Real-Time Φ-OTDR System Based on FPGA Digital Signal Processing Scheme

The phase-sensitive optical time domain reflectometry (Φ-OTDR) is a powerful tool for a variety of applications, such as pipeline safety monitoring, perimeter safety, and geological exploration. However, real-time demodulation and status monitoring remain a challenge since a huge amount of data is collected all the time in such system. Here, we demonstrate a real-time Φ-OTDR system based on FPGA digital signal processing scheme, utilizing a single rectangular pulse for the heterodyne coherent detection system. The experimental results indicate that the comprehensive resource consumption of the demodulation algorithm is controllable. Subsequently, the distributed acoustic sensing (DAS) with a sensing distance of 9 km, a demodulation rate of 10kHz, and a spatial sampling interval of 10m is obtained. Hence, such a real-time Φ-OTDR system can achieve a long distance and high resolution detection of DAS.