CN111750912B - High-spatial-resolution high-capacity grating array OTDR differential demodulation method and system - Google Patents
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Abstract
The invention provides an OTDR differential demodulation method for a high-capacity grating array with high spatial resolution, which comprises the following steps of: modulating continuous sweep frequency light emitted by a light source into pulse light, and emitting the pulse light with different pulse widths in two continuous periods, wherein the difference values of adjacent pulse widths are equal; the pulse light is reflected by the high-density fiber bragg grating array to be detected, the reflected light is converted into an electric signal, and sampling is carried out; performing differential operation on sampling data of pulse light with two adjacent periodic pulse widths every time the pulse width is stepped to obtain a reflection signal of each grating; and if the stepping value is N, obtaining N groups of reflection signals by each grating, and carrying out N-order averaging on the N groups of reflection signals to be used as the final reflection signal of each grating. The invention can improve the spatial resolution of the demodulation signal of the OTDR system under the condition of not adding any device.
Description
Technical Field
The invention relates to the field of fiber grating sensing, in particular to an OTDR differential demodulation method and system capable of providing high spatial resolution for a large-capacity grating array sensing system.
Background
The large-capacity grating array sensing system is a novel optical fiber sensing system which is rapidly developed in recent years, tens of thousands of sensing gratings can be continuously written on one optical fiber, and the minimum writing interval reaches 10 cm. However, the spatial resolution of the demodulation by the OTDR technique cannot reach the level of 10cm at present, and the spatial resolution of the OTDR demodulation system is related to two indexes: one is the pulse width of the light source, which is 2.0X 10 according to the speed of light propagation in the optical fiber8m/s, the spatial resolution reaches 10cm, and the pulse width must reach 0.1m × 2/2.0 × 108The m/s is 1ns, limited by the current hardware level, the rising edge of an optical pulse is generally about 2ns, the pulse width can only reach 5-10 ns, if the pulse width reaches 1ns, the rising edge time must be about 0.1ns, a very high hardware bandwidth and a very fast response speed are required, and thus the cost is greatly increased. Another factor influencing the spatial resolution is the sampling frequency, according to the nyquist sampling law, if a signal with a pulse width of 1ns needs to be accurately restored, the sampling frequency is at least 2 times as high, namely 2/1ns is approximately equal to 2GHz, and the current data acquisition card with the frequency of more than 2GHz is relatively common and has moderate price. Therefore, the main factor limiting the spatial resolution of the OTDR demodulation system at present is the pulse width of the light source, so that the invention of an OTDR demodulation method with low cost and high spatial resolution is urgent.
Disclosure of Invention
The invention aims to improve the spatial resolution of the fiber grating array demodulation without adding any device.
The technical scheme adopted by the invention for achieving the purpose is as follows:
a high-spatial-resolution large-capacity grating array OTDR differential demodulation method is provided, which comprises the following steps:
modulating continuous sweep frequency light emitted by a light source into pulse light, and emitting the pulse light with different pulse widths in two continuous periods, wherein the difference values of adjacent pulse widths are equal;
the pulse light is reflected by the high-density fiber bragg grating array to be detected, the reflected light is converted into an electric signal, and sampling is carried out;
performing differential operation on sampling data of pulse light with two adjacent periodic pulse widths every time the pulse width is stepped to obtain a reflection signal of each grating;
and if the stepping value is N, obtaining N groups of reflection signals by each grating, and carrying out N-order averaging on the N groups of reflection signals to be used as the final reflection signal of each grating.
In connection with the above technical solution, the high-density fiber grating to be measured includes a grating to be measured and a light channel to be measured, where the grating to be measured is a semi-transparent and semi-reflective optical sensor, light of a wide spectrum coincident with the wavelength of the grating is reflected after entering, and light of other wavelengths is transmitted.
