T8 Novel Interrogator with 1 m Gauge Length and Suppressed Fading

Summary This paper introduces a novel Distributed Acoustic Sensing (DAS) system developed by T8 LLC, designed to overcome key limitations of conventional Φ-OTDR technology in geophysical applications. Traditional Φ-OTDR systems suffer from interference fading, and gauge length constraints. The proposed DAS features a 1-meter gauge length and effectively mitigates fading through specialized data processing, resulting in a non-zero mean Ricean distribution of the backscattered signal. This eliminates the need for costly engineered fibers or spatial averaging, which compromises locality. Performance is validated through laboratory characterization, demonstrating negligible fading (probability < 0.1%) compared to standard DAS. Furthermore, seismic field tests using a seismic gun impact successfully detect distinct seismic waves confirming the system’s efficacy for geophysical sensing. The results demonstrate a promising alternative to geophone array with improved performance for applications like seismic monitoring.