{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,11,21]],"date-time":"2025-11-21T18:17:45Z","timestamp":1763749065034,"version":"build-2065373602"},"reference-count":43,"publisher":"MDPI AG","issue":"20","license":[{"start":{"date-parts":[[2023,10,20]],"date-time":"2023-10-20T00:00:00Z","timestamp":1697760000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100011351","name":"State Key Laboratory of Information Photonics and Optical Communications (BUPT)","doi-asserted-by":"publisher","award":["IPOC2021ZT14","62021005"],"award-info":[{"award-number":["IPOC2021ZT14","62021005"]}],"id":[{"id":"10.13039\/501100011351","id-type":"DOI","asserted-by":"publisher"}]},{"name":"Funds for Creative Research Groups of China","award":["IPOC2021ZT14","62021005"],"award-info":[{"award-number":["IPOC2021ZT14","62021005"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>In the domain of optical fiber distributed acoustic sensing, the persistent challenge of extending sensing distances while concurrently improving spatial resolution and frequency response range has been a complex endeavor. The amalgamation of pulse compression and frequency division multiplexing methodologies has provided certain advantages. Nevertheless, this approach is accompanied by the drawback of significant bandwidth utilization and amplified hardware investments. This study introduces an innovative distributed optical fiber acoustic sensing system aimed at optimizing the efficient utilization of spectral resources by combining compressed pulses and frequency division multiplexing. The system continuously injects non-linear frequency modulation detection pulses spanning various frequency ranges. The incorporation of non-uniform frequency division multiplexing augments the vibration frequency response spectrum. Additionally, nonlinear frequency modulation adeptly reduces crosstalk and enhances sidelobe suppression, all while maintaining a favorable signal-to-noise ratio. Consequently, this methodology substantially advances the spatial resolution of the sensing system. Experimental validation encompassed the multiplexing of eight frequencies within a 120 MHz bandwidth. The results illustrate a spatial resolution of approximately 5 m and an expanded frequency response range extending from 1 to 20 kHz across a 16.3 km optical fiber. This achievement not only enhances spectral resource utilization but also reduces hardware costs, making the system even more suitable for practical engineering applications.<\/jats:p>","DOI":"10.3390\/s23208612","type":"journal-article","created":{"date-parts":[[2023,10,20]],"date-time":"2023-10-20T11:53:56Z","timestamp":1697802836000},"page":"8612","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":1,"title":["A Phase-Sensitive Optical Time Domain Reflectometry with Non-Uniform Frequency Multiplexed NLFM Pulse"],"prefix":"10.3390","volume":"23","author":[{"ORCID":"https:\/\/orcid.org\/0009-0002-1383-9393","authenticated-orcid":false,"given":"Zhengyang","family":"Li","sequence":"first","affiliation":[{"name":"School of Electronic Engineering, Beijing University of Posts and Telecommunications, Beijing 100876, China"}]},{"given":"Yangan","family":"Zhang","sequence":"additional","affiliation":[{"name":"School of Electronic Engineering, Beijing University of Posts and Telecommunications, Beijing 100876, China"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7277-7092","authenticated-orcid":false,"given":"Xueguang","family":"Yuan","sequence":"additional","affiliation":[{"name":"School of Electronic Engineering, Beijing University of Posts and Telecommunications, Beijing 100876, China"}]},{"given":"Zhenyu","family":"Xiao","sequence":"additional","affiliation":[{"name":"School of Electronic Engineering, Beijing University of Posts and Telecommunications, Beijing 100876, China"}]},{"given":"Yuan","family":"Zhang","sequence":"additional","affiliation":[{"name":"School of Electronic Engineering, Beijing University of Posts and Telecommunications, Beijing 100876, China"}]},{"given":"Yongqing","family":"Huang","sequence":"additional","affiliation":[{"name":"School of Electronic Engineering, Beijing University of Posts and Telecommunications, Beijing 