Two-Stage Preamplification for ϑ-OTDR Distributed Acoustic Sensing

A ϑ-OTDR interferometric sensor employing a nonlinear preamplification approach to couneract signal fading is proposed and used to characterize the noise floor for strain values in a survey well in the Netherlands. The characterization shows the system is capable of detecting strain noise levels below 1 nε in the 0.1-100 Hz frequency range.