Adaptive beamformer sample support for LFM high duty cycle sonar using dechirp

High duty cycle sonar is of interest in anti-submarine warfare due to its high update rate. As with any active sonar application, strong energy from the direct blast transmit, as well as volume and bottom reverberation can limit detection performance. The application of adaptive beamforming algorithms is limited due to the non-stationary time-frequency behavior of the active transmit. In this work, we present an approach for pre-aligning the acoustic element data in the time-frequency space using dechirp processing prior to the adaptive algorithm. Results are presented on data from the Littoral Continuous Active Sonar (LCAS-15) experiment. Results demonstrate effective mitigation of beamformer artifacts and improved spatial containment of reverberation energy.