CN109506688B - Fiber Bragg grating sensor-based measurement system and method - Google Patents

Fiber Bragg grating sensor-based measurement system and method Download PDF

Info

Publication number
CN109506688B
CN109506688B CN201910008215.0A CN201910008215A CN109506688B CN 109506688 B CN109506688 B CN 109506688B CN 201910008215 A CN201910008215 A CN 201910008215A CN 109506688 B CN109506688 B CN 109506688B
Authority
CN
China
Prior art keywords
module
fpga
conversion module
bragg grating
fiber bragg
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Active
Application number
CN201910008215.0A
Other languages
Chinese (zh)
Other versions
CN109506688A (en
Inventor
莫金海
陶辉
潘海波
徐学武
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Guilin University of Electronic Technology
Original Assignee
Guilin University of Electronic Technology
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Guilin University of Electronic Technology filed Critical Guilin University of Electronic Technology
Priority to CN201910008215.0A priority Critical patent/CN109506688B/en
Publication of CN109506688A publication Critical patent/CN109506688A/en
Application granted granted Critical
Publication of CN109506688B publication Critical patent/CN109506688B/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Classifications

    • 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
    • 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
    • G01D5/3539—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 time division multiplexing

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Optical Transform (AREA)

Abstract

The invention discloses a fiber Bragg grating sensor-based measuring system and method, comprising a tunable laser source, an electro-optical modulator, a circulator, n fiber Bragg grating sensors connected in series, a photoelectric conversion module, an FPGA embedded acquisition card and an ARM main control module. The FPGA embedded acquisition card controls the OTDR acquisition unit to acquire data, the built measurement system can realize the combination of the wavelength division multiplexing technology and the time division multiplexing technology, the number of sensors carried by the system is increased, the scale of a sensor network is enlarged, and the problem of the sensor space positioning is solved; the FPGA is used as a microprocessor, the speed control of data acquisition and transmission is realized through the functions of an internal logic unit and a state machine, and the inherent parallel working mode provides the system with the capabilities of high-speed and high-precision data and parallel processing, so that the real-time performance of the system is improved.

