DISTRIBUTED FIBRE SENSING SYSTEM AND VIBRATION DETECTION AND POSITIONING METHOD THEREFOR

摘要

A distributed fibre sensing system and a vibration detection and positioning method therefor are disclosed. The system comprises: a signal generating module, a light source module, an optical frequency comb generating module, a frequency sweeping and pulse generating module, an optical circulator, a sensing fibre, an interference module, a photoelectric conversion module and a detection and position module. The method comprises: generating a plurality of digital band-pass filters with different frequency bands without any overlapping by a positioning unit in the detection and position module, and performing digital filtering on original data segments from a plurality of swept-frequency optical probe pulses, thereby obtaining a plurality of reflectivity curves of the sensing fibre; performing a fading elimination processing on the reflectivity curves, thereby obtaining a plurality of averaged reflectivity curves of non-interference fading and polarization fading; performing a phase processing on the averaged reflectivity curves, thereby obtaining phase variance curves; and determining a vibration point according to variances in the phase variance curves, and finally obtaining a position and a vibration waveform of the vibration point. The present invention has a high positioning accuracy, a large range of vibration frequency response and a high signal-to-noise ratio of vibration waveform.