that：
The acousto-optic modulator (3) is followed by pulse image intensifer and rearmounted optical fiber filter accesses the circulator (4) again.
5. φ-OTDR quadrature phase demodulation systems according to claim 1, it is characterised in that：
The balanced detector (5) is PIN pipes or avalanche diode.
6. φ-OTDR quadrature phase demodulation systems according to claim 1, it is characterised in that：
The balanced detector (5) is followed by accessing the bandpass filter (17) after amplifying circuit is amplified again.
7. φ-OTDR quadrature phase demodulation systems according to claim 1, it is characterised in that：
The control centre (11) is computer, digital signal processor, any in field programmable gate array and industrial computer
Kind.
8. the phase demodulating method of φ-OTDR quadrature phase demodulation systems according to any one of claim 1 to 7, its
It is characterised by：
The laser beam that the narrow linewidth laser (1) sends is divided into two parts by fiber coupler (2), and fraction light is as reference
Light carries out Polarization Control through Polarization Controller (19), and most of light is modulated by acousto-optic modulator (3) and passed through after shift frequency fc
Circulator (4) enters sensor fibre (6), is scattered back the sensing optical signal come and accesses 2 × 2 fiber couplers through circulator (4)
(18), the reference light after Polarization Control also accesses 2 × 2 fiber couplers (18), and the two enters in 2 × 2 fiber couplers (18)
It is divided into two equal beam flashlights after row heterodyne is relevant and is converted to electric signal into balanced detector (5), is into centre frequency
Fc bandpass filter (17) is filtered, and is then divided into two path signal by 1 × 2 power splitter (16), wherein telecommunications all the way
Number access No.1 electricity frequency mixer (8), another way first accesses electric adjustable delay chip (15) delay 1/4fc time, then accesses two
Number electric frequency mixer (14), the frequency that signal generating module (7) is sent are that fc sinusoidal signal is also respectively connected to No.1, No. two electricity mix
Frequency device (8,14), the frequency that two path signal is sent in No.1, No. two frequency mixers (8,14) with signal generating module (15) respectively
It is mixed for fc sinusoidal signal, the orthogonal electric signal of obtained two-way is filtered by No.1, No. two low pass filters (9,13) respectively
Ripple, heterodyne frequency signal and its higher harmonic components are filtered out, be then respectively converted into through No.1, No. two modulus modules (10,12)
Data signal, it is sent into the phase information that control centre obtains sensing optical signal.
9. the phase demodulating method of φ-OTDR quadrature phase demodulation systems according to claim 8, it is characterised in that：
The method that the control centre obtains the phase information of sensing optical signal is that two beam orthogonal electrical signals are carried out into differential intersection
Multiplication phase reducing, obtain sensing the phase information of optical signal；Two beam orthogonal electrical signals are either subjected to arctangent cp cp operation, then
Obtain sensing the phase information of optical signal around algorithm by phase unwrapping.
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| CN108332735A (en) * | 2018-02-06 | 2018-07-27 | 浙江大学 | Resonance type optical fiber gyro coherent demodulation system and method based on additional beam interference |
| CN111412936A (en) * | 2020-03-10 | 2020-07-14 | 天津大学 | Full-digital orthogonal phase shift pulse COTDR sensing device and method |
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| CN113447112A (en) * | 2021-06-18 | 2021-09-28 | 天津大学 | Reflected light-based high-frequency vibration sensing system and high-frequency signal demodulation method |
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| CN114077854A (en) * | 2022-01-18 | 2022-02-22 | 之江实验室 | phi-OTDR underwater acoustic signal processing method and device based on self-adaptive VMD |
| CN115046623A (en) * | 2022-06-09 | 2022-09-13 | 北京航空航天大学 | Optical fiber acoustic emission signal demodulation system and method based on FPGA and ARM |
| CN116124188A (en) * | 2023-02-24 | 2023-05-16 | 山东飞博赛斯光电科技有限公司 | 1GSPS distributed optical fiber sensor |
| CN116295782A (en) * | 2023-03-08 | 2023-06-23 | 浙江信测通信股份有限公司 | Distributed optical fiber vibration sensing system based on phi-OTDR and phase demodulation method |
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