[jaden]

There are two main disadvantages;

1) It requires much more flexibility in the excitation hardware, ideally the signal source and/or amplifier needs to be able to generate arbitrary waveforms. This is not typically possible with conventional UT hardware (basic pulsers).

2) The received signal must also be post-processed (digitally) before it can be viewed. Although this is not such as huge disadvantage since this is also the case for many modern NDT methods (e.g. FMC TFM).