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

The DD(X) destroyer relies on sophisticated, dual frequency bow sonar for mine-avoidance, ASW, and torpedo defense. Existing approaches to in situ bow sonar calibration that use booms to extend hydrophones beyond the sonar, along with legacy nearfield-to-farfield projection algorithms, will not work for DD(X) due to the ship’s strict radar cross section requirement and unique hull and sonar array shapes. Here we propose an innovative calibration system for the DD(X) bow sonar’s mid- and high-frequency components - both transmit and receive - which can be utilized pierside or in a harbor setting. The proposed system features three main components: a nearfield transducer array used to measure the sonar’s transmitted fields and to ensonify the sonar’s receivers; algorithms to accurately project the nearfield responses to the farfield; and an acoustic positioning system which eliminates the need to fix the nearfield array to the hull. The nearfield array is comprised of multi-mode transducers, which can operate in both omnidirectional and dipole modes. In Phase I, we’ll mature the proposed algorithms, develop a preliminary system design, and specify deployment and quality control concepts.