The Effect of Spectral Normalization on Beamformed Passive

The Effect of Spectral Normalization on Beamformed Passive Sonar Data ANNE BRAY, DA NIEL TE

Table of Contents • Motivation • Recorded Hydrophone Data • Hydrophone Positions • Passive Sonar Equation • Spectral Analysis • Normalization • Question and Hypothesis • Materials and Methods • Data Results/Progress • Future Plans • Bibliography

Motivation • 71% of the world is covered by oceans • Sonar systems are vital to the exploration of these regions • Passive sonar doesn’t harm the ecosystem • Hydrophone arrays can detect acoustic sources such as: • Ships (useful to the military) • Underwater Earthquakes (disaster detection) • Sea creatures, such as whales • Underwater volcanic activity

Recorded Hydrophone Data Workboat • Lockheed Martin provided data • 38 hydrophone array (230 meters long) • Located in Puget Sound, Washington Array • Originally recorded on tape (not scotch tape) • Processing Tape 11 • A workboat hosted the recording system Array

Hydrophone Positions

Question • How much do normalization techniques enhance the spectral analysis of beamformed hydrophone data? Hypothesis • If spectral normalization techniques are applied to beamformed data from a hydrophone array, then narrowband signal detection will improve by three decibels in cluttered acoustic environments.

Spectral Analysis

Normalization • To equalize data to a common reference (typically zero)

Materials and Methods • MATLAB • Data from a 38 hydrophone array deployed in Puget Sound, Washington • Approaches • Split Window Normalizer • Two Pass Mean/Three Pass Mean • Harmonic Mean

Data Results/Progress • Spectrograms • Basic beamforming • Anomalies in data • Three Pass Mean

Future Plans • Test out more normalization algorithms • Analyze results and determine the best one

Bibliography • Haynes, T. (1998). A Primer on Digital Beamforming. Retrieved October 11, 2016. • Piper, J. E. (2011). Beamforming narrowband broadband signals. INTECH Open Access Publisher. • Struzinski, W. A. , & Lowe, E. D. (1984). A performance comparison of four noise background normalization schemes proposed for signal detection systems. 76(6), 1738 -1742. Retrieved September 29, 2016. • Technology, C. (1998). Principles of Sonar Beamforming. Retrieved September 15, 2016. • Theory of Operation of Hydrophones. (n. d. ). Retrieved October 11, 2016, from http: //www. ondacorp. com/tecref_tutorialhydrophone_theory. shtml • Shapiro, J. H. , & Green, T. J. (2000). Performance of split-window multipass-mean noise spectral estimators. IEEE Transactions on Aerospace and Electronic Systems, 36(4), 1360 -1370.