Pseudo random binary sequence techniques for ultrasonic NDE of high loss materials

To extend the applicability of ultrasonic NDT to structures containing acoustically lossy materials requires both an improvement in electrical signal to noise ratio and the matching of the acoustic wave spectral content to the acoustic characteristics of the structure. Pulse compression is capable of providing both of these improvements and with the increasing power of digital signal processing hardware with near real time operation. The flexibility offered by digital signal processing techniques allows filtering operations to be performed which are impossible using analogue methods. Ultimately the high acoustic losses associated with many polymers of engineering significance will limit the size of structures it is possible to interrogate using ultrasonic techniques.