Enhancement of the tonal components of vessel acoustic signatures

Investigator: Robert Mill Supervisor: Guy J Brown

High-resolution frequency analysers are used in sonar systems to detect and measure the tonal structure of a vessels acoustic signature. The resulting tonal set can be used to assist in the classification of the vessel. Frequency analysis is currently achieved using the Fourier transform. The study should examine optimised Fourier transform based techniques aimed at achieving enhanced tonal detection in Gaussian and ambient sea noise environments. The study should also include the investigation of alternative signal analysis techniques that may be effective in the detection and measurement of tonal signals in noise.

The performance of these narrowband analysis systems is often degraded by the presence of repeated, impulsive, broadband noise sources. This study will examine techniques that are able to suppress the effects of these impulsive signals to allow the optimum detection of the narrowband signals to be maintained.

An important aspect of narrowband detection is the association of multiple narrowband tonal signals that originate from the same source. These are generally harmonically related and often exhibit related frequency shifts due to Doppler effects. The study should also examine the feasibility of detection enhancement by the synchronised exploitation of these related tonal signals.

Project funded by QinetiQ.