Bioinspired Low-Frequency Material Characterisation
Figure 3
Time domain signals acquired for 40 mm thick polypropylene (PP), polyvinylchloride (PVC), and brass targets; (a) transmitted signals with water signal shown for reference, (b) reflected signals, and (c) Frequency spectra for the different signals received through water: normalised spectra for the linear frequency-modulated (LFM) chirp and zero phase (ZPH) ladder chirp.
