Ejercicios del cap´ıtulo

The concept of a weapons system is a generalized term encompassing a broad spectrum of components and subsystems. These components range from simple devices directed or fired manually by a single individual against one specific class of target to a com-plex array of components or subsystems that are interconnected via data buses to onboard computers, and data communication links that are capable of performing multiple functions or engaging numerous targets or target classes simultaneously.

Although each subsystem may be specifically designed to solve a particular part of the fire-control problem, it is these components operating in seamless concert that allows the whole system to achieve its ultimate goal – the destruction or neutralization of the designated target.

Modern weapons systems, regardless of the medium they operate in (land, sea, or air) or the type of weapon they employ (missile, bomb, or projectile), are composed of specific components that allow the system to detect, track, and engage the target. These sensors must be designed for the anticipated environments in which the weapons system and the target operate. A weapons system must employ at least one sensor but quite often has multiple sensors integrated to provide an optimal choice and redundancy, depending on the actual situation. These sensors ideally must also be capable of dealing with widely varying target characteristics, including target range, bearing, altitude, speed, size, heading, aspect, maneuvering, and countermeasures.

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The main advantages of radar with respect to other sensors are:

● long detection and long tracking ranges that enable the firing of long-range weapons;

● all-weather operation, day and night; and

● full 3D localization and tracking (range, angles, and velocities).

Therefore, the majority of fire-control systems use radar as their main sensor. This chapter presents an overview of the radar technology and radar system concepts required to satisfy the fire-control mission.

The following is a list of abbreviations used in this chapter.

DazandDel azimuth and elevation difference (channels)

S sum (channel)

AACQ auto-acquisition ABF adaptive beam forming

ACM air-combat mode

ACQ acquisition

AESA active electronically scanned array AGR air-to-ground ranging

AI air interception

AIM air-interception missiles

AMRAAM advanced medium-range air-to-air missile AMSAR airborne multirole solid-state active array radar ASCM antiship cruise missiles

ASIC application-specific integrated circuit BVR beyond visual range

CAS close air support

CCIP constantly computed impact point CCRP constantly computed release point CFAR constant false alarm rate

CIWS close-in weapons system

CNI communication, navigation, and identification COTS commercial off-the-shelf

CPA closest point of approach DBS Doppler beam sharpening DPCA displaced phase-center antenna DRA driver amplifier

DTM digital terrain model

EA electronic attack

ECM electronic countermeasures

ECCM electronic counter-countermeasurements ELINT electronic intelligence

EOTS electro-optical targeting system

EP electronic protection E-SCAN electronically scanned EW electronic warfare EWS electronic warfare system FAC forward air controller FCC fire-control computer FCR fire-control radars FCS fire-control systems FFR forward-firing rocket FLIR forward-looking infrared FPGA field-programmable gate array GaAs galium arsenide

GaN galium nitride

GMTI ground-moving target indicator GMTT ground-moving target tracking GPS Global Positioning System HMD helmet-mounted display HMI human–machine interface HPRF high-pulse repetition frequency HRRP high-range resolution profiling HPA high-power amplifier

HUD heads-up display

IFF identification friend or foe IMM interacting multiple model INS inertial navigation system IRST infrared search and track ISAR inverse synthetic aperture radar

IVVQ integration, verification, validation, and qualification JDAM joint direct attack munition

JEM jet-engine modulation

Joint STARS Joint Surveillance Target Attack Radar System JSOW joint standoff weapon

JSTARS Joint Surveillance Target Attack Radar System LNA low-noise amplifier

MFD multifunction display

MPRF medium-pulse repetition frequency M-SCAN mechanically scanned

MSL mean or medium sea level NCTR noncooperative target recognition

NM Nautical miles

OODA observe, orient, decide, and act

PRF pulse repetition frequency

RA raid assessment

RABFAC radar forward-air-controller beacon RADFAC radar beacon forward air controller RAT ram air turbine

RBGP real beam ground mapping RCS radar cross section

RGPO range gate pull-off

ROR range-only radar

RWR radar warning receiver RWS range while search SAM surface-to-air missiles SAR synthetic aperture radar SLC sidelobe canceller SLS sidelobe suppression

STAP space–time adaptive processing STT single target track

TA terrain avoidance

TF terrain following

TOF time of flight

TWS track while scan

TVM track via missile TWT traveling wave tube VGPO velocity gate pull-off

VS velocity search

WAS wide area search

WQT weapon-quality track

When possible, radar measurements may be refined by those coming from other sensors – data fusion, for instance, with the electro-optical targeting system (EOTS), Forward-Looking Infrared (FLIR), and the infrared search-and-track (IRST) system. For effective fire-control applications, the radar must have a number of specific character-istics. The main features are the following.

● Detection and tracking ranges: They should be higher than those of the weapons unless the system efficiency is limited by the sensor.

● Sufficient tracking accuracy (in range, angle, and velocity vector) occurs with respect to the guidance requirements of the weaponry.

● Adequate discrimination occurs during both the detection and tracking phases.

Indeed, the targets within a raid can be close to each other (both in position and velocity). These targets should be individually detected and properly localized, and then the tracking system should be able to maintain a given track on a given target without swapping or merging the tracks.

● Efficient electronic counter-countermeasurements (ECCM). The presence of these ECCM techniques is one specificity of fire-control radar.

● Fire-control systems include fire-control radar (FCR) as well as electronic warfare systems (EWS). The ability of both FCR and EWS to work together efficiently is an important feature of a fire-control system.