CN109059970A - A kind of multi-channel long optical fiber sensing system - Google Patents
A kind of multi-channel long optical fiber sensing system Download PDFInfo
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- CN109059970A CN109059970A CN201810888695.XA CN201810888695A CN109059970A CN 109059970 A CN109059970 A CN 109059970A CN 201810888695 A CN201810888695 A CN 201810888695A CN 109059970 A CN109059970 A CN 109059970A
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- 239000013307 optical fiber Substances 0.000 title claims abstract description 25
- 239000000835 fiber Substances 0.000 claims abstract description 29
- 238000005086 pumping Methods 0.000 claims abstract description 7
- 239000003990 capacitor Substances 0.000 claims description 83
- 230000003287 optical effect Effects 0.000 claims description 50
- 230000003044 adaptive effect Effects 0.000 claims description 28
- 230000009466 transformation Effects 0.000 claims description 18
- 230000005611 electricity Effects 0.000 claims description 14
- 239000000919 ceramic Substances 0.000 claims description 13
- 238000006243 chemical reaction Methods 0.000 claims description 12
- 238000004891 communication Methods 0.000 claims description 7
- 238000013519 translation Methods 0.000 claims description 6
- 238000002310 reflectometry Methods 0.000 claims description 3
- 230000003321 amplification Effects 0.000 claims 1
- 238000003199 nucleic acid amplification method Methods 0.000 claims 1
- 238000005516 engineering process Methods 0.000 abstract description 5
- 238000004519 manufacturing process Methods 0.000 description 7
- 230000008859 change Effects 0.000 description 6
- 238000000985 reflectance spectrum Methods 0.000 description 6
- 238000001514 detection method Methods 0.000 description 5
- 238000010586 diagram Methods 0.000 description 5
- 238000012544 monitoring process Methods 0.000 description 4
- 230000008901 benefit Effects 0.000 description 3
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- 238000010168 coupling process Methods 0.000 description 3
- 238000005859 coupling reaction Methods 0.000 description 3
- 238000005259 measurement Methods 0.000 description 3
- 230000010287 polarization Effects 0.000 description 3
- 230000002411 adverse Effects 0.000 description 2
- 230000007613 environmental effect Effects 0.000 description 2
- 239000004744 fabric Substances 0.000 description 2
- 238000001914 filtration Methods 0.000 description 2
- 238000000034 method Methods 0.000 description 2
- YMHOBZXQZVXHBM-UHFFFAOYSA-N 2,5-dimethoxy-4-bromophenethylamine Chemical class COC1=CC(CCN)=C(OC)C=C1Br YMHOBZXQZVXHBM-UHFFFAOYSA-N 0.000 description 1
- 229910052691 Erbium Inorganic materials 0.000 description 1
- 230000018199 S phase Effects 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 238000003486 chemical etching Methods 0.000 description 1
- UYAHIZSMUZPPFV-UHFFFAOYSA-N erbium Chemical compound [Er] UYAHIZSMUZPPFV-UHFFFAOYSA-N 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 238000005305 interferometry Methods 0.000 description 1
- 238000011031 large-scale manufacturing process Methods 0.000 description 1
- 238000013507 mapping Methods 0.000 description 1
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- 230000002463 transducing effect Effects 0.000 description 1
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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
- G01D5/35306—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 an interferometer arrangement
- G01D5/35309—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 an interferometer arrangement using multiple waves interferometer
- G01D5/35316—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 an interferometer arrangement using multiple waves interferometer using a Bragg gratings
-
- 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
- G01D5/35383—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 multiple sensor devices using multiplexing techniques
- G01D5/35387—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 multiple sensor devices using multiplexing techniques using wavelength division multiplexing
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Abstract
A kind of multi-channel long optical fiber sensing system of the invention belongs to fiber optic sensor technology field.Its primary structure has pumping source (1), light wavelength division multiplexing (2), Er-doped fiber (3) etc..The present invention uses sinusoidal signal as modulated signal, will not generate High-frequency Interference, has the characteristics that work is more reliable, sensing accuracy is high, has a wide range of application.
Description
Technical field
The invention belongs to the technical field of fibre optical sensor, in particular to a kind of multi-channel long optical fiber sensing system.
Background technique
Electromagnetism interference, resistant to chemical etching, transmission loss is small, weight small in size because having for bragg grating (FBG)
Gently, convenient for large-scale production the advantages that, and it is widely used in field of sensing technologies.Especially in microstress detection, adverse circumstances
Temperature sensing etc., fibre optical sensor have unique advantage, the very small variation of one side temperature or stress, Bradley
Lattice fiber grating can be detected sensitively, have very high sensitivity, on the other hand in adverse circumstances such as humidity, strong electromagnetic
Under disturbed condition, bragg grating is hardly damaged, and working performance is unaffected, and signal transmission is interference-free.These are excellent
Point so that Bragg optical-fiber grating sensor be widely used in bridge, tunnel and fabric structure microstress variation monitoring,
The important safeties Workplace such as mine temperature safety monitoring.
It is doctor's thesis " fiber grating sensing system of Nankai University Liu Bo with the immediate prior art of the present invention
Research and realization ", the document provides a kind of bragg fiber based on your interferometry demodulation techniques of non-equilibrium Mach Zehnder
Grating sensing system (referring to Fig. 3 .6 of page 26 of the document), the optical fiber sensing system use Mach Zehnder that principle of interference,
Change the length of the arm using the modulated signal that piezoelectric ceramics (PZT) is provided on a wherein arm in interferometer two-arm, to change
Exsiccation interferometer output intensity, interferometer output intensity is regular in cosine function with the variation of PZT modulated signal, if using ideal
Modulated signal of the sawtooth wave as PZT, then the output of optical fiber sensing system is directly cosine wave.Optical fiber sensing system passes through Bradley
Lattice grating perceives the variation of measurement point stress or temperature, and is reflected as the variation of reflectance spectrum central wavelength, central wavelength
Change the variation that output cosine wave phase is presented as after your interferometer of above-mentioned Mach Zehnder, finally by the phase of cosine wave and
The phase of sawtooth wave compares, and can reflect the variation of bragg grating reflectance spectrum central wavelength, to realize measurement
The variation of extraneous stress or temperature.
