Design of multi‐input interleaved multisine excitation signals for ultrasonic testing

Multisines are periodic signals consisting of harmonically‐related sine waves. By optimizing the phases of the different sine waves, a periodic signal is obtained with a small crest factor resulting in high signal‐to‐noise ratios. One disadvantage of multisines when several ultrasonic actuators are used simultaneously is that, in general, it is very difficult to distinguish from a measured ultrasonic signal the contribution of the different actuators. This is easier when pulses are used and when they do not overlap. In this contribution, a new approach for periodic continuous wave signals will be presented to separate the contribution coming from the different actuators (senders) at every receiver. The proposed approach is based on the use of multi‐input interleaved multisines. Interleaved multisines contain energy at different spectral lines allowing an easy separation by means of a discrete Fourier transform. The separation becomes more complex when non‐linear effects are present, but even then it is po...