According to the technical scheme, if one pulse width of adjacent periods is i, the other pulse width is j, and the pulse width difference is 1ns of optical path, the data collected by the pulse with the pulse width i are as follows:
the first sample data is marked as D1,iThe information carried by it is a raster G1～G10The sum of the reflected light intensities;
the second sample data is denoted as D2,iAnd the first data D1,iAt intervals of 0.5ns, the information carried by the grating is grating G1～G10+0.05m；
By D1,i、D2,iTwo sampling points restore G1～G10The reflection spectrum of each grating;
the third sample data is marked as D3,iAnd the first data D1,iAt intervals of 1ns, the information carried by the grating G is grating G2～G11Sum of reflected light intensity, which is equal to D4,iReduction to yield G2～G11The reflection spectrum of each grating;
……
in the data collected by the pulse with the pulse width j:
the first sample data is denoted as D1,jThe information carried by it being a raster G1～G11Sum of the reflected light intensity, which is equal to D2,jReduction to yield G1～G11The reflection spectrum of each grating;
the third sample data is denoted as D3,jThe information carried by it is a raster G2～G12Sum of reflected light intensity, which is equal to D4,jReduction to G2～G12The reflection spectrum of each grating;
……
reflection signal G of nth gratingnFrom D2n-1,j-D2n,i，D2n,j-D2n+1,iBoth data are restored.
In connection with the above technical solution, when the step value is N, N sets of differential arrays (D) can be obtained2n-1,j-D2n,i，D2n,j-D2n+1,i) Obtaining N groups of G according to the m groups of difference arraysnTo G, tonAn N-th order averaging is performed.
The invention also provides a system of the OTDR differential demodulation method of the large-capacity grating array with spatial resolution, which comprises the following steps:
a light source emitting continuous sweep light;
the pulse modulation unit modulates the continuous sweep frequency light into pulse light which emits different pulse widths in two continuous periods, and the difference values of the adjacent pulse widths are the same;
the high-density fiber grating array to be detected comprises a grating to be detected and a light channel to be detected, wherein the interval between the grating to be detected and the light channel to be detected is 0.1m, the grating to be detected is a semi-transparent and semi-reflective optical sensor, light with the wavelength coincident with that of the grating is reflected after wide-spectrum light enters, light with other wavelengths can penetrate through the grating, and the light channel to be detected is connected with the grating to be detected;
the photoelectric conversion module is used for converting an optical signal returned by the optical channel to be detected into an electric signal for the data acquisition module to acquire;
the data acquisition module comprises an A/D sampling chip and an FPGA control chip, the A/D sampling chip performs A/D conversion on the analog signal output by the photoelectric conversion module and then is acquired by the FPGA control chip, and the FPGA control chip performs difference on the data acquired under different pulse widths and uploads the data to the data processing module;
and the data processing module is used for carrying out difference on the data acquired under different pulse widths to obtain a high spatial resolution signal, and carrying out filtering demodulation on the signal to obtain the final grating wavelength.
According to the technical scheme, the wavelength of the grating to be measured does not exceed the spectral coverage range of the light source.
In connection with the above technical solution, the photoelectric conversion module includes a photoelectric conversion probe and an operational amplifier.
According to the technical scheme, the data acquisition module and the data processing module transmit data through the USB3.0 high-speed interface.
According to the technical scheme, the difference value of the lengths of the adjacent pulse widths is 1ns of optical path, and the sampling frequency is not lower than 2 GHz.
The invention has the following beneficial effects: the invention can obtain the demodulation signal with ultrahigh resolution of the OTDR system under the condition of lower hardware cost without adding any device, and can obtain the demodulation signal with any spatial resolution of the OTDR system through different pulse width combinations, thereby providing possibility for a low-cost scheme of detecting with ultrahigh spatial resolution, such as temperature monitoring of a storage battery electrode.
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The invention will be further described with reference to the accompanying drawings and examples, in which:
fig. 1 is a system block diagram of a large-capacity grating array OTDR differential demodulation system with spatial resolution according to an embodiment of the present invention.