In above-mentioned sensor-based system, existing greatest problem is that sawtooth wave can not accomplish absolute idealization, preferably
Sawtooth wave failing edge is vertical, and the failing edge of actual sawtooth wave always has certain gradient, so that rear class can be made defeated
There are a high dithers for cosine wave out, generally necessary in grade demodulator circuit behind in order to eliminate the high-frequency jitter signal
Using bandpass filter (BPF), DC component and high fdrequency component are filtered out.But on the one hand the high fdrequency component inherently can be to remaining
The phase-detection of string wave impacts (zero crossing change in location)；On the other hand the frequency of the high-frequency jitter signal is driven by PZT
(electrical characteristics of PZT are equivalent to capacitor to the lagging characteristics of circuit performance, PZT itself, and both end voltage cannot jump, therefore
The failing edge of sawtooth wave be do not accomplish it is unlimited short) and the factors such as optical fiber elasticity itself influence, frequency size is indefinite, very
Difficulty filters out completely；Moreover, when using filter, it, can also be simultaneously other than it can be had an impact to the amplitude-frequency characteristic of output signal
The phase-frequency characteristic of signal is had an impact, i.e., filtering is that phase will receive influence near cutoff frequency, this is for relying on phase
It is very unfavorable for changing for the fibre optical sensor to measure stress variation.Therefore, existing bragg grating sensing
Device also requires further improvement.
Summary of the invention
In order to overcome existing Bragg optical-fiber grating sensor there are the shortcomings that, the present invention provides a kind of using sinusoidal letter
Multi-channel long optical fiber sensing system number as PZT driving signal, so as to avoid the generation of high-frequency interferencing signal, and is being docked
Without using filter when the signal received is handled, the influence that phase is generated so as to avoid filtering.
The purpose of the present invention is achieved through the following technical solutions:
A kind of multi-channel long optical fiber sensing system, structure have, the end the 980nm phase of pumping source 1 and light wavelength division multiplexing 2
Even, the end 1550nm of light wavelength division multiplexing 2 is connected with the one end for being wrapped in delay line adjustable optic fibre 11, delay line adjustable optic fibre 11
The other end be connected with the input terminal of the first optoisolator 10, the control terminal of delay line adjustable optic fibre 11 and electrical level transferring chip 12
Output port be connected, the input port of electrical level transferring chip 12 is connected with single-chip microcontroller 18；The output end of first optoisolator 10
It is connected with the light input end of optical filter 9, the electric control end of optical filter 9 is connected with single-chip microcontroller 18, the light output of optical filter 9
End is connected with the first port of optical circulator 7, and the second port of optical circulator 7 is connected with one end of Bragg grating group 8, the ring of light
The third port of shape device 7 is connected with the input terminal of the first photo-coupler 5,90% output end and the second light of the first photo-coupler 5
The input terminal of isolator 4 is connected, and the output end of the second optoisolator 4 is connected with one end of Er-doped fiber 3, Er-doped fiber 3 it is another
One end is connected with the common end of wavelength division multiplexer 2；The output of 10% output end and the second photo-coupler 6 of first photo-coupler 5
Input terminal is connected, and an output end of the second photo-coupler 6 is connected with an input terminal of third photo-coupler 23, the second optocoupler
The another output of clutch 6 is connected with the one end for the optical fiber being wrapped on piezoelectric ceramics 22, is wrapped on piezoelectric ceramics 22
The other end of optical fiber is connected with another input terminal of third photo-coupler 23, the output end of third photo-coupler 23 and the first light
The input terminal of detector 24 is connected, and the output end of third photo-coupler 23 is also connected with the input terminal of the second optical detector 25；
It is characterized in that, structure is in addition, the output end of the first optical detector 24 and the homophase input of differential amplifier circuit 26
End is connected, and the output end of the second optical detector 25 is connected with the inverting input terminal of differential amplifier circuit 26, differential amplifier circuit 26
The input terminal of output end and function translation circuit 27 be connected, the output end of functional transformation circuit 27 and adaptive amplitude normalizing electricity
The input terminal on road 28 is connected, an input terminal phase of the output end and phase-comparison circuit 29 of adaptive amplitude normalizing circuit 28
Even；The input terminal in controllable frequency source 20 is connected with single-chip microcontroller 18, another input terminal phase of output end and phase-comparison circuit 29
Even, the output end of phase-comparison circuit 29 is connected with single-chip microcontroller 18；The output end in controllable frequency source 20 also with PZT driving circuit 21
Input terminal be connected, the output end of PZT driving circuit 21 is connected with the control terminal of piezoelectric ceramics 22；The output of constant-current source circuit 14
End be connected with thermistor 15, thermistor 15 is connected with the input terminal of analog to digital conversion circuit 16, analog to digital conversion circuit 16 it is defeated
Outlet is connected with single-chip microcontroller 18；Single-chip microcontroller 18 is also connected with input key 13, serial communication modular 17, display screen 19 respectively；
The structure of the functional transformation circuit 27 is, one end of capacitor C3 and the pin 12 of trigonometric function converter U1 and
One end of resistance R2 is connected, and input terminal of the other end of capacitor C3 as functional transformation circuit 27 is denoted as port ACOS_in, with
The output end of differential amplifier circuit 26 is connected；The other end of resistance R2 is grounded；The pin 2 of trigonometric function converter U1,3,4,5,
8,11,13 ground connection, pin 9,10 are connected with one end of capacitor C2 and -12V power supply, the other end ground connection of capacitor C2；Trigonometric function
The pin 6 of converter U1 is connected with pin 7, and pin 16 is connected with one end of+12V power supply and capacitor C1, the other end of capacitor C1
Ground connection；The pin 1 of trigonometric function converter U1 is connected with the sliding end of slide rheostat W1, one end of slide rheostat W1 and electricity
The one end for hindering R1 is connected, and the other end of resistance R1 is connected with the pin 14 of trigonometric function converter U1, the cunning of slide rheostat W1
Output end of the moved end as functional transformation circuit 27, is denoted as port ACOS_out, the input with adaptive amplitude normalizing circuit 28
