Passive detection of low frequency sources using vector sensor channel cross correlation

Acoustic vector sensors consisting of an omnidirectional hydrophone and three orthogonal velocity sensors offer new opportunities for passive detection of acoustic sources at low frequencies. In the frequency range from 10 to 300 Hz, the predominant noise sources in the ocean are surface wave action and distant shipping. Omnidirectional hydrophones are affected by both noise types whereas vertically-oriented velocity sensors are more affected by surface wave action, and horizontally-oriented velocity sensors are more affected by distant shipping. Under these ambient conditions, when no source is present, the vector sensor channels have low cross-correlation levels. When a source is present, propagation conditions cause an increase in correlation between all vector channels. This increase is measurable in the magnitude and phase of the correlation coefficients between each channel pair, which forms the basis of an algorithm for detecting acoustic sources. This paper presents the response of an acoustic vec...