DISTRIBUTION STATEMENT A: Approved for public release; distribution is unlimited.

NONRESIDENTTRAININGCOURSE

October 2000

Fire Controlman,Volume 2–Fire-ControlRadar FundamentalsNAVEDTRA 14099

DISTRIBUTION STATEMENT A: Approved for public release; distribution is unlimited.

Although the words “he,” “him,” and“his” are used sparingly in this course toenhance communication, they are notintended to be gender driven or to affront ordiscriminate against anyone.

i

PREFACE

By enrolling in this self-study course, you have demonstrated a desire to improve yourself and the Navy.Remember, however, this self-study course is only one part of the total Navy training program. Practicalexperience, schools, selected reading, and your desire to succeed are also necessary to successfully roundout a fully meaningful training program.

COURSE OVERVIEW: After completing this course, you will have a basic knowledge of thefollowing topics:

• basic radar concepts,• equipment requirements for basic radar systems,• types of energy transmission used in radar systems,• scanning techniques used in radar systems,• major components in today’s radar transmitters,• design requirements of an effective radar receiver,• radiation and other types of hazards associated with maintaining and operating radars, and• safety precautions associated with radar

THE COURSE: This self-study course is organized into subject matter areas, each containing learningobjectives to help you determine what you should learn along with text and illustrations to help youunderstand the information. The subject matter reflects day-to-day requirements and experiences ofpersonnel in the rating or skill area. It also reflects guidance provided by Enlisted Community Managers(ECMs) and other senior personnel, technical references, instructions, etc., and either the occupational ornaval standards, which are listed in the Manual of Navy Enlisted Manpower Personnel Classificationsand Occupational Standards, NAVPERS 18068.

THE QUESTIONS: The questions that appear in this course are designed to help you understand thematerial in the text.

VALUE: In completing this course, you will improve your military and professional knowledge.Importantly, it can also help you study for the Navy-wide advancement in rate examination. If you arestudying and discover a reference in the text to another publication for further information, look it up.

2000 Edition Prepared byFCC(SW) Charles F. C. Mellen

Published byNAVAL EDUCATION AND TRAINING

PROFESSIONAL DEVELOPMENTAND TECHNOLOGY CENTER

NAVSUP Logistics Tracking Number0504-LP-022-5620

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Sailor’s Creed

“ I am a United States Sailor.

I will support and defend theConstitution of the United States ofAmerica and I will obey the ordersof those appointed over me.

I represent the fighting spirit of theNavy and those who have gonebefore me to defend freedom anddemocracy around the world.

I proudly serve my country’s Navycombat team with honor, courageand commitment.

I am committed to excellence andthe fair treatment of all.”

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TABLE OF CONTENTS

CHAPTER PAGE

1 Introduction to Basic Radar Systems...................................................................... 1-1

2 Fire Control Radar Systems.................................................................................... 2-1

3 Radar Safety ........................................................................................................... 3-1

APPENDIX

I References .............................................................................................................. AI-1

INDEX ................................................................................................................................. Index-1

Course Assignments follow the index.

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INSTRUCTIONS FOR TAKING THE COURSE

ASSIGNMENTS

The text pages that you are to study are listed atthe beginning of each assignment. Study thesepages carefully before attempting to answer thequestions. Pay close attention to tables andillustrations and read the learning objectives.The learning objectives state what you should beable to do after studying the material. Answeringthe questions correctly helps you accomplish theobjectives.

SELECTING YOUR ANSWERS

Read each question carefully, then select theBEST answer. You may refer freely to the text.The answers must be the result of your ownwork and decisions. You are prohibited fromreferring to or copying the answers of others andfrom giving answers to anyone else taking thecourse.

SUBMITTING YOUR ASSIGNMENTS

To have your assignments graded, you must beenrolled in the course with the NonresidentTraining Course Administration Branch at theNaval Education and Training ProfessionalDevelopment and Technology Center(NETPDTC). Following enrollment, there aretwo ways of having your assignments graded:(1) use the Internet to submit your assignmentsas you complete them, or (2) send all theassignments at one time by mail to NETPDTC.

Grading on the Internet: Advantages toInternet grading are:

• you may submit your answers as soon asyou complete an assignment, and

• you get your results faster; usually by thenext working day (approximately 24 hours).

In addition to receiving grade results for eachassignment, you will receive course completionconfirmation once you have completed all the

assignments. To submit your assignmentanswers via the Internet, go to:

http://courses.cnet.navy.mil

Grading by Mail: When you submit answersheets by mail, send all of your assignments atone time. Do NOT submit individual answersheets for grading. Mail all of your assignmentsin an envelope, which you either provideyourself or obtain from your nearest EducationalServices Officer (ESO). Submit answer sheetsto:

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Answer Sheets: All courses include one“scannable” answer sheet for each assignment.These answer sheets are preprinted with yourSSN, name, assignment number, and coursenumber. Explanations for completing the answersheets are on the answer sheet.

Do not use answer sheet reproductions: Useonly the original answer sheets that weprovide—reproductions will not work with ourscanning equipment and cannot be processed.

Follow the instructions for marking youranswers on the answer sheet. Be sure that blocks1, 2, and 3 are filled in correctly. Thisinformation is necessary for your course to beproperly processed and for you to receive creditfor your work.

COMPLETION TIME

Courses must be completed within 12 monthsfrom the date of enrollment. This includes timerequired to resubmit failed assignments.

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PASS/FAIL ASSIGNMENT PROCEDURES

If your overall course score is 3.2 or higher, youwill pass the course and will not be required toresubmit assignments. Once your assignmentshave been graded you will receive coursecompletion confirmation.

If you receive less than a 3.2 on any assignmentand your overall course score is below 3.2, youwill be given the opportunity to resubmit failedassignments. You may resubmit failedassignments only once. Internet students willreceive notification when they have failed anassignment--they may then resubmit failedassignments on the web site. Internet studentsmay view and print results for failedassignments from the web site. Students whosubmit by mail will receive a failing result letterand a new answer sheet for resubmission of eachfailed assignment.

COMPLETION CONFIRMATION

After successfully completing this course, youwill receive a letter of completion.

ERRATA

Errata are used to correct minor errors or deleteobsolete information in a course. Errata mayalso be used to provide instructions to thestudent. If a course has an errata, it will beincluded as the first page(s) after the front cover.Errata for all courses can be accessed andviewed/downloaded at:

http://www.advancement.cnet.navy.mil

STUDENT FEEDBACK QUESTIONS

We value your suggestions, questions, andcriticisms on our courses. If you would like tocommunicate with us regarding this course, weencourage you, if possible, to use e-mail. If youwrite or fax, please use a copy of the StudentComment form that follows this page.

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NAVAL RESERVE RETIREMENT CREDIT

If you are a member of the Naval Reserve, youmay earn retirement points for successfullycompleting this course, if authorized undercurrent directives governing retirement of NavalReserve personnel. For Naval Reserveretirement, this course is evaluated at 3 points.(Refer to Administrative Procedures for NavalReservists on Inactive Duty, BUPERSINST1001.39, for more information about retirementpoints.)

vii

Student Comments

Course Title: Fire Controlman, Volume 2—Fire-Control Radar Fundamentals

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CHAPTER 1

INTRODUCTION TO BASICRADAR SYSTEMS

INTRODUCTION

This chapter discusses radar principles and basicradar systems. As a Fire Controlman, and a possiblework-center supervisor, you must understand basicradar principles and safety requirements for radarmaintenance. You will find valuable supportinginformation in the Navy Electricity and ElectronicsTraining Series (NEETS), especially Module 18,Radar Principles, NAVEDTRA 172-18-00-84, and inElectronics Installation and Maintenance Book,Radar, NAVSEA SE000-00-EIM-020. By referring tothese publications on a regular basis, you can increaseyour understanding of this subject matter.

This chapter is not designed to teach you everyradar system the Navy uses, but simply to familiarizeyou with the radars and their general characteristics.Because there are so many different models of radarequipment, we will describe only the radars and radaraccessories that will be around for several years. Wewill not discuss older radar systems that are scheduledfor replacement in the near future. Refer to yourspeci fic technical publ icat ions for detai leddescriptions of the operation and maintenance of yourspecific radar system.

BASIC RADAR CONCEPTS

The term radar is an acronym made from thewords radio, detection, and ranging. It refers toelect ronic equipment that uses ref lectedelectromagnetic energy to determine the direction to,height of, and distance of detected objects.Electromagnetic energy of the frequency used forradar is unaffected by darkness. However, it can beaffected by weather to some degree, depending on itsfrequency. It permits radar systems to determine thepositions of ships, planes, and land masses that areinvisible to the naked eye because of distance,darkness, or weather. Radar systems provide only alimited field of view and require reference coordinatesystems to define the positions of detected objects.Radar surface angular measurements are normallymade in a clockwise direction from true north, asshown in figure 1-1, or from the heading line of the shipor aircraft. The radar is located at the center of thiscoordinate system.

Table 1-1 defines the basic terms used in figure 1-1.You must know these terms to understand thecoordinate system.

1-1

LEARNING OBJECTIVES

Upon completing this chapter, you should be able to do the following:

1. Explain the terms “range”, “bearing”, and “altitude” as they are associated with radar.

2. Explain the two basic methods for detecting objects with radar.

3. Identify and explain the use of equipment found in basic radar.

4. Identify and state the use of the four basic types of military radar systems.

5. Identify and explain the three phases of fire-control radar.

6. Identify the radar systems currently used in the U. S. Navy.

1-2

Figure 1-1.—Radar surface angular measurements.

Term Definition

Energy pulses The pulses that are sent out by the radar and are received back from the target.

Reflecting target The air or surface contact that provides an echo.

True north The direction of the north geographical pole.

True bearing/azimuth The angle measured clockwise from true north in the horizontal plane.

Line-of-sight range The length of the line from the radar set directly to the object.

Vertical plane All angles in the up direction, measured in a secondary imaginary plane.

Elevation angle The angle between the horizontal plane and the line of sight.

Horizontal plane The surface of the Earth, represented by an imaginary flat plane which istangent (or parallel) to the Earth’s surface at that location.

Table 1-1.—Radar Reference Coordinate Terms

RADAR MEASUREMENTS

We stated earlier that radar is used to determine thedistance and direction to and the height of distantobjects. These three pieces of information are known,respectively, by the standard terms range, bearing, andaltitude. The use of these standard terms allows anyoneinterested in a specific target to establish its positionquickly and accurately. Radar operators determine atarget’s range, bearing, and altitude by interpreting itsposition displayed on a specially designed cathode-raytube (CRT) installed in a unit known as a plan positionindicator (PPI).

While most radars are used to detect targets, sometypes are used to guide missiles to targets and to directthe firing of gun systems; other types providelong-distance surveillance and navigation information.

Range and bearing (and in the case of aircraft,altitude) are necessary to determine target movement.To be a successful radar operator, you must understandthe capabilities and limitations of your radar system indetermining range, bearing, and altitude.

Range

The radar measurement of range (or distance) ispossib le due to the proper t ies of radiatedelectromagnetic energy. This energy normally travelsthrough space in a straight line, at a constant speed, andvaries only slightly due to atmospheric and weatherconditions. The frequency of the radiated energycauses the radar system to have both a minimumeffective range and a maximum effective range.

MINIMUM RANGE .—Radar duplexersalternately switch the antenna between the transmitterand the receiver so that one antenna can be used forboth functions. The timing of this switching is criticalto the operation of the radar and directly affects theminimum range of the radar system. A reflected pulsewill not be received during the transmit pulse andsubsequent receiver recovery time. The minimumrange of a radar, therefore, is the minimum distancebetween the radar’s antenna and a target at which aradar pulse can be transmitted, reflected from thetarget, and received by the radar receiver. If theantenna is closer to the target than the radar’s minimumrange, any pulse reflected from the target will returnbefore the receiver is connected to the antenna and willnot be detected.

MAXIMUM RANGE .—The maximum range ofa pulse-radar system depends on carrier frequency;

peak power of the transmitted pulse; pulse-repetitionfrequency (PRF) or pulse-repetition rate (PRR) (PRFand PRR are synonymous terms.); and receiversensitivity, with PRF/PRR as the primary limitingfactor.

