Time Difference of Arrival 

TDOATime Difference of Arrival is a triangulation technique used in acoustic emission (AE) testing to establish the position of the source of a particular acoustic signal within the component under test. It relies on the assumptions that the source transmits sound at a constant wave speed in all directions and that there is an uninterrupted path between the source and the sensors placed to listen for the acoustic signals. By measuring the time difference of arrival of a signal at two separate sensors it is possible to identify the locus of source positions. Adding the time difference of arrival at a third sensor allows the source position to be identified as a point in a planar geometry, while a fourth sensor is required to locate the source in a volumetric geometry.

However, the assumptions inherent in the time difference of arrival technique are not always applicable in real structures. In addition, any errors in the identification and measurement of the arrival time of the signals will impact on the accuracy of the location of the source. As a result, more advanced techniques for source location have been developed and reported.

For more information on TDOA, see:

Further information on source location can be found at: Methods/AE/AE_Source 

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