Fig. 2 is a flowchart of a large-capacity grating array OTDR differential demodulation method with spatial resolution according to an embodiment of the present invention.
Fig. 3 is a schematic diagram of sampling at two different pulse widths according to the present invention.
In fig. 1, a light source 1, a pulse modulation unit 2, a high-density grating 3 to be detected, a photoelectric conversion module 4, a data acquisition module 5, and a data processing module 6.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and do not limit the invention.
Fig. 1 shows a block diagram of an OTDR differential demodulation system of a large-capacity grating array with spatial resolution according to an embodiment of the present invention. The system comprises a light source 1, a pulse modulation unit 2, a high-density grating 3 to be detected, a photoelectric conversion module 4, a data acquisition module 5 and a data processing module 6.
The light source 1 modulates continuous light into pulsed light by the pulse modulation unit 2 by emitting continuous frequency-sweeping light, wherein the width of the pulsed light is controlled by the unit, and two continuous periods emit pulsed light with different pulse widths, for example, one period of the pulsed light is 10ns, and the other period of the pulsed light is 11 ns. The pulse light passes through the high-density grating 3 to be detected, the grating interval of the high-density grating 3 to be detected is 0.1m, the pulse light is reflected by the grating and enters the photoelectric conversion module 4, the module converts a returned optical signal into an electric signal and is acquired by the data acquisition module 5, the acquired data is transmitted to the data processing module 6 through the USB3.0 high-speed interface, and the data acquired in two periods are differentially demodulated by the module to obtain final data.
The light source 1 provides an original continuous frequency-sweeping light signal for the system, and the spectral bandwidth of the light source is 8nm, and the output spectral range of the light source should not exceed the modulation range of the pulse modulation unit 2 in the embodiment of the present invention.
The pulse modulation unit 2 provides a pulse light signal for the system, modulates continuous light into pulse light with the width of several ns, and changes the pulse widths of two continuous demodulation periods through program control, and the difference value of the two pulse widths determines the spatial resolution of the system.
The high-density grating 3 to be measured is composed of a grating to be measured with a spacing of 0.1m and a light channel to be measured, wherein the grating to be measured is a semi-transparent semi-reflective optical sensor, light with the wavelength coincident with that of the grating is reflected after the wide-spectrum light enters, and light with other wavelengths can penetrate through the grating. The light channel to be measured can be connected with the grating to be measured, and the wavelength of the grating to be measured cannot exceed the spectral coverage of the light source 1.
The photoelectric conversion module 4 converts the optical signal returned by the channel to be detected into an electric signal for the data acquisition module 5 to acquire. The photoelectric conversion module 4 includes a photoelectric conversion probe, an operational amplifier, and the like.
The data acquisition module 5 comprises an A/D sampling chip and an FPGA control chip, the A/D chip performs A/D conversion on the analog signals output by the photoelectric conversion module 4 and then the analog signals are acquired by the FPGA chip, the FPGA performs difference on the data acquired under different pulse widths, the acquisition frequency is not lower than 2GHz, and the data are uploaded to the data processing module 6.
The data processing module 6 performs difference on the data acquired under different pulse widths to obtain a signal with high spatial resolution, and performs filtering demodulation on the signal to obtain the final wavelength.
The method for realizing the high-spatial-resolution large-capacity grating array OTDR differential demodulation by using the system comprises the following steps as shown in FIG. 2:
s1, modulating the continuous sweep frequency light emitted by the light source into pulse light, emitting the pulse light with different pulse widths in two continuous periods, wherein the difference of the adjacent pulse width lengths is 1 ns;
s2, reflecting the pulse light by the high-density fiber grating array to be detected, converting the reflected light into an electric signal, and sampling, wherein the sampling frequency is not lower than 2 GHz;
s3, carrying out differential operation on the sampling data of the pulse light with the pulse width of two adjacent periods every time the pulse width is stepped, and respectively obtaining the reflection signal of each grating;
and S4, if the stepping value is N, obtaining N groups of reflection signals by each grating, and carrying out N-order averaging on the N groups of reflection signals to obtain the final reflection signal of each grating.
