Electronic support measures (ESM) is the passive side of the total elecronic warfare capability of the ship. Its function is to detect electronic emissions and aid in the rapid identification of the source platform or weapon. A low-flying antiship cruise missile (ASCM), such as our Harpoon, may not be detected by the radar of your ship. The first indication you might see is the electronic emissions of the missile seeker when it initiates its homing phase. This first indication could give you just 90 seconds, or less, to react before the missile strikes your ship.

Modern ESM not only detects the emission but also supplies the operator with a suggestion regarding the source. The operator must then visually verify the accuracy of the suggestion. If he agrees with the evaluation, the push of a button sends the data to the NTDS. Should he disagree, he inputs his evaluation through a manual keyboard.

The LAMPS III helicopter is also equipped with ESM equipment that further extends sensory range. A single ESM unit can only supply target bearing data. The LAMPS III helicopter, however, can be sent out away from the ship to monitor the same emission, thus allowing a vector of the position of the target and range data. Two ships can perform the same maneuver.

Figure 10-2 shows the configuration of a modern weapon system aboard an AEGIS-equipped ship. Remember that the NTDS function is accomplished by the C&D equipment in the AEGIS system.

WEAPONS DIRECTION SYSTEM

LEARNING OBJECTIVE Discuss the function of the weapons direction system (WDS).

Figure 10-2.-The AEGIS combat system.

The weapons direction system (WDS), also referred to as weapons control system (WCS), functions to schedule, control, and assess the engagement of targets with the weapon systems of the ship. WDS consists of a computer set, a computer program, and two or more operator consoles.

WDS receives target data from NTDS. Each target is analyzed and assigned a threat priority. The system then assigns a weapons system to engage the highest priority target. Weapons system assignment includes (in the case of a missile engagement) the selection of the number and type of missiles to be fired, as well as which director will be used to track and illuminate the target. In the case of a fully automatic engagement, the system will also initiate missile firing. However, not all systems are capable of full automatic operation. In all cases, the operator may manually override the system to alter the method of engagement.

Before the advent of WDS, each of these functions was performed by the individual action of system operators. Therefore, response time and accuracy were limited to the speed and skill of the operators. A rapid and accurate response is required to defend against the sophisticated modem weapons currently in the arsenal of the world. WDS enables the entire engagement (or portions thereof) to be executed rapidly and automatically.

The WDS computers programmed to prioritize and engage targets that exhibit certain characteristics. In addition to this programming, the operator consoles can also be programmed to include quick reaction (QR) zones. These zones determine at what range, and from which direction, approaching targets are automatically engaged. These parameters are constantly updated as the tactical situation changes. QR zones may also be used to help make sure friendly ships and aircraft are not mistakenly engaged.