Time and Frequency Localized Pulse Shape for Resolution Enhancement in STFT-BOTDR

Luo, Linqing; Li, Bo; Yu, Yifei; Xu, Xiaomin; Soga, Kenichi; Yan, Jize

doi:10.1155/2016/3204130

Cited by 12 publications

(7 citation statements)

References 30 publications

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Section: Civil Engineering Applications Of Dasmentioning

confidence: 99%

“…Researchers (Soga et al 2008, Bao and Chen 2011, Luo et al 2016, Luo et al 2019 are using DFOS to monitor strain in various types of infrastructure. Civil engineering applications of DFOS currently include continuous monitoring of bridges, dams, pipelines, piles, mines, and security (Luo et al 2016, Soga and Luo 2018, Jousset et al 2018, Li et al 2018, Luo et al 2019). This dissertation focuses on DAS, but if the reader wishes to learn more about other DFOS such as DTS and DSS (Brillouin optical time domain reflectometry or BOTDR), please see Soga and Luo (2018) and Soga et al (2015) for excellent overviews.…”

Section: Civil Engineering Applications Of Dasmentioning

confidence: 99%

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Geotechnical effects on fiber optic distributed acoustic sensing performance

Quinn¹

2021

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Distributed Acoustic Sensing (DAS) is a fiber optic sensing system that is used for vibration monitoring. At a minimum, DAS is composed of a fiber optic cable and an optic analyzer called an interrogator. The oil and gas industry has used DAS for over a decade to monitor infrastructure such as pipelines for leaks, and in recent years changes in DAS performance over time have been observed for DAS arrays that are buried in the ground. This dissertation investigates the effect that soil type, soil temperature, soil moisture, time in-situ, and vehicle loading have on DAS performance for fiber optic cables buried in soil. This was accomplished through a field testing program involving two newly installed DAS arrays. For the first installation, a new portion of DAS array was added to an existing DAS array installed a decade prior. The new portion of the DAS array was installed in four different soil types: native fill, sand, gravel, and an excavatable flowable fill. Soil moisture and temperature sensors were buried adjacent to the fiber optic cable to monitor seasonal environmental changes over time. Periodic impact testing was performed at set locations along the DAS array for over one year. A second, temporary DAS array was installed to test the effect of vehicle loading on DAS performance. Signal to Noise Ratio (SNR) of the DAS response was used for all the tests to evaluate the system performance. The results of the impact testing program indicated that the portions of the array in gravel performed more consistently over time. Changes in soil moisture or soil temperature did not appear to affect DAS performance. The results also indicated that time DAS performance does change somewhat over time. Performance variance increased in new portions of array in all material types through time. The SNR in portions of the DAS array in native silty sand material dropped slightly, while the SNR in portions of the array in sand fill and flowable fill material decreased significantly over time. This significant change in performance occurred while testing halted from March 2020 to August 2020 due to the Covid-19 pandemic. These significant changes in performance were observed in the new portion of test bed, while the performance of the prior installation remained consistent. It may be that, after some time in-situ, SNR in a DAS array will reach a steady state. Though it is unfortunate that testing was on pause while changes in DAS performance developed, the observed changes emphasize the potential of DAS to be used for infrastructure change-detection monitoring. In the temporary test bed, increasing vehicle loads were observed to increase DAS performance, although there was considerable variability in the measured SNR. The significant variation in DAS response is likely due to various industrial activities on-site and some disturbance to the array while on-boarding and off-boarding vehicles. The results of this experiment indicated that the presence of load on less than 10% of an array channel length may improve DAS performance. Overall, this dissertation provides guidance that can help inform the civil engineering community with respect to installation design recommendations related to DAS used for infrastructure monitoring.

