Pier-Side, Bow Sonar Calibration Methodology for Wave Piercing Hull Forms

Existing near-field calibration methods for cylindrical MF and HF bow arrays are not easily applied to combatant ships with complex hull forms. The objective of this proposed project is to develop and deliver a cost effective in-situ system for providing sonar transducer acoustic calibration and quality monitoring. The output is a sonar element calibration or verification that will be fed into an array analysis program. The degradation in array performance due to the failure or performance decrease (as might be due to aging, delamination, flooding, shock, etc.) of individual transducer elements will be ultimately predicted with an array performance model. Our proposed method is called the VIP-Delta-Z method and is based on measuring the voltage, current and phase (VIP) of elements within the array to determine the complex admittance or impedance (see “On the methods of experimental investigating of acoustical interaction between transducers,” Boris Aronov, J. Acoust. Soc. Am., Published, June 2006). The method involves measuring the mutual radiation impedances between elements in the array, which will permit a self calibration and monitoring of changes to the impedances (Delta-Z) as a function of time or different electrical and acoustical loading conditions.