Description

Fiber Bragg grating sensor-based measurement system and method
Technical Field
The invention relates to the technical field of optical fiber sensing measurement, in particular to a measuring system and a measuring method based on an optical fiber Bragg grating sensor.
Background
The fiber bragg grating has the characteristics of easy connection with the optical fiber, small transmission loss, good spectral characteristics, high reliability and the like. The fiber bragg grating is used as a sensing element, can realize high-capacity and distributed dynamic monitoring of physical quantity through wavelength modulation, can effectively overcome the defects of the traditional electric sensing technology and a measuring system thereof in the aspects of long-term stability, environmental adaptability, distributed sensing detection and the like, can effectively measure the physical quantity such as temperature, strain, vibration, pressure and the like, is widely applied to health monitoring in the fields of bridge tunnels, dam power stations, oilfield oil tanks, mechanical equipment and the like, and greatly meets the physical quantity measurement requirements of military and civil applications.
Along with the development of fiber bragg grating sensing technology and the demands of practical application, fiber bragg grating sensing measurement systems are developing towards high-capacity and multi-parameter measurement directions, and how to effectively collect and process a huge amount of sensing signals transmitted by optical fibers in the measurement systems becomes an important problem of the fiber bragg grating sensing measurement systems, particularly in high-precision and large-range distributed measurement, and the data collection and processing technology is a key to influence the practicability of the systems.
At present, the data acquisition of the fiber Bragg grating sensing measurement system is realized by adopting a universal data acquisition card in a hard acquisition and soft processing mode, but the acquisition mode is difficult to meet the use environment with higher requirements on the realizability of the acquisition system. Although the method of hard acquisition and hard processing is adopted, the technology such as assembly line can be applied, the processing speed of data is greatly improved, the high-speed and high-precision real-time data acquisition is easy to realize, and the method has better practicability. However, due to different data acquisition requirements, no general data acquisition card with a hardware algorithm processing function exists in the market at present.
Disclosure of Invention
The invention aims to solve the problem that the existing fiber Bragg grating sensing measurement system is not strong in real-time performance, and provides a fiber Bragg grating sensor-based measurement system and method.
In order to solve the problems, the invention is realized by the following technical scheme:
the fiber Bragg grating sensor-based measuring system comprises a tunable laser source, an electro-optic modulator, a circulator, n fiber Bragg grating sensors connected in series, a photoelectric conversion module, an FPGA embedded acquisition card and an ARM main control module; the FPGA embedded acquisition card, the electro-optical modulator, the circulator and the photoelectric conversion module form an OTDR signal acquisition unit; the output end of the tunable laser source is connected with the input end of the electro-optical modulator, and the output end of the electro-optical modulator is connected with the first light splitting port of the circulator; the second light splitting port of the circulator is connected with n fiber Bragg grating sensors which are connected in series; the optical signal output by the third light splitting port of the circulator is connected to the input end of the photoelectric conversion module; the ARM main control module is connected with the tunable laser source and the FPGA embedded acquisition card; the output end of the photoelectric conversion module is connected with the input end of the FPGA embedded acquisition card, and the output end of the FPGA embedded acquisition card is connected with the control end of the electro-optic modulator.
In the scheme, the FPGA embedded acquisition card comprises an FPGA module, an analog-to-digital conversion module, a trigger pulse module and an SDRAM; the input end of the analog-to-digital conversion module is connected with the output end of the photoelectric conversion module, and the output end of the analog-to-digital conversion module is connected with the input end of the FPGA module; the output end of the FPGA module is connected with the input end of the trigger pulse module, and the output end of the trigger pulse module is connected with the control end of the electro-optic modulator; SDRAM is connected with FPGA module; the FPGA module is connected with the ARM main control module through a parallel bus.
In the scheme, the analog-to-digital conversion module comprises an input SMA connector, a differential driver, an AD converter and a differential oscillator; the input end of the input SMA connector forms the input end of the FPGA embedded acquisition card and is connected with the photoelectric conversion module; the output end of the input SMA connector is connected with the input end of the differential driver; the output end of the differential driver is connected with the input end of the AD converter, and the output end of the AD converter is connected with the input end of the FPGA module; the differential oscillator is connected with the clock control end of the AD converter.
In the scheme, the output end of the FPGA module is connected with the input end of the single-path inverter, and the output end of the single-path inverter is connected with the input end of the output SMA connector; the output end of the output SMA connector forms the output end of the FPGA embedded acquisition card and is connected with the electro-optic modulator.
The measuring method based on the fiber Bragg grating sensor realized by the system comprises the following steps:
step 1, a tunable laser source outputs wavelength step lambda under the control of an ARM main control module step Is fed into the electro-optic modulator;
