CN101034035A - Method for enhancing performance of distributed sensing system by subcarrier wave technique - Google Patents
Method for enhancing performance of distributed sensing system by subcarrier wave technique Download PDFInfo
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- CN101034035A CN101034035A CNA200710048376XA CN200710048376A CN101034035A CN 101034035 A CN101034035 A CN 101034035A CN A200710048376X A CNA200710048376X A CN A200710048376XA CN 200710048376 A CN200710048376 A CN 200710048376A CN 101034035 A CN101034035 A CN 101034035A
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Abstract
This invention relates to a method of applying subcarrier wave technology to advance distributivity sensing system's behavior. The invention modulate impulse signal to one carrier frequency, at receiving end, signal mostly lay carrier frequency band, but noise produced by not ideal extinction ratio mostly lay baseband. Then adopt bandpass filtering technology to fliter off noise; at last down converse signal to baseband for disposing.
Description
Technical field
The invention belongs to the fiber optic sensor technology field, be specifically related to a kind of method that the subcarrier technology improves performance of distributed sensing system of using, described distributed sensing system refers to the distributed sensing system based on optical time domain reflectometer, specifically is polarization state light time domain method (POTOR)/Brillouin light time domain reflectometry (BOTDR)/coherent phase optical time domain reflectometry (distributed sensing system of φ-OTDR).
Background technology
Optical time domain reflectometer (OTDR) is the main technology of present optical fiber, optical cable production and line upkeep, has the ability of remote detection and position monitor fiber transmission attenuation, junction loss, breakpoint and fracture.POTDR/BOTDR/ φ-OTDR is based on the distributed optical fiber sensing system of OTDR technology.POTDR is very responsive to the optical cable perturbation, and measuring distance can be greater than 100km, and spatial resolution is less than 100m, and this technology has been used for PMD measurement and distributed stress measurement at present; Cloth amount deep pool distributed measurement technology since have can measure temperature and strain simultaneously, can long-distance distributedly measure, spatial resolution height, strain measurement precision be considered to the most rising optical fiber distributed type sensing technology than advantages such as height, the existing at present measuring distance 100km of BOTDR, spatial resolution less than 20m, strain precision 35 μ ε, answer variable resolution 10 μ ε, repetition rate 85 μ ε, result's report; φ-OTDR the technology of report is expected to obtain the perturbation detection sensitivity higher than POTDR recently, becomes another kind of effectively distributed sensing technology.POTDR/BOTDR/ Φ-OTDR not only can the monitoring incident take place, and the accurate localizing objects of energy, and such sensor also has characteristics such as hypersensitivity, disguise.POTDR/BOTDR/ φ-OTDR system can be used for the fence protection of sensitizing ranges such as military base, international navigation mark, prison, nuclear facilities.
Yet these systems are along with the further improve to spatial resolution and measuring distance requirement, it is more and more narrow that its light impulse length will become, the dutycycle of signal is also more and more littler thereupon, thereby cause signal to noise ratio (S/N ratio) sharply to descend, that is to say in the cycle that sends a pulse, do not have the energy of gross energy relative pulse of light in the time slot of pulse own very big, its result just will have a strong impact on the signal to noise ratio (S/N ratio) of system, thereby sensing capabilities is severely limited.
Summary of the invention
The object of the present invention is to provide a kind of method that the subcarrier technology improves the POTDR/BOTDR/-OTDR performance of distributed sensing system of using, this method can be eliminated the influence of imperfect extinction ratio to system performance, improves the signal to noise ratio (S/N ratio) of system effectively.
For achieving the above object, the technical solution used in the present invention comprises the steps: that (1) is modulated to incident light pulse on the carrier frequency; (2) adopt coherent detection with Rayleigh scattering light or Brillouin scattering conversion of signals are electric signal dorsad; (3) adopt the noise that is positioned at the base band position that produces by imperfect extinction ratio in the band-pass filtering filtering above-said current signal; (4) adopt down-conversion technique that above-said current signal is converted on the base band, so that carry out subsequent treatment.
