Detection of Surface Ships From Interception of Cyclostationary Signature With the Cyclic Modulation Coherence

This paper addresses the problem of passive detection of surface ships from radiated propeller noise in the far field. This is traditionally accomplished by means of envelope analysis, a largely empirical technique. The first contribution of the paper is to give a formal justification why this approach is sound based on the cyclostationary modeling of propeller noise. Pursuing along similar lines, the paper proposes a new statistical test based on the recently introduced cyclic modulation coherence (CMC), which is close to optimal in detecting cyclostationary noise, while at the same time being easy and extremely fast to compute. Detection capability is thoroughly investigated as a function of the blade pass frequency and other parameter settings. Finally, the cyclostationarity framework makes possible the proposal of a closed-form statistical threshold that opens the way to automatic detection.