Distributed acoustic sensing phase unwrapping compensation algorithm based on extreme point detection

Distributed Acoustic Sensing (DAS) technology has demonstrated significant potential in applications such as security, pipeline monitoring, and geological vibration detection due to its unique advantages of high sensitivity and long monitoring distance. DAS technology recovers the true phase changes caused by vibrations through phase unwrapping algorithms. However, its effective dynamic range is limited by the maximum phase gradient that the unwrapping process can handle. When monitoring high-frequency, large-amplitude vibration events, the phase gradient between adjacent sampling points can exceed the limits of traditional unwrapping algorithms, leading to unwrapping failures. This severely restricts the application of DAS in monitoring strong vibration sources. To break through this limitation, this paper proposes a new phase unwrapping algorithm. This method does not require increasing the sampling rate of the DAS system or adding additional hardware costs. Instead, it compensates for the phase in the unwrapping failure intervals by detecting extreme points, thereby recovering the true phase and effectively extending the maximum phase gradient that the phase unwrapping algorithm can handle. To verify the effectiveness of the proposed method, we used a piezoelectric ceramic (PZT) module to simulate vibration events of different intensities and collected data using a DAS system. Experimental results show that, compared with traditional unwrapping methods, this method can restore phase signals with larger vibration amplitudes, enhancing the monitoring capability of the DAS system for high-intensity vibration events.