The peak power of a pulse determines how far thepulse can travel to a target and still return a usable echo.A usable echo is the weakest signal that a receiver candetect, process, and present on a display.

The PRR determines the rate at which the rangeindicator is reset to zero. As the leading edge of eachpulse is transmitted, the indicator time base used tomeasure the returned echo is reset, and a new sweepappears on the screen.

RANGE ACCURACY .—The shape and width ofthe radio-frequency (RF) pulse influences minimumrange, range accuracy, and maximum range. The idealpulse shape is a square wave that has vertical leadingand trailing edges. The vertical edge provides adefinite point from which to measure elapsed time onthe indicator time base. A sloping trailing edgelengthens the pulsewidth. A sloping leading edgeprovides no definite point from which to measureelapsed time on the indicator time base.

Other factors affecting range are the antenna’sheight, beamwidth, and rotation rate. A higher antennawill create a longer radar horizon, allowing a greaterrange of detection. An antenna with a narrowbeamwidth, provides a greater range capability, since itprovides more concentrated beam with a higher energydensity per unit area. A slower antenna rotation rate,providing more transmitted pulses during the sweep,allows the energy beam to strike each target moretimes, providing stronger echo returns and a greaterdetection range.

From the range information, the operator knowsthe distance to an object. He now needs bearinginformation to determine where the target is inreference to the ship.

Bearing

Radar bearing is determined by the echo’s signalstrength as the radiated energy lobe moves past thetarget . S ince search radar antennas movecontinuously, the point of maximum echo return isdetermined either by the detection circuitry as thebeam passes the target or visually by the operator.Weapons control and guidance radar antennas arepositioned to the point of maximum signal return and

1-3

are maintained at that position either manually or byautomatic tracking circuits.

You need to be familiar with two types of bearing:true and relative.

TRUE BEARING .—True bearing is the anglebetween true north and a line pointed directly at thetarget. This angle is measured in the horizontal planeand in a clockwise direction from true north.

RELATIVE BEARING .—Relative bearing is theangle between the centerline of the ship and a linepointed directly at the target. This angle is measured ina clockwise direct ion from the bow. Mostsurface-search radars provide only range and bearinginformation. Both true and relative bearing angles areillustrated in figure 1-2.

Altitude

Altitude or height-finding radars use a very narrowbeam in the vertical plane. This beam is scanned inelevation, either mechanically or electronically, topinpoint targets. Tracking and weapons-control radarsystems in current use scan the beam by moving theantenna mechanically or the radiation sourceelectronically.

Most air-search radars use electronic elevationscanning techniques. Some older air-search radarsystems use a mechanical elevation scanning device;but these are being replaced by electronically scanningradar systems.

RADAR TRANSMISSION METHODS

Radar systems are normally divided into twooperational categories (purposes) based on their

method of transmitting energy. The most commonmethod, used for applications from navigation to firecontrol, is thepulse-modulationmethod. The othermethod of transmitting iscontinuous-wave(CW).CW radars are used almost exclusively for missileguidance.

Pulse Modulation

In the pulse method, the radar transmits the RF in ashort, powerful pulse and then stops and waits for thereturn echo. By measuring the elapsed time betweenthe end of the transmitted pulse and the received echo,the radar can calculate a range. Pulse radars use oneantenna for both transmitting and receiving. While thetransmitter is sending out its high-power RF pulse, theantenna is connected to the transmitter through aspecial switch called aduplexer. As soon as thetransmitted pulse stops, the duplexer switches theantenna to the receiver. The time interval betweentransmission and reception is computed and convertedinto a visual indication of range in miles or yards.Pulse-radar systems can also be modified to use theDoppler effect to detect a moving object. The Navyuses pulse radars to a great extent.

Continuous Wave

In a CW radar the transmitter sends out a“continuous wave” of RF energy. Since this beam ofRF energy is “always on”, the receiver requires aseparate antenna. One disadvantage of this method isthat an accurate range measurement is impossiblebecause there is no specific “stop time”. This can beovercome, however, by modulating the frequency. Afrequency-modulated continuous wave (FM-CW)radar can detect range by measuring the differencebetween the transmitted frequency and the receivedfrequency. This is known as the “Doppler effect”. Thecontinuous-wave method is usually used byfire-control systems to illuminate targets for missilesystems.

RADAR SYSTEM ACCURACY

To be effective, a radar system must provideaccurate indications. That is, it must be able todetermine and present the correct range, bearing, and,in some cases, altitude of an object. The degree ofaccuracy is primarily determined by two factors: theresolut ion of the radar system and exist ingatmospheric conditions.

1-4

Figure 1-2.—True and relative bearings.

Range Resolution

Range resolution is the ability of a radar todistinguish between two targets on the same bearing,but at slightly different ranges. The degree of rangeresolution depends on the width of the transmittedpulse, the types and sizes of the targets, and theefficiency of the receiver and the indicator.

Bearing Resolution

Bearing, or azimuth, resolution is the ability of aradar system to separate objects at the same range, butat slightly different bearings. The degree of bearingresolution depends on the radar’s beamwidth and therange of the targets. The physical size and shape of theantenna determines beamwidth. Two targets at thesame range must be separated by at least onebeamwidth to be distinguished as two objects.

Atmospheric Conditions

Several conditions within the atmosphere can havean adverse effect on radar performance. A few of theseare temperature inversion, moisture lapse, waterdroplets, and dust particles.

The temperature and moisture content of theatmosphere normally decrease uniformly with anincrease in altitude. However, under certain conditionsthe temperature may first increase with height and thenbegin to decrease. Such a situation is called atemperature inversion. An even more importantdeviation from normal may exist over the ocean. Sincethe atmosphere close to the surface over large bodies ofwater may contain more than a normal amount ofmoisture, the moisture content may decrease morerapidly at heights just above the sea. This effect isreferred to asmoisture lapse.

Either temperature inversion or moisture lapse,alone or in combination, can cause a large change in therefraction index of the lowest few-hundred feet of theatmosphere. The result is a greater bending of the radarwaves passing through the abnormal condition. Thisincrease in bending, referred to asducting, may greatlyaffect radar performance. The radar horizon may beextended or reduced, depending on the direction inwhich the radar waves are bent. The effect of ducting isillustrated in figure 1-3.

Water droplets and dust particles diffuse radarenergy through absorption, reflection, and scattering.This leaves less energy to strike the target, so the returnecho is smaller. The overall effect is a reduction in

usable range. Usable range varies widely with suchweather conditions. The higher the frequency of theradar system, the more it is affected by weatherconditions, such as rain or clouds.

Other Factors

Some other factors that affect radar performanceare operator skill; size, composition, angle, andaltitude of the target; possible Electronic Attack (EA)activity; readiness of equipment (completed plannedmaintenance system requirements); and weatherconditions.

Q1. For radar surface angular measurements, whatis considered to be at the center of the coordinatesystem?

Q2. What determines radar bearing?

Q3. What is the most common method of radartransmission?

Q4. What two factors determine radar accuracy?

BASIC RADAR SYSTEMS

Radar systems, like other complex electronicssystems, are composed of several major subsystemsand many individual circuits. Although modern radarsystems are quite complicated, you can easilyunderstand their operation by using a basic blockdiagram of a pulse-radar system.

FUNDAMENTAL (PULSE) RADAR SYSTEM

Since most radars used today are some variation ofthe pulse-radar system, this section discussescomponents used in a pulse radar. All other types ofradars use some variation of these units. Refer to theblock diagram in figure 1-4.

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Figure 1-3.—Ducting effect on the radar wave.

Synchronizer

The heart of the radar system is thesynchronizer. Itgenerates all the necessary timing pulses (triggers) thatstart the transmitter, indicator sweep circuits, andranging circuits. The synchronizer may be classifiedas either self-synchronized or externally synchro-nized. In a self-synchronized system, pulses aregenerated within the transmitter. Externallysynchronized system pulses are generated by sometype of master oscillator external to the transmitter,such as a modulator or a thyratron.

Transmitter

The transmitter generates powerful pulses ofelectromagnetic energy at precise intervals. It createsthe power required for each pulse by using ahigh-power microwave oscillator (such as a mag-netron) or a microwave amplifier (such as a klystron)supplied by a low power RF source.

For further information on the construction andoperation of microwave components, review NEETSModule 11, Microwave Principles, NAVEDTRA172-11-00-87.

Duplexer

The duplexer is basically an electronic switch thatpermits a radar system to use a single antenna totransmit and receive. The duplexer disconnects theantenna from the receiver and connects it to thetransmitter for the duration of the transmitted pulse.The switching time is calledreceiver recovery time,and must be very fast if close-in targets are to bedetected.

Receiver

The receiver accepts the weak RF echoes from theantenna system and routes amplified pulses to thedisplay as discernible video signals. Because the radarfrequencies are very high and difficult to amplify, asuperheterodyne receiver is used to convert the echoesto a lower frequency, called theintermediate frequency(IF), which is easier to amplify.

Displays

Most of the radars that FCs operate and maintainhave a display, or multiple displays, to provide theoperator with information about the area the radar issearching or the target, or targets, being tracked. Theusual display is a cathode-ray tube (CRT) that providesa combination of range, bearing (azimuth), and (insome cases) elevation data. Some displays provide rawdata in the form of the signal from the radar receiver,while others provide processed information in the formof symbology and alphanumerics.

Figure 1-5 shows four basic types of displays.There are other variations, but these are the major typesencountered in fire control and 3-D search radars.

TYPE A .—The type A sweep, or range sweep,display shows targets as pulses, with the distance fromthe left side of the trace representing range. Variationsin target amplitude cause corresponding changes in thedisplayed pulse amplitude. The display may be bipolarvideo when used with Moving Target Indicator (MTI)or pulse Doppler radars.

TYPE B.—The type B sweep, or bearing sweep, ismostly found with gunfire control radars and is usedwith surface gunfire to spot the fall of shot. The rangemay be full range or an interval either side of the rangegate.

TYPE E.—Two variations of type E are shown.Both provide range and elevation or height of a target.These are associated with height-finding radars and are

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DUPLEXERDUPLEXER RECEIVER

SYNCHRONIZER

TRANSMITTER

DISPLAY

SUPPORTSYSTEMSCOOLING

AIRPOWER

CONTROLGROUP

Figure 1-4.—Basic radar block diagram.

generally used to determine the height or elevationangle only. Range is determined from processing or atype P display.

TYPE P.—This display is commonly called a PPI(plan position indicator). Own ship is usually thecenter. Range is measured radially from the center.The range display can be selected, and the radar sourceis usually selectable. The PPI can display raw video orsymbology and alphanumerics, or both. The type Pdisplay is most commonly found in the CombatInformation Center (CIC) and in weapons controlstations.

Additional information on how individual displaysare produced is available in NEETS modules 6, 9, and18.

Antenna System

The antenna system routes the pulse from thetransmitter, radiates it in a directional beam, picks upthe returning echo, and passes it to the receiver with aminimum of loss. The antenna system includes theantenna; transmission lines and waveguide from thetransmitter to the antenna; and transmission lines andwaveguide from the antenna to the receiver.

Before we discuss some types of antennas used infire control, we need to review the basic principles ofelectromagnetic wave radiation and reflectors.

The radar energy that forms the target-trackingand illumination beams is transmitted by an antennaat the control point. Radiated energy tends to spread

1-7

Figure 1-5.—Types of radar displays.

out equally in all directions, as shown in figure 1-6.Figure1-6comparestheradiationfrom aradioantennawith that from a lamp. Both light waves and radiowaves are electromagnetic radiation; the two arebelieved to be identical, except in frequency ofvibration. From both sources, energy spreads out inspherical waves. Unless they meet some obstruction,these waves wil l travel outward indefinitely at thespeed of light.

Theenergy at any givenpoint decreaseswithrangesince the wave, and therefore the energy, is spreadingout to cover a larger area. Becauseof itsmuch higherfrequency, light has amuch shorter wavelength than aradiowave. Thisissuggestedinfigure1-6but it cannotbeshown accurately to scale. Thewavelength of radartransmissionmay bemeasuredincentimeters,whereasthewavelengthof light variesfromabout threetoseventen-thousandthsof a millimeter. Wementioned earlier

that radio wave energy must be concentrated to beuseful. Wecan concentratethisenergy by mounting asuitable reflector behind the antenna, to form a largepart of the radiated energy into a relatively narrowbeam. The following paragraphs discuss the morecommonly used reflectors.