step 2, modulating the tunable wavelength into a pulse laser signal by an electro-optical modulator, and then entering a circulator, wherein the circulator sends the pulse laser signal to an optical fiber Bragg grating sensor;
step 3, the fiber Bragg grating sensor responds to the pulse laser signal, forms a reflected light signal with obvious wave crest, reflects the reflected light signal back to the circulator and sends the reflected light signal to the photoelectric conversion module;
step 4, the photoelectric conversion module converts the reflected light signals into reflected electric signals and sends the reflected electric signals to the FPGA embedded acquisition card;
step 5, the FPGA embedded acquisition card judges whether an acquisition system working signal sent by the ARM main control module is received or not;
if the working signal of the acquisition system is received, the step 6 is entered;
if the working signal of the acquisition system is not received, continuing to execute the step 5;
step 6, the FPGA embedded acquisition card judges whether the reflected electric signal sent by the photoelectric conversion module is received or not;
if the reflected electric signal is detected to be triggered, the FPGA embedded acquisition card sends the reflected photoelectric signal to the analog-to-digital conversion module for analog-to-digital conversion, the reflected photoelectric signal is written into a first-in first-out buffer of the FPGA module, and 1 is added to the data count of the analog-to-digital conversion module every time one data is written into the first-in first-out buffer of the FPGA module, and the step 7 is carried out;
if the reflected electric signal is not detected, namely the reflected electric signal is not triggered, continuing to execute the step 6;
step 7, the FPGA module judges the relation between the data count value of the analog-to-digital conversion module and the acquisition depth of a first-in first-out buffer of the FPGA module:
when the data count value of the analog-to-digital conversion module is more than or equal to the acquisition depth of a first-in first-out buffer of the FPGA module, completing sampling of the acquisition depth once, setting 0 to the data count value of the analog-to-digital conversion module by the FPGA module, and executing step 8;
when the data count value of the analog-to-digital conversion module is smaller than the acquisition depth of a first-in first-out buffer of the FPGA module, the FPGA module executes the output trigger pulse setting 0, the trigger pulse module controls the electro-optical modulator to output pulse light, at the moment, the OTDR acquisition unit starts to work, after one clock period is output, the FPGA module executes the trigger pulse setting 1, the electro-optical modulator ends to output the pulse light, and after time delay, the step 6 is executed in a return mode;
step 8, the FPGA module judges whether the sampling is the first sampling;
when the sampling is completed for the first time, the FPGA module stores the sampling result into the SDRAM through a first-in first-out buffer of the FPGA module, and the step 6 is executed in a return mode;
when the sampling is not completed for the first time, the FPGA module reads data stored in the SDRAM corresponding to the address, accumulates the acquisition result to the data stored in the corresponding address, stores the accumulation result in the SDRAM, and enters the step 9;
step 9, the FPGA module judges whether the last sampling is finished or not;
when the finished sampling is the last sampling, finishing the sampling, reading the data from the SDRAM by the FPGA module, carrying out average processing and noise suppression processing, and transmitting the data to the ARM main control module through a parallel bus;
when the completed sample is not the last sample, the process returns to step 6.
In the above step 1, the wavelength is stepped by λ step Greater than or equal to the resolution R of the tunable laser source, i.e. lambda step ≥R。
In the step 1, the tunable laser source outputs the wavelength lambda of the laser signal m Equal to the wavelength lambda of the last output laser signal m-1 Plus a wavelength sweep step lambda step I.e. lambda m ＝λ m-1 +λ step 。
Compared with the prior art, the invention has the following characteristics:
1. the FPGA embedded acquisition card controls the OTDR acquisition unit to acquire data, the built measurement system can realize the combination of the wavelength division multiplexing technology and the time division multiplexing technology, the number of sensors carried by the system is increased, the scale of a sensor network is enlarged, and the problem of the sensor space positioning is solved;
2. the system adopts an FPGA-based microprocessor, realizes the speed control of data acquisition and transmission through an internal logic unit and a state machine function, and provides the system with the capability of high-speed and high-precision data and parallel processing in an inherent parallel working mode, thereby improving the real-time performance of the system;
3. SDRAM is adopted to improve the data acquisition capacity of the system so as to meet the requirements of massive cross-clock data processing and conversion; by adopting FSMC technology, the data exchange convenience and instantaneity between ARM and FPGA are improved by sending out corresponding data/address/control signal types to match the speed of signals.
Drawings
FIG. 1 is a schematic diagram of a fiber Bragg grating sensor based measurement system; wherein the dashed lines represent optical signals and the solid lines represent electrical signals.
Fig. 2 is a schematic structural diagram of an FPGA embedded acquisition card.
Fig. 3 is a flow chart of a fiber bragg grating sensor based measurement method.
Detailed Description
The invention will be further described in detail below with reference to specific examples and with reference to the accompanying drawings, in order to make the objects, technical solutions and advantages of the invention more apparent.
