Tracking the Target

the maximum range at which they can reliably detect a target and their ability to distinguish individual targets in a multi-target group. In addition, sensor subsystems must be able to detect targets in a medium cluttered with noise, which is any energy sensed other than that attributed to a target. Such noise or clutter is always present in the environment due to reflections from rain or the earth’s surface or because of deliberate radio interference or jamming. It is also generated within the electronic circuitry of the detecting device. Tracking the Target Sensing the presence of a target is an essential first step to the solution of the fire control problem. To successfully engage the target and solve the problem, updates of the target’s position and velocity relative to the weapon system must be continually estimated. This information is used to both evaluate the threat represented by the target and to predict the target’s future position and a weapon intercept point so the weapon can be accurately aimed and controlled. To obtain target trajectory information, methods must be devised to enable the sensor to follow or track the target. This control or “aiming” may be done by a collection of motors and position-sensing devices called a servo system. Inherent in the servo process is a concept called feedback. In general, feedback provides the system with the difference between where the sensor is pointing and where the target is actually located. This difference is called system error. The system takes the error and, through a series of electro-mechanical devices, moves the sensor or weapon launcher in the proper direction and at a rate that reduces the error. The goal of any tracking system is to reduce this error to zero. Realistically this isn’t possible, so when the error is minimal the sensor is said to be “on target.” Sensor and launcher positions are typically determined by devices that are used to convert mechanical motion to electrical signals. Synchro transformers and optical encoders are commonly used in servo systems to detect the position and to control the movement of power drives and indicating devices. Power drives move the radar antennas, directors, gun mounts, and missile launchers. The scenario presented in the beginning of this section was in response to a single target. In reality, this is rarely the case. The modern “battlefield” is one in which sensors are detecting numerous contacts, friendly and hostile, and information is continually being gathered on all of them. The extremely high speed, precision, and flexibility of modern computers enable the weapons systems and their operators to compile, coordinate, and evaluate the data, and then initiate an appropriate response. Special-purpose and general-purpose computers enable a weapons system t o d e t e c t , t r a c k , a n d p r e d i c t t a r g e t m o t i o n automatically. These establish the target’s presence and define how, when, and with what weapon the target will be engaged. Engaging the Target Effective engagement and neutralization of the target requires that a destructive mechanism, in this case a warhead, be delivered to the vicinity of the target (see figure 2-24). How close to the target a warhead must be delivered depends on the type of warhead and the type of target. In delivering the warhead, the 2-19 Figure 2-25. —Enemy submarine.