WHY TRACKING AND PREDICTION ARE NEEDED IN A RADAR Let us first start by indicating why tracking and prediction are needed in a radar. Assume a fan-beam surveillance radar such as shown in Figure . For such a radar the fan beam rotates continually through 360 , typically with a period of 10 sec. Such a radar provides two-dimensional information about a target. The first dimension is the target range (., the time it takes for a transmitted pulse to go from the transmitter to the target and back); the second dimension is the azimuth of the target,. | Tracking and Kalman Filtering Made Easy. Eli Brookner Copyright 1998 John Wiley Sons Inc. ISBNs 0-471-18407-1 Hardback 0-471-22419-7 Electronic 1 g-h AND g-h-k FILTERS WHY TRACKING AND PREDICTION ARE NEEDED IN A RADAR Let us first start by indicating why tracking and prediction are needed in a radar. Assume a fan-beam surveillance radar such as shown in Figure . For such a radar the fan beam rotates continually through 360 typically with a period of 10 sec. Such a radar provides two-dimensional information about a target. The first dimension is the target range . the time it takes for a transmitted pulse to go from the transmitter to the target and back the second dimension is the azimuth of the target which is determined from the azimuth angle see Figure the fan beam is pointing at when the target is detected 1 . Figures through show examples of fan-beam radars. Assume that at time t 11 the radar is pointing at scan angle d and two targets are detected at ranges R 1 and R 2 see Figure . Assume that on the next scan at time t 11 T . 11 10 see again two targets are detected see Figure . The question arises as to whether these two targets detected on the second scan are the same two targets or two new targets. The answer to this question is important for civilian air traffic control radars and for military radars. In the case of the air traffic control radar correct knowledge of the number of targets present is important in preventing target collisions. In the case of the military radar it is important for properly assessing the number of targets in a threat and for target interception. Assume two echoes are detected on the second scan. Let us assume we correctly determine these two echoes are from the same two targets as observed on the first scan. The question then arises as to how to achieve the proper association of the echo from target 1 on the second scan with the echo from 3 4 g-h AND g-h-k FILTERS Figure .
