Signification and Use of A-scan Images
© ElektroPhysik
QuintSonic 7
55 von 184
limits should be set in a way that the following requirements can be met: On the one hand, the
clipping limits must efficiently include the of noise components, on the other hand, the desired
signal components must clearly be higher than the clipping limits (see fig. above). The different
clipping methods enable a good adaptation to both: noise components being asymmetrical to the
zero line and to noise components of a strength varying over the time.
Sometimes adjacent layers are very similar with respect to their acoustic properties. Hence, the
sound reflections at the layer interfaces is very small. In such case, a compromise must be found
between noise floor suppression and non-suppression of the layer interface reflections. The
parameter setting must ensure to maintain all layer interface reflections. Any remaining
components of the noise floor can be suppressed later on by means of the post processor (see
section 8.5).
7.3.3.3
Layer interface echoes
Example: Layer interface echoes
Once the clipping parameters have been set correctly, apart from the coupling echoes, only the
layer interface echoes remain after the preprocessor procedure has been carried out. These
echoes will be fed to the subsequent post-processing procedure to finally give the coating
thickness values.
In some measuring objects exhibiting blowholes, inclusions or other material discontinuities in a
layer, additional echoes may occur that do not represent a layer interface. Please refer to section
7.3.3.5 for further details on such echoes.
Echoes at layer interfaces are numbered from the left to the right. The reference number
corresponds to the single coating thickness values as shown on the left of screen.
Layer interface
echoes