The bounded geometry of the experimental setup used to measure the directivity and sensitivity of array elements may raise several difficulties. In order to obtain the frequency response of wideband elements, the most straightforward method would be to transmit short pulses, and then to derive the transfer functions by applying Fourier transforms to the received signals. Unfortunately this approach often leads to poor signal-to-noise ratios within each frequency band because the amplitude of the transmitted pulse is limited. The usual solution consists of measuring the frequency responses by means of successive harmonic pings. However, the duration of such signals is also limited because of the possible interference between the waves following the direct path and those occurring from reflection with the tank envelope. The delays between the times of arrival are as much shorter as the distance between the source and the array to be calibrated is large. On the other hand, this distance must be sufficient to have an acoustic field that is uniform in the receiving area, and also to limit the parallax effect. The balance between these competing parameters leads to configurations where the direct signal and the first specular echo are as close as possible before overlapping. In order to properly derive the transfer functions, it is therefore mandatory to be able to delineate precisely the boundaries of the signals received from the direct path. We present here a reliable method for tracking these signals.