RT info:eu-repo/semantics/conferenceObject T1 Code length limit in phase-sensitive OTDR using ultralong (>1M bits) pulse sequences due to fading induced by fiber optical path drifts A1 Fidalgo Martins, Hugo A1 Shi, K. A1 Thomsen, B.C. A1 Martín López, Sonia A1 González Herráez, Miguel A1 Savory, S.J. K1 Distributed vibration sensing K1 Dynamic strain sensing K1 I/Q detection K1 Phase-sensitive OTDR K1 Phase-shift keying K1 Pulse coding K1 Trace fading K1 Electrónica K1 Electronics AB Recently, it has been demonstrated that by recovering the amplitude and phase of the backscattered optical signal, a ΦOTDR using pulse coding can be treated as a fully linear system in terms of trace coding/decoding, thus allowing for the use of tens of thousands of bits with a dramatic improvement of the system performance. In this communication, as a continuation of previous work by the same authors, a preliminary study aiming at characterizing the limits of the system in terms of maximum usable code length is presented. Using a code exceeding 1million bits over a duration of 0.26ms, it is observed that fiber optical path variations exceeding π occurring over a time inferior to the pulse code length can lead to localized fading in the ΦOTDR trace. The occurrence, positions and form of the fading points along the ΦOTDR trace is observed to be strongly dependent on the type, frequency and amplitude of the perturbations applied to the fiber. PB Spie SN 978-1-51061-091-0 SN 0277-786X YR 2017 FD 2017 LK http://hdl.handle.net/10017/31059 UL http://hdl.handle.net/10017/31059 LA eng NO European Commission DS MINDS@UW RD 29-mar-2024