Target Acquisition

Applications
Title	Target Acquisition
Author(s)	GMV
Level	Medium
Year of Publication	2011

Satellite navigation has become very important for military target acquisition operations, reconnaissance, and weapon guidance systems.

Tracking of potential targets before they are declared hostile, is a requirement in modern military operations. A number of military systems use GNSS information to track the movement of these potential targets. This data is also collected to feed situation awareness systems and weapon systems.

Conventional weapon systems such as smart bombs and guided missiles use the acquired tracking information, enhanced by GNSS receivers information and other guidance systems.

Application Architecture

These applications are considered safety critical applications.

Target Acquisition Systems

The Surveillance Target Acquisition systems are military applications aimed to encompass tracking, reconnaissance and map creation systems, in order to help the missile and bomb guidance mechanisms and battlefield management systems.

The tracking mechanisms are performed by military weapons to detect potential hostile targets both in the air or on the ground, using satellite navigation information to accurately detect the target's coordinates position. The GNSS position data is then fed into weapon systems, such as smart bombs or missiles.

Missile Precision Guidance

The cruise missile guidance is another feature that uses satellite navigation technology. The missiles are installed with multichannel receivers controlled to accurately guide the cruise missile to the target, upon launching.

In order to reduce the time to set a missile ready on a position to be lunched, the vehicles that are used for launching the missiles are also equipped with GNSS receivers.

The precise guidance weapons require aerodynamic control actuation to perform trajectory control. In order to improve artillery accuracy such devices could automatically adjust the projectile in-flight trajectory. The technology present in these projectiles include GPS transceivers, inertial measurement units (IMU's) for safing and arming, and miniature actuation systems.

Application Characterization

Target Acquisition Systems

The Surveillance Target Acquisition devices consist in a number of sensors and devices. Some systems are able to integrate the information from all those sensors in order to build a precise awareness of target's positions. For instance the correct position of a certain target can be obtain using information from a Laser rangefinder sensor, fused with digital magnetic compass and GNSS information.

The mapping is a feature used in military domains, e.g., in application for battlefield management or commander's digital assistant devices, and consists in the collection of precise location data used to update maps. The military forces require to map the locations of installations and weapons, the troop forces on the ground, as well as military bases location, which are in many situations temporary locations. In order to obtain a detailed map of the base, the military users use GNSS/DGNSS to quickly update or create a detailed map of the base.

Missile Precision Guidance

The weapon guidance systems using GNSS can be found in Intercontinental ballistic missiles (ICBMs), cruise missiles, precision-guided munitions, bombs and even mortar rounds.

The GNSS receivers are miniaturized to fit into existing artillery fuzes and are ruggedized to withstand severe gun launch dynamics. They incorporate full 12-channel, all-in-view capability and fast signal acquisition, which is crucial for the short flight times of artillery.

Recent development of inertial sensors and GNSS receivers capable of withstanding very strong g-forces renewed the interest in unpowered guided munitions. Guidance schemes seek to increase the static targeting accuracy by decreasing the error to the target.

The cruise missiles guidance system is highly susceptible to GPS jamming. In order to deal with this problem the guidance systems rely on TERCOM navigation, which uses geographic data of specific terrain, that is compared to measurements made during flight by an on-board radar altimeter. Since the contrast of a ground scene can vary between night and day or with the changing seasons, the imagery must be specific to those conditions.

Application Examples

Military GNSS devices appear in most of target acquisition applications and weapon guidance systems. Many battlefield management systems, or commander's digital assistant devices use the GNSS information obtained by target acquisition systems.

Some systems integrate the data received from target acquisition systems into weapon guidance system, for instance the Truth Data Acquisition, Recording and Display System or TDARDS, developed by U. S. Army, is a GPS-based system, which provide real-time, accurate position locations on vehicles and aircraft, tracking several targets in parallel.