Integrated Fading Suppression for Phase-Sensitive OTDR: An Algorithm Set

Interference fading problem is an inevitable challenge in distributed acoustic sensing (DAS) system, and the uncertainty of the dynamic external environment further increases the difficulty of denoising. Based on the conventional single-domain fading suppression methods, we propose the concept of integrated fading suppression (IFS) algorithm set, which provides four denoising approaches and each of them is composed of at least two independent techniques. The combination of multiple single-domain denoising methods enhances the reliability of the proposed method. In an experiment involving 30 sets of data, the IFS algorithm set succeeded in completely eliminating all fading noise. In addition, the demodulation results show that compared to only applying a bandpass filter, these four IFS algorithms could improve the intensity signal-to-noise ratio by an average of 5.82 dB, while decreasing the amplitude fluctuation range by 31.84 dB on average. Benefiting from its powerful fading suppression capability, the average strain noise of the demodulated results obtained by the proposed algorithm set goes down to 0.47 nϵ. It is worth noting that the IFS algorithm set with four denoising methods is highly flexible and could meet different requirements and preferences. With the proposed IFS algorithm set, it is expected that the DAS system could be thoroughly free from the influence of interference fading.