End is connected；The model AD639 of the trigonometric function converter U1；
The structure of the adaptive amplitude normalizing circuit 28 is one end of capacitor C9 and one end of resistance R3 and chip U2
Pin 3 be connected, the other end of resistance R3 ground connection, input of the other end of capacitor C9 as adaptive amplitude normalizing circuit 28
End, is denoted as port ADAPT_in, and the port ACOS_out of and function translation circuit 27 is connected；Pin 1, pin 7, the pipe of chip U2
Foot 8, pin 14 are grounded, and pin 2 is connected with+5V power supply with pin 4, and pin 11 is connected and one with capacitor C5 with pin 12
End and+5V power supply are connected, the other end ground connection of capacitor C5；The pin 13 of chip U2 is connected with one end of capacitor C4, capacitor C4's
Other end ground connection；The pin 9 of chip U2 is connected with one end of capacitor C6, the other end ground connection of capacitor C6；The pin 5 of chip U2 with
One end of resistance R12 and resistance R11 are connected, the other end ground connection of resistance R12, the output of the other end and amplifier U4 of resistance R11
End and one end of capacitor C8 are connected, the positive supply termination+5V power supply of amplifier U8, negative power end ground connection；The other end of capacitor C8 with
One end of resistance R10 is connected, and the other end of resistance R10 is connected with the non-inverting input terminal of amplifier U4；The inverting input terminal of amplifier U4
It is connected with the sliding end of sliding variohm W3, one end of slide rheostat W3 is connected with+5V power supply, and slide rheostat W3's is another
One end ground connection；One end of capacitor C7 is connected with the non-inverting input terminal of one end of resistance R9 and amplifier U4, another termination of capacitor C7
The other end on ground, resistance R9 is connected with the output end of one end of resistance R7 and amplifier U3, and the other end of resistance R7 is with amplifier U3's
Inverting input terminal is connected；One end of resistance R8 is connected with the non-inverting input terminal of amplifier U3, other end ground connection；The positive supply of amplifier U3
Termination+5V power supply, negative power end ground connection；Output end of the pin 10 of chip U2 as adaptive amplitude normalizing circuit 28, is denoted as
Port ADAPT_out is connected with an input terminal of phase-comparison circuit 29；The pin 10 of chip U2 and the anode of diode D1
It is connected, the cathode of diode D1 is connected with one end of resistance R4, the other end of resistance R4 and one end of resistance R5 and amplifier U3's
Inverting input terminal is connected, and the other end of resistance R5 is connected with the anode of diode D2, the cathode and slide rheostat of diode D2
The sliding end of W2 is connected；One end of slide rheostat W2 is connected and is grounded with the cathode of diode D3, and slide rheostat W2's is another
One end is connected with the anode of one end of resistance R6 and diode D3, another termination -5V power supply of resistance R6；The chip U2 is
Variable gain amplifier chip, model are AD8367；
The structure of the phase-comparison circuit 29 is one end of capacitor C10 and the non-inverting input terminal and resistance of amplifier U5
One end of R13 is connected, and an input terminal of the other end of capacitor C10 as phase-comparison circuit 29 is denoted as port PHASE_
In1 is connected with the port ADAPT_out of adaptive amplitude normalizing circuit 28；The other end of resistance R13 is grounded；Amplifier U5 is just
Power supply termination+5V power supply, negative power end ground connection, reverse inter-input-ing ending grounding, the end CLK of output termination d type flip flop U6A；D type flip flop
The port D of U6A is grounded；The one end capacitor C11 ground connection, the end PR of another termination d type flip flop U6A；Resistance R14 mono- terminates d type flip flop
The end PR of U6A, the end Q of another termination d type flip flop U6A；CLR termination+5V the power supply of d type flip flop U6A, the Q of d type flip flop U6A are non-
Terminate the end PR of d type flip flop U8A；One end of capacitor C12 is connected with one end of the non-inverting input terminal of amplifier U7 and resistance R15, electricity
Hold another input terminal of the other end of C12 as phase-comparison circuit 29, port PHASE_in2 is denoted as, with controllable frequency source
20 port SineM_out is connected；The other end of resistance R15 is grounded；Positive supply termination+5V the power supply of amplifier U7, negative power end
Ground connection, reverse inter-input-ing ending grounding, the end CLK of output termination d type flip flop U6B；The port D of d type flip flop U6B is grounded；Capacitor C13 mono-
End ground connection, the end PR of another termination d type flip flop U6B；Resistance R16 mono- terminates the end PR of d type flip flop U6B, another termination d type flip flop
The end Q of U6B；CLR termination+5V the power supply of d type flip flop U6B, the end CLR of the Q non-terminated d type flip flop U8A of d type flip flop U6B；D touching
The end D and the end CLK for sending out device U8A are grounded, and output end of the end Q as phase-comparison circuit 29 is denoted as port PHASE_out, with
The input terminal of single-chip microcontroller 18 is connected；
The structure in the controllable frequency source 20 is the inverting input terminal of a termination amplifier U9 of thermistor Rt1, another
Terminate the output end of amplifier U9；Resistance R17 mono- terminates the inverting input terminal of amplifier U9, other end ground connection；Amplifier U9's is same mutually defeated
Enter the pin 2 of chip termination U11, positive supply termination+5V power supply, negative supply termination -5V power supply exports the pipe of chip termination U10
Foot 2；The pin 3 of a chip termination U10 of capacitor C14, the pin 2 of another chip termination U11；A chip termination of capacitor C15
The pin 2 of U11, other end ground connection；The pin 5 of a chip termination U10 of capacitor C16, other end ground connection；One end of capacitor C17
Connect the pin 5 of chip U11, other end ground connection；The pin 1 and pin 10 of chip U10 connects+5V power supply, and pin 4 and pin 6 are grounded；
One end of 9 connecting resistance R18 of pin, one end of 8 connecting resistance R19 of pin, one end of 7 connecting resistance R20 of pin；Resistance R18's is another
An input port as controllable frequency source 20 is held, port SineM_in1 is denoted as；The other end of resistance R19 is as controllable frequency
Another input port in rate source 20, is denoted as port SineM_in2；Port SineM_in1 and port SineM_in2 and single-chip microcontroller
18 input terminal is connected；Another termination+5V power supply of resistance R20；The pin 1 and pin 10 of chip U11 connects+5V power supply, pin 4
It is grounded with pin 6；One end of 9 connecting resistance R21 of pin, one end of 8 connecting resistance R22 of pin, one end of 7 connecting resistance R23 of pin；Electricity
Hinder another termination port SineM_in1 of R21；Another termination port SineM_in2 of resistance R22；Another termination of resistance R23
+ 5V power supply；Output port of the pin 2 of chip U10 as controllable frequency source 20, is denoted as SineM_out.