Referring to fig. 1, a fiber bragg grating sensor-based measurement system comprises a tunable laser light source, an electro-optical modulator, a circulator, n fiber bragg grating sensors connected in series, a photoelectric conversion module, an FPGA embedded acquisition card and an ARM main control module; the FPGA embedded acquisition card, the electro-optical modulator, the circulator and the photoelectric conversion module form an OTDR signal acquisition unit.
On the light path, the output end of the tunable laser source is connected with the input end of the electro-optical modulator, and the output end of the electro-optical modulator is connected with the first light splitting port of the circulator; the second light splitting port of the circulator is connected with n fiber Bragg grating sensors which are connected in series; the optical signal output by the third light splitting port of the circulator is connected to the input end of the photoelectric conversion module.
On the circuit, the ARM main control module is connected with the tunable laser source and the FPGA embedded acquisition card; the output end of the photoelectric conversion module is connected with the input end of the FPGA embedded acquisition card, and the output end of the FPGA embedded acquisition card is connected with the control end of the electro-optic modulator.
The tunable laser source generates laser under the control of the ARM main control module and sends the laser to the electro-optical modulator. When the trigger signal is sent out by the FPGA embedded acquisition card, the electro-optical modulator changes the laser signal sent by the tunable laser source into pulse laser and sends the pulse laser to the circulator. The circulator sends pulse laser to n fiber Bragg grating sensors connected in series, and the n fiber Bragg grating sensors can have different working wavelength regions and are distributed at different test positions so as to realize fiber Bragg grating sensing measurement. Meanwhile, the circulator sends the response reflected light of the fiber Bragg grating sensor into the photoelectric conversion module, and the photoelectric conversion module converts weak reflected light power into an electric signal and sends the electric signal to the FPGA embedded acquisition card. And when the FPGA embedded acquisition card switches scanning wavelength at each tunable laser source, sending a synchronous trigger signal to the electro-optical modulator, starting data acquisition, preprocessing acquired data, and sending the preprocessed acquired data to the ARM main control module.
The FPGA embedded acquisition card is shown in fig. 2, and comprises an FPGA module, an analog-to-digital conversion module, a trigger pulse module and an SDRAM. The input end of the analog-to-digital conversion module is connected with the output end of the photoelectric conversion module, and the output end of the analog-to-digital conversion module is connected with the input end of the FPGA module; the output end of the FPGA module is connected with the input end of the trigger pulse module, and the output end of the trigger pulse module is connected with the control end of the electro-optic modulator; SDRAM is connected with FPGA module; the FPGA module is connected with the ARM main control module through a parallel bus.
The analog-to-digital conversion module comprises an input SMA connector, a differential driver, an AD converter and a differential oscillator. The input end of the input SMA connector forms the input end of the FPGA embedded acquisition card and is connected with the photoelectric conversion module; the output end of the input SMA connector is connected with the input end of the differential driver; the output end of the differential driver is connected with the input end of the AD converter, and the output end of the AD converter is connected with the input end of the FPGA module; the differential oscillator is connected with the clock control end of the AD converter.
The trigger pulse module comprises a single-path reverser and an output SMA connector. The output end of the FPGA module is connected with the input end of the single-path inverter, and the output end of the single-path inverter is connected with the input end of the output SMA connector; the output end of the output SMA connector forms the output end of the FPGA embedded acquisition card and is connected with the electro-optic modulator.
The measuring method based on the fiber Bragg grating sensor realized by the system is shown in fig. 3, and the specific working steps are as follows:
I. tunable laser source in scanning wavelength range lambda ALL Internal output tunable wavelength lambda m Wavelength ofStep lambda step 。
Setting lambda according to effective wavelength range of tunable laser source output ALL Value, lambda step Values, where lambda m+1 ＝λ m +λ step ，λ step The value cannot be less than the resolution R of the light source, i.e. lambda step ≥R。
The wavelength tuning range of the tunable laser source is 1527-1568 nm, the resolution is 1pm, the precision is 5pm, and the total bandwidth lambda ALL 41nm, lambda step The value was 20pm.
II. And generating OTDR data of the OTDR acquisition signal unit.
Step I output wavelength lambda m Continuous light, which is controlled by FPGA to output pulse signals to trigger the photoelectric modulator to modulate, and the output wavelength is lambda m The pulse light of the pulse light is transmitted into n optical fiber Bragg grating sensors connected in series through the circulator, and when the wavelength of the pulse light meets the response working wavelength of the optical fiber Bragg grating sensors, the pulse light is reflected back to a reflection spectrum with obvious wave peaks. The optical power value is converted into electric signals with different amplitudes.
