High-performance PGC algorithm for a Φ-OTDR system based on multi-carrier mixing

This is the authors' abstract. We don't add key points for this paper.

The conventional phase-generated carrier (PGC) demodulation algorithm is often susceptible to three major disturbances in practical distributed fiber sensing applications, namely modulation depth, carrier phase delay, and laser intensity disturbance. These disturbances significantly render the Φ-OTDR system less capable of achieving high-accuracy vibration sensing under complex environmental conditions. To address these limitations, this study proposes a high-performance PGC demodulation algorithm based on multi-carrier mixing (PGC-MCM). By establishing mathematical logic operations between multiple mixed carrier signals and the intrinsic interference signal, the proposed method enables accurate reconstruction of the measured phase signal while effectively suppressing the influence of the aforementioned disturbances. Experimental results verify that the algorithm can precisely demodulate vibration signals with varying frequencies and amplitudes at different locations along the sensing fiber, achieving high fidelity recovery of the original signal. The proposed approach demonstrates excellent linearity and noise immunity. It yields a total harmonic distortion (THD) of −66.32 dB, a signal-to-noise and distortion ratio (SINAD) of 54.74 dB, with an amplitude error rate ( R error ). as low as 0.46%, highlighting its strong potential for high-accuracy distributed optical fiber sensing applications.