Fault Detection Algorithm of Acoustic Inspection System for Underground Telecommunication Conduit

This paper describes afault detection algorithm from acoustic reflection waveforms. The purpose of the proposed algorithm is to detect a fault in a telecommunication conduit from abnormal changes in its cross sectional area. To detect such a abnormal changes, we demonstrate a technique for reconstructing the pipe shape directly from the impulse response of the acoustic reflection dynamics. This algorithm enables a rough reconstruction of the cross sectional changes to be obtained. Examples of pipe shape reconstruction are given, for a numerical simulation and for a telecommunication conduit damaged by the earthquake.