The FPGA sends out each trigger pulse signal, a group of OTDR data can be generated, and each sampling time point corresponds to one acquired data, so that a relation table of the acquired time and the acquired data can be obtained. Because each fiber Bragg grating sensor has a respective response working wavelength, each response working wavelength can be reflected back to a spectrogram with a peak, each sampling time has a respective amplitude through the functions of the photoelectric conversion module and the digital-to-analog conversion module, and a unique time point is determined according to the corresponding highest amplitude on a time axis. From the formulaThe spatial position of the sensor, namely the position of the fiber Bragg grating sensor, can be accurately determined, wherein DeltaL is the optical path, and C is the laser in the optical fiberΔt is the pulse light propagation time, n is the refractive index of the transmission medium.
The digital-to-analog conversion module in the embodiment consists of an input SMA connector, a differential driver, an AD converter and a differential oscillator, and can realize the sampling requirement of 200 MHz. The differential driver adopts an AD8138 chip, realizes the conversion from single-ended input to differential input, improves the anti-interference and electromagnetic interference suppression capability of the sampling signal, and provides the AD converter with the best conversion performance; the AD converter selects an AD9211 chip, a 10-bit sampling analog-to-digital converter with the conversion rate up to 300MSPS, and the chip integrates input buffering, sampling holding and an on-chip reference voltage source, has the characteristics of high performance and low power consumption, and the output LVDS signal can support two-system complementary codes, offset two-system or Gray code formats and can be connected with an FPGA; the differential oscillator provides a 200MHz sampling clock and outputs in the form of LVDS signals.
And III, acquiring physical parameters of the corresponding test points of the fiber Bragg grating sensors in real time.
According to the relation table of the acquisition time and the acquisition data obtained in the step II, for each set wavelength lambda m Step lambda in wavelength over a wavelength sweep step In the increasing process, the FPGA outputs a plurality of pulse trigger signals, and performs a plurality of OTDR tests to obtain a plurality of groups of OTDR data. The SDRAM realizes the reading/writing operation of data in two clock domains through the dual-port working mode of the RAM and the FIFO buffer memory in the FPGA chip, performs data interaction, and processes OTDR data so as to meet the requirements of large-capacity cross-clock data processing and conversion. The processed data result is transmitted back to the FPGA, the FSMC bus is utilized to adjust the signal width and the time sequence, the speed of matching signals is improved, the convenience and the instantaneity of data exchange between the ARM and the FPGA are improved, and the communication between the FPGA and the ARM is completed. The method comprises the following specific steps:
i. the FPGA embedded acquisition card detects and judges whether an acquisition system working signal is received or not;
i-1, when a system acquisition working signal is received, executing the step ii;
i-2, executing the step i when the system acquisition working signal is not received;
ii. Judging whether an acquisition signal triggers or not;
ii-1, when the acquisition signal is detected to be triggered, writing AD conversion data into the FIFO, adding 1 to an AD data counter every time one data is written, and entering a step iii;
ii-2, when the acquisition signal is not triggered, returning to execute the step ii;
iii, judging whether the FIFO buffer memory is full;
iii-1, completing sampling of the acquisition depth once when the AD data counter value is more than or equal to the FIFO acquisition depth, setting the AD data counter to 0, and executing the step iv;
iii-2, when the AD data counter value is less than the FIFO acquisition depth, executing output trigger pulse setting 0, controlling the electro-optical modulator to output pulse light, starting the OTDR acquisition unit to work at the moment, after outputting one clock period, setting 1 to trigger pulse, ending the electro-optical modulator to output pulse light, and after delaying for 1ms, returning to execute step ii;
iv, judging whether the sampling is the first sampling;
iv-1, when the sampling is finished for the first time, storing the sampling result into SDRAM through a buffer dual-port RAM, and returning to execute the step ii;
iv-2, when the sampling is not completed for the first time, reading data stored in the SDRAM corresponding to the address through the dual-port RAM of the buffer, accumulating the acquisition result to the data stored in the corresponding address, storing the accumulation result in the SDRAM, and entering the step v;
v, judging whether the last sampling is finished or not;
v-1, finishing sampling when the finished sampling is the last sampling, carrying out noise suppression processing on the data after carrying out average processing, reading the result into an FPGA by an SDRAM, and transmitting the result to an ARM by the FPGA through a parallel bus;
v-2, when the completed sample is not the last sample, returning to execute step ii;
vi, continuously collecting the data of the physical quantity to be measured in real time.
In the fiber Bragg grating sensing measurement system based on the tunable laser source, the method adopts the wavelength division multiplexing and time division multiplexing method, so that the number of sensors carried by the measurement system is increased, and the problem of space positioning of the measurement system is solved; based on the FPGA embedded system, the high-speed high-precision real-time performance of data acquisition is improved. SDRAM is adopted to improve the data acquisition capacity of the system so as to meet the requirements of massive cross-clock data processing and conversion; by adopting FSMC technology, the data exchange convenience and instantaneity between ARM and FPGA are improved by sending out corresponding data/address/control signal types to match the speed of signals.
It should be noted that, although the examples described above are illustrative, this is not a limitation of the present invention, and thus the present invention is not limited to the above-described specific embodiments. Other embodiments, which are apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein, are considered to be within the scope of the invention as claimed.

