Homomorphic Processing in Ultrasonic NDE

Modern signal processing techniques used in computing flaw impulse response are based on comparative analysis of a reference signal with the signal scattered from flaws. The underlying hypothesis in these techniques is that, in the noise free case, the scattered flaw signal is due to the linear convolution of the ultrasonic reference signal with the flaw impulse response. The flaw characterization problem thus reduces to determining the kernel of the convolution integral given the input and output time signals. The impulse response recovery (system identification) has been carried out both in the frequency and time domains for flaw characterization.1–3