Fraunhofer Institute for Nondestructive Testing IZFP 
Use of coded excitation to optimize the correlation properties of ultrasonic signals
In this research area, methods and applications are investigated that optimize existing NDT methods in connection with coded ultrasound in terms of speed, interference immunity and accuracy.
The encodings include frequency and amplitude modulation, both separately and in combination. In addition, the applicability in existing ultrasonic systems or a necessary extension or adaptation is discussed in more detail.
The application spectrum ranges from simple methods, such as wall thickness determination, to modern, complex methods such as full matrix capture and total focus.