Fast coarse-fine locating method for φ-OTDR

Area of Science:

• Optical Engineering
• Sensing Technology
• Signal Processing

Background:

• Phase-sensitive optical time-domain reflectometer (φ-OTDR) systems are crucial for distributed sensing.
• Accurate and fast external vibration locating remains a challenge in long-haul φ-OTDR systems.
• Existing methods often involve high computational costs for signal processing.

Purpose of the Study:

• To propose and demonstrate a novel coarse-fine locating method for external vibrations.
• To enhance the speed and efficiency of vibration detection in φ-OTDR sensing systems.
• To reduce the computational burden associated with signal processing in long-distance sensing.

Main Methods:

• Spatially segmenting backscattered traces from heterodyne coherent φ-OTDR for coarse locating.
• Comparing phase differences between adjacent segments to exclude irrelevant data.
• Implementing amplitude-based locating within targeted segments for fine-tuning vibration detection.

Main Results:

• The proposed coarse-fine method was numerically and experimentally validated.
• Significant reduction in computation cost for signal processing was achieved.
• Effective vibration locating was demonstrated on a 50-km sensing fiber.

Conclusions:

• The coarse-fine locating method offers a substantial improvement in efficiency for φ-OTDR systems.
• This technique shows strong potential for real-time external vibration locating in long-haul applications.
• The reduced computational load makes it suitable for practical, large-scale distributed sensing networks.