Design and Operational Features of the SCAN-100 Collision Avoidance System

Abstract

The scan-100 collision Avoidance System (CAS) has been designed to assist in the avoidance of collision at sea by automating the radar plotting functions in a small digital computer linked to the ship's radar. A clear and easily understandable display is provided to present numerical data and computer-generated plots to the ship's officer for evaluation of the radar data and for planning a safe and timely action to avoid collisions. This paper discusses the system design philosophy as implemented and tested in an engineering prototype of the SCAN-100 CAS. This philosophy utilizes an integrated man-machine concept which employs the best capabilities of each. The routine functions of radar tracking and plotting are performed by the system, which then presents the information to the operator in the form of displays combining graphic plots and numerical data. Automatic alarms are provided by the computer, one based on closest-point-of-approach (CPA) and another based on target arrival at a guard-ring distance. A vital requirement for the effective operation of such a radar-based system is the processing of radar data prior to tracking. In particular, the system must distinguish between receiver noise, sea clutter, and valid targets. The SCAN-100 uses a radar preprocessor, especially designed for this purpose, as well as computer processing to achieve the necessary radar signal enhancement. Several aspects of this processing technique are discussed in the paper. The system has recently undergone testing. Results of these tests are also described.