As you have seen, the majority of sensor systems you will work with are of the RF type. That is, RF energy is transmitted via a complex system of components to detect and destroy a target. There are also other sensors used in today's Navy that use a different method of locating targets and helping in the direction of weapons. These systems use light or heat as a source for target detection. They are described as "Optronic" systems because they use light frequency rather than RF energy as a detecting element and a system of optical lenses for focusing a light source. An example of this type of system used in the Navy today is the Thermal Imaging Sensor System (TISS). It is representative of other similar optronics systems in use today.

THERMAL IMAGING SENSOR SYSTEM (TISS)

The Thermal Imaging Sensor System (TISS) is a shipboard electro-optical system that consists of a low-light television camera and an eye-safe laser rangefmder. The TISS director is designed to be mast mounted. The control console can be mounted in CIC or in the pilothouse. In addition to providing surface and air target data to combat systems, the TISS can also be used to detect mines and to provide good night identification and detection capabilities.

TISS was originally tested on board the USS Ticonderoga (CG-47) and later installed on the USS Vicksburg (CG-69) for her deployment to the Middle East in April 1997. TISS will initially be installed as a stand-alone system on deploying ships. As more units are completed, permanent installation and integration into the combat systems will become standard. Systems that use TISS are the Mk 86 Gun Fire Control System, CIWS, SSDS, and RAM.

Q8. What type of system is TISS? UPCOMING DEVELOPMENTS IN RADAR

To keep pace with the approaching 21St century needs for multi-mission surface warships, the Navy is continually developing new technology that allows it to do more with less. We mention some of these developments, related to radar and sensors, below.

HIGH FREQUENCY SURFACE WAVE RADAR

High frequency surface wave radar is used to detect low-altitude missiles beyond the ship's horizon. The transmitting antennas are meandering-wave type units and are mounted on either side of the ship, near the bridge. The receivers are separate deck-edge or superstructure units. This radar uses an FMCW (Frequency Modulated-Continuous Wave) transmitter with a 50% duty cycle, with co-located transmit and receive antennas.

MULTI-FUNCTION RADAR

The Multi-Function radar is a development for the DD-21 Land Attack destroyer that provides ship self-defense and local area defense against air and missile threats. The new Multi-Function radar (MFR) will greatly enhance ship defense capability against modern air and missile threats in the littoral environment (areas close to shoreline). This system is based on solid-state, active-array radar technology that will provide search, detect, track, and weapon control functions while dramatically reducing manning and life-cycle costs associated with the multiple systems that perform these functions today. The MFR will be complemented by a new Volume Search Radar (VSR), which will provide timely cueing to MFR at long ranges and above the horizon. The VSR will be acquired as part of the DD-21 total ship system. (See Figure 2-19)

INFRARED SEARCH AND TRACK (IRST)

The Infrared Search and Track (IRST) system is an integrated sensor designed to detect and report low-flying antiship cruise missiles by detecting their thermal heat plume or heat signature. IRST will continually scan the horizon and report any contacts to the ship's combat information center for tracking and engagement. The scanner is designed to search several degrees above and below the horizon but can be slewed manually to search for higher flying targets. IRST is a passive system providing bearing, elevation angle, and thermal intensity of a target. The system consists of a mast-mounted and stabilized scanner, below decks electronics, and a UYQ-70 operator's console.

Figure 2-19.-Artist's conception of DD-21 land attack destroyer.