BASICS

BASIC RADAR CONCEPTS The term radar is an acronym made up of the words radio, detection, and ranging. It refers to elec- tronic equipment that detects the presence, direction, height, and distance of objects by using reflected electromagnetic energy. The frequency of electromag- netic energy used for radar is unaffected by darkness and weather. This permits radar systems to determine the position of ships, planes, and landmasses that are invisible to the naked eye because of distance, dark- ness, or weather. Radar systems provide only a limited field of view and require reference coordinate systems to define the positions of detected objects. Radar surface angular measurements are normally made in a clockwise direction from true north, as shown in figure 1-1, or from the heading line of a ship or aircraft. The actual radar location is the center of this coordinate system. Table 1-1 defines the basic terms in figure 1-1 that you need to know to understand the coordinate sys- tem. 1-1