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Добірка наукової літератури з теми "OTDR"

Автор: Grafiati

Опубліковано: 4 червня 2021

Оновлено: 12 червня 2025

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Статті в журналах з теми "OTDR"

Xu, Shaohua, Zujun Qin, Wentao Zhang та Xianming Xiong. "Monitoring Vehicles on Highway by Dual-Channel φ-OTDR". Applied Sciences 10, № 5 (2020): 1839. http://dx.doi.org/10.3390/app10051839.

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Анотація:

As a fully distributed sensor, the phase-sensitive optical time domain reflectometer (φ-OTDR) has attracted remarkable attention in real-time vibration detection. We present a dual-channel φ-OTDR (DC-φ-OTDR), formed by two single-channel φ-OTDRs (SC-φ-OTDR), to monitor running vehicles on a highway. In the double-channel system, an improved algorithm (will be referred to as the CDM&V) is proposed to alleviate the strong dependence of vibration detection on the differential step as in the widely used conventional differential method (CDM). The DC-φ-OTDR is first tested over campus road before applying it to locate moving vehicles on the highway. For comparison purposes, both the DC-φ-OTDR and SC-φ-OTDR are used to monitor the vehicles with respective signal processing methods of the CDM and CDM&V. The experimental results at campus show that the dual-path scheme can undoubtedly reduce vibration misjudgment relative to the single one due to the very small possibility of false measurements occurred simultaneously at the same location in both channels. In signal demodulation, the CDM&V greatly relaxes the constraints on the differencing interval for identifying the vehicle-caused vibration. With a step size of 5 or lower, the CDM fails to locate the running vehicle at z=~8.5 km, but the CDM&V successfully demonstrates the feasible capability of locating the vibration. With an increase in the differential interval, both the CDM and CDM&V are able to detect the vibration signal, but with the latter showing a much better noise suppression performance and hence a larger SNR. Importantly, in comparison with the SC-φ-OTDR system, the DC-φ-OTDR exhibits a considerable enhanced SNR for the detection signal regardless of which processing algorithm (i.e., CDM, CDM&V) is used. The vehicle locations positioned by the DC-φ-OTDR are confirmed by the monitoring cameras.

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Wang, Ji Qiang, Yuan Liu, Mo Yu Hou, Lin Zhao та Tong Yu Liu. "The Performance Analysis of Fiber Distributed Vibration Monitoring Technology Based on φ-OTDR". Applied Mechanics and Materials 336-338 (липень 2013): 192–95. http://dx.doi.org/10.4028/www.scientific.net/amm.336-338.192.

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Анотація:

The performance of the fiber distributed vibration monitoring technology based on the phase sensitive optical time domain reflectometer (φ-OTDR) is reseached. the principle of fiber distributed vibration monitoring of the φ-OTDR and multi-point positioning are illustrated. And this paper indicates the feasibility of realizing multi-point positioning by the φ-OTDR system, and carry on a further research on the φ-OTDR system ́s frequency response range, measuring distance, spatial resolution and other aspects. The inverse proportion relations between the frequency range and distance of the φ-OTDR system, and the relations among spatial resolution, laser pulse width, refractive index and sampling rate are illustrated.

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Jin, Xiu Mei, Yu Mei Lv, and Li Feng Du. "Research on a New Detection Technique of FBG Using OTDR." Advanced Materials Research 317-319 (August 2011): 2346–50. http://dx.doi.org/10.4028/www.scientific.net/amr.317-319.2346.

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Анотація:

A new technique of using Optical Time Domain Reflectometry (OTDR) to detect the reflected power of FBG sensing array was researched systematically. The theoretical model between the reflected power detected by OTDR and the reflected wavelength of FBG was established by analyzing, and consequently the selection rule of FBG wavelength in OTDR detection system was proposed. Moreover, experiments about multi-combination of FBGs with high reflectivity were carried out. The cause of dummy peak and resonance peak in OTDR test curves were analyzed, and meanwhile the selection basis of FBG reflectivity was also given. Based on time division multiplexing theory, detecting low-reflectivity FBG by OTDR can increase the FBG multiplexing number greatly, which has wide prospect to be applied in FBG array detection.

