The purpose of a tracking system is to determine the location or direction of a target on a near-continuous basis. An ideal tracking system would maintain contact and constantly update the target's bearing (azimuth), range and elevation. The output of the tracking system can be sent to the receiving system, which stores the information and derives the target's motion and therefore its future position. As we shall see, tracking systems not only provide an automatic target following feature but also determine the target's position with sufficient accuracy for weapons delivery. Radar Servo Tracking System
One of the most basic tracking system designs is the servo tracking system. Here, the radar antenna is initially directed on a target after which it automatically remains pointed at the target as it follows its motion. Furthermore, the system provides continuous position information to the operator. The antenna is rotated by a motor which provides a negative position feedback signal to a controller. This subsystem is known as a servo-mechanism. Fig. 1 shows a basic servo-mechanism system used in radar system.
Figure 1. Servo mechanism system
Operation servo-mechanism system:
(i)The commanded input signal is the desired azimuth of the antenna. (ii)The error signal drives the motor to reposition the antenna until the position feedback indicates the antenna is at the desired azimuth, at which point the error signal is zero and the motor stops. (iii)This servo-mechanism can be combined with a tracker, which determines the azimuth at the target, which the system now uses as the input.
Figure 2. Servo tracking mechanism.
Operation of radar servo-tracking system:
(i)This is the same servo-mechanism block diagram, but its input comes from the tracker. The combination is called a radar servo-tracking system. (ii)The heart of this system is the tracker, which takes the return signal and position information and determines the...
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