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Section: Civil Engineering Applications Of Dasmentioning

confidence: 99%

Section: Civil Engineering Applications Of Dasmentioning

confidence: 99%

Geotechnical effects on fiber optic distributed acoustic sensing performance

Quinn¹

2021

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“…It has been proved that the performance parameters of BOTDR are restricted by each other instead of being independent. For example, there is a trade-off between the spatial resolution (time-domain accuracy) and BFS measurement accuracy (frequency-domain accuracy) [31,179]. Meanwhile, the measurement speed is related to the SNR, measurement distance and measurement accuracy [100].…”

Section: Conclusion and Prospectsmentioning

confidence: 99%

Recent Advances in Brillouin Optical Time Domain Reflectometry

Bai

Wang

et al. 2019

Sensors

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In the past two decades Brillouin-based sensors have emerged as a newly-developed optical fiber sensing technology for distributed temperature and strain measurements. Among these, the Brillouin optical time domain reflectometer (BOTDR) has attracted more and more research attention, because of its exclusive advantages, including single-end access, simple system architecture, easy implementation and widespread field applications. It is realized mainly by injecting optical pulses into the fiber and detecting the Brillouin frequency shift (BFS), which is linearly related to the change of ambient temperature and axial strain of the sensing fiber. In this paper, the authors provide a review of new progress on performance improvement and applications of BOTDR in the last decade. Firstly, the recent advances in improving the performance of BOTDRs are summarized, such as spatial resolution, signal-to-noise ratio and measurement accuracy, measurement speed, cross sensitivity and other properties. Moreover, novel-type optical fibers bring new characteristics to optic fiber sensors, hence we introduce the different Brillouin sensing features of special fibers, mainly covering the plastic optical fiber, photonic crystal fiber, few-mode fiber and other special fibers. Additionally, we present a brief overview of BOTDR application scenarios in many industrial fields and intelligent perception, including structural health monitoring of large-range infrastructure, geological disaster prewarning and other applications. To conclude, we discuss several challenges and prospects in the future development of BOTDRs.

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“…Several signal processing schemes have been proposed to effectively mitigate ICI and lower the error floor of the channel. Examples of such schemes include precoding [15], time-domain equalization [16], and timefrequency localization [17]. Recently, empirical investigations have demonstrated that high-mobility OFDM system channels encountered in practice tend to exhibit a sparse structure [5], especially at high signal space dimension −particularly the delay-Doppler domain [11], [18], [19].…”

Section: Introductionmentioning

confidence: 99%

Spectrum-Efficient Distributed Compressed Sensing Based Channel Estimation for OFDM Systems Over Doubly Selective Channels

Uwaechia

Mahyuddin

2019

IEEE Access

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In this paper, we deal with channel estimation (CE) for high-mobility orthogonal frequency division multiplexing (OFDM) systems. To make the numerous (unknown) estimation for the high-mobility OFDM systems practicable, the channels are assumed to be time-and frequency-selective−or doubly selective (DS) and approximated by a basis expansion model (BEM). As the DS channel requires the distributed acquisition of multiple correlated signals in the delay-Doppler channel domain, we proceed to estimate jointly sparse BEM coefficient vectors over a DS channel as against numerous channel coefficients. On account of channel time-variation, the resulting channel matrix in the frequency domain exhibits (approximately banded) pseudo-circular structure, which gives rise to a diagonally dominant yet full matrix rather than a diagonal matrix and thus induces inter-channel interference (ICI). On the premise of this observation, we propose a new pilot design scheme that identifies the optimal pilot placement and values for each pilot cluster to combat ICI. Furthermore, to obtain a channel estimator consistent with the jointly sparse delay-Doppler [i.e., two dimensional (2D)] channel model, an algorithm namely, distributed compressed sensing (DCS)-based stage determined matching pursuit (DCS-SdMP), is proposed. Our claims are supported by simulation results, which are obtained considering Jakes' channels with fairly high Doppler spreads, which show the superiority of the proposed schemes over other different methods of CE. INDEX TERMSChannel estimation (CE), doubly selective (DS) channel, orthogonal frequency division multiplexing (OFDM), distributed compressed sensing (DCS), basis expansion model (BEM), pilot design, wireless communication.

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Time and Frequency Localized Pulse Shape for Resolution Enhancement in STFT-BOTDR

Cited by 12 publications

References 30 publications

Geotechnical effects on fiber optic distributed acoustic sensing performance

Geotechnical effects on fiber optic distributed acoustic sensing performance

Recent Advances in Brillouin Optical Time Domain Reflectometry

Spectrum-Efficient Distributed Compressed Sensing Based Channel Estimation for OFDM Systems Over Doubly Selective Channels

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