Abstract:

A signal processing algorithm that utilizes coherent addition of the acoustic pressures usually provides greater noise suppression with a corresponding increase in signal-to-noise ratio (SNR) than one that uses incoherent addition. Furthermore, fluctuation based processing (FBP) algorithms that are designed to operate on signals from submerged sources (i.e., small fluctuations) generally utilize incoherent averaging techniques to provide various enhancements over conventional algorithms that are also incoherent, including greater SNR, increased resolution, clutter suppression/elimination, and unalerted auto-detection/classification (submerged/not-submerged). An algorithm that combines the desirable features of the coherent approach and the incoherent FBP approach could possess desirable features of both types of algorithms and be very useful for enhancing the processor's performance. Such an algorithm has been devised. It operates on the combined amplitude and phase fluctuations in the acoustic pressures in a semicoherent manner to substantially improve the processor's performance. The algorithm will be defined, and results from measured undersea data will be presented to illustrate the gains that are achieved by this new algorithm. [Work supported by ONR and NRL.]