Detection of Ship Propeller Tonals

The noise produced by the cavitation of the propellers is the main acoustic signature used to detect and classify the ships in underwater recordings. Propeller noise exhibits cyclostationarity and creates acoustic traces called tonals which depends on the characteristic of the propellers and can be detected by using Integrated Cyclic Modulation Coherence (ICMC) method. However, ICMC does not contain information about time. So, we propose a visual tool named ICMC-gram, which allows to examine the changes in cyclic frequencies over time and show its application on real data collected from the Sea of Marmara.