On the Use and the Performance of Adaptive Filters for Fiber Optic Distributed Acoustic Sensors

The use of phase-OTDR based fiber optic distributed sensors are becoming widespread nowadays in the field of pipeline, perimeter and borderline security as well as in structural health monitoring. In this paper, the application and the performance results of an adaptive filtering method to suppress the speckle-like profile of phase-OTDR based acoustic sensor systems is presented. With the proposed digital processing technique, the results show that more than 15 dB of SNR values can be achieved without any reduction in the system bandwidth and without using additional optical amplifier stages in the hardware. Additionally, it has been observed that activities such as digging and hitting with a hammer can be detected from a lateral distance of 25 m from the buried fiber.