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. 2017 Nov 1;17(11):2511. doi: 10.3390/s17112511

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© 2017 by the authors.

Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).

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Experimental setup of a pulse-coded standard $ϕ$ -OTDR system. DFB: Distributed Feedback, AOM: Acousto-Optic Modulator, EDFA: Erbium-Doped Fiber Amplifier, MZM: Mach–Zehnder Modulator, OBPF: Optical Bandpass Filter, PC: Polarization Controller, AWG: Arbitrary Waveform Generator, OC: Optical Coupler, PD: Photodetector, and ADC: Analog-Digital Converter [35].