The inventive method has improved the extinction ratio and the signal to noise ratio (S/N ratio) of light pulse signal equivalently, has solved the influence of imperfect extinction ratio to system performance, has improved the sensing capabilities of system significantly, has important practical value.
Description of drawings
Fig. 1 is the structural representation of the φ-OTDR sensor-based system of use inventive method.
Fig. 2 is the experimental result of sensor-based system shown in Figure 1.
Fig. 3 is an experimental result of not using the φ-OTDR sensor-based system of the inventive method.
Among Fig. 1: 1-laser instrument 2-x: y coupling mechanism 3-electrooptic modulator 4,12-signal generating circuit 5-Erbium-Doped Fiber Amplifier (EDFA) 6-circulator 7-sensor fibre 8-p: q coupling mechanism 9-detector 10-bandpass filter 11-frequency mixer 13-low-pass filter
Specific embodiments
As shown in Figure 1, φ-OTDR sensor-based system of using the inventive method comprises that bandpass filter, frequency mixer 11 and cutoff frequency that narrow linewidth laser 1,9: 1 coupling mechanisms 2, electrooptic modulator 3, signal generating circuit 4,12, Erbium-Doped Fiber Amplifier (EDFA) 5, circulator 6, sensor fibre 7,1: 1 coupling mechanism 8, detector 9, centre frequency are 1GHZ are the low-pass filter of 50MHZ.The continuous laser that laser instrument 1 sends was through 9: 1 coupling mechanism separated into two parts, what signal generating circuit 4 produced is that carrier frequency is the light pulse of 1GHZ, 90% continuous laser is through electrooptic modulator 3 output carrier frequency light pulses, the carrier frequency light pulse power is amplified into the port one of circulator 6 through Erbium-Doped Fiber Amplifier (EDFA) 5, enters sensor fibre 7 after port 2 comes out.Rayleigh scattering light or Brillouin scattering enter the port 2 of circulator 6 dorsad, after coming out, the port 3 of circulator 6 enters 1: 1 coupling mechanism 8, the another one input end of this coupling mechanism is 10% part of the continuous laser that sends of narrow linewidth laser 1, its arrives detector 9 simultaneously with Rayleigh scattering light/Brillouin scattering dorsad and carries out coherent detection and obtain electric signal, electric signal is bandpass filter 10 filtering noises of 1GHZ through centre frequency, through frequency mixer 11 (signal generating circuit 12 produces the local oscillation signals of 1GHZ) and cutoff frequency is that the low pass filtered filter 13 of 50MHZ obtains baseband signal, carry out subsequent treatment again, the treatment step when subsequent processing steps is not used the inventive method with system is identical.
It is 10 μ s that Fig. 3 has been to use the inventive method, pulse width, and sensor fibre length is the experimental result of φ-OTDR sensor-based system of 25km, and the dynamic range of system is 19.13dB as can be seen from Figure.Fig. 4 is 10 μ s for not using the inventive method, pulse width, and sensor fibre length is the experimental result of φ-OTDR sensor-based system of 25km, and as can be seen from Figure, the dynamic range of system is 8dB.From Fig. 3, Fig. 4 more as can be known, adopt the inventive method the dynamic range of system can be improved about 11dB.
By present embodiment as can be seen, the noise that produces owing to imperfect extinction ratio is positioned on the base band, and signal is positioned on the carrier frequency, therefore can this The noise of filtering by filtering.
Claims (1)
1. use the method that the subcarrier technology improves performance of distributed sensing system for one kind, this sensor-based system is based on the distributed sensing system of optical time domain reflectometer, it is characterized in that this method comprises the steps:
(1) incident light pulse is modulated on the carrier frequency;
(2) adopt coherent detection with Rayleigh scattering light or Brillouin scattering conversion of signals are electric signal dorsad;
(3) adopt the noise that is positioned at the base band position that produces by imperfect extinction ratio in the band-pass filtering filtering above-said current signal;
(4) adopt down-conversion technique that above-said current signal is converted on the base band.