Determining N +1 pulse width values T according to the step value N1～Tn+1The difference between the pulse widths is equal to Deltat if T1Is 10ns, then T2Is 10ns +. DELTA.t, … … Tn+110ns + N Δ t. Target spatial resolution x ═ Δ t × 108m (the speed of propagation of the illumination light in the optical fiber is 2.0X 10)8m/s). When Δ T is 1ns, T1Is 10ns, then T2Is 11ns, … … Tn+1Is (10+ N) ns, the target spatial resolution x is 0.1 m.
In one embodiment of the invention, the pulse width of the pulse light is controlled by a frequency synthesis clock generation chip AD9833BRMZ, and the chip can obtain ns-level pulse by the difference of high-frequency clock signalsThe impulse signal, two periods of the system respectively send out light pulse with different pulse width, such as 11ns and 10 ns. The modulated pulse signal enters the high-density grating 3 to be measured, and the high-density grating 3 to be measured reflects the optical signal. As shown in fig. 3, when light with a pulse width of 11ns is reflected back to the photoelectric probe by the grating, the range of the carried grating signal is: 11X 10-9s×2×108The range of 1.1m, 1m for m/s × 0.5, and 10ns for a pulse width is 1m, i.e., 10 gratings. The reflected signal enters the photoelectric module 4 to convert the optical signal into an electric signal and is subjected to A/D acquisition by the acquisition module 5, the acquired data is stored in an FPGA chip, the data is uploaded to the data processing module 6, the two groups of signals are subtracted by the module, namely, the signals covering 10 gratings are subtracted from the signals covering 11 gratings, and then the signals of 1 grating can be obtained, the spatial resolution reaches 0.1m, and finally, the signals are filtered and demodulated to obtain the final wavelength.
In this embodiment, a tunable narrow-band laser is used as the light source. A switch type semiconductor SOA ring laser is selected as a pulse modulator, and a frequency synthesis clock generation chip AD9833BRMZ is selected as a driving chip. The high-density grating to be detected is a self-made grating array, an intensive grating array sensing optical cable is manufactured by adopting a unique and internationally advanced on-line fiber grating inscription technology of a drawing tower in China, a single sensing optical cable can be used for continuously inscribing tens of thousands of grating measuring points in an industrial automatic manner, the consistency is good, and the mechanical strength is high; the photoelectric conversion module adopts a self-developed high-bandwidth photoelectric conversion circuit.
The system work flow is as follows: the tunable narrow-band laser 1 emits continuous light of varying wavelength. The method comprises the steps of entering a pulse width modulation system 2 consisting of a switch type semiconductor SOA annular laser and a frequency synthesis clock generation chip, automatically generating pulse sequences with different pulse widths by the frequency synthesis clock generation chip according to expected spatial resolution and stepping values set by a user, and selecting a narrow pulse width sequence as much as possible as the pulse width is wider and the rising edge time is longer. For example, a signal with a spatial resolution of 0.1m is expected to be obtained, if the step value is 5 times, the frequency synthesis clock generation chip will generate a pulse sequence of 10ns to 15ns, the sampling frequency is 2GHz, that is, 0.5ns, and one data is acquired, and in the data acquired by the 10ns pulse:
the first sample data is marked as D1,10The information carried by the grating is 1-10 (G)1～G10) The sum of the reflected light intensities.
