Conventional active sonar signal processing for multistatic fields has evolved to account for sonobuoy drift that is presumed constant as the transmission travels from source to target to receiver. Moderate to rough sea states, although attenuated by compliant elements in the deployed buoys, cause transducers to experience oscillatory motions that violate the constant drift assumption and degrade detection, classification, and localization performance. When amplitudes are large enough and oscillation periods are commensurate with the active pulse length, the degradations of echo SNR, time of arrival, Doppler, and bearing estimates can be significant. This project uses in-situ sensors to measure the unwanted sonobuoy motions induced by large ocean waves. An advanced physics based algorithm being developed under this SBIR accounts for the oscillatory motions of the source and receiver. Consequently, the sonar system can operate with little or no degradation caused by moderate to rough sea states.
