Nuisance alarm rate reduction using pulse-width multiplexing [formula omitted]-OTDR with optimized positioning accuracy

Abstract

High nuisance alarm rates and missing alarm rates in phase-sensitive optical time-domain reflectometer (ϕ-OTDR) greatly restrict their practical application. In this paper, an asynchronous sampling pulse width multiplexing ϕ-OTDR is proposed to reduce both of these rates. Intersection and inclusion relationships among multiple positioning intervals are used to optimize the positioning accuracy. We construct an eight-pulse-width multiplexed ϕ-OTDR system and adopt a multisensor information fusion algorithm to verify the feasibility of the method. The experimental results show that this method can reduce the missing alarm rate by 93% and the number of nuisance alarms by 97%. The average positioning accuracy of the system is 21.4 m, which is equivalent to the spatial resolution level corresponding to the minimum pulse width in the optical pulse sequence. The positioning accuracy of some groups was as low as 6.4 m, far less than 20m. The proposed method provides a simple and feasible new approach for reducing nuisance alarm and missing alarm rates and optimizing the positioning accuracy of ϕ-OTDR.