Analysis of Disturbance-Induced “Virtual” Perturbations in Chirped Pulse $\phi$ -OTDR

When a disturbance acts on a fiber it induces a change in the local refractive index that influences the fiber backscattering trace. If a chirped pulse φ-OTDR setup is used to interrogate the fiber, this refractive index change appears as a local shift of the received trace, linear to the acting perturbation. However, the refractive index change influences the round trip time of all the backscatte...