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Rao, Yunjiang, Zinan Wang, Huijuan Wu, Zengling Ran та Bing Han. "Recent Advances in Phase-Sensitive Optical Time Domain Reflectometry (Ф-OTDR)". Photonic Sensors 11, № 1 (2021): 1–30. http://dx.doi.org/10.1007/s13320-021-0619-4.

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Анотація:

AbstractPhase-sensitive optical time domain reflectometry (Ф-OTDR) is an effective way to detect vibrations and acoustic waves with high sensitivity, by interrogating coherent Rayleigh backscattering light in sensing fiber. In particular, fiber-optic distributed acoustic sensing (DAS) based on the Ф-OTDR with phase demodulation has been extensively studied and widely used in intrusion detection, borehole seismic acquisition, structure health monitoring, etc., in recent years, with superior advantages such as long sensing range, fast response speed, wide sensing bandwidth, low operation cost and long service lifetime. Significant advances in research and development (R&D) of Ф-OTDR have been made since 2014. In this review, we present a historical review of Ф-OTDR and then summarize the recent progress of Ф-OTDR in the Fiber Optics Research Center (FORC) at University of Electronic Science and Technology of China (UESTC), which is the first group to carry out R&D of Ф-OTDR and invent ultra-sensitive DAS (uDAS) seismometer in China which is elected as one of the ten most significant technology advances of PetroChina in 2019. It can be seen that the Ф-OTDR/DAS technology is currently under its rapid development stage and would reach its climax in the next 5 years.

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Guo, Lin, Pei Zhang, and Yan Shao. "Use Case and Functional Requirements of Optical Time Domain Reflectometer." Applied Mechanics and Materials 543-547 (March 2014): 3696–99. http://dx.doi.org/10.4028/www.scientific.net/amm.543-547.3696.

Повний текст джерела

Анотація:

As the scalable deployment of PON network and the maturity of next generation PON technologies, optical link fault management should be well considered. OTDR is now under study in the industry. Based on our study and real network operation experience, we give an analysis on use case and functional requirements of OTDR, which could be used as a guide in OTDR development and implementation.

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Lipovac, Adriana, Vlatko Lipovac, Mirza Hamza, and Vedran Batoš. "Extending OTDR Distance Span by External Front-End Optical Preamplifier." Electronics 10, no. 18 (2021): 2275. http://dx.doi.org/10.3390/electronics10182275.

Повний текст джерела

Анотація:

Optical time-domain reflectometer (OTDR) is used to characterize fiber optic links by identifying and localizing various refractive and reflective events such as breaks, splices, and connectors, and measuring insertion/return loss and fiber length. Essentially, OTDR inserts a pulsed signal into the fiber, from which a small portion that is commonly referred to as Rayleigh backscatter, is continuously reflected back with appropriate delays of the reflections expressed as the power loss versus distance, by conveniently scaling the time axis. Specifically, for long-distance events visibility and measurement accuracy, the crucial OTDR attribute is dynamic range, which determines how far downstream the fiber can the strongest transmitted optical pulse reach. As many older-generation but still operable OTDR units have insufficient dynamic range to test the far-end of longer fibers, we propose a simple and cost-effective solution to reactivate such an OTDR by inserting a low-noise high-gain optical preamplifier in front of it to lower the noise figure and thereby the noise floor. Accordingly, we developed an appropriate dynamic range and distance span extension model which provided the exemplar prediction values of 30 dB and 75 km, respectively, for the fiber under test at 1550 nm. These values were found to closely match the dynamic range and distance span extensions obtained for the same values of the relevant parameters of interest by the preliminary practical OTDR measurements conducted with the front-end EDFA optical amplifier, relative to the measurements with the OTDR alone. This preliminary verifies that the proposed concept enables a significantly longer distance span than the OTDR alone. We believe that the preliminary results reported here could serve as a hint and a framework for a more comprehensive test strategy in terms of both test diversification and repeating rate, which can be implemented in a network operator environment or professional lab.

