Experimental study on target characters of divers

Experimental results of diver´s time-frequency characteristics such as target strength, radiated source level, breathing sound power spectrum and envelope spectrum are presented in this paper, which provide significant references to the development of diver detection systems. Target strength was measured using different incident wave frequencies, while the diver maintained different orientations. Power spectrum and envelop spectrum of diver´s exhalations were employed to analyze the characteristics for the sound of breathing in different frequency bands and at different breathing cycles. The results show that the oxygen tank contributes more to target strength than lung and breathing bubbles. The results also indicate that the characteristics of breathing sound vary in frequency band and high frequency band is better suited for diver detection. One of the findings of the experiment is that the diver detection improves when the breathing cycle of the diver increases.