Patent ID: 11920974
Assignee: NIPPON TELEGRAPH AND TELEPHONE CORPORATION
Field: Measurement (Instruments)
Classification: CPC G | IPC G

Claim 7:
8. A vibration waveform analysis device for analyzing a waveform of a vibration applied to a sensing fiber, the device analyzing a distribution waveform of a beat signal obtained by mixing backscattered light from the sensing fiber as signal light with local light, the backscattered light being obtained by causing probe light to be incident on the sensing fiber, and the probe light and the local light being obtained by splitting frequency sweep light, the device comprising:
a processor configured to estimate a distance offset due to a vibration by using cross-correlation between the distribution waveform and a reference waveform, and correct a distance from a light incident end to a vibration measurement interval;
wherein the distribution waveform is an electric field waveform at each vibration measurement interval and obtained by Fourier transforming the beat signal from the sensing fiber;
the processor further configured to obtain a frequency offset to calculate the distance offset at a measurement time, the frequency offset being from a peak of autocorrelation in the reference waveform to a peak of the cross-correlation between the distribution waveform and the reference waveform; and
obtain the waveform of the vibration based on the distance corrected by the distance offset.