PARABOLI C REFLECTORS.—You should befamiliar with the use of polished reflectors to formbeams of light. An automobile headlight uses aparabolic reflector to produce afairly wide beam. Aspotlight uses aslightly differently shaped parabolicreflector to produce amore narrow beam.

A type of reflector generally used in missilefire-control radarsistheparabolic dish. It issimilar inappearance to the reflector used in an automobileheadlight. Since radar operates in the microwaveregionof theelectromagneticspectrum, itswaveshavepropertiesand characteristicssimilar to thoseof light.This permits radar antennas to be designed usingwell-known optical design techniques.

A basic principle of optics is that a light raystriking areflectingsurfaceat agivenanglewil l reflectfromthat surfaceat thesameangle. Now refer to figure1-7. Think of the circular wavefronts generated bysource F as consisting of an infinite number of rays.Theantenna’sparabolic reflecting surfaceisdesigned,using the reflection principle, so that as the circularwavefronts strike the reflector, they are reflected asstraight wavefronts. This action concentrates theminto anarrow circular beam of energy.

HORN RADI ATORS.—Horn radiators (fig.1-8), li ke parabolic reflectors, may be used to createconcentrated electromagnetic waves. Horn radiatorsarereadily adaptablefor usewith waveguidesbecausethey serveboth asan impedance-matching deviceand

1-8

LIGHT

RADIO

Figure1-6.—Radiation waves from a radio antenna

and a lamp.

F

Figure1-7.—Principles of theparabolic reflector.

as a directional radiator. Horn radiators may be fed bycoaxial or other types of lines.

Horns are constructed in a variety of shapes, asillustrated in figure 1-8. The shape of the horn, alongwith the dimensions of the length and mouth, largelydetermines the beam’s shape. The ratio of the horn’slength to mouth opening size determines thebeamwidth and thus the directivity. In general, thelarger the opening of the horn, the more directive is theresulting field pattern.

FEEDHORNS.—A waveguide horn may be usedto feed into a parabolic dish. The directivity of thishorn, or feedhorn, is then added to that of the parabolicdish. The resulting pattern (fig. 1-9, view A) is a verynarrow and concentrated beam. Such an arrangementis ideally suited for fire control use. In most radars, thefeedhorn is covered with a window of polystyrenefiberglass to prevent moisture and dirt from enteringthe open end of the waveguide.

One problem associated with feedhorns is theshadow introduced by the feedhorn if it is in the path of

the beam. (The shadow is a dead spot directly in frontof the feedhorn.) To solve this problem the feedhorncan be offset from center (fig. 1-9, view B). This takesit out of the path of the RF beam, thus eliminating theshadow.

LENS ANTENNA .—Another antenna that canchange spherical waves into flat plane waves is the lensantenna. This antenna uses a microwave lens, which issimilar to an optical lens to straighten the sphericalwavefronts. Since this type of antenna uses a lens tostraighten the wavefronts, its design is based on thelaws of refraction, rather than reflection.

Two types of lenses have been developed toprovide a plane-wavefront narrow beam for trackingradars, while avoiding the problems associated withthe feedhorn shadow. These are theconducting(acceleration) type and thedielectric(delay) type.

The lens of an antenna is substantially transparentto microwave energy that passes through it. It will,however, cause the waves of energy to be eitherconverged or diverged as they exit the lens. Considerthe action of the two types of lenses.

The conducting type of lens is illustrated in figure1-10, view A. This type of lens consists of flat metalstrips placed parallel to the electric field of the waveand spaced slightly in excess of one-half of awavelength. To the wave these strips look like parallelwaveguides. The velocity of phase propagation of awave is greater in a waveguide than in air. Thus, sincethe lens is concave, the outer portions of thetransmitted spherical waves are accelerated for alonger interval of time than the inner portion. The

1-9

Figure 1-9.—Reflector with feedhorn.

Figure 1-10.—Antenna lenses: A. Conducting (acceleration)type of microwave lens; B. Dielectric (delay) type ofmicrowave lens.

Figure 1-8.—Horn radiators.

spherical waves emerge at the exit side of theconducting lens (lens aperture) as flat-fronted parallelwaves. This type of lens is frequency sensitive.

The dielectric type of lens, shown in figure 1-10,view B, slows down the phase propagation as the wavepasses through it. This lens is convex and consists ofdielectric material. Focusing action results from thedifference between the velocity of propagation insidethe dielectric and the velocity of propagation in the air.The result is an apparent bending, or refracting, of thewaves. The amount of delay is determined by thedielectric constant of the material. In most cases,artificial dielectrics, consisting of conducting rods orspheres that are small compared to the wavelength, areused. In this case, the inner portions of the transmittedwaves are decelerated for a longer interval of time thanthe outer portions.

In a lens antenna, the exit side of the lens can beregarded as an aperture across which there is a fielddistribution. This field acts as a source of radiation,just as do fields across the mouth of a reflector or horn.For a returning echo, the same process takes place inthe lens.

ARRAY ANTENNAS .—An array type ofantenna is just what the name implies—an array orregular grouping of individual radiating elements.These elements may be dipoles, waveguide slots, orhorns. The most common form of array is the planararray, which consists of elements linearly aligned intwo dimensions—horizontal and vertical—to form aplane (fig. 1-11).

Unlike the lens or parabolic reflector, the arrayapplies the proper phase relationship to make the

wavefront flat before it is radiated by the source feed.The relative phase between elements determines theposition of the beam; hence the often used term,phased array. This phase relationship is what allowsthe beam to be rotated or steered without moving theantenna. This characteristic of array antennas makes itideal for electronic scanning or tracking. (We willdiscuss scanning shortly.)

Radomes

The termradomeis a combination of the wordsradar and dome. Radomes are used to cover andprotect radar antennas from environmental effects suchas wind, rain, hail, snow, ice, sand, salt spray,lightening, heat, and erosion. The ideal radome istransparent to the RF radiation from the antenna and itsreturn pulses and protects the antenna from theenvironment. A radome’s design is based on theexpected environmental factors and the mechanicaland electronic requirements of the RF antenna.

Although, in theory, a radome may be invisible toRF energy, in real life the radome effects antenna’sperformance in four ways. These are;beam deflection,transmission loss, reflected power, and secondaryeffects. Beam deflectionis the shift of the RF beam’saxis. This is a major consideration with tracking (i.e.FC) radar. Transmission lossis the loss of energyassociated with reflection and absorption within theradome.Reflected powercan cause antenna mismatchin small radomes and sidelobes in large radomes.Depolarization and increased antenna noise are a resultof secondary effects.

As an FC, you will be primarily responsiblemaintaining the radome associated with yourequipment. This normally will include routinecleaning and inspection according to your prescribedpreventive maintenance schedule. Some minor repairsmay be authorized by your technical manuals, but mostrepairs will normally be done by an authorized factoryrepresentative. You may be required to repaint theradome because of normal environmental wear andtear. If so, be especially careful to use only paint(s)authorized by the manufacturer and to follow theauthorized step-by-step procedures.

Figure 1-12 is an example of a radome in use intoday’s Navy. Other systems that use radomes include,the Combined Antenna System of the Mk 92 FireControl System, the AN/SPQ-9 series antenna for theMk 86 Gun Fire Control System, and the Mk 23 Target

1-10

HORIZONTAL LINEAR

SUBARRAY

TRANSMITTER AND RECEIVER

SLOT

ANTENNA FCRf0111

Figure 1-11.—Planar array antenna.

Acquisitioning System for the SEASPARROWmissile system.

Control Group

The Control Group provides computer control foran equipment group, processes target detections todevelop and maintain a track file, and interfaces withthe specific weapon system being used. The ControlGroup normally consists of the following equipment: acomputer, data terminal set, magnetic tape unit, andtest set.

Support Systems

The equipment we discussed above composes thecore of the radar system. To operate properly andefficiently, it requires a certain amount of supportequipment. Examples of such equipment includepower supplies (some also have frequency converters),chilled water systems, and dry air systems. Althoughyour radar system normally receives 440 VAC directly

from the ship’s primary power source, it has othervoltage requirements that may be stepped up, steppeddown, or converted in order to make the radar fullyoperational. High-voltage amplifiers and peripheralequipment associated with producing RF energy createtremendous amounts of heat. Chilled water systemsremove excessive heat from such equipment. Coolingsystems may be either liquid-to-liquid or liquid-to-airtypes that use either sea water, or chilled waterprovided by the ship itself. Another important supportsystem is the dry air system. Dry air is used for keepingthe internal part of the waveguide assembly moisturefree and to aid in properly conducting the RF energybeing transmitted. The dry air may be either air takenfrom ship spaces and circulated through various filtersor dehydrated air provided by the ship. Some systemsuse a special gas for their waveguides. An example ofthis is the Mk 92 Fire Control System, which uses thegas SF6 for its Continuous Wave Illumination (CWI)mode.

These are very important support systems to yourradar. As you know, any system is only as good as itsweakest link. Therefore, you must be sure to maintainthe support equipment as required by the equipment’stechnical manuals and maintenance instructions.

Stable Elements

Hitting a target on a regular basis requires that thegun or launcher be stable in relation to the target.Ideally, the platform on which the gun or launcher ismounted is stable throughout the target acquisition anddestruction cycle. Unfortunately Navy ships, on whichthe guns and launchers are mounted, are seldom stable.In even the calmest sea, they pitch and roll to someextent. The solution lies in stabilizing the guns andlaunchers while the ship continues to pitch and roll.This is done with gyroscopes (gyros) installed in thefire control systems.

Gyros provide a stable platform, called thehorizontal plane, as an unvarying reference fromwhich the fire control problem is computed. The basicfundamentals and functions of gyros are covered inNEETS Module 15—Principles of Synchros, Servos,and Gyros.

In fire control, we call the stabilizing unit astableelement. As its name implies, the stable element uses astabilizing gyro. The stabilizing gyro is also theprimary reference for navigation of the ship. It givesthe ship a true North reference for all navigationalequipment. The WSN-2 or WSN-5 are examples of

1-11

3A1A1SEARCH RADARRADOME ASSEMBLY

3A1A2SEARCHRADARANTENNAASSEMBLY

3A1A7TRACKANTENNA

FORWARD

3A1A13TRACKRADARRADOME

CABLINGDETAILSOMITTEDFOR CLARITY

NOTE:

LEFT SIDE CUTAWAY VIEW

FCRf0112

Figure 1-12.—Example of a search and track radome.

stabilizing gyros used in today’s ships. Themaintenance and operation of these gyros is theresponsibility of the Interior Communications (IC)technicians. Figure 1-13 shows a phantom view of agyro you might see on your ship.

The primary purpose of the stable element for firecontrol equipment is to measure accurately anydeviation of the reference element (antenna, director,launcher, etc.) from the horizontal plane. Deviationmeasurements are sent to the fire control computer tocreate a stationary foundation from which to solve thefire control problem. They are also sent to the gundirector, radar antenna, or optical equipment,depending upon the fire control system, to stabilizethese units of the fire control system.

Q5. What is the switching time of a duplexer called?

Q6. What are the two types of lens antennas?

Q7. What determines the position of a phased arrayantenna beam?

Q8. What part of a radar system provides computercontrol for an equipment group?

Q9. What is the primary purpose of the stableelement for fire control equipment?

TYPES OF RADAR SYSTEMS

Because of different design parameters, no singleradar set can perform all the many radar functionsrequired for military use. The large number of radarsystems used by the military has forced the

development of a joint-services classification systemfor accurate identification of radars. Radar systems areusually classified according to their specific functionand instal lat ion vehicle. The joint-servicestandardized classification system divides these broadcategories for more precise identification.

Since no single radar system can fulfill all therequirements of modern warfare, most modernwarships, aircraft, and shore installations have severalradar sets, each performing a specific function. Ashipboard radar insta l la t ion may inc ludesurface-search and navigation radars, a 3D radar, anair-search radar, and various fire-control radars.

