Covert sonar tracking

Applying covert sonar tracking using low probability of intercept (LPI) sonar systems to the torpedo attack problem where a torpedo tracks and intercepts a target has the potential to improve attack success. Using realistic simulations of the ocean environment and acoustic interactions, we show that the maximum likelihood-probabilistic data association (ML-PDA) algorithm is well suited to this problem. Previous ML-PDA implementations used a multi-pass grid search to find the maximum of the log likelihood ratio. Use of either a genetic algorithm or a newly developed "intelligent search" algorithm is shown to be significantly more efficient making possible real-time implementation. Reliable tracking down to 5dB (postprocessing SNR: in a resolution cell) using a 10-frame sliding window is demonstrated, this being 3.5 dB better than the multi-pass grid search. The ML-PDA algorithm is also shown to be effective in tracking the target through realistic maneuvers