1. A defect detection system for identifying defects in weld seams having a scanning apparatus which is fitted to a movement apparatus of a processing device, with the scanning apparatus being moveable by the movement apparatus over at least one weld seam to be examined, wherein the scanning apparatus scans the weld seam at a predeterminable frequency, each scan is correlated with a time signal, with the time of the scanning of at least one defective scan point being recorded with the time signal, an analysis module is provided which determines the coordinates of the defect locations from the scan signals obtained by means of the scans, the analysis module is also intended to store the coordinates of the defect locations, and a localization module determines the spatial arrangement of the defects in the weld seam by evaluation of a velocity profile of the movement apparatus during the scans, of the time signal associated with the defective scan points, and of the coordinates of the defect locations produced by the analysis module.