The Mk 23 Target Acquisition System JAS) is a detection, tracking, identification, threat evaluation, and weapon assignment system. It is used against high-speed, small cross-section targets that approach the ship from over the horizon at very low altitudes or from very high altitudes at near vertical angles. The TAS integrates a medium-range, two-dimensional, air-search radar subsystem, an IFF subsystem, a display subsystem, and a computer subsystem. This allows TAS to provide automatic or manual target detection and tracking, target identification, threat evaluation, and weapon assignment capabilities for engagement of air tracks. The Mk 23 TAS automatic detection and tracking radar is also an element of the Mk 91 Missile Fire Control system and is used on SPRUANCE class destroyers, carriers, LHDs, LHAs, and the LPD-17 class amphibious assault ships. The Mk 91 MFCS and TAS control the SEASPARROW missile as their primary weapon. Figure 2-9 shows a Mk 29 box launcher for SEASPARROW missiles.

Figure 2-9.-Mk 29 box launcher for SEASPARROW missiles.

MK 91 FIRE CONTROL SYSTEM

The Mk 91 NATO SEASPARROW Guided Missile Fire Control System (GMFCS) integrates the Mk 157 NATO SEASPARROW Surface Missile System (NSSMS) into the Ship Self Defense System (SSDS) to provide an additional layer of ship missile defense. In this system, the Firing Officer Console and Radar Set Consoles are combined into a single Advanced Display System Console (AN/UYQ 70); the Signal Data Processor is modified; the Mk 157 Computer Signal Data Converter and the System Evaluation and Trainer (SEAT) are eliminated; and the microprocessor circuitry within the SSDS electronics is upgraded. This eliminates the limited input-output channel and computer processing deficiencies resident in the older Mk 57 NSSMS. The radar associated with the Mk 91 Fire Control System includes the Mk 95 illuminator, Mk 23 Target Acquisitioning System, and the AN/SPQ-9 series radar.

The Mk 95 illuminator is used exclusively with the NATO SEASPARROW GMFCS. It is an X-band tracker-illuminator on a Mk 78 director and works with the Mk 23 TAS. The Mk 91 Fire Control System and its associated radar systems are found on Spruance class destroyers, carriers, LHDs, AOEs, AORs, and TARAWA class amphibious assault ships.

See figure 2-10 for the various weapons systems and radar associated with the Mk 86 and Mk 91 fire control systems on a SPRUANCE class destroyer.

MK 92 FIRE CONTROL SYSTEM RADAR

The Mk 92 Fire Control System (FCS) provides FFG-7 class frigates (Figure 2-11) and other surface combatants with a fast reaction, high firepower, all-weather weapons control system for use against air and surface targets. The Mark 92's surface and air surveillance capability gives highly accurate gun and missile control against air and surface targets.

The Mark 92 fire control system, an American version of the WM-25 system designed in the Netherlands, was approved for service use in 1975. Introduction to the fleet and follow-on test and evaluation began in 1978. In 1981, an aggressive program to improve performance and reliability of the Mk 92 fire control system in clutter and electronic counter-measure environments was launched, with an at-sea evaluation aboard the USS Estocin completed in

Figure 2-11.-FFG-57 PERRY class frigate.

Figure 2-10.-Weapons and sensors on SPRUANCE class destroyer.

Figure 2-12.-Mk 75 Naval Gun system.

1986. Following the evaluation, the upgraded system, identified as Mk 92 Mod 6 was installed in USS Ingraham (FFG-61). The Mk 92 Mod 6 will replace the Mod 2 systems in the fleet.

The Mk 92 Fire Control System (FCS) is deployed on board FFG-7 PERRY class ships in conjunction with the Mk 75 Naval Gun (fig. 2-12) and the Mk 13 Guided Missile Launching System (fig. 2-13). The Mk 92 FCS integrates target detection with multichannel

Figure 2-13.-Mk 13 Guided Missile Launcher system.

antiair and antisurface missile and gun systems control, engaging up to four targets simultaneously. The Mk 92 "track-while-scan" radar uses the Combined Antenna System (CAS), which houses a search antenna and a tracker antenna inside a single egg-shaped radome (fig.2-14). A Separate Target Illumination Radar (STIR) (fig. 2-14) designed for the PERRY class Mk 92 FCS application provides a large diameter antenna for target illumination at ranges beyond CAS capabilities.

A Mod 1 version of the Mk 92 system is installed on the US Coast Guard's WMEC (Medium-Endurance Cutter, figure 2-15) and its WHEC (High-Endurance Cutter). This version can track one air or surface target using the monopulse tracker and two surface or shore targets using track-while-scan data from CAS. Using STIR, the Mod 2 system on FFG-7 class frigates can track an additional air or surface target.