Comparative analysis of intensity and phase frequency demodulation based on DAS

This study, based on Distributed Acoustic Sensing (DAS) equipment, investigates two primary methods—intensity demodulation and phase demodulation. Through theoretical analysis and experimental validation, it provides an in-depth comparison of their performance differences in terms of frequency response and sensitivity. Experiments employed Fast Fourier Transform (FFT) to analyze vibration signals of low intensity (1Hz, 1Vpp) and high intensity (1Hz, 20Vpp). The results indicate that phase demodulation offers higher frequency resolution for low-intensity signals but performs poorly under high-intensity conditions. In contrast, intensity demodulation demonstrates more stable responses to high-intensity signals, making it suitable for scenarios with large amplitudes and rapid responses.The study further summarizes the applicability of these two demodulation methods, highlighting their advantages and limitations in various vibration monitoring scenarios. It provides theoretical support and experimental reference for optimizing signal processing in DAS systems for icing monitoring of transmission lines.