Figure 1-14 is a listing of equipment identificationindicators. You can use this table and the radarnomenclature to identify the parameters of a particularradar set. The example given explains the equipmentindicators for the AN/SPY-1A radar system.

The letters AN were originally adopted by theJoint Army-Navy Nomenclature System, also knownas the AN system, to easily classify all militaryelectronic equipment. In 1985, Military StandardMIL-STD-196D changed the name of the JointArmy-Navy Nomenclature System to the “JointElectronics Type Designation System (JETDS)”, butthe letters AN are still used in identifying militaryelectronics equipment.

AIR-SEARCH RADAR

The primary function of an air-search radar is tomaintain a 360-degree surveillance from the surface tohigh altitudes and to detect and determine ranges andbearings of aircraft targets over relatively large areas.

The following are some uses of an air-search radar:

• Give early warning of approaching enemyaircraft and missiles, by providing the directionfrom which an attack could come. This allowstime to bring antiaircraft defenses to the properdegree of readiness and to launch fighters if anair attack is imminent.

• Observe constantly the movement of enemyaircraft. When it detects an enemy aircraft,guide combat air patrol (CAP) aircraft to aposition suitable for an intercept.

• Provide security against attacks at night andduring times of poor visibility.

• Provide information for aircraft control duringoperations that require a specific geographic

1-12

Figure 1-13.—Phantom view of a gyro.

track (such as an antisubmarine barrier or asearch and rescue pattern).

Together, surface- and air-search radars provide agood early-warning system. However, the ship must beable to determine altitude to effectively intercept anyair target. This requires the use of another type of radar.

MULTI-DIMENSIONAL RADAR

The primary function of a multi-dimensional radaris to compute accurate ranges, bearings, and altitudesof targets detected by an air-search radar. Thisinformation is used to direct fighter aircraft duringinterception of air targets.

The multi-dimensional radar is different from theair-search radar in that it has a higher transmittingfrequency, higher output power, and a much narrowervertical beamwidth. In addition, it requires a stabilizedantenna for altitude accuracy.

The following are some applications of amulti-dimensional radar:

• Obtain range, bearing, and altitude data onenemy aircraft and missiles to assist in theguidance of CAP aircraft.

• Provide precise range, bearing, and heightinformation for fast and accurate initialpositioning of fire-control tracking radars.

• Detect low-flying aircraft.

• Determine the range to distant landmasses.

• Track aircraft over land.

• Detect certain weather phenomena.

• Track weather balloons.

The modern warship has several radars. Eachradar is designed to fulfill a particular need, but it mayalso be capable of performing other functions. Forexample, most multi-dimensional radars can be used as

1-13

Figure 1-14.—AN equipment indicator system.

secondary air-search radars; in emergencies,fire-control radars have served as surface-searchradars. A multi-dimensional air-search radar is shownin figure 1-15.

MISSILE GUIDANCE RADAR

The purpose of a guidance subsystem is to directthe missile to target intercept regardless of whether ornot the target takes deliberate evasive action. Theguidance function may be based on informationprovided by a signal from the target, information sentfrom the launching ship, or both. Every missileguidance system consists of two separate systems—anattitude control system and a flight path controlsystem. The attitude control system maintains themissile in the desired attitude on the ordered flight pathby controlling it in pitch, roll, and yaw (fig. 1-16). Thisaction, along with the thrust of the rocket motor, keepsthe missile in stabilized flight. The flight path controlsystem guides the missile to its designated target. Thisis done by determining the flight path errors,generating the necessary orders needed to correct theseerrors, and sending these orders to the missile’s controlsubsystem. The control subsystem exercises control insuch a way that a suitable flight path is achieved andmaintained. The operation of the guidance and controlsubsystems is based on the closed-loop or servoprinciple (fig. 1-17). The control units make correctiveadjustments to the missile control surfaces when aguidance error is present. The control units also adjustthe wings or fins to stabilize the missile in roll, pitch,and yaw. Guidance and stabilization are two separateprocesses, although they occur simultaneously.

Phases of Guidance

Missile guidance is generally divided into threephases (fig. 1-18). As indicated in the figure, the three

phases areboost, midcourse,and terminal .STANDARD SM-2 missiles (MR & ER) use all threeof these phases. Not all missiles, however, go throughthe three phases. As shown in figure 1-18, somemissiles (STANDARD SM-1, SEASPARROW) donot use midcourse guidance. With that thought inmind, let’s examine each phase, beginning with boost.

INITIAL (BOOST) PHASE .—Navysurface-launched missiles are boosted to flight speedby the booster component (which is not always aseparate component) of the propulsion system. Theboost period lasts from the time the missile leaves thelauncher until the booster burns up its fuel. In missileswith separate boosters, the booster drops away fromthe missile at burnout (fig. 1-18, view A). Discardingthe burnt-out booster shell reduces the drag on themissile and enables the missile to travel farther. SMSmissiles with separate boosters are the STANDARD(ER) and HARPOON.

The problems of the initial (boost) phase and themethods of solving them vary for different missiles.The method of launch is also a factor. The basicpurposes, however, are the same. The missile can beeither pre-programmed or physically aimed in aspecific direction on orders from the fire control

1-14

Figure 1-16.—Missile axes: pitch, roll, yaw.

Figure 1-17.—Basic missile guidance and control systems.

Figure 1-15.—Multi-dimensional (3-D) radar.

computer. This establishes the line of fire (trajectoryor flight path) along which the missile must fly duringthe boosted portion of its flight. At the end of the boostperiod, the missile must be at a precalculated point.

There are several reasons why the boost phase isimportant. If the missile is a homing missile, it must“look” in a predetermined direction toward the target.The fire control computer (on the ship) calculates thispredicted target position on the basis of where themissile should be at the end of the boost period. Beforelaunch, this information is fed into the missile.

When a beam-riding missile reaches the end of itsboosted period, it must be in a position where it can becaptured by a radar guidance beam. If the missile doesnot fly along the prescribed launching trajectory asaccurately as possible, it will not be in position toacquire the radar guidance beam and continue its flightto the target. The boost phase guidance system keepsthe missile heading exactly as it was at launch. This isprimarily a stabilizing function.

During the boost phase of some missiles, themissile’s guidance system and the control surfaces arelocked in position. The locked control surfacesfunction in much the same manner as do the tailfeathers of a dart or arrow. They provide stability andcause the missile to fly in a straight line.

MIDCOURSE PHASE.—Not all guided missiles

have a midcourse phase; but when present, it is often

the longest in both time and distance. During this part

of flight, changes may be needed to bring the missile

onto the desired course and to make certain that it stays

on that course. In most cases, midcourse guidance is

used to put the missile near the target, where the final

phase of guidance can take control. The HARPOON

and STANDARD SM-2 missiles use a midcourse

phase of guidance.

TERMINAL PHASE .—The terminal or final

phase is of great importance. The last phase of missile

guidance must have a high degree of accuracy, as well

as fast response to guidance signals to ensure an

intercept. Near the end of the flight, the missile may be

required to maneuver to its maximum capability in

order to make the sharp turns needed to overtake and

hit a fast-moving, evasive target. In some missiles,

maneuvers are limited during the early part of the

terminal phase. As the missile gets closer to the target,

it becomes more responsive to the detected error

signals. In this way, it avoids excessive maneuvers

during the first part of terminal phase.

1-15

A.

B.

Figure 1-18.—Guidance phases of missile flight.

Types of Guidance

As we mentioned earlier, missiles have a pathcontrol system and an attitude control system.Guidance systems are usually classified according totheir path control system, since many missiles use thesame type of attitude control. The type of attitudecontrol used in the fleet isinertial . The following is adiscussion of the types of path control (guidance) inuse in SMS missiles.

INERTIAL GUIDANCE .—An inertial guidancesystem is one that is designed to fly a predeterminedpath. The missile is controlled by self-containedautomatic devices calledaccelerometers.

Accelerometers are inertial devices that measureaccelerations. In missile control, they measure thevertical, lateral, and longitudinal accelerations of thecontrolled missile (fig. 1-19). Although there may notbe contact between the launching site and the missileafter launch, the missile is able to make corrections toits flight path with amazing precision.

During flight, unpredictable outside forces, suchas wind, work on the missile, causing changes in speedcommands. These commands are transmitted to themissile by varying the characteristics of the missiletracking or guidance beam, or by the use of a separateradio uplink transmitter.

BEAM-RIDER GUIDANCE .—A beam-riderguidance system is a type of command guidance inwhich the missile seeks out the center of a controlleddirectional energy beam. Normally, this is a narrowradar beam. The missile’s guidance system receivesinformation concerning the position of the missilewithin the beam. It interprets the information andgenerates its own correction signals, which keep themissile in the center of the beam. The fire control radar

keeps the beam pointed at the target and the missile“rides” the beam to the target.

Figure 1-20 illustrates a simple beam riderguidance system. As the beam spreads out, it is moredifficult for the missile to sense and remain in thecenter of the beam. For this reason, the accuracy of thebeam-rider decreases as the range between the missileand the ship increases. If the target is crossing (notheading directly at the firing ship), the missile mustfollow a continually changing path. This may causeexcessive maneuvering, which reduces the missile’sspeed and range. Beam-riders, therefore, are effectiveagainst only short- and medium-range incomingtargets.

HOMING GUIDANCE .—Homing guidancesystems control the path of the missile by means of adevice in the missile that detects and reacts to somedistinguishing feature of (or signal from) the target.This may be in the form of light, radio, heat, soundwaves, or even a magnetic field. The homing missilesuse radar or RF waves to locate the target whileair-to-air missiles sometimes use infrared (heat)waves.

Since the system tracks a characteristic of thetarget or energy reflecting off the target, contactbetween the missile and target is established andmaintained. The missile derives guidance error signalsbased on its position relative to the target. This makeshoming the most accurate type of guidance system,which is of great importance against moving airtargets. Homing guidance methods are normallydivided into three types:, active homing, semi-activehoming, and passive homing (fig. 1-21).

Active Homing.—With active homing, the missilecontains both a radar transmitter and a receiver. Thetransmitter radiates RF energy in the direction of the

1-16

Figure 1-19.—Accelerometers in a guided missile.

target (fig. 1-21, view A). The RF energy strikes thetarget and is reflected back to the missile. (Thisprocess is referred to as “illuminating the target.”) Themissile seeker (receiving) antenna detects the reflectedenergy and provides it as an input to the missileguidance system. The guidance system processes theinput, usually called the homing error signal, anddevelops target tracking and missile controlinformation. Missile control causes the missile to fly adesired flight path.

The effective range of the missile transmitter issomewhat limited because of its size (power output).For this reason, relatively long-range missiles, such asHARPOON, do not switch to active guidance untilafter midcourse guidance has positioned the missile sothat the transmitter is within its effective range.

Semiactive Homing.—In a semiactive homingsystem, the target is illuminated by a transmitter (anilluminator) on the launching site (fig. 1-21, view B).As with active homing, the transmitted RF is reflectedby the target and picked up by the missile’s receiver.The fact that the transmitter’s size is not limited, aswith active homing, allows a much greater range.

The missile, throughout its flight, is between thetarget and the radar that illuminates the target. It willreceive radiation from the launching ship, as well asreflections from the target. The missile must thereforehave some means of distinguishing between the twosignals, so that it can home on the target rather than onthe launching ship. This can be done in several ways.For example, a highly directional antenna may bemounted in the nose of the missile; or the Dopplerprinciple may be used to distinguish between thetransmitter signal and the target echoes. Since themissile is receding from the transmitter andapproaching the target, the echo signals will be of ahigher frequency. Most SMS missiles use both of thesemethods.

A drawback of this system is that the shipboardillumination is not free to engage another target whilethe missile is in flight. STANDARD SM-1 and SEA-SPARROW all use semi-active homing as theirprimary guidance; they do not use midcourseguidance. The STANDARD SM-2 uses midcourseguidance, and then semi-active homing only forterminal guidance. As a result, the SM-2 needsillumination from the ship only for the last few secondsof flight.

1-17

A.

B.

Figure 1-20.—Simplified command guidance systems: A. Radar/radio command; B. Beam rider.

