Enhanced noise measurement and analysis in distributed acoustic sensing systems

A Distributed Acoustic Sensing (DAS) unit is widely used for seismic, volcanic, and health monitoring activities. Most DAS systems are based on Phase-Optical Time Domain Reflectometry (φ-OTDR) which offers high sensitivity by detecting phase changes in Rayleigh backscattered light along the optical fiber cable. The performance and accuracy of DAS systems can be affected by various noise types, which depend on system components and environmental conditions. Therefore, noise measurement and analysis are essential both prior to and during data acquisition to ensure optimal system functionality. One technique to evaluate the performance of a DAS system is the Spatial Noise Resolution test, which provides critical insights into system precision and reliability. The Spatial Noise Resolution test in DAS systems is essential for evaluating the system’s ability to differentiate between spatially distinct signals in the presence of noise. The system's precision in detecting events along the fiber is directly correlated with the Signal-to-Noise Ratio (SNR). Following this, filtering techniques are applied to reduce noise, enhancing the precision and reliability of the detected signals and improving overall performance of the DAS system.