Fig. 6. Plots of measured (red circles) and simulated (lines) waveforms of a probe submerged in water to different depths. The top chart is of the 251-point waveform with optimized cable-tester resolution; the bottom chart shows the 1024-point measurements with fixed cable-tester resolution. The waveforms marked with the letter a are difficult to analyze with the algorithm by Heimovaara and Bouten (1990). The first reflection of waveform marked with the letter t is not identified correctly by the tangent analysis method.