Claims (5)

1. The fiber Bragg grating sensor-based measuring system for realizing the method comprises a tunable laser source, an electro-optical modulator, a circulator, n fiber Bragg grating sensors connected in series, a photoelectric conversion module, an FPGA embedded acquisition card and an ARM main control module; the FPGA embedded acquisition card further comprises an FPGA module, an analog-to-digital conversion module, a trigger pulse module and an SDRAM; the output end of the tunable laser source is connected with the input end of the electro-optical modulator, and the output end of the electro-optical modulator is connected with the first light splitting port of the circulator; the second light splitting port of the circulator is connected with n fiber Bragg grating sensors which are connected in series; the optical signal output by the third light splitting port of the circulator is connected to the input end of the photoelectric conversion module; the ARM main control module is connected with the tunable laser source; the input end of the FPGA embedded acquisition card, namely the input end of the analog-to-digital conversion module, is connected with the output end of the photoelectric conversion module, and the output end of the analog-to-digital conversion module is connected with the input end of the FPGA module; the output end of the FPGA module is connected with the input end of the trigger pulse module, and the output end of the FPGA embedded acquisition card, namely the output end of the trigger pulse module, is connected with the control end of the electro-optic modulator; SDRAM is connected with FPGA module; the FPGA module is connected with the ARM main control module through a parallel bus; the method is characterized by comprising the following steps of:
step 1, a tunable laser source outputs wavelength step lambda under the control of an ARM main control module step Is fed into the electro-optic modulator;
step 2, modulating the tunable wavelength into a pulse laser signal by an electro-optical modulator, and then entering a circulator, wherein the circulator sends the pulse laser signal to an optical fiber Bragg grating sensor;
step 3, the fiber Bragg grating sensor responds to the pulse laser signal, forms a reflected light signal with obvious wave crest, reflects the reflected light signal back to the circulator and sends the reflected light signal to the photoelectric conversion module;
step 4, the photoelectric conversion module converts the reflected light signals into reflected electric signals and sends the reflected electric signals to the FPGA embedded acquisition card;
step 5, the FPGA embedded acquisition card judges whether an acquisition system working signal sent by the ARM main control module is received or not;
if the working signal of the acquisition system is received, the step 6 is entered;
if the working signal of the acquisition system is not received, continuing to execute the step 5;
step 6, the FPGA embedded acquisition card judges whether the reflected electric signal sent by the photoelectric conversion module is received or not;
if the reflected electric signal is detected to be triggered, the FPGA embedded acquisition card sends the reflected electric signal to the analog-to-digital conversion module for analog-to-digital conversion, the reflected electric signal is written into a first-in first-out buffer of the FPGA module, and 1 is added to the data count of the analog-to-digital conversion module every time one data is written into the first-in first-out buffer of the FPGA module, and the step 7 is carried out;
if the reflected electric signal is not detected, namely the reflected electric signal is not triggered, continuing to execute the step 6;
step 7, the FPGA module judges the relation between the data count value of the analog-to-digital conversion module and the acquisition depth of a first-in first-out buffer of the FPGA module:
when the data count value of the analog-to-digital conversion module is more than or equal to the acquisition depth of a first-in first-out buffer of the FPGA module, completing sampling of the acquisition depth once, setting 0 to the data count value of the analog-to-digital conversion module by the FPGA module, and executing step 8;
when the data count value of the analog-to-digital conversion module is smaller than the acquisition depth of a first-in first-out buffer of the FPGA module, the FPGA module executes the output trigger pulse setting 0, the trigger pulse module controls the electro-optical modulator to output pulse light, at the moment, the OTDR acquisition unit starts to work, after one clock period is output, the FPGA module executes the trigger pulse setting 1, the electro-optical modulator ends to output the pulse light, and after time delay, the step 6 is executed in a return mode;
step 8, the FPGA module judges whether the sampling is the first sampling;
when the sampling is completed for the first time, the FPGA module stores the sampling result into the SDRAM through a first-in first-out buffer of the FPGA module, and the step 6 is executed in a return mode;
when the sampling is not completed for the first time, the FPGA module reads data stored in the SDRAM corresponding to the address, accumulates the acquisition result to the data stored in the corresponding address, stores the accumulation result in the SDRAM, and enters the step 9;
step 9, the FPGA module judges whether the last sampling is finished or not;
when the finished sampling is the last sampling, finishing the sampling, reading the data from the SDRAM by the FPGA module, carrying out average processing and noise suppression processing, and transmitting the data to the ARM main control module through a parallel bus;
when the completed sample is not the last sample, the process returns to step 6.
2. The method for measuring a fiber bragg grating based sensor as claimed in claim 1, wherein in step 1, the wavelength is stepped by λ step Greater than or equal to the resolution R of the tunable laser source, i.e. lambda step ≥R。
3. The method of claim 1, wherein in step 1, the tunable laser source outputs a wavelength λ of the laser signal at a current time m Equal toWavelength lambda of laser signal output last time m-1 Plus a wavelength sweep step lambda step I.e. lambda m ＝λ m-1 +λ step 。
4. The fiber bragg grating sensor-based measurement method of claim 1, wherein the analog-to-digital conversion module comprises an input SMA connector, a differential driver, an AD converter, and a differential oscillator;
the input end of the input SMA connector forms the input end of the FPGA embedded acquisition card and is connected with the photoelectric conversion module; the output end of the input SMA connector is connected with the input end of the differential driver; the output end of the differential driver is connected with the input end of the AD converter, and the output end of the AD converter is connected with the input end of the FPGA module; the differential oscillator is connected with the clock control end of the AD converter.
5. The fiber bragg grating sensor based measurement method of claim 1, wherein the trigger pulse module comprises a single-path inverter and an output SMA connector;
the output end of the FPGA module is connected with the input end of the single-path inverter, and the output end of the single-path inverter is connected with the input end of the output SMA connector; the output end of the output SMA connector forms the output end of the FPGA embedded acquisition card and is connected with the electro-optic modulator.
CN201910008215.0A 2019-01-04 2019-01-04 Fiber Bragg grating sensor-based measurement system and method Active CN109506688B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN201910008215.0A CN109506688B (en) 2019-01-04 2019-01-04 Fiber Bragg grating sensor-based measurement system and method

