Adaptive motion compensation in sonar array processing

In recent years, sonar performance has mainly improved via a significant increase in array ap-erture, signal bandwidth and computational power. This thesis aims at improving sonar array processing techniques based on these three steps forward. In applications such as anti-submarine warfare and mine hunting motion of the sonar needs to be accounted for. For towed anti-submarine warfare sonar, beamforming methods are developed for the port/starboard (PS) discrimination problem and for Doppler compensation. In mine hunting, synthetic aperture sonar (SAS) is a promising technique to improve sonar performance by combining of multiple pings. Efficient imaging techniques with adequate motion compensa-tion are examined to control the data flow. Each processing method is implemented, tested and assessed. For the PS discrimination prob-lem three beamformers are investigated. These beamformers and the Doppler compensation methods are investigated theoretically, with simulations and with datasets recorded at sea. For mine hunting a complete SAS processing chain with motion estimation, motion compensation and imaging is developed. It is tested on simulations and on five independent experimental datasets. The processing techniques proposed substantially improve sonar performance. Triplet tech-nology is a successful solution for the PS discrimination problem. The ambiguous direction is sufficiently suppressed with the beamformers proposed. The requirements for Doppler com-pensation are derived analytically and are met without complicated adaptations. The SAS re-search showed that for the cases considered, wavenumber frequency imaging is preferred when using adequate motion compensation. A key-finding while comparing the imaging algo-rithms was enhancement of an important sonar classification clue, the acoustic shadow