100876, China"}]}],"member":"1968","published-online":{"date-parts":[[2023,10,20]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","unstructured":"Palmieri, L., Schenato, L., Santagiustina, M., and Galtarossa, A. (2022). Rayleigh-Based Distributed Optical Fiber Sensing. Sensors, 22.","DOI":"10.3390\/s22186811"},{"key":"ref_2","doi-asserted-by":"crossref","unstructured":"Pend\u00e3o, C., and Silva, I. (2022). Optical Fiber Sensors and Sensing Networks: Overview of the Main Principles and Applications. Sensors, 22.","DOI":"10.3390\/s22197554"},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"102577","DOI":"10.1016\/j.yofte.2021.102577","article-title":"Distributed optical fibre sensor for infrastructure monitoring: Field applications","volume":"64","author":"Hendrik","year":"2021","journal-title":"Opt. Fiber Technol."},{"key":"ref_4","first-page":"80","article-title":"Analyzing the Results of Monitoring the Situations that May Occur in Emergency Situations of Bridges Through Various Optical Sensors","volume":"8","author":"Xakimovich","year":"2022","journal-title":"Glob. Sci. Rev."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"30789","DOI":"10.1109\/ACCESS.2020.2973229","article-title":"Pipeline Leak Detection Technology Based on Distributed Optical Fiber Acoustic Sensing System","volume":"8","author":"Zuo","year":"2020","journal-title":"IEEE Access"},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"57","DOI":"10.1016\/j.measurement.2018.03.018","article-title":"Pipeline corrosion and leakage monitoring based on the distributed optical fiber sensing technology","volume":"122","author":"Ren","year":"2018","journal-title":"Measurement"},{"key":"ref_7","doi-asserted-by":"crossref","unstructured":"Zhu, H.-H., Liu, W., Wang, T., Su, J.-W., and Shi, B. (2022). Distributed Acoustic Sensing for Monitoring Linear Infrastructures: Current Status and Trends. Sensors, 22.","DOI":"10.3390\/s22197550"},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"132713","DOI":"10.1016\/j.conbuildmat.2023.132713","article-title":"Applications of optical fiber sensor in pavement Engineering: A review","volume":"400","author":"Wang","year":"2023","journal-title":"Constr. Build. Mater."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"9684","DOI":"10.1364\/OE.27.009684","article-title":"Performance analysis of distributed optical fiber acoustic sensors based on \u03c6-OTDR","volume":"27","author":"Chen","year":"2019","journal-title":"Opt. Express"},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"109128","DOI":"10.1016\/j.optlastec.2023.109128","article-title":"Influences of pulse parameters on the performance of double-pulse \u03d5-OTDR","volume":"161","author":"Zhong","year":"2023","journal-title":"Opt. Laser Technol."},{"key":"ref_11","doi-asserted-by":"crossref","unstructured":"Wang, Z., Lu, B., Ye, Q., and Cai, H. (2020). Recent Progress in Distributed Fiber Acoustic Sensing with \u03a6-OTDR. Sensors, 20.","DOI":"10.3390\/s20226594"},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"391","DOI":"10.1364\/OL.42.000391","article-title":"High spatial resolution phase-sensitive optical time domain reflectometer with a frequency-swept pulse","volume":"42","author":"Lu","year":"2017","journal-title":"Opt. Lett."},{"key":"ref_13","doi-asserted-by":"crossref","unstructured":"Jiang, C., Li, Z., Zhang, Z., and Wang, S. (2023). A New Design to Rayleigh Wave EMAT Based on Spatial Pulse Compression. Sensors, 23.","DOI":"10.3390\/s23083943"},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"512","DOI":"10.1364\/OE.23.000512","article-title":"Optical pulse compression reflectometry: Proposal and proof-of-concept experiment","volume":"23","author":"Zou","year":"2015","journal-title":"Opt. Express"},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1109\/JPHOT.2022.3152816","article-title":"Adaptable Pulse Compression in \u03d5-OTDR With Direct Digital Synthesis of Probe Waveforms and Rigorously Defined Nonlinear Chirping","volume":"14","author":"Muanenda","year":"2022","journal-title":"IEEE Photonics J."