The preferred 980nm laser light source of pumping source 1.
The Bragg grating group 8 is preferably made of 3 Bragg gratings, and the reflectivity of each grating is 90%,
Bandwidth is 0.6nm, and central wavelength is respectively 1550nm, 1560nm and 1630nm.
The utility model has the advantages that
1, the present invention uses sinusoidal signal as modulated signal, compared with the prior art is modulated using sawtooth signal,
High-frequency Interference will not be generated, so that sensor-based system work is more reliable.
2, the present invention uses adaptive amplitude normalizing circuit by the amplitude auto-changing of signal after demodulation at suitable phase ratio
Compared with the size that circuit is compared, so that phase-detection error is smaller, the sensing accuracy of entire sensor-based system is effectively increased.
3, compared with prior art, frequency modulating signal of the invention is adjustable, so that sensor-based system applied field of the invention
It closes wider.
4, the present invention has temperature compensation function, effectively overcomes influence of the environment temperature to parameter sensing.
Detailed description of the invention
Fig. 1 is whole functional block diagram of the invention.
Fig. 2 is the basic circuit diagram for the functional transformation circuit that the present invention uses.
Fig. 3 is the basic circuit diagram for the adaptive amplitude normalizing circuit that the present invention uses.
Fig. 4 is the basic circuit diagram for the phase-comparison circuit that the present invention uses.
Fig. 5 is the basic circuit diagram in the controllable frequency source that the present invention uses.
Specific embodiment
The working principle of the invention is further illustrated with reference to the accompanying drawing, it should be appreciated that the component marked in attached drawing
Parameter is the preferred parameter that following embodiment uses, rather than limiting the scope of the invention.
The overall structure of the invention of embodiment 1
As shown in Figure 1, overall structure of the invention has, pumping source 1 be (Shanghai Ke Naite laser Science and Technology Ltd.
VENUS series 980nm high power single mode pump light source, model VLSS-980-B, maximum single-mode output optical power are 1200mW)
With (the fused tapered 980/1550nm pump light of Shanghai Han Yu Fibre Optical Communication Technology Co., Ltd production of light wavelength division multiplexing 2
Wave division multiplex coupler) the end 980nm be connected, the end 1550nm of light wavelength division multiplexing 2 and be wrapped in delay line adjustable optic fibre 11
The one end of (the electronic fibre delay line of VDL-40-15-S9-1-FA type of Sichuan space fixed star Micron Technology Co., Ltd) is connected, delay
10 (the 1310/ of Shanghai Han Yu Fibre Optical Communication Technology Co., Ltd production of the other end of line adjustable optic fibre 11 and the first optoisolator
1480/1550nm polarization independent optical isolator) input terminal be connected, the control terminal of delay line adjustable optic fibre 11 and level conversion core
The output port of piece 12 (MAX232) is connected, and the input port of electrical level transferring chip 12 is connected with single-chip microcontroller 18 (STC89C51)；
(Micron Optics company produces the output end and optical filter 9 of first optoisolator 10, model FFP-TF-1060-
Light input end 010G0200-2.0) is connected, and the electric control end of optical filter 9 is connected with single-chip microcontroller 18, and the light of optical filter 9 is defeated
Outlet is connected with the first port of optical circulator 7 (the PIOC3-15 optical circulator of Shanghai Han Yu company production), optical circulator 7
(reflectivity is 90 percent to second port, and bandwidth is 0.6nm, and central wavelength is respectively with Bragg grating group 8
Three Bragg gratings of 1550nm, 1560nm and 1630nm) one end be connected, the third port of optical circulator 7 and the first light
Coupler 5 (production of OZ-OPTICS company, model FUSED-12-1064-7/125-90/10-3U-3mm, splitting ratio 90:
10) input terminal is connected, 4 (the vast space Fibre Optical Communication Technology in Shanghai of 90% output end of the first photo-coupler 5 and the second optoisolator
The 1310/1480/1550nm polarization independent optical isolator of Co., Ltd's production) input terminal be connected, the second optoisolator 4 (on
Hai Hanyu Fibre Optical Communication Technology Co., Ltd production 1310/1480/1550nm polarization independent optical isolator) output end with mix
Erbium optical fiber 3 (the C-Band Er-doped fiber of the high-performance 980nm pumping of Nu fern company of U.S. production, model EDFC-980-
HP, 3 meters) one end be connected, the other end of Er-doped fiber 3 is connected with the common end of wavelength division multiplexer 2.Above structure constitutes light
The basic luminaire part of fiber sensor and transducing part.The output of 10% output end and the second photo-coupler 6 of first photo-coupler 5
The input terminal of (1 × 2 standard single mode photo-coupler, splitting ratio 50:50) is connected, an output end of the second photo-coupler 6 with
One input terminal of third photo-coupler 3 (2 × 2 standard single mode photo-couplers, splitting ratio 50:50) is connected, the second optical coupling
It the another output of device 6 and is wrapped in piezoelectric ceramics 22 (cylindrical piezoelectric ceramics, outer diameter 50mm, internal diameter 40mm, high 50mm)
On one end of optical fiber be connected, another for being wrapped in the other end of the optical fiber on piezoelectric ceramics 22 and third photo-coupler 23 is defeated
Enter end to be connected, the 24 (LSIPD- of the quick Micron Technology Co., Ltd in Beijing of the output end of third photo-coupler 23 and the first optical detector
LD50 type optical detector) input terminal be connected, the output end of third photo-coupler 23 also with 25 (the quick light in Beijing of the second optical detector
The LSIPD-LD50 type optical detector of Science and Technology Ltd.) input terminal be connected.Above-mentioned second photo-coupler 6, third optical coupling
Device 23 and piezoelectric ceramics 22 collectively constitute Mach Zehnder that interference structure.