The second sample data is marked as D2,10With the first data D1,10At an interval of 0.5ns, the information carried by the grating is 1-10 (G)1～G10)+0.5×10-9s×2×1081-10 (G) of m/sx 0.5 ═ grating1～G10) +0.05m of information carried;
by D1,10、D2,10G can be recovered by two sampling points1～G10The reflection spectrum of each grating, e.g. by averaging the first sampled data and the second sampled data, is taken as G1～G10The reflection spectrum of each grating.
By analogy with the above
The third sample data is marked as D3,10And the first data D1,10At intervals of 1ns, the information carried by the grating is 1-10 (G)1～G10)+1×10-9s×2×1081-10 gratings (G) m/s 0.51～G10) (G +0.1 m) of gratings 2 to 112～G11) Sum of the reflected light intensity, which is equal to D4,10Can be reduced to G2～G11The reflection spectrum of each grating.
In data collected by 11ns pulses:
the first sample data is marked as D1,11The information carried by the grating is 1-11 (G)1～G11) Sum of reflected light intensity, which is equal to D2,11Can be reduced to G1～G11The reflection spectrum of each grating.
The third sample data is denoted as D3,11The information carried by the grating is 2-12 (G)2～G12) Sum of the reflected light intensity, which is equal to D4,11Can be reduced to G2～G12The reflection spectrum of each grating.
……
To sum up, the reflection signal G of the nth gratingnCan be composed of D2n-1,11-D2n,10，D2n,11-D2n+1,10The two data are restored … …, and if the step value is 5, 5 sets of difference arrays (D) can be obtained2n-1,11-D2n,10，D2n,11-D2n+1,10) When n is 1,2,3,4,5 groups G can be obtained from 5 groups of difference arraysnTo Gn5-order averaging can improve the signal-to-noise ratio of the final result
And (4) multiplying.
In addition, it is also possible to obtain demodulated signals of any spatial resolution of the OTDR system by different pulse width combinations, such as pulse width combinations spaced 2ns apart, but with a reduced spatial resolution compared to pulse width combinations spaced 1ns apart.
The invention can obtain the demodulation signal with ultrahigh resolution of the OTDR system under the condition of lower hardware cost without adding any device. The invention can obtain the demodulation signal with any space resolution of the OTDR system through different pulse width combinations. The invention provides the possibility of a low-cost solution for ultra-high spatial resolution detection, such as temperature monitoring of battery electrodes.
It will be appreciated that modifications and variations are possible to those skilled in the art in light of the above teachings, and it is intended to cover all such modifications and variations as fall within the scope of the appended claims.
Claims (8)
1. A high-spatial-resolution large-capacity grating array OTDR differential demodulation method is characterized by comprising the following steps:
modulating continuous sweep frequency light emitted by a light source into pulse light, and emitting the pulse light with different pulse widths in two continuous periods, wherein the difference values of adjacent pulse widths are equal;
the pulse light is reflected by a high-density fiber bragg grating array to be detected, reflected light is converted into an electric signal, and sampling is carried out, wherein the high-density fiber bragg grating to be detected comprises a grating to be detected and a light channel to be detected, and the distance between the grating to be detected and the light channel to be detected is 0.1 m;
carrying out differential operation on sampling data of pulse light with pulse widths of two adjacent periods every time the pulse width is stepped, and respectively obtaining a reflection signal of each grating; if one pulse width of the adjacent period is i, the other pulse width is j, and the pulse width difference is 1ns, the data acquired by the pulse with the pulse width i is as follows:
the first sample data is denoted as D1,iThe information carried by it being a raster G1～G10The sum of the reflected light intensities;
the second sample data is denoted as D2,iWith the first data D1,iAt intervals of 0.5ns, the information carried by the grating is grating G1～G10+0.05m；
By D1,i、D2,iTwo sampling points restore G1～G10The reflection spectrum of each grating;
the third sample data is marked as D3,iWith the first data D1,iAt intervals of 1ns, the information carried by the grating is grating G2～G11Sum of reflected light intensity, which is equal to D4,iReduction to yield G2～G11The reflection spectrum of each grating;
……
in the data collected by the pulse with the pulse width j:
the first sample data is denoted as D1,jThe information carried by it is a raster G1～G11Sum of the reflected light intensity, which is equal to D2,jReduction to G1～G11The reflection spectrum of each grating;
the third sample data is denoted as D3,j，The information it carries is a grating G2～G12Sum of reflected light intensity, which is equal to D4,jReduction to yield G2～G12The reflection spectrum of each grating;
……
reflected signal G of the nth gratingnFrom D2n-1,j- D2n,i， D2n,j- D2n+1,iRestoring the two data;
and if the stepping value is N, obtaining N groups of reflection signals by each grating, and carrying out N-order averaging on the N groups of reflection signals to be used as the final reflection signal of each grating.
