Large Aperture Acoustic Array
Abstract
A large aperture acoustic array for investigating the spatial distribution of low frequency ambient noise has been designed, built and deployed from Research Platform FLIP in the NE Pacific. Design constraints of such an array include a large dynamic range to accommodate the absolute levels encountered within this band and a large aperture with many elements to achieve good spatial resolution at low frequencies. Deployed vertically, the large aperture subjects the array to an inhomogeneous current field which necessitates the implementation of a navigation subsystem for estimating the array shape prior to beamforming. Navigation results show that the array is nearly vertical, responding to wind, tides, internal waves and surface motion. Knowledge of the individual element response is also required for accurate beamforming, thus a system calibration must be executed. An intimate understanding of the array as a measurement system is required for accurate analysis of the data it collects. Due to the constraints imposed by the physical size and number of elements, an in-situ method was utilized to evaluate array system performance and characterize the response of individual elements. Acoustic measurements recorded during the passage of a local storm, provide a unique opportunity to investigate the impact of the wind driven source mechanism on the structure of the low frequency noise field. Beamformed data illustrate the detailed spatial structure of low frequency noise.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 01, 1989
- Accession Number
- ADA215541
Entities
People
- Barbara J. Sortirin
Organizations
- Scripps Institution of Oceanography