# A Fading Suppression Method for Φ-OTDR Systems Based on Multi-Domain Multiplexing

## TL;DR

This paper introduces a new method to reduce false alarms in Φ-OTDR systems by combining multiple signal processing techniques.

## Contribution

The novel fading suppression method uses multi-domain multiplexing to optimize noise reduction in Φ-OTDR systems.

## Key findings

- Single-domain multiplexing methods struggle to fully suppress fading noise.
- Multi-domain multiplexing achieves better noise suppression with optimized parameter combinations.
- MDM provides a practical solution for improving Φ-OTDR performance in real-world applications.

## Abstract

The phase-sensitive optical time domain reflectometry (Φ-OTDR) has been widely applied in various fields. However, due to fading noise, false alarms often occur; this limits its engineering applications. In this paper, a fading suppression method for Φ-OTDR systems based on multi-domain multiplexing (MDM) is proposed. The principles and limitations of existing suppression methods such as spatial-domain multiplexing (SDM), polarization-domain multiplexing (PDM), and frequency-domain multiplexing (FDM) are analyzed. The principle of MDM is explained in detail, and an experimental system is established to test the fading noise suppression capabilities of different parameter combinations of the PDM, FDM, and SDM methods. Experimental results show that it is difficult to comprehensively suppress fading noise with single-domain multiplexing. Through optimizations of different parameter combinations, MDM can comprehensively suppress fading noise by appropriately selecting the number of FDM frequencies, the spatial weighting intervals, and using PDM, thus obtaining the optimal anti-fading solution between performance and hardware complexity. Through MDM, the fade-free measurement is achieved, providing a promising technical solution for the practical application of the Φ-OTDR technology.