Distributed Acoustic Sensing: Fading Noise and Impact of Optical Pre-Amplification

We present a φ-OTDR preamplification method intended for the suppression of fading noise by providing nonlinear preamplification for the Rayleigh Backscatter light to improve signal to noise ratio (SNR) for lower intensity signals. Compared to linear preamplification, the system increases the Rayleigh Backscattering trace minimum and average intensities by 170% and 70% respectively, improving the SNR for small signals.