Passive Homing.—Passive homing requires thatthe target be a source of radiated energy (fig. 1-21, viewC). Typical forms of energy used in passive homing areheat, light, and RF energy. One of the most commonuses of passive homing is with air-to-air missiles thatuse heat-sensing devices. It is also used with missilesthat home on RF energy that originates at the target(ships, aircraft, shore-based radar, and so forth). Anexample of th is is the STANDARD ARM(anti-radiation missile) used for both air-to-surface andsurface-to-surface engagements. An advantage of thistype of homing is that the target cannot detect an attackbecause the target is not illuminated.

Several missiles that normally use other homingmethods (active or semi-active) are capable of

switching to the passive home-on-jamming (HOJ)mode in a countermeasure environment. That is, ifthe target detects that it is being illuminated by anactive or semiactive guidance radar and initiatesjamming (RF interference), the missile will home onthe jamming signal if it is unable to maintain track onthe reflected illumination signal.

Tracking Radar/Fire-Control Radar

Radar that provides continuous positional data iscalled tracking radar. Most tracking radar systemsused by the military are also called fire-control radars,the two names being interchangeable. A fire-controltracking radar system produces a very narrow,circular beam.

PHASES OF RADAR OPERATION

The three sequential phases of radar operation(designation, acquisition, and track) are oftenreferred to as modes and are common to thetarget-processing sequence of most fire-controlradars.

Designation Phase

During the designation phase, the fire-controlradar is directed to the general location of the target.

Acquisition Phase

The fire-control radar switches to the acquisitionphase once its beam is in the general vicinity of thetarget. During this phase, the radar system searches inthe designated area in a predetermined search patternuntil it either locates the target or is redesignated.

Track Phase

The fire-control radar enters into the track phasewhen it locates the target. The radar system locks onto the target during this phase.

Typical fire-control radar characteristics includehigh pulse-repetition frequency, a very narrowpulsewidth, and a very narrow beamwidth. A typicalfire-control antenna is shown in figure 1-22.

Detect-to-Engage Sequence

The basic sequence can be divided into sixfundamental operations: detection, acquisition andtracking, prediction, launcher/gun positioning,

1-18

A.

B.

C.

Figure 1-21.—Homing guidance: A. Active homing; B.Semi-active homing; C. Passive homing.

guidance (missiles), and evaluation (intercept andtarget destruction). Figure 1-23 illustrates the firecontrol problem sequence.

DETECTION .—In this phase, the radar looks fora target. After the radar (usually a search radar) detectsa target, the system obtains precise target positioninformation. This information can be provided by thesame source that detected the target, or it can beprovided from some other source, such as anotherradar. In the majority of the cases, a second radar, a firecontrol radar, is used.

The search radar establishes the target’s initialposition and transmits this information to thedesignated fire control system.

ACQUISITION AND TRACKING .—Duringthis phase, the fire control radar director/antenna isaligned with the search radar’s target position

information until it locks on the reflected target signal(acquisition). Either an operator or an automaticcontrol circuit maintains that alignment (track) whilethe ship and target are moving. In this way,continuous, accurate target position information isavailable to the weapon system for processing. Notonly is the continuous present position of the targetobtained, but its movement (course and speed) is alsodetermined.

Data other than target data is equally important forweapon flight path (trajectory) determination. Wind,for example, could blow the weapon off its flight path.Appropriate corrections would require that winddirection and velocity be determined. The course andspeed of the launching ship and its motion, because ofthe sea (pitch and rol l) , are also importantconsiderations. If this type of data is not included inthe flight path determinations, it could cause largeerrors in the flight path (trajectory).

Data of this nature, along with target data, istransmitted to the fire control system’s computer. Thecomputer performs the necessary calculations forcomputing the launcher or gun mount position anglesand the weapon’s flight path.

After target detection and target acquisition haveoccurred, the fire control system provides threeoperations for the tracking, computation (prediction),and positioning functions.

The first operation tracks the target and providesall necessary data on the target. The fire control radarperforms this function by establishing a tracking LineOf Sight (LOS) along which it receives the returned orreflected energy from the target. It also providesaccurate range data.

Since the speed of the propagated RF energy isabout 186,000 miles per second (the same as the speedof light), and since the target ranges involved arerelatively small, the time for the energy to travel to andfrom the target can be considered as instantaneous.Therefore, the radar indications of the target can beconsidered as instantaneous, present-target positions.

PREDICTION .—The second operation of thefire control problem that must be performed is thecomputation of the gun/launcher positioning angle(line of fire) and the weapon flight path trajectory. Thisoperation consists of two parts. First, the systemprocesses received data into a usable form. Then thefire control computer performs arithmetic operationsto predict the future position of the target.

1-19

Figure 1-22.—Typical fire-control radar.

LAUNCHER/GUN POSITIONING .—Thethird operation that must be performed is thepositioning of the gun/launcher, based on thecalculated line of fire to the future target position. Thisamounts to using the gun/launcher drive mechanism tooffset the gun/launcher axis from the LOS by theamount of the predicted lead angle. In some cases, themissile is positioned (guided) in flight by the firecontrol system.

GUIDANCE (MISSILES) .—For the GuidedMissile Fire Control System (GMFCS), additionalfunctions must be performed during the time themissile is in flight. Prior to launching, the fire controlcomputer performs certain computations to providethe missile with information about the target and its

own flight path. If the target maneuvers during themissile’s flight, the computer can send coursecorrection data to the missile via the fire control radaror the missile can correct itself.

EVALUATION .—The fire control radar displaysare used to evaluate the weapon’s destruction of thetarget. If the missile misses the target or causes onlyminor damage, additional weapons can be used. Inmissile fire control, another missile is fired. In gun firecontrol, corrections are made to bring the fall of shotonto a target using the radar indicators, opticaldevices, or spotter corrections. Normally, a targetwill be fired at until it is evaluated as either destroyedor damaged to the point it is no longer a threat.

1-20

DETECTION

ACQUISITIONAND

TRACKING

PREDICTION

GUN ORLAUNCHER

POSITIONING

GUIDANCE

EVALUATION

FCRf0123

Figure 1-23.—Fire-control problem sequence.

Q10. What type of radar system provides earlywarning of approaching enemy aircraft ormissiles?

Q11. What phase of guidance is NOT necessary forsomemissiles

Q12. What are the three types of homing guidanceused for missiles?

Q13. What are the three sequenti8al phases of radaroperation?

Q14. In what phase of the fire control problemsequence does fore control radar first play apart?

RADAR SYSTEMSIN TODAY’ SNAVY

Thereare too many radar systemsused in today’sNavy to cover in this volume. However, table 1-2providesan overview of the radarsand sensors in use,by AN system designator, ship class, and related FCsystems.

SUMMA RY

Radio, detecting, and ranging (radar) uses radiofrequency (RF) energy and a complex integration ofcomputers, displays, andsupport equipment todetect atarget. However, radar is just onetypeof sensor that isavailable to the modern Fire Controlman. Other typesof sensors (e.g., infrared and optical) use different

1-21

Designator Type Ship Class Range Weapon/Function Related FCSystem

SEARCH

SPS 48 C/E/F 3D Air Search,phased array

CV/CVN,LHA, LCC, LHD

220 NM Primary Search SYS-1,SYS-2

SPS 52 C 3D Air Search LHD 240 NM Primary Search SYS-1

FIRE CONTROL

Mk 92 CAS(CombinedAntennaSystems)

FireControl,Track-While-Scan,Search

FFG 25 NM Mk 75 Gun, SM-1missiles

Part of Mk 92 FCS

Mk 95 radar FireControl, CWtracker, illuminator

DD (Spruance),CV/CVN

20 NM SEASPARROWmissiles

Mk 23 TAS,Part of Mk 91 FCS

SPG 51 D FireControl,pulse-doppler,COSRO tracker,CWI

DDG (Kidd) 100 NM SM-1(MR) missiles,SM-2 missiles

Part of Mk 74 FCS

SPG 60 FireControl DD (Spruance),DDG (Kidd)

50 NM SM-1/2 missiles,Mk 45 LWG

SPY-1, Mk 86 GFCS

SPG 62 FireControl, CW,illuminator

DDG (ArleighBurke),CG (Ticonderoga)

20 NM SM-2 missiles SPY-1,Part of Mk 99 FCS

SPQ 9 Series FireControl,Track-While-Scan,(Surface),pulse-doppler

DD (Spruance),DDG (Kidd),CG (Ticonderoga),LHA

20 NM SM-1/2 missilesMk 45 LWG

SPY-1Mk 86 GFCS

STIR (SeparateTargetIlluminatingRadar)

FireControl,monopulse tracker-illuminator

FFG 60 NM Mk 75 Gun,SM-1 missiles

Part of Mk 92 FCS

Table1-2.—Radar Systems in theU. S. Navy

parts of the electromagnetic spectrum. It is importantthat you, as a modern Fire Controlman, understand thebasic concepts of the sensors used on your ship andother ships in the Navy. These sensors play a key partin accomplishing the ship’s mission. As sensor

technology improves, the Fire Controlman of thefuture will be expected to have a broader spectrum ofknowledge and experience in order to keep our Navyon the cutting edge of naval warfare.

1-22

Designator Type Ship Class Range Weapon/Function Related FCSystem

OTHER

CIWS (Close-InWeapon System)

Combined (searchand track),pulse-doppler

ALL 5 NMSearch 1 NMtrack

Anti-ship missileand air defense

None

HF Surface Wave FM CW LSD 6-12 NM Anti-ship missiles Sea SkimmermissileDetection/Air (Thisradar is still indevelopment)

Mk 23 TAS(Target AcquistionSystem)

Air search, CW,tracker/illuminator

DD (Spruance),CV/CVN, LCC, LHD,LHA, LPD 17

20 NM SEASPARROWmissiles

Part of Mk 91FCS/Mk 95 Radar

SPY 1 Series Multi-function,phased array

D for DDG (ArleighBurke), D forCG (Ticonderoga)

>100 NM SM-2 missiles;search, track, andmissile guidance,Mk 45 LWG

AEGIS, Mk 34GWS, Mk 86 GFCS,Mk 99 FCS

SSDS Mk 1 (ShipSelf-DefenseSystem)

Integrated use ofmultiple ship sensors

FFG, LHD, LSD,LPD 17, AOE 6

Range as pereach sensor

CIWS/RAM, SLQ32, SPS 49,SEASPARROWmissiles

Mk 2 replacesNATOSEASPARROWwith ESSM(EvolvedSEASPARROWmissile)

OPTRONICS SYSYEMS

Optical SightingSystem (OSS) orRemote OpticalSighting System(ROS)

Sensor/View finder Arleigh Burke (DDG),Ticonderoga (CG)

20 kmsurface, 10km air

Mk 45 LWG MK 34 GWS, MK86 GFCS

FLIR (ForwardLooking Infra-red)

Sensor All ships upgraded toBlock 1B

Surface/Air Mk 15 Mods 11-14 CIWS Block 1 B

TISS (ThermalImaging SensorSystem)

Sensor Arleigh Burke (DDG),Ticonderoga (CG),AOE-6, CV/CVN,LPD-17, LSD-41,LHD/LKA, DDG 993,DD 963

55 kyd/air,45 kydsurface

Mk 31 RAM(Rolling AirframeMissile), CIWS,SSDS

AEGIS, Mk 86GFCS

Table 1-2.—Radar Systems in the U.S. Navy—Continued

ANSWERS TO CHAPTER QUESTIONS

A1. The radar.

A2. Radar bearing is determined by the echo signalstrength as the radiated energy lobe moves past atarget.

A3. Pulse-modulation.

A4. The resolution of the radar system andatmospheric conditions.

A5. Receiver recovery time.

A6. Conducting (acceleration) and dielectric (delay)types.

A7. The relative phase between elements.

A8. The control group.

A9. To measure accurately any deviation of thereference element from the horizontal plane.

A10. Air-search radar.

A11. Mid-course guidance.

A12. Active, semi-active, and passive homing.

A13. Designation, acquisition, and track.

A14. The acquisition and tracking phase.

