TARGET DETECTION AND WEAPONS CONTROL
Up to now we have centered our discussion on guns and GMLSs and their operation. However, modern weapons systems rarely, if ever, function independently. A complete weapons system also includes elements that detect and track the target, compute a fire control solution, and generate control orders.
We will begin this chapter by describing some of the equipment and processes used to detect and identify a target. We will then describe the different elements involved in the fire control problem and the major fire control systems now in the fleet. We will introduce the subject of system testing and a very important piece of equipment, a guided missile training round (GMTR).
THE DETECTION PROCESS
LEARNING OBJECTIVE: Describe the major components of Navy fire control systems.
The modern detection process involves more than the location of possible targets by the sensors of the ship. Before sensor information from your ship (or other ships) can be fully used by the weapons system, it must first be processed. Processing involves the extraction of data concerning the course of the target, speed, bearing, range, identity as friend or foe, and type of target (air, surface, or subsurface). This information is called target data and it is processed by the Naval Tactical Data System (NTDS). The NTDS function is central to the modern detection process, so we will describe it first-then we will describe the types of sensors that supply the data to the NTDS.
Many different detection systems are in use today. A discussion of the operation of each one is beyond the scope and intent of this book. Therefore, in this chapter we will not discuss specific systems, only the general characteristics of the different system types. For detailed information on a specific system, consult the system's technical manual(s).
NAVAL TACTICAL DATA SYSTEM
The NTDS consists of high-speed computers, data display consoles, communication links, and operational computer programs. The total system functions to collect, analyze, and correlate sensor data to obtain a clear picture of the tactical situation. A good tactical picture includes complete target data on all ships, aircraft, and submarines in the area of concern. This picture is then converted to digital format and supplied to the weapon systems of the ship and to other ships over the communications data link
Figure 10-1 is a simple line drawing that shows the NTDS function. The picture supplied by the NTDS is a "real time" display; it is not a projection, but a representation of the tactical situation as it is at that moment, based on available sensor data. Some weapon systems are able to use raw sensor data to engage targets, although this use is not the most effective mode of operation. The use of raw data is normally reserved for casualty mode use.
When two or more ships operate together, one ship will be designated to maintain the communications link network This designation allows ships in the task force to feed target data into the link for use by the entire group. Each ship in the link will be able to use all the processed target data from all the other ships in the link Access to this collective data serves to broaden the tactical picture for the task force commander and for individual commanders as well.
Figure 10-1.-The NTDS function.
In the past, as with other systems, the NTDS was considered an individual unit instead of a component of the combat system of the ship. This is no longer true. Older ships are adopting a one-system philosophy. Newer systems are designed as a single system. The NTDS function is now being performed by the same equipment that performs other functions formerly not associated with NTDS. The AEGIS weapon system is the first system designed under the one-system concept. The AEGIS Command and Decision (C&D) system not only performs the NTDS function but also controls the electronic warfare (EW) system, IFF challenges, and several other functions as well.
The NTDS collects data from each of the sensors of the ship (radar, IFF, ESM, and sonar) as well as other target data of the ship over the data link, We will now provide brief descriptions of the type of information each sensor supplies. Sonar will not be covered in this text.
The Navy uses a variety of search radars to detect surface and air targets. However, they can all be classified as either surface search/navigation or two- or three-coordinate air search radars.
SURFACE SEARCH/NAVIGATION RADARS.- Radar sets (such as the AN/SPS-65) are short-range, two-coordinate, narrow-beam radars capable of good discrimination in range and bearing for surface search and low-flying aircraft. They are also valuable because of their ability to detect modern low-flying antiship missiles.
THREE-COORDINATE RADARS.- Threecoordinate radars (such as AN/SPS-48 or AN/SPY-1) are normally the primary source of air target information. These radars provide precise air search data consisting of range, bearing, and elevation angle to the NTDS or weapons direction system (WDS). These radars also provide IFF (identification, friend or foe) data. IFF is a subsystem that issues an electronic challenge to aircraft. Depending upon the response or lack of response from the aircraft, the aircraft is determined to befriendly or hostile. The air search data and synchronized IFF interrogation information are displayed on operator consoles in the combat information center (CIC) for target engagement evaluation. Electronic counter-countermeasure (ECCM) features improve the display when jamming environments are encountered.
TWO-COORDINATE RADARS.- An alternate source of air target information for a weapon system is a two-coordinate radar. These are the primary means for detection of long-range air targets. These radars (such as the AN/SPS-49) provide course range and bearing information and IFF capabilities similar to those of the three-coordinate radars. They do not, however, provide elevation information.