No abstract

By applying randomized sampling to interference fading suppressed coherent phase-sensitive optic time domain reflectometry (φ-OTDR) system, quantitative vibration signal measurement with much higher frequency than the Nyquist sampling theorem determined upper limit was demonstrated.

A novel distributed twist sensor utilizing frequency-scanning φ-OTDR in a spun fiber is theoretically analyzed and experimentally demonstrated by tracking the fiber twist induced frequency shift of correlation peak, enabling distributed quantitative twist measurement.