Horizontal Linear Array Sensor Localization and Preliminary Coherence Measurements from the 2001 ASIAEX South China Sea Experiment

Theodore Schroeder, S.M., 2002
James Lynch, Advisor

Arrays obtain their gain by coherently adding the energy that impinges on them. To maximize the efficiency of an array, the size of the aperture over which the signal remains coherent is needed. Scattering of sound by the ocean environment reduces the coherence of acoustic signals, and thereby limits the useful aperture of an array. This thesis examines data collected in the South China Sea (SCS) component of the 2001 Asian Seas International Acoustic Experiment (ASIAEX), where a Horizontal Linear Array (HLA) was deployed on the continental shelf to study transverse array coherence in a coastal environment. 224 Hz and 400 Hz sources were placed on the continental slope and a 400 Hz source was placed on the shelf to provide up slope and along shelf propagation paths. In this thesis, sensor-to-sensor correlations of one day of transmissions from these three sources were completed to give a first look at coherence lengths of the HLA. The thesis also analyzes the data from the Long Base Line (LBL) navigation system and two days of light bulb drops to provide array sensor localization. Accurate sensor positions are needed to determine the correlation versus sensor separation distance and ultimately the array coherence length.