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CHAPTER 2

FIRE CONTROL RADAR SYSTEMS

INTRODUCTION

In the preceding chapter, you read about the basicprinciples of radar operation. You also read about thebasic components of a radar system and theirrelationship to each other. This chapter deals withspecific radar systems and terms associated with thosesystems. You must understand those terms to get themaximum benefit from the information contained inthis chapter. If you don’t have a good understanding ofradar operation and theory, we suggest that you reviewthe following Navy Electricity and ElectronicsTraining Series (NEETS) modules:MicrowavePrinciples, Module 11, NAVEDTRA 172-11-00-87,and Radar Principles, Module 18, NAVEDTRA172-18-00-84. We also suggest that you refer to theFunctional Descriptionsection in your own technicalmanuals for the specific operation of your radarequipment.

The Fire Controlman rating deals with a largenumber of different radar systems, but you willprobably be trained in only one or two of these systems.To help you develop a broad understanding of FireControl radar, we will first discuss the Fire Controlradars and sensors used in the Fleet today. We will doth is by category: search radar, miss i ledirection/illumination radar, multi-function radar, andoptronics systems. Then we will give you an overviewof upcoming developments in radar.

SEARCH RADAR

You may think the function of Fire Control radar isto lock on to and identify a specific hostile target inorder to direct a weapon to destroy it. Thatis thefunction ofmostFC radars. However, most FC radarsuse a narrow beam to perform their function. Thismakes using FC radar forlocatinga target impractical,since a narrow beam can easily miss targets. Locatingtargets requires using a radar with a wide beam. Searchradar has such a beam. Search radar provideslong-range (200 nautical miles or more), 360-degreecoverage. It can determine a target’s range, bearing,and elevation, and can then hand over that informationto the more accurate narrow-beamed FC radar. SomeFire Control systems have built-in search and trackradar; others rely on completely separate search radar.In this section, we will cover the separate search radarsyou will see in the surface Navy. These are theAN/SPS-52C and the AN/SPS-48 series search radars.

AN/SPS-52 SEARCH RADAR

The AN/SPS-52C is a ship mounted, air search,three-dimensional radar system that provides targetposition data in range, bearing, and elevation. Itproduces three-dimensional coverage from a singleantenna by using electronic scanning in elevation andmechanical rotation in azimuth. The 52C uses theAN/SPA-72B antenna as did the earlier AN/SPS-52systems, but has completely different below-the-decks

2-1

LEARNING OBJECTIVES

Upon completing this chapter, you should be able to do the following:

1. Identify and describe search radar systems associated with fire control radar.

2. Identify and describe missile and gun fire control radar systems.

3. Identify and describe other related sensor systems associated with fire control radar.

4. Describe the detect-to-engage scenario.

5. Describe the fire control problem in relationship to the detect to engage scenario.

electronics. Because of this, the 52C has significantimprovements over earlier versions of the 52 radar inthe areas of detection, reliability, and maintenance.

The antenna assembly (fig. 2-1) is a planar array,tilted back at an angle of 25 degrees. This 25-degree tiltallows the antenna to provide high-elevation coverage.The array is a collection of rows of slotted waveguidesand is fed RF from a feed system running the length ofone side of the total array assembly. This antenna scansin the vertical plane by transmitting differentfrequencies, as selected by a digital computer.

The AN/SPS-52C radar has four modes ofoperation:high angle, long range, high data rate, andMTI (Moving Target Indicator). The operator selectsthe appropriate mode, depending on the threat type andenvironment. The primary mode ishigh angle. In thismode, the radar provides coverage to a range ofapproximately 180 miles and an elevation ofapproximately 45 degrees. In thelong-rangemode,the radar prov ides coverage to a range ofapproximately 300 miles and an elevation ofapproximately 13 degrees. Thehigh data ratemodeprovides a range of approximately 110 miles and anelevation of approximately 45 degrees. This mode isused because of its unique ability to acquire pop-upand close-in targets quickly. TheMTI mode is useful ina high-clutter environment (such as weather in extremesea-state conditions) where targets are normally hardto locate. Coverage is about 70 miles and up to anelevation of 38 degrees.

The 52C radar is used with the SYS-1/SYS-2 radarsystem. The SYS-1/SYS-2 system coordinates allradar sensors on a ship into a single system. It does thisby using a processor designed around integratedautomatic detection-and-tracking (IADT). Theadvantage of using such a system is that the unique

characteristics of the various ship’s radars can beintegrated, resulting in more accurate and quickerdetection of threats. This is part of a program fornon-AEGIS class ships called New Threat Upgrade(NTU).

The AN/SPS-52C radar is presently found on theWASP (LHD) class and the TARAWA (LHA) classamphibious assault ships. It will eventually be replacedby the AN/SPS-48E.

AN/SPS-48 RADAR

The AN/SPS-48 radar is a complete systemupgrade of the AN/SPS-52C including all componentelements — transmitter, receiver, computer (radar andautomatic detection and tracking), frequencysynthesizer and height display indicator. Figure 2-2shows an antenna for the SPS-48 radar on the USSBoxerLHD-4 (see arrow).

The SPS-48 radar is a long-range, three-dimensional, air-search radar system that providescontact range, bearing, and height information to bedisplayed on consoles and workstations. It doesthis by using a frequency-scanning antenna,which emits a range of different frequencies inthe E/F band. The SPS-48 radar has three powermodes: high, medium, and low.

An upgrade was needed because the 52C radar’ssingle elevation beam could not dwell long enough inany particular direction. To solve this problem, the 48series uses a process that stacks nine beams (a train ofnine pulses at di fferent frequencies) into apulse-group. The nine beams simultaneously scan a5-degree elevation area, allowing the stack to cover 45degrees of elevation.

Two versions of the SPS-48 are currently in use:the 48C and the latest version, the 48E. Maximumelevation has increased somewhat, 65 degrees versus45 degrees for the 52C. The “E” version has twice theradiated power of the “48C”, developed by reducingthe sidelobes and increasing the peak power. Receiversensitivity is increased and the 48E has a four-stagesolid state transmitter. The main operating modes are:

• EAC (Equal Angle Coverage)—The radar’senergy is concentrated at a low angle.

• MEM (Maximum Energy Management)—Bothhigh and medium power are regulated.

• AEM (Adaptive Energy Management)—Allowsthe radar to be adapted to a priority target radar

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Figure 2-1.—AN/SPS-52 radar antenna.

cross section and a potential jammingenvironment.

• LOW-E (Low Elevation)—Gives priority to thelower beam groups and transmits them as aDoppler wave.

The radar can also transmit as a single steerablebeam group or it can burn through jamming using achirp pulse.

Radar video, converted to a digital format, isdisplayed on consoles to allow operators to performmanual radar search, detection and tracking functions.True bearing indications appear when the trackposition is displayed in relation to true north, ratherthan to ownship.

Variation in frequency tends to make this radarmore resistant to jamming than if it were operated at afixed frequency. This provides a solution to the blindspeed problem (“blind speed” is the speed a targettravels that is too fast for the radar to track it) insystems. Frequency scanning imposes somelimitations because a large portion of the availablefrequency band is used for scanning rather than toincrease the resolution of targets. It also requires thatthe receiver bandwidth be extremely wide or that thereceiver be capable of shifting the bandwidth centerwith the transmitted frequency.

The radar provides accurate height data byfactoring in the effects of pitch and roll of the ship andchanging the transmitted frequency accordingly. The

ship’s gyro system provides the radar set with thispitch and roll data.

The AN/SPS-48 radar works with other onboardradar sensors through the SYS-1/SYS-2, as did theAN/SPS-52C. Search data from the AN/SPS-48 radaris sent to multiple weapon systems. These include theMk 91 Fire Control System for the SEASPARROWmissile system, the Mk 95 radar, the Mk 23 TargetAcquisition System, the Close-In Weapon System, andthe Rolling Airframe Missile (RAM) System.

The AN/SPS-48 search radar is found onboardNIMITZ (CVN-68) (figure 2-3), KITTY HAWK(CV-63), and ENTERPRISE (CVN-65) class carriers,BLUE RIDGE (LCC) class amphibious commandships, and WASP (LHD) and TARAWA (LHA) classamphibious assault ships.

Q1. What operational characteristic makes theAN/SPS-48 series radar resistant to jamming?

MISSILE AND GUN FIRE CONTROLRADAR

Although you may be involved in the operation ofsearch radar, the majority of your work will be withradar systems used to control the direction and fire ofgun and missile systems. These radar systems arenormally part of a larger system. They are called GunFire Control Systems (GFCS) or Missile Fire ControlSystems (MFCS). Some systems may be able tocontrol the fire of either guns or missiles. These are

2-3

Figure 2-2.—SPS-48 series radar on USSBoxer, a WASP classamphibious assault ship.

simply called Fire Control Systems (FCS). Thissection will look at the radar associated with these gunand missile fire control systems.

MK 7 AEGIS FIRE CONTROL SYSTEMRADAR

The Mk 7 AEGIS Weapon System is installed onARLEIGH BURKE class destroyers (fig. 2-4) andTICONDEROGA class cruisers (fig. 2-5). The Mk 7AEGIS system contains the SPY-1 radar system, the

Mk 99 Missile Fire Control System (MFCS) and theMk 86 Gun Fire Control System (GFCS) or the Mk 34GWS (Gun Weapon System). We will discuss each ofthese systems briefly as they relate to their associatedradar systems.

AN/SPY-1 Radar

The latest technology in multi-function radar isfound in the AN/SPY-1 series on TICONDEROGAclass cruisers and ARLEIGH BURKE class

2-4

Figure 2-3.—USSNimitz (CVN-68).

Figure 2-4.—AEGIS class destroyer DDG-60 USSPaul Hamilton.

destroyers. Ships that do not use the AN/SPY-1 arebeing upgraded to a system known as ShipSelf-Defense System (SSDS). We will discuss SSDSin another section.

For more than four decades, the U.S. Navy hasdeveloped systems to protect itself from surface and airattacks. After the end of World War II, severalgenerations of anti-ship missiles emerged as threats tothe fleet. The first anti-ship missile to sink a combatantwas a Soviet-built missile that sank an Israeli destroyerin October 1967. This threat was reconfirmed in April1988 when two Iranian surface combatants fired onU.S. Navy ships and aircraft in the Persian Gulf. Theresulting exchange of anti-ship missiles led to thedestruction of an Iranian frigate and a corvette byU.S.-built Harpoon missiles.

The U.S. Navy’s defense against this threat reliedon a strategy of gun and missile coordinated defense.Guns were supplemented in the late fifties by the firstgeneration of guided missiles in ships and aircraft. Bythe late sixties, although these missiles continued toperform well, there was still a need to improve missiletechnology in order to match the ever-changing threat.To counter the newer enemy missile threat, theAdvanced Surface Missile System (ASMS) wasdeveloped. ASMS was re-named AEGIS (after themythological shield of Zeus) in December 1969.

The AEGIS system was designed as a total weaponsystem, from “detection” to “kill”. The heart of the

AEGIS system is an advanced, automatic detect andtrack, multi-functional phased-array radar, theAN/SPY-1. This high-powered (four-megawatt) radarcan perform search, track, and missile guidancefunctions simultaneously, with a capability of over 100targets. The first system was installed on the test ship,USS Norton Sound(AVM-1) in 1973. Figure 2-6shows the weapons and sensors on an AEGIS classcruiser.

The system’s core is a computer-based commandand decision element. This interface enables theAEGIS combat system to operate simultaneously inant i -a i r war fare, ant i -sur face warfare, andanti-submarine warfare.

The AN/SPY-1 series radar system works withtwo fire control systems on AEGIS class ships: the Mk99 Missile Fire Control System and the Mk 86 GunFire Control System (part of the Mk 34 Gun WeaponSystem). The Mk 86 GFCS is also found onSPRUANCE class destroyers and works with the Mk91 Missile Fire Control System. We will discuss theMk 91 MFCS in a later section.

Mk 99 Missile Fire Control System

The Mk 99 MFCS controls the loading and armingof the selected weapon, launches the weapon, andprovides terminal guidance for AAW (Anti-AirWarfare) missiles. It also controls the targetillumination for the terminal guidance of SM-2

2-5

Figure 2-5.—USSTiconderogaCG-47.