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN201910008215.0A CN109506688B (en) 2019-01-04 2019-01-04 Fiber Bragg grating sensor-based measurement system and method

Publications (2)

Publication Number Publication Date
CN109506688A CN109506688A (en) 2019-03-22
CN109506688B true CN109506688B (en) 2023-09-26

Family

ID=65756234

Family Applications (1)

Application Number Title Priority Date Filing Date
CN201910008215.0A Active CN109506688B (en) 2019-01-04 2019-01-04 Fiber Bragg grating sensor-based measurement system and method

Country Status (1)

Country Link
CN (1) CN109506688B (en)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113551701B (en) * 2021-06-19 2023-01-31 湖北经济学院 Bus type fiber grating demodulation system
CN114577264A (en) * 2022-03-02 2022-06-03 北京卫星环境工程研究所 Optical fiber multi-module multi-parameter ground online testing method

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN201322623Y (en) * 2008-11-21 2009-10-07 中国科学院上海光学精密机械研究所 Embedded multi-channel high-speed fiber grating sensor demodulation system
CN102102998A (en) * 2010-12-16 2011-06-22 华中科技大学 Distributed sensing system based on weak Bragg reflection structure
CN103453921A (en) * 2013-09-18 2013-12-18 电子科技大学 Brillouin distributed optical fiber sensing system
CN103837179A (en) * 2014-02-25 2014-06-04 华中科技大学 Distributed optic fiber sensor based on multi-domain mixed and multiplex mode and modulation and demodulation method thereof
CN106525091A (en) * 2016-10-25 2017-03-22 华中科技大学 Fiber grating array sensing demodulation system based on multi-wavelength pulse differential modulation
CN209117041U (en) * 2019-01-04 2019-07-16 桂林电子科技大学 Based on fiber Bragg grating sensor measuring system

