Because of different design parameters, no single radar set can perform all the many radar functions required for military use. The large number of radar systems used by the military has forced the

Figure 1-13.-Phantom view of a gyro.

development of a joint-services classification system for accurate identification of radars. Radar systems are usually classified according to their specific function and installation vehicle. The joint-service standardized classification system divides these broad categories for more precise identification.

Since no single radar system can fulfill all the requirements of modern warfare, most modern warships, aircraft, and shore installations have several radar sets, each performing a specific function. A shipboard radar installation may include surface-search and navigation radars, a 3D radar, an air-search radar, and various fire-control radars.

Figure 1-14 is a listing of equipment identification indicators. You can use this table and the radar nomenclature to identify the parameters of a particular radar set. The example given explains the equipment indicators for the AN/SPY-IA radar system.

The letters AN were originally adopted by the Joint Army-Navy Nomenclature System, also known as the AN system, to easily classify all military electronic equipment. In 1985, Military Standard MIL-STD-196D changed the name of the Joint Army-Navy Nomenclature System to the "Joint Electronics Type Designation System (JETDS)", but the letters AN are still used in identifying military electronics equipment.

AIR-SEARCH RADAR

The primary function of an air-search radar is to maintain a 360-degree surveillance from the surface to high altitudes and to detect and determine ranges and bearings of aircraft targets over relatively large areas.

The following are some uses of an air-search radar:

Give early warning of approaching enemy aircraft and missiles, by providing the direction from which an attack could come. This allows time to bring antiaircraft defenses to the proper degree of readiness and to launch fighters if an air attack is imminent.

Observe constantly the movement of enemy aircraft. When it detects an enemy aircraft, guide combat air patrol (CAP) aircraft to a position suitable for an intercept.

Provide security against attacks at night and during times of poor visibility.

Provide information for aircraft control during operations that require a specific geographic

Figure 1-14.-AN equipment indicator system.

track (such as an antisubmarine barrier or a search and rescue pattern).

Together, surface- and air-search radars provide a good early-warning system. However, the ship must be able to determine altitude to effectively intercept any air target. This requires the use of another type of radar.