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| Application Number | Priority Date | Filing Date | Title |
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| CNB200710048376XA CN100538311C (en) | 2007-02-01 | 2007-02-01 | Use the method that the subcarrier technology improves performance of distributed sensing system |
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| CNB200710048376XA CN100538311C (en) | 2007-02-01 | 2007-02-01 | Use the method that the subcarrier technology improves performance of distributed sensing system |
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| CN101034035A true CN101034035A (en) | 2007-09-12 |
| CN100538311C CN100538311C (en) | 2009-09-09 |
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Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102136867A (en) * | 2010-12-22 | 2011-07-27 | 华为技术有限公司 | Method, device and system for detecting branch optical fiber |
| CN103528606A (en) * | 2013-09-18 | 2014-01-22 | 中国电子科技集团公司第五十研究所 | Amplitude modulating and demodulating device for phi-OTDR (Optical Time Domain Reflectometer) distributed type sensing |
| CN104283610A (en) * | 2014-09-02 | 2015-01-14 | 上海交通大学 | Multistage passive optical network fault monitoring system and implementation method thereof |
| CN104316091A (en) * | 2014-10-27 | 2015-01-28 | 国家电网公司 | Modular distributed optical fiber sensing device |
| CN107560644A (en) * | 2017-07-20 | 2018-01-09 | 全球能源互联网研究院 | A kind of distribution type optical fiber sensing equipment perceived based on signal multiplexing with demodulating |
| CN108981890A (en) * | 2018-06-06 | 2018-12-11 | 重庆大学 | Distributed vibration sensor based on multicarrier nonlinear frequency modulation |
| US11512986B2 (en) | 2020-01-24 | 2022-11-29 | Nokia Solutions And Networks Oy | Fiber phase sensing using a ladder topology |
-
2007
- 2007-02-01 CN CNB200710048376XA patent/CN100538311C/en not_active Expired - Fee Related
Cited By (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102136867A (en) * | 2010-12-22 | 2011-07-27 | 华为技术有限公司 | Method, device and system for detecting branch optical fiber |
| WO2012083782A1 (en) * | 2010-12-22 | 2012-06-28 | 华为技术有限公司 | Detection method, device and system of branch optical fiber |
| CN102136867B (en) * | 2010-12-22 | 2014-03-12 | 华为技术有限公司 | Method, device and system for detecting branch optical fiber |
| CN103528606A (en) * | 2013-09-18 | 2014-01-22 | 中国电子科技集团公司第五十研究所 | Amplitude modulating and demodulating device for phi-OTDR (Optical Time Domain Reflectometer) distributed type sensing |
| CN104283610A (en) * | 2014-09-02 | 2015-01-14 | 上海交通大学 | Multistage passive optical network fault monitoring system and implementation method thereof |
| CN104283610B (en) * | 2014-09-02 | 2017-01-11 | 上海交通大学 | Multistage passive optical network fault monitoring system and implementation method thereof |
| CN104316091A (en) * | 2014-10-27 | 2015-01-28 | 国家电网公司 | Modular distributed optical fiber sensing device |
| CN107560644A (en) * | 2017-07-20 | 2018-01-09 | 全球能源互联网研究院 | A kind of distribution type optical fiber sensing equipment perceived based on signal multiplexing with demodulating |
| CN107560644B (en) * | 2017-07-20 | 2020-01-14 | 全球能源互联网研究院 | Distributed optical fiber sensing device based on signal multiplexing perception and demodulation |
| CN108981890A (en) * | 2018-06-06 | 2018-12-11 | 重庆大学 | Distributed vibration sensor based on multicarrier nonlinear frequency modulation |
| US11512986B2 (en) | 2020-01-24 | 2022-11-29 | Nokia Solutions And Networks Oy | Fiber phase sensing using a ladder topology |
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| Publication number | Publication date |
|---|---|
| CN100538311C (en) | 2009-09-09 |
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Assignee: Jiangsu Liantong Cable Co., Ltd. Assignor: University of Electronic Science and Technology of China Contract record no.: 2011320000345 Denomination of invention: Method for enhancing performance of distributed sensing system by subcarrier wave technique Granted publication date: 20090909 License type: Exclusive License Open date: 20070912 Record date: 20110321 |
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