A OFDR Signal Processing Method Based on Wavelet Transform for Improving Its Sensing Performance

Distributed optical fiber sensing based on optical frequency domain reflectormeter (OFDR) is a promising technology to achieve a high spatial resolution downward to several millimeters. To reduce the interaction between the spatial and spectral resolution, the OFDR signal processing method based on Morlet wavelet transform (WT) is proposed to enrich spectrum information especially under a high spatial resolution, and the resolution of spectrum/measured distributed sensing physical quantity can thus be improved. The relationship among distributed sensing parameters and wavelet parameters is demonstrated. And the spectral resolution, spatial interval of the measured gauge and spatial resolution are all manually controllable by adjusting wavelet parameters. To the best of our knowledge, it is the first time to report a practical WT method for high-performance OFDR. The experimental results indicate that the significant improvements, such as a strain resolution of 1 $\mu \varepsilon $ , average repeatability over a full strain range (3000) $\mu ~\varepsilon $ of $4.3~\mu \varepsilon $ , and a nonlinearity of lower than 0.67%, have been achieved. The advantages of this method include high spatial resolution, high spectral resolution, high robustness, and excellent applicability with current OFDR systems.