2. The high-spatial-resolution high-capacity grating array OTDR differential demodulation method of claim 1, wherein the grating to be measured is a transflective optical sensor, light of a wide spectrum that coincides with the grating wavelength is reflected after entering, and light of other wavelengths is transmitted.
3. The OTDR differential demodulation method of spatial resolution large capacity grating array of claim 2, wherein N sets of differential arrays (D) are obtained when the step value is N2n-1,j- D2n,i， D2n,j- D2n+1,i) Obtaining N groups of G according to the N groups of difference arraysnTo GnAn N-th order averaging is performed.
4. A system of large capacity grating array OTDR differential demodulation method based on spatial resolution of claim 1, characterized by comprising:
a light source emitting continuous sweep light;
the pulse modulation unit modulates the continuous sweep frequency light into pulse light which emits different pulse widths in two continuous periods, and the difference values of the adjacent pulse widths are the same;
the high-density fiber grating array to be detected comprises a grating to be detected and an optical channel to be detected, wherein the grating to be detected is a semi-transparent and semi-reflective optical sensor, wide-spectrum light is reflected after entering the optical sensor, light with the wavelength coincident with that of the grating is reflected, light with other wavelengths is transmitted, and the optical channel to be detected is connected with the grating to be detected;
the photoelectric conversion module is used for converting an optical signal returned by the optical channel to be detected into an electric signal for the data acquisition module to acquire;
the data acquisition module comprises an A/D sampling chip and an FPGA control chip, the A/D sampling chip performs A/D conversion on the analog signal output by the photoelectric conversion module and then is acquired by the FPGA control chip, and the FPGA control chip performs difference on the data acquired under different pulse widths and uploads the data to the data processing module;
and the data processing module is used for carrying out difference on the data acquired under different pulse widths to obtain a high-spatial resolution signal, and carrying out filtering demodulation on the signal to obtain the final grating wavelength.
5. The system of claim 4, wherein the wavelength of the grating under test does not exceed the spectral coverage of the light source.
6. The system of claim 4, wherein the photoelectric conversion module comprises a photoelectric conversion probe and an operational amplifier.
7. The system of claim 4, wherein the data acquisition module and the data processing module transmit data via a USB3.0 high-speed interface.
8. A system according to any of claims 4-7, characterized in that the difference between adjacent pulse widths is 1ns and the sampling frequency is not lower than 2 GHz.