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"16138","DOI":"10.1364\/OE.26.016138","article-title":"High-fidelity distributed fiber-optic acoustic sensor with fading noise suppressed and sub-meter spatial resolution","volume":"26","author":"Chen","year":"2018","journal-title":"Opt. Express"},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"4748","DOI":"10.1109\/JLT.2019.2919671","article-title":"80 km Fading Free Phase-Sensitive Reflectometry Based on Multi-Carrier NLFM Pulse Without Distributed Amplification","volume":"37","author":"Zhang","year":"2019","journal-title":"J. Light. Technol."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"19","DOI":"10.1016\/j.yofte.2017.02.005","article-title":"Distributed measurement of acoustic vibration location with frequency multiplexed phase-OTDR","volume":"36","author":"Iida","year":"2017","journal-title":"Opt. Fiber Technol."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"7181","DOI":"10.1364\/AO.54.007181","article-title":"Microwave interrogated large core fused silica fiber Michelson interferometer for strain sensing","volume":"54","author":"Hua","year":"2015","journal-title":"Appl. Opt."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"103428","DOI":"10.1016\/j.yofte.2023.103428","article-title":"Lyot filter-induced Vernier effect for sensitivity improvement of fiber birefringence sensor","volume":"80","author":"Huang","year":"2023","journal-title":"Opt. Fiber Technol."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"5192","DOI":"10.1364\/OL.40.005192","article-title":"Ultra-broadband phase-sensitive optical time-domain reflectometry with a temporally sequenced multi-frequency source","volume":"40","author":"Wang","year":"2015","journal-title":"Opt. Lett."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"768","DOI":"10.1109\/JLT.2022.3217346","article-title":"Frequency Response Enhancement of \u03a6-OTDR Using Interval-Sweeping Pulse Equivalent Sampling Based on Compressed Sensing","volume":"41","author":"Xiao","year":"2023","journal-title":"J. Light. Technol."},{"key":"ref_23","doi-asserted-by":"crossref","unstructured":"Wang, D., Liu, X., Wu, X., and Wang, Z. (2020). Reconstruction of Periodic Band Limited Signals from Non-Uniform Samples with Sub-Nyquist Sampling Rate. Sensors, 20.","DOI":"10.3390\/s20216246"},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"2037","DOI":"10.1109\/JLT.2017.2657640","article-title":"Distributed Fiber-Optic Acoustic Sensor with Enhanced Response Bandwidth and High Signal-to-Noise Ratio","volume":"35","author":"Chen","year":"2017","journal-title":"J. Light. Technol."},{"key":"ref_25","unstructured":"Wang, Z., Wang, Z., Xiong, J., and Rao, Y. (2020, January 8\u201312). Variable Frequency Division Multiplexing \u03a6-OTDR Based on Chirped Continuous Wave. Proceedings of the 2020 Optical Fiber Sensors Conference 2020 Special Edition, Washington, DC, USA."},{"key":"ref_26","doi-asserted-by":"crossref","unstructured":"Xiong, J., Wang, Z., Wu, Y., Chen, Y., Li, J., and Rao, Y. (2018, January 24\u201328). High performance CP-\u03a6OTDR utilizing the negative band. Proceedings of the 2018 International Conference on Optical Fiber Sensors, Lausanne, Switzerland.","DOI":"10.1364\/OFS.2018.FB5"},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"685","DOI":"10.1364\/OL.415087","article-title":"Continuous chirped-wave phase-sensitive optical time domain reflectometry","volume":"46","author":"Jiang","year":"2021","journal-title":"Opt. Lett."},{"key":"ref_28","unstructured":"Luo, F., Ruan, L.T., Wu, S.J., Zhao, Q.S., and Zhang, Z.Q. (2009, January 26\u201330). Design of modified spectrum filter based on mismatched window for NLFM signal. Proceedings of the 2009 IEEE Conference on Synthetic Aperture Radar, Xi\u2019an, China."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"814","DOI":"10.1109\/LGRS.2019.2930817","article-title":"A Novel NLFM Waveform with Low Sidelobes Based on Modified Chebyshev Window","volume":"17","author":"Zhang","year":"2020","journal-title":"IEEE Geosci. Remote Sens. Lett."