Experimental study for feature extraction of diver with atmospheric diving suit

To find acoustic signature of diver equipped with atmospheric diving suit (ADS), a logarithmic normalized frequency-domain multi-band matched-filter (LNMF) algorithm is presented, which can mitigate the influence of the background noise and short-duration transient interference. Based on experimental study, test data of a diver equipped with ADS was recorded and analyzed in time-domain, frequency-domain and time-frequency domain, and the results showed that the diver's exhaust periodicity is about 5s, diver acoustic characteristics are a wide frequency spectrum, the band width is about 60kHz during the exhaust phase. The exhaust repetition frequency of a diver with ADS was extracted using the proposed algorithm. The experimental results show the exhaust repetition frequency is about 0.2Hz, which corresponds to the exhaust rate of the diver with ADS, and verify the effectiveness of LNMF on exhaust frequency feature extraction in a complex underwater environment. In addition, statistical analysis results of the exhaust repetition frequency are in the interval between 0.13Hz to 0.2Hz. The proposed algorithm can also be used to diver with open circuit breathing systems.