A weapon, however powerful, is only as good as its accuracy. The process by which a projectile, missile, bomb, or torpedo is guided to its target is called weapon control. A potential target is first detected by a sensor (radar, sonar, or lookout). It is then evaluated, either by human judgment, or by computer, or by a combination of the two. If the target is evaluated to be hostile, a decision is made, according to prescribed weapons doctrine, whether or not to engage. If the target is to be engaged, the appropriate weapon is selected. All available information is assimilated to produce a weapon-control solution that will guide the weapon to contact. The weapon is then fired.
Weapon systems and their components are identified by a “Mark” and “Mod” (modification) system. A new weapon system may be designated the “Mark 22” system, for example. If it is later modified, the improved system would be called the “Mark 22 Mod 1” (Mk 22 Mod 1) system.
Before electronics arrived on the scene, enemies were detected and aimed at using the human senses, primarily the eyes. Modern weapons rely on electronic systems for detection of targets and to control weapons. Most common are radar and sonar. Both operate on the same principle but differ in the medium used.
In its most elemental form, radar (radio detection and ranging) uses a transceiver to send out (transmit) a radio-like electronic signal that reflects off a target and then returns the signal to a receiver where a very accurate timing system measures the amount of time that the signal took to travel to and from the target and, using the known speed of the signal, calculates the range to the target. A built-in direction-finding system also provides a bearing (direction) to the target.
Sonar works on the same principle, except that the signal used is sound rather than radio waves. Because radio signals work well in air and sound is more effective underwater, radar is used effectively in the detection of surface or air targets, but sonar is the sensor used in the detection of subsurface (underwater) targets.
Radar, sonar, and other Navy electronic equipments are identified by the joint electronics type designation system. This system was originally called the “Army-Navy nomenclature system” and still retains the prefix identifier “AN” (for “Army-Navy”). The rest of the designation consists of three letters plus a number. Each letter tells you something about the equipment and the number is the series number. For example, using Table 15.1, you can see that the designation AN/SPY-1 describes a multifunction (Y) radar (P) that is installed on surface ships (S). It is the first in the series of this type of radar, hence the number 1. If another radar of this type is later developed, it will be the AN/SPY-2.
Ships, aircraft, and submarines all incorporate various types of weapon-control systems. Surface- and air-search radars have been continuously improved since World War II to detect high-performance targets at long ranges in any weather. The newer surface-ship control systems work with guns and missiles, and include radars and digital computers that can quickly acquire and track targets while directing shipboard weapons.
The Mark 86 fire-control system is used in destroyers and larger ships, while the lightweight Mark 92 system is used in missile frigates. The most sophisticated weapon system currently used in U.S. Navy warships is the Aegis system, a rapid-reaction, long-range fleet air-defense system capable of effectively handling multiple surface and air targets simultaneously. It includes the very capable AN/SPY-1 radar, a quick-reaction tactical computer for overall command control, a digital weapon-control system, and state-of-the-art guided-missile launchers. Found in Ticonderoga-class cruisers and Arleigh Burke–class guided missile destroyers, the Aegis system gives a force commander the capability of controlling all the surface and aerial weapons of an entire battle group in a multithreat environment.
The SQQ-89 surface-ship ASW (antisubmarine warfare) combat system is an integrated system for detecting, identifying, tracking, and engaging modern submarines.
Submarines and aircraft have their own control systems, similar in general principle to those used in surface ships.
Fleet ballistic missiles fired from submarines are controlled by a missile fire-control system, which is connected to the submarine’s inertial navigation system. The navigation system keeps accurate track of the ship’s position. When missiles are to be fired, the fire-control system takes current position data and quickly computes firing information to put missiles on the proper ballistic course. While in flight, the missile keeps itself on course with the aid of a built-in navigational system.