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Citations (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2001041849A (en) * | 1999-08-02 | 2001-02-16 | Advantest Corp | Otdr measuring instrument |
| CN1661333A (en) * | 2004-02-25 | 2005-08-31 | 韩国科学技术院 | Physical quantity measuring method using brillouin optical fiber sensor |
| JP2007033183A (en) * | 2005-07-26 | 2007-02-08 | Shibaura Institute Of Technology | Method for measuring brillouin spectrum of optical fiber and apparatus using this method |
| EP1912049A1 (en) * | 2006-10-13 | 2008-04-16 | AT&T Corp. | Method and apparatus for acoustic sensing using multiple optical pulses |
| CN103808342A (en) * | 2014-03-05 | 2014-05-21 | 武汉理工大学 | High-speed demodulation method and device for high-capacity weak grating sensing network |
| CN106066203A (en) * | 2016-05-25 | 2016-11-02 | 武汉理工大学 | Distributed highly sensitive vibration-detection system based on ultrashort optical fiber optical grating array and method |
| CN106525092A (en) * | 2016-11-03 | 2017-03-22 | 华南理工大学 | High-spatial resolution long-distance distributed optical fiber temperature strain sensing system |
| 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 |
| CN108180930A (en) * | 2017-12-29 | 2018-06-19 | 武汉理工光科股份有限公司 | Long range arrayed optical fiber grating sensing demodulation method and device |
| CN109506686A (en) * | 2018-12-19 | 2019-03-22 | 武汉理工光科股份有限公司 | A method of it improves entirely with optical fiber Grating examinations performance |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP4421229B2 (en) * | 2003-07-11 | 2010-02-24 | 株式会社東芝 | Fiber Bragg Grating Physical Quantity Measuring Method and Apparatus |
| CN107835001A (en) * | 2017-10-27 | 2018-03-23 | 上海辰竹仪表有限公司 | Processing method, system, signal processing apparatus and the medium of pulse width modulation wave |
| CN109000694B (en) * | 2018-10-19 | 2020-11-10 | 武汉烽理光电技术有限公司 | Grating preparation on-line monitoring method and system |
| CN110855371B (en) * | 2019-11-08 | 2022-10-04 | 武汉理工光科股份有限公司 | Method and system for improving optical fiber sensing detection spatial resolution |
-
2020
- 2020-06-23 CN CN202010582634.8A patent/CN111750912B/en active Active
Patent Citations (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2001041849A (en) * | 1999-08-02 | 2001-02-16 | Advantest Corp | Otdr measuring instrument |
| CN1661333A (en) * | 2004-02-25 | 2005-08-31 | 韩国科学技术院 | Physical quantity measuring method using brillouin optical fiber sensor |
| JP2007033183A (en) * | 2005-07-26 | 2007-02-08 | Shibaura Institute Of Technology | Method for measuring brillouin spectrum of optical fiber and apparatus using this method |
| EP1912049A1 (en) * | 2006-10-13 | 2008-04-16 | AT&T Corp. | Method and apparatus for acoustic sensing using multiple optical pulses |
| CN103808342A (en) * | 2014-03-05 | 2014-05-21 | 武汉理工大学 | High-speed demodulation method and device for high-capacity weak grating sensing network |
| CN106066203A (en) * | 2016-05-25 | 2016-11-02 | 武汉理工大学 | Distributed highly sensitive vibration-detection system based on ultrashort optical fiber optical grating array and method |
| 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 |
| CN106525092A (en) * | 2016-11-03 | 2017-03-22 | 华南理工大学 | High-spatial resolution long-distance distributed optical fiber temperature strain sensing system |
| CN108180930A (en) * | 2017-12-29 | 2018-06-19 | 武汉理工光科股份有限公司 | Long range arrayed optical fiber grating sensing demodulation method and device |
| CN109506686A (en) * | 2018-12-19 | 2019-03-22 | 武汉理工光科股份有限公司 | A method of it improves entirely with optical fiber Grating examinations performance |
Non-Patent Citations (3)
| Title |
|---|
| Coherent Φ-OTDR based on polarization-diversity integrated coherent receiver and heterodyne detection;Qizhong Yan et.al;《2017 25th Optical Fiber Sensors Conference》;20171231;第1-4页 * |
| Simulation of the performance of phase-sensitive OTDR based on Ultra-weak FBG array using double pulses;Tao Liu et.al;《2017 16th International Conference on Optical Communications and Networks》;20171231;第1-3页 * |
| 基于弱光栅阵列低成本大长周界系统及其报警机制;陶鑫等;《中国激光》;20200430;第47卷(第4期);第1-9页 * |
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