High-Resolution and High-Precision ϕ-OFDR Strain Sensing Scheme Based on Adaptive Phase Unwrapping and Wavelet Packet Denoising

In this article, a distributed strain sensing system based on a standard single-mode fiber is implemented using the Phase-Optical Frequency Domain Reflectometry (ϕ-OFDR). Compared to traditional amplitude cross-correlation algorithms, phase demodulation can achieve higher sensing resolution, but it is more susceptible to phase noise interference. To address this issue, an adaptive phase noise suppression algorithm based on the adjacent window boundary continuity conditions has been proposed to correct error phase jumps in the phase unwrapping process and recover the phase difference curve. Additionally, wavelet denoising is employed to eliminate Gaussian white noise in the linear phase term, which weakens the trade-off between sensing resolution and accuracy. With a spatial resolution of 15.8 μm, the system achieved a sensing resolution of 1.5 mm, and a root mean square error of 0.9343 μϵ in single mode fiber.