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6571027B2 (en) * 1999-10-07 2003-05-27 Peter W. E. Smith Method and devices for time domain demultiplexing of serial fiber bragg grating sensor arrays

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN201322623Y (en) * 2008-11-21 2009-10-07 中国科学院上海光学精密机械研究所 Embedded multi-channel high-speed fiber grating sensor demodulation system
CN102102998A (en) * 2010-12-16 2011-06-22 华中科技大学 Distributed sensing system based on weak Bragg reflection structure
CN103453921A (en) * 2013-09-18 2013-12-18 电子科技大学 Brillouin distributed optical fiber sensing system
CN103837179A (en) * 2014-02-25 2014-06-04 华中科技大学 Distributed optic fiber sensor based on multi-domain mixed and multiplex mode and modulation and demodulation method thereof
CN106525091A (en) * 2016-10-25 2017-03-22 华中科技大学 Fiber grating array sensing demodulation system based on multi-wavelength pulse differential modulation
CN209117041U (en) * 2019-01-04 2019-07-16 桂林电子科技大学 Based on fiber Bragg grating sensor measuring system

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
光纤布拉格光栅数据采集系统研究;张志利;郭进军;;光学仪器(03);第52-57页 *

Also Published As

Publication number Publication date
CN109506688A (en) 2019-03-22

Similar Documents

Publication Publication Date Title
CN103604446B (en) A kind of demodulation method of the multi-channel fiber Bragg grating absolute wavelength demodulating system based on simple detector
CN100580383C (en) Embedded multi-channel high-speed fiber grating sensor demodulation system
CN103017804B (en) High time synchronized multi-path optical fiber grating sensing system
CN103017934B (en) Self-correction method capable of eliminating wavelength dispersion of distributed Raman temperature measurement system
CN101943615B (en) Temperature measuring method based on Raman light reflection
CN103674079B (en) Based on the method for real-time measurement of fiber Bragg grating sensor measuring system
CN103592261A (en) All-fiber temperature compensating gas sensor and compensating method thereof
CN101650509B (en) Bragg grating high-speed demodulating system based on cascade-connection long period fiber grating
CN107328429A (en) The device and method for closely sensing stability can be improved in optical frequency domain reflection technology
CN109506688B (en) Fiber Bragg grating sensor-based measurement system and method
CN110375781B (en) Adaptive data acquisition system with variable measurement range in OFDR (offset OFDR)
CN107102173B (en) Calibration device and method of chirped grating based on optical frequency domain reflection principle
CN111998884B (en) Demodulation method of wavelength self-calibration optical fiber FP sensor
CN102269573A (en) Quasi-distributed composite structure strain and temperature detection system
CN105444793A (en) Fiber Bragg raster sensing device based on high-speed pulse laser
CN100576048C (en) Optical fiber optical grating multiplexing demodulation method based on Fourier domain mode-locking laser
CN113503901A (en) Device and method for eliminating measurement signal jitter of white light interferometer
CN105241482A (en) Active fiber grating sensor wavelength demodulation system and method
CN101241029A (en) Optical fiber Bragg grating sensor demodulator
CN207147508U (en) The device for closely sensing stability can be improved in optical frequency domain reflection technology
CN110243472B (en) Self-calibration integrated high-speed real-time spectrum analyzer based on dispersion Fourier transform
CN201322623Y (en) Embedded multi-channel high-speed fiber grating sensor demodulation system
CN110118532B (en) Dual-wavelength nonlinear displacement demodulation method and system of fiber Fabry-Perot displacement sensor
CN101520509B (en) Method for comparatively measuring range of interframe of chaotic light time domain waveform
CN103823175A (en) Photoelectric detection circuit frequency response characteristic test method based on OTDR

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination
GR01 Patent grant
GR01 Patent grant