The above scenario is not something out of a war novel, but rather an example of a possible engagement between a hostile force (the enemy attack aircraft) and a Naval Weapons System (the ship). This scenario illustrates the concept of the "detect-to-engage" sequence, which is an integral part of the modern Fire Control Problem. Although the scenario was one of a surface ship against an air target, every weapon system performs the same functions: target detection, resolution or localization, classification, tracking, weapon selection, and ultimately neutralization. In warfare, these functions are performed by submarines, aircraft, tanks, and even Marine infantrymen. The target may be either stationary or mobile; it may travel in space, through the air, on the ground or surface of the

Figure 2-24. -Successful engagement of a missile.

sea, or even beneath the sea (figure 2-25). It may be manned or unmanned, guided or unguided, maneuverable or in a fixed trajectory. It may travel at speeds that range from a few knots to several times the speed of sound.

The term weapons system is a generalization encompassing a broad spectrum of components and subsystems. These components range from simple devices operated manually by a single person to complex devices operated by computers.

To accomplish one specific function, a complex array of subsystems may be interconnected by computers and data communication links. This interconnecting allows the array to perform several functions or to engage numerous targets simultaneously. Although each subsystem may be specifically designed to solve a particular part of the fire control problem, having these components operate in concert that allows the whole system to achieve its ultimate goal - the neutralization of the target.

COMPONENTS

All modern naval weapons systems, regardless of the medium they operate in or the type of weapon they use, consist of the basic components that allow the system to detect, track and engage the target. Sensor components must be designed for the environments in which the weapon system and the target operate. These components must also be capable of coping with widely varying target characteristics, including target range, bearing, speed, heading, size and aspect.

Detecting the Target

There are three phases involved in target detection by a weapons system. The first phase is surveillance and detection, the purpose of which is to search a predetermined area for a target and detect its presence. This may be accomplished actively, by sending energy out into the medium and waiting for the reflected energy to return, as in radar, or passively, by receiving energy being emitted by the target, as by ESM in our scenario. The second phase is to measure or localize the target's position more accurately and by a series of such measurements estimate its behavior or motion relative to ownship. This is done by repeatedly determining the target's range, bearing, and depth or elevation. Finally, the target must be classified; that is, its behavior must be interpreted to estimate its type, number, size and most importantly identity. The capabilities of weapon system sensors are measured by

Figure 2-25. -Enemy submarine.

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 to detect, track, and predict target motion 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 aiming, launch, type of weapon propulsion system, and the forces to which the weapon is subjected enroute to the target must be considered. The weapon's capability to be guided or controlled after launch dramatically increases its accuracy and probability of kill. The use of guidance systems also dramatically complicates system designs. These factors as well as the explosive to be used, the fuzing mechanism, and warhead design are all factors in the design and effectiveness of a modern weapon.

Q9. What is the sequence of events in fire control that begins with the initial detection of an enemy target and ends with the destruction of that target?

Q10. What phase of target detection estimates the type, number, size, and identity of a target? SUMMARY

This chapter has given you an overview of many of the radar systems used in today's Navy. The goal of this chapter was not to tell you about every radar system or every detail of every radar system, but to simply explain what radar systems are found on which ships in the Navy and on what types of ships you will find various radar systems.

One of the key tools used for the "detectto-engage" scenario is radar systems. Understanding how your ship accomplishes the detect-to-engage scenario is extremely important to every Fire Controlman. Doing so will give you a clear, firm grasp of what your ship does in a battle scenario and how you fit in the big picture of naval warfare for your ship. You should also understand the fire control problem in relationship to this scenario. The detect-to-engage process and fire control problem work together to accomplish the goal of destroying an enemy target. Each ship has its own, unique configuration of weapons and radar systems; it is your responsibility as a Fire Controlman to learn how these work together in the detect-to-engage sequence and the fire control problem.

ANSWERS TO CHAPTER QUESTIONS

Al. Variation infrequency.

A2. TICONDEROGA class cruisers and ARLEIGH BURKE class destroyers.

A3. The ANISPG-62 radar.

A4. Air, ,surface, and beacon.

A5. The Mk 91 Guided Missile Fire Control System..

A6. The Perry class frigate.

A7. Non-AEGIS ships.

A8. A shipboard electro-optical system.

A9. Detect-to-engage.

A10. The classification phase.