SNR enhancement for dual wavelength distributed fiber acoustic sensing system using improved recursive least squares method

Abstract

In this paper, an improved recursive least squares (RLS) method has been proposed to enhance the signal-to-noise ratio (SNR) of dual wavelength distributed fiber acoustic sensing system. The raw detected signals of 1550 nm differential signal and 1310 nm interference signal are processed by wavelet decomposition and reconstruction techniques to obtain the estimation of the reference signal. The tap factor is self-iterated according to the parameters at the previous time under the corresponding evaluation metrics. The system allows detecting and locating acoustic signal at an arbitrary position on a single optical fiber without using additional sensitizing devices. Experimental results demonstrate that the SNR of the acoustic restoration and localization are substantially improved by 14.98 ∼ 20.33 dB and 19.27 ∼ 29.71 dB, respectively. The proposed system exhibits considerable potential for demodulating and reconstructing acoustic signals over long distances and in wide ranges.