Structure of the invention in addition, the output end and differential amplifier circuit 26 of the first optical detector 24 non-inverting input terminal phase
Even, the output end of the second optical detector 25 is connected with the inverting input terminal of differential amplifier circuit 26, differential amplifier circuit 26 it is defeated
The input terminal of outlet and function translation circuit 27 is connected, the output end of functional transformation circuit 27 and adaptive amplitude normalizing circuit 28
Input terminal be connected, the output end of adaptive amplitude normalizing circuit 28 is connected with an input terminal of phase-comparison circuit 29；It can
The input terminal of control frequency source 20 is connected with single-chip microcontroller 18, and output end is connected with another input terminal of phase-comparison circuit 29, phase
The output end of bit comparison circuit 29 is connected with single-chip microcontroller 18；The output end in controllable frequency source 20 is also defeated with PZT driving circuit 21
Enter end to be connected, the output end of PZT driving circuit 21 is connected with the control terminal of piezoelectric ceramics 22.Above structure constitutes sensor
Demodulation part.The output end of constant-current source circuit 14 is connected with thermistor 15 (25 ° of 10k Ω@), thermistor 15 and analog-to-digital conversion
The input terminal of circuit 16 is connected, and the output end of analog to digital conversion circuit 16 is connected with single-chip microcontroller 18.Above structure provides for the present invention
Temperature compensation function.Single-chip microcontroller 18 is also connected with input key 13, serial communication modular 17, display screen 19 respectively.For setting
It sets parameter, the functions such as information is communicated and shown with computer.
2 functional transformation circuit of embodiment
As shown in Fig. 2, the structure of functional transformation circuit 27 used in the present invention is one end of capacitor C3 and trigonometric function
The pin 12 of converter U1 and one end of resistance R2 are connected, input terminal of the other end of capacitor C3 as functional transformation circuit 27,
It is denoted as port ACOS_in, is connected with the output end of differential amplifier circuit 26；The other end of resistance R2 is grounded；Trigonometric function conversion
The pin 2,3,4,5,8,11,13 of device U1 is grounded, and pin 9,10 is connected with one end of capacitor C2 and -12V power supply, and capacitor C2's is another
One end ground connection；The pin 6 of trigonometric function converter U1 is connected with pin 7, one end phase of pin 16 and+12V power supply and capacitor C1
Even, the other end ground connection of capacitor C1；The pin 1 of trigonometric function converter U1 is connected with the sliding end of slide rheostat W1, sliding
One end of rheostat W1 is connected with one end of resistance R1,14 phase of pin of the other end and trigonometric function converter U1 of resistance R1
Even, output end of the sliding end of slide rheostat W1 as functional transformation circuit 27 is denoted as port ACOS_out, with adaptive width
The input terminal for spending normalizing circuit 28 is connected；The model AD639 of the trigonometric function converter U1；The circuit has anticosine
Mapping function, the signal that differential amplifier circuit 26 is exported carry out anticosine processing.
The adaptive amplitude normalizing circuit of embodiment 3
Since the signal amplitude that functional transformation circuit 27 exports is smaller, and influenced by multiple parameters in optical path and circuit,
Size is indefinite, therefore the present invention devises adaptive amplitude normalizing circuit 28, for the signal for exporting functional transformation circuit 27
Amplitude normalization at best size, to further increase the precision of demodulation.The knot of the adaptive amplitude normalizing circuit 28
Structure is that one end of capacitor C9 is connected with the pin 3 of one end of resistance R3 and chip U2, the other end ground connection of resistance R3, capacitor C9
Input terminal of the other end as adaptive amplitude normalizing circuit 28, be denoted as port ADAPT_in, and function translation circuit 27
Port ACOS_out is connected；Pin 1, pin 7, pin 8, the pin 14 of chip U2 is grounded, and pin 2 and pin 4 are electric with+5V
Source is connected, and pin 11 is connected with pin 12 and is connected with one end of capacitor C5 and+5V power supply, the other end ground connection of capacitor C5；Core
The pin 13 of piece U2 is connected with one end of capacitor C4, the other end ground connection of capacitor C4；The pin 9 of chip U2 and one end of capacitor C6
It is connected, the other end ground connection of capacitor C6；The pin 5 of chip U2 is connected with one end of resistance R12 and resistance R11, and resistance R12's is another
One end ground connection, the other end of resistance R11 are connected with one end of the output end of amplifier U4 and capacitor C8, the positive supply termination of amplifier U8
+ 5V power supply, negative power end ground connection；The other end of capacitor C8 is connected with one end of resistance R10, the other end and amplifier of resistance R10
The non-inverting input terminal of U4 is connected；The inverting input terminal of amplifier U4 is connected with the sliding end of sliding variohm W3, slide rheostat
One end of W3 is connected with+5V power supply, the other end ground connection of slide rheostat W3；One end of capacitor C7 and one end of resistance R9 and fortune
The non-inverting input terminal for putting U4 is connected, the other end ground connection of capacitor C7, the other end of resistance R9 and one end of resistance R7 and amplifier U3
Output end be connected, the other end of resistance R7 is connected with the inverting input terminal of amplifier U3；One end of resistance R8 is same with amplifier U3's
Phase input terminal is connected, other end ground connection；Positive supply termination+5V the power supply of amplifier U3, negative power end ground connection；The pin 10 of chip U2
As the output end of adaptive amplitude normalizing circuit 28, it is denoted as port ADAPT_out, an input with phase-comparison circuit 29
End is connected；The pin 10 of chip U2 is connected with the anode of diode D1, and the cathode of diode D1 is connected with one end of resistance R4, electricity
The other end of resistance R4 is connected with the inverting input terminal of one end of resistance R5 and amplifier U3, and the other end of resistance R5 is with diode D2's
Anode is connected, and the cathode of diode D2 is connected with the sliding end of slide rheostat W2；One end of slide rheostat W2 and diode
The cathode of D3 is connected and is grounded, and the other end of slide rheostat W2 is connected with the anode of one end of resistance R6 and diode D3, electricity
Hinder another termination -5V power supply of R6；The chip U2 is variable gain amplifier chip, and model is AD8367.
