Waveform performance and sidelobe reduction techniques for continuous active sonar (CAS)

Abstract

The ability to conduct surveillance and tracking of targets over a wide area necessitates the use of a distributed sensing network and an appropriate processing scheme. One such technique that may be appropriate for the target tracking problem is continuous active sonar (CAS). In September 2016, an experiment was performed in Narragansett Bay, RI, to assess the performance of CAS for tracking a single unmanned underwater vehicle (UUV). PN sequence-coded chirps and LFM pulses of various bandwidths and center frequencies were transmitted from one transducer and received at two hydrophones in different locations. Following the experiment, several range-doppler sidelobe reduction techniques were experimented with to improve target detections and range-doppler estimations. During processing, waveform properties critical to sidelobe reduction performance were identified, and new waveforms have been chosen which exhibit these properties. A new experiment will be conducted in the coming months to demonstrate the performance of these waveforms, and results are expected to show improved detections and range-doppler estimations for various targets.