The ability to identify overlapping echoes is crucial to the enhancement of temporal resolution in ultrasonic testing. The majority of the techniques currently being investigated for separation of overlapping ultrasonic echoes are based on deconvolution. However, single reference deconvolution techniques are sensitive to the choice of the reference waveform and dictionary based deconvolution techniques require the enforcement of sparsity conditions. We propose a new post-processing algorithm that exploits the consistent frequency domain amplitude and phase relationships of two overlapping echoes. The frequency amplitude profiles are used as inputs and the corresponding set of phase values are calculated as the outputs. An example of the time profile and phase difference between two overlapping echoes are shown in Figure 1. The suitability of the output phase responses are then used as a metric to determine the accuracy of the trial amplitude inputs. Compared to dictionary based deconvolution approaches, the proposed method has a reduced search space in the optimization problem as the phases are now by-products of the algorithm. Compared to single reference deconvolution schemes this method is applicable to a much wider variety of echo combinations.
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