  Using fiber network as a huge sensing system will enrich monitoring methods
of public infrastructures and geological disasters. With traditional
cross-correlation method, laser interferometer has been used to detect and
localize the vibration event. However, the random error induced by
cross-correlation method limits the localization accuracy, and makes it not
suitable for ultrahigh precision localizing applications. We propose a novel
time shifting deviation (TSDEV) method, which has advantages over
cross-correlation method in practicability and localization accuracy. Three
experiments are carried out to demonstrate the novelty of the TSDEV method. In
lab test, vibration localization accuracy of ~2.5 m is realized. In field
tests, TSDEV method enhanced interferometry is applied to monitor the urban
fiber link. Traffic vibration events on the campus road and Beijing ring road
have been precisely localized and analyzed, respectively. The proposed
technique will extend the function of existing urban fiber network, and better
serve the future smart city.
