Comparison Between Time Shifting Deviation and Cross-Correlation Methods.

Time delay estimation (TDE) is an important step in identifying and locating vibration sources. The TDE result can be obtained by the cross-correlation method through seeking the maximum correlation peak of two signals. However, the cross-correlation method will induce random error when dealing with the nonstationary signal. We propose a novel time shifting deviation (TSDEV) method to solve this problem, which has been proven to achieve ultrahigh-precision localization results in the fiber vibration monitoring system. This paper compares the TSDEV method with cross-correlation in detail by simulating the TDE process in different conditions, such as signals with arbitrary intercepted length, nonstationary drift and correlated noise. In addition, an experimental demonstration was carried out on a 60 km fiber to localize a wide band vibration signal. The typical localization error is 3.0 m with a standard deviation of 23.0 m using the TSDEV method. It stands in clear contrast to the result of cross-correlation method, whose localization error is 76.3 m and the standard deviation is 216.5 m. Compared with cross-correlation method, TSDEV has the same resistance to white noise, but has fewer boundary conditions and better suppression effect on linear drift or common noise, which leads to more precise TDE results. [ABSTRACT FROM AUTHOR]