},{"key":"ref_30","doi-asserted-by":"crossref","unstructured":"Thakur, A., and Talluri, S.R. (2017, January 6\u20138). A novel pulse compression technique for side-lobe reduction using woo filter concepts. Proceedings of the 2017 International Conference on Communication and Signal Processing, Chennai, India.","DOI":"10.1109\/ICCSP.2017.8286543"},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"6155","DOI":"10.1109\/TGRS.2019.2904627","article-title":"An Advanced Nonlinear Frequency Modulation Waveform for Radar Imaging with Low Sidelobe","volume":"57","author":"Jin","year":"2019","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"74","DOI":"10.1049\/iet-rsn.2018.5095","article-title":"Sidelobe level reduction in ACF of NLFM waveform","volume":"13","author":"Ghavamirad","year":"2019","journal-title":"IET Radar Sonar Nav."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"62","DOI":"10.1186\/s13634-019-0658-9","article-title":"Evaluation of a class of NLFM radar signals","volume":"2019","author":"Alphonse","year":"2019","journal-title":"EURASIP J. Adv. Sig. Process."},{"key":"ref_34","doi-asserted-by":"crossref","unstructured":"Zhang, P., Feng, Q., Li, W., Zheng, Q., and Wang, Y. (2019). Simultaneous OTDR Dynamic Range and Spatial Resolution Enhancement by Digital LFM Pulse and Short-Time FrFT. Appl. Sci., 9.","DOI":"10.3390\/app9040668"},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"119","DOI":"10.2528\/PIERC14010605","article-title":"Some Aspects of Sidelobe Reduction in Pulse Compression Radars Using Nlfm Signal Processing","volume":"47","author":"Vizitiu","year":"2014","journal-title":"Prog. Electromagn. Res."},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"2674","DOI":"10.1007\/s11431-011-4533-7","article-title":"Study on interference suppression based on joint fractional Fourier domain and time domain","volume":"54","author":"Huang","year":"2011","journal-title":"Sci. China Technol. Sci."},{"key":"ref_37","first-page":"1056","article-title":"Reduction in sidelobe and SNR improves by using Digital Pulse Compression Technique","volume":"6","author":"Devesh","year":"2017","journal-title":"Int. J. Adv. Res. Sci. Eng."},{"key":"ref_38","unstructured":"Pan, Y.H., Peng, S.R., Yang, K.F., and Dong, W.F. (2005, January 9\u201312). Optimization design of NLFM signal and its pulse compression simulation. Proceedings of the 2005 IEEE International Radar Conference, Arlington, VA, USA."},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"138","DOI":"10.7236\/IJASC.2015.4.2.138","article-title":"Spectral Analysis of Rectangular, Hanning, Hamming and Kaiser Window for Digital Fir Filter","volume":"4","author":"Gautam","year":"2015","journal-title":"Int. J. Adv. Smart Converg."},{"key":"ref_40","first-page":"3243","article-title":"Distributed Vibration Sensor Based on Coherent Detection of Phase-OTDR","volume":"28","author":"Lu","year":"2010","journal-title":"J. Light. Technol."},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"2470","DOI":"10.1364\/AO.21.002470","article-title":"Analysis of the phase unwrapping algorithm","volume":"21","author":"Itoh","year":"1982","journal-title":"Appl. Opt."},{"key":"ref_42","doi-asserted-by":"crossref","unstructured":"Costa, L., Martins, H.F., Martin-Lopez, S., Fern\u00e1ndez-Ruiz, M.R., and Gonz\u00e1lez-Herr\u00e1ez, M. (2018, January 24\u201328). Reaching p\u03b5\/\u221aHz sensitivity in a distributed optical fiber strain sensor. Proceedings of the 26th International Conference on Optical Fiber Sensors, Lausanne, Switzerland.","DOI":"10.1364\/OFS.2018.TuD3"},{"key":"ref_43","doi-asserted-by":"crossref","first-page":"5969","DOI":"10.1364\/OL.44.005969","article-title":"Quasi-distributed fiber-optic acoustic sensing system based on pulse compression technique and phase-noise compensation","volume":"44","author":"Wu","year":"2019","journal-title":"Opt. Lett."}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/23\/20\/8612\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,10]],"date-time":"2025-10-10T21:09:25Z","timestamp":1760130565000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/23\/20\/8612"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2023,10,20]]},"references-count":43,"journal-issue":{"issue":"20","published-online":{"date-parts":[[2023,10]]}},"alternative-id":["s23208612"],"URL":"https:\/\/doi.org\/10.3390\/s23208612","relation":{},"ISSN":["1424-8220"],"issn-type":[{"type":"electronic","value":"1424-8220"}],"subject":[],"published":{"date-parts":[[2023,10,20]]}}}