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Zinsou, Romain, Xin Liu, Yu Wang, Jianguo Zhang, Yuncai Wang, and Baoquan Jin. "Recent Progress in the Performance Enhancement of Phase-Sensitive OTDR Vibration Sensing Systems." Sensors 19, no. 7 (2019): 1709. http://dx.doi.org/10.3390/s19071709.

Повний текст джерела

Анотація:

Recently, phase-sensitive Optical Time-Domain Reflectometry (Φ-OTDR)-based vibration sensor systems have gained the interest of many researchers and some efforts have been undertaken to push the performance limitations of Φ-OTDR sensor systems. Thus, progress in different areas of their performance evaluation factors such as improvement of the signal-to-noise ratio (SNR), spatial resolution (SR) in the sub-meter range, enlargement of the sensing range, increased frequency response bandwidth over the conventional limits, phase signal demodulation and chirped-pulse Φ-OTDR for quantitative measurement have been realized. This paper presents an overview of the recent progress in Φ-OTDR-based vibration sensing systems in the different areas mentioned above.

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Wang, Chen, Ying Shang, Wen-An Zhao, Xiao-Hui Liu, Chang Wang, and Gang-Ding Peng. "Investigation and Comparison of $\varphi $ -OTDR and OTDR-Interferometry via Phase Demodulation." IEEE Sensors Journal 18, no. 4 (2018): 1501–5. http://dx.doi.org/10.1109/jsen.2017.2785358.

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Muanenda, Yonas. "Recent Advances in Distributed Acoustic Sensing Based on Phase-Sensitive Optical Time Domain Reflectometry." Journal of Sensors 2018 (2018): 1–16. http://dx.doi.org/10.1155/2018/3897873.

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Анотація:

Distributed acoustic sensing (DAS) using coherent Rayleigh backscattering in an optical fiber has become a ubiquitous technique for monitoring multiple dynamic events in real time. It has continued to constitute a steadily increasing share of the fiber-optic sensor market, thanks to its interesting applications in many safety, security, and integrity monitoring systems. In this contribution, an overview of the recent advances of research in DAS based on phase-sensitive optical time domain reflectometry (ϕ-OTDR) is provided. Some advanced techniques used to enhance the performance of ϕ-OTDR sensors for measuring backscattering intensity changes through reduction of measurement noise are presented, in addition to methods used to increase the dynamic measurement capacity of ϕ-OTDR schemes beyond conventional limits set by the sensing distance. Recent ϕ-OTDR configurations which significantly enhance the measurement spatial resolution, including those which decouple it from the probing pulse width, are also discussed. Finally, a review of recent advances in more precise quantitative measurement of an external impact based on frequency shift and phase demodulation methods using simple direct detection ϕ-OTDR schemes is given.

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Жирнов, А. А., К. В. Степанов, А. О. Чернуцкий та ін. "Влияние дрейфа частоты лазера в фазочувствительной рефлектометрии". Журнал технической физики 127, № 10 (2019): 603. http://dx.doi.org/10.21883/os.2019.10.48364.177-19.

Повний текст джерела

Анотація:

AbstractThe influence of the laser frequency drift on the operation of phase-sensitive optical time domain reflectometry (φ-OTDR) systems is considered. Theoretical results based on a new numerical φ-OTDR model demonstrating the influence of the laser frequency instability on a signal are reported. This model is verified based on experimental data. It has been used to calculate the signal-to-noise ratio (SNR) of the system for different parameters of the laser source stability. As a result, quantitative requirements for lasers used in φ-OTDR systems are formulated.

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