4 phase-comparison circuit of embodiment
As shown in figure 4, the structure for the phase-comparison circuit 29 that the present invention uses is, one end of capacitor C10 is with amplifier U5's
One end of non-inverting input terminal and resistance R13 are connected, an input terminal of the other end of capacitor C10 as phase-comparison circuit 29,
It is denoted as port PHASE_in1, is connected with the port ADAPT_out of adaptive amplitude normalizing circuit 28；Another termination of resistance R13
Ground；Positive supply termination+5V the power supply of amplifier U5, negative power end ground connection, reverse inter-input-ing ending grounding, output termination d type flip flop U6A's
The end CLK；The port D of d type flip flop U6A is grounded；The one end capacitor C11 ground connection, the end PR of another termination d type flip flop U6A；Resistance R14
The end PR of one termination d type flip flop U6A, the end Q of another termination d type flip flop U6A；CLR termination+5V the power supply of d type flip flop U6A, D touching
Send out the end PR of the Q non-terminated d type flip flop U8A of device U6A；One end of capacitor C12 and the non-inverting input terminal of amplifier U7 and resistance R15's
One end is connected, another input terminal of the other end of capacitor C12 as phase-comparison circuit 29 is denoted as port PHASE_in2, with
The port SineM_out in controllable frequency source 20 is connected；The other end of resistance R15 is grounded；Positive supply termination+5V the electricity of amplifier U7
Source, negative power end ground connection, reverse inter-input-ing ending grounding, the end CLK of output termination d type flip flop U6B；The port D of d type flip flop U6B connects
Ground；The one end capacitor C13 ground connection, the end PR of another termination d type flip flop U6B；Resistance R16 mono- terminates the end PR of d type flip flop U6B, separately
The end Q of one termination d type flip flop U6B；CLR termination+5V the power supply of d type flip flop U6B, the Q non-terminated d type flip flop of d type flip flop U6B
The end CLR of U8A；The end D and the end CLK of d type flip flop U8A is grounded, and output end of the end Q as phase-comparison circuit 29 is denoted as end
Mouth PHASE_out, is connected with the input terminal of single-chip microcontroller 18.The standard sine wave that the circuit exports controllable frequency source 20 with it is adaptive
The sine wave (environment that its phase is detected by Bragg grating group 8 is influenced) for answering amplitude normalizing circuit 28 to export carries out phase ratio
Compared with, and comparison result is sent into single-chip microcontroller 18, single-chip microcontroller 18 calculates answering at Bragg grating group 8 according to the phase differential
Power or temperature change.
5 controllable frequency source of embodiment
As shown in figure 5, the structure in controllable frequency source 20 used in the present invention is, a termination amplifier of thermistor Rt1
The inverting input terminal of U9, the output end of another termination amplifier U9；Resistance R17 mono- terminates the inverting input terminal of amplifier U9, the other end
Ground connection；The pin 2 of the homophase input termination chip U11 of amplifier U9, positive supply termination+5V power supply, negative supply termination -5V power supply,
Export the pin 2 of chip termination U10；The pin 3 of a chip termination U10 of capacitor C14, the pin 2 of another chip termination U11；
The pin 2 of a chip termination U11 of capacitor C15, other end ground connection；The pin 5 of a chip termination U10 of capacitor C16, the other end
Ground connection；The pin 5 of a chip termination U11 of capacitor C17, other end ground connection；The pin 1 and pin 10 of chip U10 connects+5V electricity
Source, pin 4 and pin 6 are grounded；One end of 9 connecting resistance R18 of pin, one end of 8 connecting resistance R19 of pin, 7 connecting resistance R20 of pin
One end；An input port of the other end of resistance R18 as controllable frequency source 20, is denoted as port SineM_in1；Resistance
Another input port of the other end of R19 as controllable frequency source 20, is denoted as port SineM_in2；Port SineM_in1 and
Port SineM_in2 is connected with the input terminal of single-chip microcontroller 18；Another termination+5V power supply of resistance R20；1 He of pin of chip U11
Pin 10 connects+5V power supply, and pin 4 and pin 6 are grounded；One end of 9 connecting resistance R21 of pin, one end of 8 connecting resistance R22 of pin, pipe
One end of 7 connecting resistance R23 of foot；Another termination port SineM_in1 of resistance R21；Another termination port SineM_ of resistance R22
in2；Another termination+5V power supply of resistance R23；Output port of the pin 2 of chip U10 as controllable frequency source 20, is denoted as
SineM_out.The adjustable standard sine wave of module output frequency provides required sinusoidal letter for demodulation part of the invention
Number.
7 the working principle of the invention of embodiment
In conjunction with the various embodiments described above and each attached drawing, illustrate the working principle of the invention.When work, by bragg grating
Group 8 is placed on each position for needing to monitor, and (bridge of such as wanting monitor stress to change or wants monitoring temperature at building load-bearing pillar
The mine etc. of variation), cloth position lattice grating group 8 is by 3 different Bradleys of (can also be set to other quantity as needed) reflectance spectrum
Lattice optical grating constitution is, it can be achieved that simultaneously remotely monitor 3 (or multiple) targets, by groups such as Er-doped fiber 3, optoisolators 4
At optical fiber laser annular chamber be bragg grating group 8 wideband light source is provided, each bragg grating has one
The peak wavelength of a specific reflectance spectrum, different gratings, reflectance spectrum is different, when some measurand changes,
The reflectance spectrum peak wavelength of bragg grating at this can occur to deviate accordingly, and reflected light enters by the second optical coupling
In the Mach Zehnder that interferometer that device 6, piezoelectric ceramics 22, third photo-coupler 23 are constituted, while controllable frequency source 20 is Mach
Damp Dare interferometer provides a control signal sin (ω t), the light which is reflected in interferometer by bragg grating
Influence, then be converted into electric signal through the first optical detector 24, the second optical detector 25, difference carried out by differential amplifier circuit 26
Amplify and sin (ω t+ Δ θ) is obtained later by the anti-cosine transform of functional transformation circuit 27, the signal is through adaptive amplitude normalizing
28 amplitude of circuit is adjusted to a suitable size, and signal and controllable frequency source 20 at this time generates sinusoidal signal sin (ω
T) it compares, phase is changed, the phase difference detection of the two is come out to by phase-comparison circuit 29 and is sent into single-chip microcontroller 18,
The phase difference real reaction variation of the sensing amount of monitoring point is finally realized and is carried out using bragg grating to target
Detection.The present invention is no during modulation and demodulation to use sawtooth wave, so as to avoid sawtooth wave failing edge bring high frequency
Dither signal avoids the amplitude-frequency to output signal also there is no need to use bandpass filter to be filtered in demodulator circuit
Characteristic and phase-frequency characteristic have an impact.The present invention is using standard sine wave signal as PZT modulated signal, to modulated signal
When being demodulated, functional transformation circuit 27 and adaptive amplitude normalizing circuit 28 are dexterously used, modulated signal is recovered
Phase is controlled by the Bragg grating group 8 and suitable sinusoidal signal of amplitude, so that carrying out phase in phase-comparison circuit 29
When comparing, the phase difference of controlled signal and original signal can be highly precisely compared, to accurately react sensing head (i.e.