Anti-Air missiles (fig. 2-7). The radar systemassociated with the Mk 99 MFCS is the missileilluminator AN/SPG-62.

AN/SPG-62 RADAR.—The AN/SPG-62 is I/J-Band fire control radar. The SPY-1 radar systemdetects and tracks targets and then points the SPG-62toward the target, which in turn provides illuminationfor the terminal guidance of SM-2 missiles. Refer tochapter 1 for discussion on the different phases ofmissile guidance and the way radar is used for missileguidance. Remember that in order to track a target youneed a very narrow beam of RF energy. The narrowerthe beam, the more accurately you can tell if you haveone target or multiple targets (this is called radarresolution). This narrow beam radar is normally asecond radar that works with a primary search or trackradar. The AN/SPG-62 illuminating radar works as asecond radar with the AN/SPY-1 series radar. Seefigure 2-6 for the location of AN/SPG-62 on an AEGIScruiser.

In addition to the Mk 99 MFCS, the AEGIS SPY-1series radar works with the Gun Fire Control System

Mk 86. The Mk 86 GFCS controls the fire of the Mk 455-inch gun.

MK 86 GUN FIRE CONTROL SYSTEM

The Mk 86 Gun Fire Control System (GFCS)provides ships of destroyer size and larger with aneconomical, versatile, lightweight, gun and missile firecontrol system that is effective against surface and airtargets.

The Mk 86 Gun Fire Control System (GFCS) is thecentral sub-element of the Mk 34 Gun WeaponsSystem (GWS) on AEGIS class ships. It controls theship’s forward and aft 5"/54 caliber Mk 45 gun mounts(fig. 2-8) and can engage up to two targetssimultaneously. The SPQ-9 series and Mk 23 TAS(Target Acquisition System) work together to providecontrol for Naval Gun Fire Support (NGFS),Submarine Warfare (SUW) and Anti-Air Warfare(AW) gun engagements. The Mk 86 GFCS also uses aRemote Optical Sighting system. This is a separate TVcamera with a telephoto zoom lens mounted on themast and each of the illuminating radars. The opticalsighting system is known as ROS on the SPRUANCEclass destroyers and is mounted on the SPG-60illumination radar. The Mk 34 GWS on AEGIS classdestroyers and cruisers uses the Mk 46 Mod 0 OpticalSight System on the SPG-62 illuminators.

The Mk 86 GFCS is the controlling element, whereloading and firing orders originate. After an operatorselects the GFCS mode, the system calculates ballisticgun orders. These orders can be modified to correct forenvironmental effects on ballistics. The GFCSconducts direct firing attacks against surface radar andoptically tracked targets, as well as indirect firingduring Naval Gun Fire Support (NGFS).

2-6

Figure 2-6.—Radar and weapon systems on an AEGIS class cruiser.

Figure 2-7.—SM-2 ER Anti-Air missile on launcher.

See figure 2-10 for a list of weapon systems andtheir sensors related to the Mk 86 GFCS on aSPRUANCE class destroyer.

AN/SPQ-9 Radar

The AN/SPQ-9 Surface Surveillance and TrackingRadar, developed by Northrop Grumman NordenSystems, Melville, NY, is a track-while-scan radarused with the Mk-86 Gunfire Control system onsurface combatants. Since it is a typical fire controlradar, we will discussed it in more detail to help youunderstand the basic function of fire control radar.

The AN/SPQ-9B detects sea-skimming missiles atthe hor izon, even in heavy clut ter, whi lesimultaneously providing detection and tracking ofsur face targets and beacon responses. TheAN/SPQ-9B is available as a stand-alone radar or as areplacement for the AN/SPQ-9 in the Mk 86 Gun FireControl System, which will be integrated into the Mk 1Ship Self Defense System (SSDS).

The Radar Set AN/SPQ-9B is a high resolution,X-band narrow beam radar that provides both air andsurface tracking information to standard plan positionindicator (PPI) consoles. The AN/SPQ-9B scans theair and surface space near the horizon over 360 degreesin azimuth at 30 revolutions per minute (RPM).Real-time signal and data processing permit detection,acquisition, and simultaneous tracking of multipletargets. The AN/SPQ-9B provides raw and clear plot(processed) surface video, processed radar airsynthetic video, gate video, beacon video synchro

signals indicating antenna relative azimuth, AzimuthReference Pulses (ARP), and Azimuth Change Pulse(ACP). The radar will maintain its capabilities in thepresence of clutter from the sea, rain, land, discreteobjects, birds, chaff, and jamming.

The AN/SPQ-9B has three modes of operation:air,surface,and beacon. The air and surface modes have asubmode for Combat Systems training. TheAN/SPQ-9B complements high-altitude surveillanceradar in detecting missiles approaching just above thesea surface. The system emits a one-degree beam that,at a range of approximately 10 nautical miles, candetect missiles at altitudes up to 500 feet. Since thebeamwidth expands over distance, the maximumaltitude will increase at greater ranges.

The air mode uses the Pulse-Doppler radar fordetecting air targets. When the AN/SPQ-9B radardetects an air target and initiates a track, it willdetermine the target’s position, speed, and heading.The air mode has a sector function called the Anti-ShipMissile Defense (ASMD). When the radar is radiating,the air mode is enabled continuously.

The surface modegenerates a separate surfacefrequency and an independent pulse with a pulserepetition interval (PRI) associated with a range of40,000 yds. In the surface mode, the AN/SPQ-9B radarhas 360-degree scan coverage for surface targets. Theradar displays raw and clear plot video, has a submodecalled Surface-Moving Target Indicator (MTI), andoperates concurrently with the air mode. While theradar is in the radiate state, the surface mode is enabledcontinuously.

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Figure 2-8.—A 5”/54 Mk 45 gun mount.

The beacon modegenerates a separate beaconfrequency and an independent pulse with a PRI havinga range of 40,000 yds. The AN/SPQ-9B radar has360-degree scan coverage for beacon targets. Thereceived beacon video is sent to the console for displayand distribution, while beacon track data is sent to thecomputer for processing. The AN/SPQ-9B beaconmode operates at the same time as the air and surfacemodes.

The ASMD Sector function allows the air mode toprovide quick response detection of low-flyinghigh-threat targets. Through this function, the radarautomatically detects, tracks, and reports any targetsentering the ASMD sector that require a reaction timeof less than 30 seconds. The operator can select anASMD azimuth sector width between five and 360degrees and a range of up to 20 NMI. The ASMD sectorfunction operates together with the air, surface, andbeacon modes.

The Surface-MTI Submode allows the surfacemode to cancel non-moving targets. The Surface-MTIazimuth sector width is operator selectable between abearing width of five and 360 degrees, with theAN/SPQ-9B automatically displaying any targets witha relative speed exceeding 10 knots. The AN/SPQ-9BRadar Sur face-MTI submode wi l l operateconcurrently with the air, surface, and beacon modes.

The AN/SPQ-9B is installed on ships and aircraftcarriers in the following classes:

• CG-47 TICONDEROGA class cruisers (figure2-5)

• LHD-1 amphibious ships (figure 2-2)

• LPD-17 SAN ANTONIO class amphibious

ships

• DD-963 SPRUANCE class destroyers (figure

2-10)

• DDG-51 destroyers (figure 2-4)

The AN/SPQ-9 series radar also works with theSPY-1 series radar. SPQ-9 radar helps to control anumber of weapons which include: SM-1/SM-2missiles and the Mk 45 5”/54 gun.

Mk 23 Target Acquisition System (TAS)

The Mk 23 Target Acquisition System (TAS) is adetection, tracking, identification, threat evaluation,and weapon assignment system. It is used againsthigh-speed, small cross-section targets that approachthe ship from over the horizon at very low altitudes orfrom very high altitudes at near vertical angles. TheTAS integrates a medium-range, two-dimensional,air-search radar subsystem, an IFF subsystem, adisplay subsystem, and a computer subsystem. Thisallows TAS to provide automatic or manual targetdetection and tracking, target identification, threatevaluation, and weapon assignment capabilities forengagement of air tracks. The Mk 23 TAS automaticdetection and tracking radar is also an element of theMk 91 Missile Fire Control system and is used onSPRUANCE class destroyers, carriers, LHDs, LHAs,and the LPD-17 class amphibious assault ships. TheMk 91 MFCS and TAS control the SEASPARROWmissile as their primary weapon. Figure 2-9 shows aMk 29 box launcher for SEASPARROW missiles.

2-8

Figure 2-9.—Mk 29 box launcher for SEASPARROW missiles.

MK 91 FIRE CONTROL SYSTEM

The Mk 91 NATO SEASPARROW GuidedMissile Fire Control System (GMFCS) integrates theMk 157 NATO SEASPARROW Surface MissileSystem (NSSMS) into the Ship Self Defense System(SSDS) to provide an additional layer of ship missiledefense. In thissystem, theFiring Officer ConsoleandRadar Set Consoles are combined into a singleAdvancedDisplay SystemConsole(AN/UYQ70); theSignal Data Processor is modified; the Mk 157Computer Signal Data Converter and the SystemEvaluationandTrainer (SEAT) areeliminated; and themicroprocessor circuitry within the SSDS electronicsis upgraded. This eliminates the limited input-outputchannel andcomputer processingdeficienciesresidentin theolder Mk 57 NSSMS. Theradar associated withthe Mk 91 Fire Control System includes the Mk 95illuminator, Mk 23Target AcquisitioningSystem, andthe AN/SPQ-9 series radar.

TheMk 95 illuminator isusedexclusively with theNATO SEASPARROW GMFCS. It is an X-bandtracker-illuminator on aMk 78director andworkswiththeMk 23TAS. TheMk 91FireControl Systemand itsassociated radar systems are found on Spruance classdestroyers, carriers, LHDs, AOEs, AORs, andTARAWA class amphibious assault ships.

See figure 2-10 for the various weapons systemsand radar associated with the Mk 86 and Mk 91 firecontrol systems on aSPRUANCE class destroyer.

MK 92 FIRE CONTROL SYSTEM RADAR

The Mk 92 Fire Control System (FCS) providesFFG-7 class frigates (Figure 2-11) and other surfacecombatants with a fast reaction, high firepower,all-weather weaponscontrol system for useagainst airand surface targets. The Mark 92’s surface and airsurveillance capability gives highly accurate gun andmissile control against air and surface targets.

The Mark 92 fire control system, an Americanversion of the WM-25 system designed in theNetherlands, was approved for service use in 1975.Introduction to the fleet and foll ow-on test andevaluation began in 1978. In 1981, an aggressiveprogram to improveperformanceand reliability of theMk 92 fire control system in clutter and electroniccounter-measure environments was launched, with anat-seaevaluationaboard theUSSEstocincompleted in

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Figure2-11.—FFG-57 PERRY class frigate.

Figure2-10.—Weapons and sensors on SPRUANCE class destroyer.

1986. Following the evaluation, the upgraded system,identified as Mk 92 Mod 6 was installed in USSIngraham(FFG-61). The Mk 92 Mod 6 will replace theMod 2 systems in the fleet.

The Mk 92 Fire Control System (FCS) is deployedon board FFG-7 PERRY class ships in conjunctionwith the Mk 75 Naval Gun (fig. 2-12) and the Mk 13Guided Missile Launching System (fig. 2-13). The Mk92 FCS integrates target detection with multichannel

antiair and antisurface missile and gun systemscontrol, engaging up to four targets simultaneously.The Mk 92 “track-while-scan” radar uses theCombined Antenna System (CAS), which houses asearch antenna and a tracker antenna inside a singleegg-shaped radome (fig.2-14). A Separate TargetIllumination Radar (STIR) (fig. 2-14) designed for thePERRY class Mk 92 FCS application provides a largediameter antenna for target illumination at rangesbeyond CAS capabilities.

A Mod 1 version of the Mk 92 system is installedon the US Coast Guard’s WMEC (Medium-EnduranceCutter, figure 2-15) and its WHEC (High-EnduranceCutter). This version can track one air or surface targetusing the monopulse tracker and two surface or shoretargets using track-while-scan data from CAS. UsingSTIR, the Mod 2 system on FFG-7 class frigates cantrack an additional air or surface target.

