Radar Measurement and Tracking

While radar search and target detection are essential to radar use, most applications also require measurement of target characteristics. These may include target position and velocity, as described in Sections 8.1 through 8.3, and indicators of target size, shape and rotation, as described in Section 8.4. The use of multiple radar to improve measurement accuracy is discussed in Section 8.5. Combining radar measurements into target tracks, issues associated with radar tracking, and tracking methods are discussed in Sections 8.6 and 8.7. Radar can provide measurement of target position in range and in two angular coordinates, relative to the radar location. The angular coordinates are usually defined as elevation angle relative to the local horizontal, and azimuth, which may be measured relative to true north, or for phased arrays, relative to array broadside azimuth. This measurement geometry is illustrated in Figure 8.1. Radars employing coherent processing may also directly measure the target radial velocity. To measure target characteristics, the target must be resolved by the radar. This requires that the target be separated from other targets by the radar resolution in at least one of the measurement coordinates [1, pp. 3–6]. Radar resolution in angle is usually defined by the beamwidth in two orthogonal angular coordinates, usually azimuth and elevation (see Section 3.2). The required target separation, D, in an angular coordinate, often called cross-range separation, is given by: