Sensing Accuracy Enhancement of Phase-Sensitive Optical Frequency Domain Reflectometry Using Hybrid Hampel-Median Filter

We propose a novel filter scheme to enhance the sensing accuracy of phase-sensitive optical frequency domain reflectometer (Φ-OFDR) while maintaining high spatial resolution via cascading Hampel filter and median filter. The working principle is theoretically analyzed and optimal filtering parameters are analyzed with the practical experimental configuration. Experimental results demonstrate that the proposed method achieves a temperature accuracy of 0.49°C, indicating a 28 dB enhancement compared with the raw data while maintaining 4.6 mm spatial resolution. Compared to other conventional filtering methods applied in Φ-OFDR, the proposed hybrid Hampel-Median filter yields about 2∼4 times improvement in sensing accuracy and increases SNR by more than 5 dB with consistent spatial resolution condition. On the other hand, the proposed filtering method enhances the spatial resolution about 2∼6 times with the same sensing accuracy. The experimental results reveal that the novel filtering approach enables high sensing accuracy and spatial resolution for the distributed temperature or strain sensing scenarios of Φ-OFDR, without any hardware modifications.