A periscope detection radar

Detection of small cross-sectional periscopes with short, transient exposure periods requires a radar system with a sensitive detection threshold. Airborne radar detection systems were designed to provide such a capability in the open ocean. In littoral regions, however, these systems are manually intensive, and operators are overwhelmed by the numerous objects detected. The Automatic Radar Periscope Detection and Discrimination Program was implemented to automate the detection of transient periscope exposures while maintaining an extremely low false alarm rate. The approach incorporates a high-resolution radar with a two-stage periscope declaration process: conventional target detection with a moderate false alarm rate followed by signature discrimination to reduce the false alarms. Detected objects and persistent ocean clutter spikes are identified and eliminated by their spatial and temporal characteristics that differ from periscope signatures. This article discusses techniques used to achieve a sensitive detection threshold and resultant clutter spike false alarm rates. Theoretical analysis, radar data analysis, and radar emulation results are presented. (Author)