Modeling the Demodulated Phase Precision of Standard Heterodyne-Detection Phase-Sensitive Optical Time-Domain Reflectometry

An analytical model linking the demodulated phase precision and system parameters for standard heterodyne-detection phase-sensitive optical time-domain reflectometry ($\Phi$-OTDR) is proposed and experimentally validated. This model innovatively leverages the independence of additive noise and phase noise, circumventing the traditional challenge of clarifying the intricate relationship between phase-noise-involved signal-to-noise ratio (SNR) and the phase precision. The developed model serves as a theoretical tool for understanding how phase precision is determined by system parameters, allowing for theoretical anticipations of phase precision at any fiber position under given measurement conditions. Additionally, the model enables the optimization of system parameters for high performance and low cost, with no need to build up an experimental system.