Bragg grating group 8) environmental parameter that is detected.
Since optical fiber laser annular chamber (is generally sensed with bragg grating group 8 vulnerable to environment temperature at work
Pop one's head in not in same position) influence, therefore temperature compensation function has also been devised in the present invention, by constant-current source 14, thermistor 15,
Analog to digital conversion circuit 16 is constituted.Thermistor 15 is temperature sensor, its resistance value can be caused to produce when the environmental temperature is changed
Changing, since constant-current source circuit 14 provides constant current for it, the variation of 15 resistance value of thermistor can cause its both ends
The variation of generated voltage, then it is converted into digital signal input single-chip microcontroller 18 through analog to digital conversion circuit 17, it is used for compensated optical fiber
Measurement result bring error is given in the variation of environment temperature locating for laser annular chamber.
Claims (3)
1. a kind of multi-channel long optical fiber sensing system, structure have, the end the 980nm phase of pumping source (1) and light wavelength division multiplexing (2)
Even, the end 1550nm of light wavelength division multiplexing (2) is connected with the one end for being wrapped in delay line adjustable optic fibre (11), delay line tunable optical
The other end of fine (11) is connected with the input terminal of the first optoisolator (10), the control terminal and level of delay line adjustable optic fibre (11)
The output port of conversion chip (12) is connected, and the input port of electrical level transferring chip (12) is connected with single-chip microcontroller (18)；First light
The output end of isolator (10) is connected with the light input end of optical filter (9), the electric control end of optical filter (9) and single-chip microcontroller
(18) it is connected, the light output end of optical filter (9) is connected with the first port of optical circulator (7), the second end of optical circulator (7)
Mouth is connected with one end of Bragg grating group (8), the third port of optical circulator (7) and the input terminal of the first photo-coupler (5)
It is connected, 90% output end of the first photo-coupler (5) is connected with the input terminal of the second optoisolator (4), the second optoisolator (4)
Output end be connected with one end of Er-doped fiber (3), the common end phase of the other end and wavelength division multiplexer (2) of Er-doped fiber (3)
Even；The 10% output end output of first photo-coupler (5) is connected with the input terminal of the second photo-coupler (6), the second photo-coupler
(6) a output end is connected with an input terminal of third photo-coupler (23), another output of the second photo-coupler (6)
Hold and be connected with the one end for the optical fiber being wrapped on piezoelectric ceramics (22), be wrapped in the other end of the optical fiber on piezoelectric ceramics (22) with
Another input terminal of third photo-coupler (23) is connected, the output end and the first optical detector (24) of third photo-coupler (23)
Input terminal be connected, the output end of third photo-coupler (23) is also connected with the input terminal of the second optical detector (25)；
It is characterized in that, structure is in addition, the output end of the first optical detector (24) and the homophase input of differential amplifier circuit (26)
End is connected, and the output end of the second optical detector (25) is connected with the inverting input terminal of differential amplifier circuit (26), differential amplification electricity
The input terminal of the output end and function translation circuit (27) on road (26) is connected, the output end of functional transformation circuit (27) and adaptive
The input terminal of amplitude normalizing circuit (28) is connected, the output end of adaptive amplitude normalizing circuit (28) and phase-comparison circuit (29)
An input terminal be connected；The input terminal in controllable frequency source (20) is connected with single-chip microcontroller (18), output end and phase-comparison circuit
(29) another input terminal is connected, and the output end of phase-comparison circuit (29) is connected with single-chip microcontroller (18)；Controllable frequency source
(20) output end is also connected with the input terminal of PZT driving circuit (21), the output end and piezoelectric ceramics of PZT driving circuit (21)
(22) control terminal is connected；The output end of constant-current source circuit (14) is connected with thermistor (15), thermistor (15) and modulus
The input terminal of conversion circuit (16) is connected, and the output end of analog to digital conversion circuit (16) is connected with single-chip microcontroller (18)；Single-chip microcontroller (18)
Also it is connected respectively with input key (13), serial communication modular (17), display screen (19)；
The structure of the functional transformation circuit (27) is one end of capacitor C3 and the pin 12 and electricity of trigonometric function converter U1
The one end for hindering R2 is connected, and input terminal of the other end of capacitor C3 as functional transformation circuit (27) is denoted as port ACOS_in, with
The output end of differential amplifier circuit (26) is connected；The other end of resistance R2 is grounded；The pin 2 of trigonometric function converter U1,3,4,
5,8,11,13 ground connection, pin 9,10 are connected with one end of capacitor C2 and -12V power supply, the other end ground connection of capacitor C2；Triangle letter
The pin 6 of number converter U1 is connected with pin 7, and pin 16 is connected with one end of+12V power supply and capacitor C1, and capacitor C1's is another
End ground connection；The pin 1 of trigonometric function converter U1 is connected with the sliding end of slide rheostat W1, one end of slide rheostat W1 with
One end of resistance R1 is connected, and the other end of resistance R1 is connected with the pin 14 of trigonometric function converter U1, slide rheostat W1's
Output end of the sliding end as functional transformation circuit (27), is denoted as port ACOS_out, with adaptive amplitude normalizing circuit (28)
Input terminal be connected；The model AD639 of the trigonometric function converter U1；
The structure of the adaptive amplitude normalizing circuit (28) is, one end of capacitor C9 and one end of resistance R3 and chip U2's
Pin 3 is connected, the other end ground connection of resistance R3, input of the other end of capacitor C9 as adaptive amplitude normalizing circuit (28)
End, is denoted as port ADAPT_in, and the port ACOS_out of and function translation circuit (27) is connected；The pin 1 of chip U2, pin 7,
Pin 8, pin 14 are grounded, and pin 2 is connected with+5V power supply with pin 4, and pin 11 is connected with pin 12 and with capacitor C5's
One end and+5V power supply are connected, the other end ground connection of capacitor C5；The pin 13 of chip U2 is connected with one end of capacitor C4, capacitor C4
The other end ground connection；The pin 9 of chip U2 is connected with one end of capacitor C6, the other end ground connection of capacitor C6；The pin 5 of chip U2
