A Continuous Wavelet Transform Based Time Delay Estimation Method for Long Range Fiber Interferometric Vibration Sensor

We propose a time delay estimation (TDE) method based on a continuous wavelet transform (CWT), which can be applied to the different-wavelength-based fiber interferometric vibration sensors. Using a CWT-based characteristic extraction algorithm, we successfully eliminate the asymmetry of the interference outputs that would seriously deteriorate the positioning accuracy of the sensor. A positioning measurement experiment using an asymmetric dual Mach-Zehnder interferometric sensor was carried out to verify the effectiveness of the proposed method. The experiment achieved a positioning accuracy of 0.029% at the sensing length of 85 km, with a mean processing time of 591.2 ms.