Abstract: In a method for the automatic inspection of a welding seam using heat flow thermography, a feature vector is established which represents a time course of a detected heat flow. The feature vector is used to determine, from a series of thermal images, a first characteristic thermal image, which corresponds to a minimum heat flow through an object to be examined, and a second characteristic thermal image, which corresponds to a maximum heat flow through the object, wherein a heat flow directly from an excitation source has already dissipated. A suitable thermal image is used from the series of thermal images to detect and evaluate the welding seam in relation to defects of various defect types, for each defect type, the characteristic thermal images being used as references to determine the respective suitable thermal image.

Abstract: In a method for the automatic inspection of a welding seam using heat flow thermography, a feature vector is established which represents a time course of a detected heat flow. The feature vector is used to determine, from a series of thermal images, a first characteristic thermal image, which corresponds to a minimum heat flow through an object to be examined, and a second characteristic thermal image, which corresponds to a maximum heat flow through the object, wherein a heat flow directly from an excitation source has already dissipated. A suitable thermal image is used from the series of thermal images to detect and evaluate the welding seam in relation to defects of various defect types, for each defect type, the characteristic thermal images being used as references to determine the respective suitable thermal image.

Abstract: Digital signals are commonly transmitted using the single-carrier method or the multicarrier method, for example. Both methods use one carrier frequency per transmission channel or subchannel of predetermined bandwidth. According to the invention, at least two carrier frequencies (f1, f2, f3) are used to increase the transmission capacity of a channel. The distance between two carrier frequencies is less than the absolute value of a carrier frequency (f1, f2, f3) by a factor of, e.g., 500. The beat frequency resulting from the combination (ADD) of several carrier frequencies (f1, f2, f3) in a channel is negligible, particularly if the transmitted carrier frequencies (f1, f2, f3) are in phase at the start of oscillations. By the combination (ADD) of several carrier frequencies (f1, f2, f3), equal resulting carrier frequencies can be obtained for different bit streams (DATA1, DATA2, DATA3).