It is connected with one end of resistance R12 and resistance R11, the other end of resistance R12 ground connection, the other end of resistance R11 is defeated with amplifier U4's
One end of outlet and capacitor C8 are connected, the positive supply termination+5V power supply of amplifier U8, negative power end ground connection；The other end of capacitor C8
It is connected with one end of resistance R10, the other end of resistance R10 is connected with the non-inverting input terminal of amplifier U4；The anti-phase input of amplifier U4
It holds and is connected with the sliding end of sliding variohm W3, one end of slide rheostat W3 is connected with+5V power supply, slide rheostat W3's
Other end ground connection；One end of capacitor C7 is connected with the non-inverting input terminal of one end of resistance R9 and amplifier U4, the other end of capacitor C7
Ground connection, the other end of resistance R9 are connected with the output end of one end of resistance R7 and amplifier U3, the other end and amplifier U3 of resistance R7
Inverting input terminal be connected；One end of resistance R8 is connected with the non-inverting input terminal of amplifier U3, other end ground connection；The positive electricity of amplifier U3
Source connects+5V power supply, negative power end ground connection；Output end of the pin 10 of chip U2 as adaptive amplitude normalizing circuit (28),
It is denoted as port ADAPT_out, is connected with an input terminal of phase-comparison circuit (29)；The pin 10 and diode D1 of chip U2
Anode be connected, the cathode of diode D1 is connected with one end of resistance R4, the other end of resistance R4 and one end of resistance R5 and fortune
The inverting input terminal for putting U3 is connected, and the other end of resistance R5 is connected with the anode of diode D2, the cathode of diode D2 and sliding
The sliding end of rheostat W2 is connected；One end of slide rheostat W2 is connected and is grounded with the cathode of diode D3, slide rheostat
The other end of W2 is connected with the anode of one end of resistance R6 and diode D3, another termination -5V power supply of resistance R6；The core
Piece U2 is variable gain amplifier chip, and model is AD8367；
The structure of the phase-comparison circuit (29) is one end of capacitor C10 and the non-inverting input terminal of amplifier U5 and resistance R13
One end be connected, an input terminal of the other end of capacitor C10 as phase-comparison circuit (29) is denoted as port PHASE_in1,
It is connected with the port ADAPT_out of adaptive amplitude normalizing circuit (28)；The other end of resistance R13 is grounded；The positive electricity of amplifier U5
Source connects+5V power supply, negative power end ground connection, reverse inter-input-ing ending grounding, the end CLK of output termination d type flip flop U6A；D type flip flop
The port D of U6A is grounded；The one end capacitor C11 ground connection, the end PR of another termination d type flip flop U6A；Resistance R14 mono- terminates d type flip flop
The end PR of U6A, the end Q of another termination d type flip flop U6A；CLR termination+5V the power supply of d type flip flop U6A, the Q of d type flip flop U6A are non-
Terminate the end PR of d type flip flop U8A；One end of capacitor C12 is connected with one end of the non-inverting input terminal of amplifier U7 and resistance R15, electricity
Hold another input terminal of the other end of C12 as phase-comparison circuit (29), port PHASE_in2 is denoted as, with controllable frequency
The port SineM_out in source (20) is connected；The other end of resistance R15 is grounded；Positive supply termination+5V the power supply of amplifier U7, negative electricity
Source ground connection, reverse inter-input-ing ending grounding, the end CLK of output termination d type flip flop U6B；The port D of d type flip flop U6B is grounded；Capacitor
The one end C13 ground connection, the end PR of another termination d type flip flop U6B；Resistance R16 mono- terminates the end PR of d type flip flop U6B, another termination D
The end Q of trigger U6B；CLR termination+5V the power supply of d type flip flop U6B, the CLR of the Q non-terminated d type flip flop U8A of d type flip flop U6B
End；The end D and the end CLK of d type flip flop U8A is grounded, and output end of the end Q as phase-comparison circuit (29) is denoted as port
PHASE_out is connected with the input terminal of single-chip microcontroller (18)；
The structure in the controllable frequency source (20) is the inverting input terminal of a termination amplifier U9 of thermistor Rt1, the other end
Connect the output end of amplifier U9；Resistance R17 mono- terminates the inverting input terminal of amplifier U9, other end ground connection；The homophase input of amplifier U9
The pin 2 of chip termination U11, positive supply termination+5V power supply, negative supply termination -5V power supply export the pin of chip termination U10
2；The pin 3 of a chip termination U10 of capacitor C14, the pin 2 of another chip termination U11；A chip termination U11 of capacitor C15
Pin 2, the other end ground connection；The pin 5 of a chip termination U10 of capacitor C16, other end ground connection；A termination core of capacitor C17
The pin 5 of piece U11, other end ground connection；The pin 1 and pin 10 of chip U10 connects+5V power supply, and pin 4 and pin 6 are grounded；Pin
One end of 9 connecting resistance R18, one end of 8 connecting resistance R19 of pin, one end of 7 connecting resistance R20 of pin；The other end of resistance R18 is made
For an input port of controllable frequency source (20), it is denoted as port SineM_in1；The other end of resistance R19 is as controllable frequency
Another input port in source (20), is denoted as port SineM_in2；Port SineM_in1 and port SineM_in2 and single-chip microcontroller
(18) input terminal is connected；Another termination+5V power supply of resistance R20；The pin 1 and pin 10 of chip U11 connects+5V power supply, pipe
Foot 4 and pin 6 are grounded；One end of 9 connecting resistance R21 of pin, one end of 8 connecting resistance R22 of pin, the one of 7 connecting resistance R23 of pin
End；Another termination port SineM_in1 of resistance R21；Another termination port SineM_in2 of resistance R22；Resistance R23's is another
One termination+5V power supply；Output port of the pin 2 of chip U10 as controllable frequency source (20), is denoted as SineM_out.
2. a kind of multi-channel long optical fiber sensing system according to claim 1, which is characterized in that the pumping source (1)
It is 980nm laser light source.
3. a kind of multi-channel long optical fiber sensing system according to claim 1 or 2, which is characterized in that described Prague
Grating group (8) is made of 3 Bragg gratings, and the reflectivity of each grating is 90%, and bandwidth is 0.6nm, central wavelength
Respectively 1550nm, 1560nm and 1630nm.
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| CN111692972A (en) * | 2020-06-16 | 2020-09-22 | 中国科学院国家授时中心 | Single-fiber unidirectional optical fiber length measuring method and system |
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