CLOSE-IN WEAPON SYSTEM RADAR

The Mk 15 Phalanx Close-In Weapon System(CIWS — pronounced “sea-whiz”) is a stand-alone,quick-reaction time defense system that provides finaldefense against incoming air targets. CIWS willautomatical ly engage anti-ship missi les andhigh-speed, low-level aircraft that penetrate the ship’sprimary defenses. As a stand-alone weapon system,CIWS automatically searches for, detects, tracks,evaluates for threat, fires at, and assesses kills oftargets. A manual override function allows the operatorto disengage a target, if necessary.

The search and track radar antennas are enclosedin a radome mounted on top of the gun assembly (see

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Figure 2-12.—Mk 75 Naval Gun system.

Figure 2-13.—Mk 13 Guided Missile Launcher system.

figure 2-16). All associated electronics for radaroperations are enclosed within either the radome or theElectronics Enclosure (called the ELX). CIWS isoperated remotely from either a Local Control Panel(LCP) or the Remote Control Panel (RCP) located inthe Combat Information Center (CIC). It has twoprimary modes of operation: automatic and manual. Inthe automatic mode, the computer program determinesthe threat target, automatically engages the target, andperforms the search-to-kill determination on its own.In the manual mode, the operator fires the gun afterCIWS has identified the target as a threat and has givena “recommend fire” indication.

CIWS was developed in the late 1970’s to defendagainst anti-ship cruise missiles. However, as thesophistication of cruise missiles increased, so did thesophistication of CIWS. Major changes to CIWS arereferred to as “Block” upgrades. The first upgrade,known as “Block 0”, incorporated a standard rotating

search antenna. Limitations of elevation in Block 0lead to the next upgrade, Block 1. Block 1 providedimproved elevation coverage and search sensitivity byusing a phased-array antenna. A minor upgrade toBlock 1, known as Block 1A, improved the processingpower of the computer by incorporating a newhigh-order language. This upgrade gave CIWS theability to (1) track maneuvering targets and (2) workwith multiple weapons coordination. The nextupgrade, Block 1B, enabled CIWS to engage surfacetargets. This upgrade is known as the Phalanx SurfaceMode (PSUM). A special radar, Forward-LookingInfrared Radar (FLIR), was added to CIWS to detectsmall surface targets (i.e., patrol/torpedo boats) andlow, slow, or hovering aircraft (i.e., helicopters). Thisradar is mounted on the side of the radome structure.FLIR can also help the radar system engage anti-shipcruise missiles. To detect targets day or night, CIWSBlock 1B uses a thermal imager and advancedelectro-optic angle tracking.

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Figure 2-14.—Mk 92 Fire Control System on PERRY class frigate.

Figure 2-15.—WMEC-910 Coast Guard CutterThetiswith Mk 92 CAS.

SHIP SELF-DEFENSE SYSTEM (SSDS)

The principal air threat to US naval surface ships isa variety of highly capable anti-ship cruise missiles(ASCMs)(figure 2-17). These include subsonic (Mach0.9) and supersonic (Mach 2+), and low altitudeASCMs. Detection, tracking, assessment, andengagement decisions must be made rapidly to defendagainst these threats, since the time from when anASCM is initially detected until it is engaged is lessthan a minute. SSDS is designed to accomplish thesedefensive actions.

SSDS, consisting of software and commercialoff-the-shelf (COTS) hardware, integrates andcoordinates all of the existing sensors and weaponssystems aboard a non-AEGIS ship to provide QuickReaction Combat Capability (QRCC). (It willeventually be installed on board most classes ofnon-AEGIS ships.) SSDS (fig. 2-18), by providing aLocal Area Network (LAN), LAN access units(LAUs), special computer programs, and operatorstations, automates the defense process, from the

detect sequence through the engage sequence. Thisprovides a quick response, multi-target engagementcapability against anti-ship cruise missiles.

The entire combat system, including the sensorsand weapons, is referred to as Quick Reaction CombatCapability (QRCC), with SSDS as the integratingelement. Although SSDS broadens the ship’sdefensive capability, it is not intended to improve theperformance of any sensor or weapon beyond itsstand-alone performance. The primary advantageSSDS brings to the combat systems suite is the abilityto coordinate both hard kill (gun and missile systems)and soft kill (decoys such as chaff) systems and to usethem to their optimum tactical advantage.

The following systems represent the SSDSinterfaces for a non-AEGIS ship:

• AN/Air Search Radar

• AN/Surface Search Radar

• AN/Electronic Warfare System

• Centralized Identification Friend or Foe (CIFF)

• Rolling Airframe Missile (RAM)

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Figure 2-16. —CIWS radome with search and track radar.

Figure 2-17.—Missile launch from an AEGIS class cruiser.

• Phalanx Close-in Weapon System (CIWS)

• Mk 36 Decoy Launching System (DLS)

SSDS options range from use as a tactical decisionaid (up to the point of recommending when to engagewith specific systems) to use as an automatic weaponsystem. SSDS will correlate target detections fromindividual radars, the electronic support measures(ESM) system, and the identification-friend or foe(IFF) system, combining these to build compositetracks on targets while identifying and prioritizingthreats. Similarly, SSDS will expedite the assignmentof weapons for threat engagement. It will provide a“recommend engage” display for operators or, if inautomatic mode, will fire the weapons, transmit ECM,

deploy chaff or a decoy, or provide some combination

of these.

Q2. What classes of ship use the AN/SPY-1 radarsystem?

Q3. In the Mk 99 MFCS, the terminal guidance phaseof a SM-2 missile is controlled by whatilluminating radar?

Q4. Name the three modes of operation of theAN/SPQ-9 radar?

Q5. The NATO SEASPARROW missile is controlledby what fire control system?

Q6. What class of ship uses the Combined AntennaSystem (CAS) and the Separate TargetIllumination Radar (STIR)?

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FIBER-OPTIC LOCAL AREA NETWORK (LAN)

ECM

QRCC

SSDSCONTROL

DETECT ENGAGE

SSDS AUTOMATES THE DETECT TO ENGAGE SEQUENCE

Figure 2-18. —Ship Self-Defense System.

Q7. What type of ships, in general, are being

upgraded with the Ship Self-Defense System

(SSDS)?

OPTRONICS SYSTEMS

As you have seen, the majority of sensor systemsyou wil l work with are of the RF type. That is, RFenergy is transmitted via a complex system ofcomponents to detect and destroy a target. There arealso other sensors used in today’s Navy that use adifferent method of locating targetsand helping in thedirection of weapons. These systems use light or heatas asource for target detection. They are described as“Optronic” systems because they use light frequencyrather than RF energy as a detecting element and asystemof optical lensesfor focusing alight source. Anexampleof this typeof system used in theNavy todayis the Thermal Imaging Sensor System (TISS). It isrepresentativeof other similar optronicssystemsinusetoday.

THERMA L IM AGING SENSOR SYSTEM(TISS)

The Thermal Imaging Sensor System (TISS) is ashipboard electro-optical system that consists of alow-light television camera and an eye-safe laserrangefinder. The TISS director is designed to be mastmounted. The control console can be mounted in CICor in the pilothouse. In addition to providing surfaceandair target datatocombat systems, theTISScanalsobe used to detect mines and to provide good nightidentification and detection capabilities.

TISS was originally tested on board the USSTiconderoga (CG-47) and later installed on the USSVicksburg (CG-69) for her deployment to the MiddleEast in April 1997. TISSwil l initiall y be installed asastand-alonesystem on deploying ships. Asmoreunitsare completed, permanent installation and integrationinto the combat systems wil l become standard.Systemsthat useTISSaretheMk 86 Gun FireControlSystem, CIWS, SSDS, and RAM.

Q8. What typeof system is TISS?

UPCOMIN G DEVELOPMENT SIN

RADAR

To keep pace with the approaching 21st centuryneeds for multi-mission surface warships, the Navy iscontinually developing new technology that allows it

to do more with less. We mention some of thesedevelopments, related to radar and sensors, below.

HIG H FREQUENCY SURFACE WAVERADAR

High frequency surface wave radar is used todetect low-altitudemissilesbeyond theship’shorizon.The transmitting antennas are meandering-wave typeunits and are mounted on either side of the ship, nearthe bridge. The receivers are separate deck-edge orsuperstructure units. This radar uses an FMCW(Frequency Modulated-ContinuousWave) transmitterwith a 50% duty cycle, with co-located transmit andreceive antennas.

MULTI-FUNCTIO N RADAR

TheMulti-Function radar is adevelopment for theDD-21 Land Attack destroyer that provides shipself-defense and local area defense against air andmissile threats. The new Multi-Function radar (MFR)wil l greatly enhance ship defense capability againstmodern air and missile threats in the littoralenvironment (areasclose to shoreline). Thissystem isbasedonsolid-state, active-array radar technology thatwil l provide search, detect, track, and weapon controlfunctions while dramatically reducing manning andlife-cycle costs associated with the multiple systemsthat perform these functions today. The MFR wil l becomplemented by anew VolumeSearch Radar (VSR),which wil l provide timely cueing to MFR at longranges and above the horizon. The VSR wil l beacquired as part of the DD-21 total ship system. (SeeFigure 2-19)

INFRARE D SEARCH AND TRACK (IRST)

TheInfraredSearchandTrack (IRST) systemisanintegrated sensor designed to detect and reportlow-flying antiship cruise missiles by detecting theirthermal heat plume or heat signature. IRST willcontinually scan thehorizon and report any contactstothe ship’s combat information center for tracking andengagement. Thescanner isdesigned to search severaldegreesaboveandbelow thehorizonbut canbeslewedmanually to search for higher flying targets. IRST isapassivesystem providingbearing, elevationangle, andthermal intensity of a target. The system consists of amast-mounted and stabilized scanner, below deckselectronics, and aUYQ-70 operator’s console.

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DETECT TO ENGAGE SEQUENCE FOR

FIRE CONTROL

This chapter has covered the radar systems youwill see as an FC in the Fleet today. You have beengiven a brief overview of the radar systems and theirfunctions and uses. You have also learned theassociated weapon systems and ship types associatedwith each radar system. Now that you have anunderstanding of these radar systems, you need toknow how these systems are used in an actual combatscenario. The following section gives you animaginary scenario of what might happen if you wereto detect an enemy target, from beginning to end.

THE DETECT-TO-ENGAGE SEQUENCE

The international situation has deteriorated and theUnited States and Nation Q have suspended diplomaticrelations. The ruler of Nation Q has threatened toannex the smaller countries bordering Nation Q andhas threatened hostilities toward any country that triesto stop him. You are assigned to a guided missilecruiser that is a member of Battle Group Bravo,currently stationed approximately 300 nautical milesoff the coast of Nation Q. The battle group commanderhas placed the Battle Group on alert by specifying theWarning Status as YELLOW in all warfare areas,meaning that hostilities are probable.

You are standing watch as the Tactical ActionOfficer (TAO) in the Combat Information Center(CIC), the nerve center for the ship’s weapons systems.

Dozens of displays indicate the activity of ships andaircraft near the Battle Group (fig. 2-20). As the TAO,you are responsible for the proper employment of theship’s weapons systems in the absence of thecommanding officer. The time is 0200. You are incharge of a multi-million dollar weapon system andresponsible for the lives and welfare of yourshipmates.

The relative quiet is shattered by an alarm on yourElectronic Warfare (EW) equipment indicating theinitial detection and identificationof a possibleincoming threat by your Electronic Support Measures(ESM) equipment. The wideband ESM receiverdetects an electromagnetic emission on a bearing in thedirection of Nation Q. Almost instantaneously theESM equipment interprets the emitter’s parametersand compares them with radar parameters stored in itsmemory. The information and a symbol indicating theemitter’s approximate line of bearing from your shipare presented on a display screen. You notify thecommanding officer of this development. Meanwhile,the information is transmitted to the rest of the BattleGroup via radio data links.

Moments later, in another section of CIC, theship’s long-range two-dimensional air search radar isjust beginning to pick up a faint return at its maximumrange. The information from the air search radarcoupled with the line of bearing from your ESM allowsyou to localizethe contact and determine an accuraterange and bearing. Information continues to arrive, asthe ESM equipmentclassifiesthe J-band emission as

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

belonging to a Nation Q attack aircraft capable ofcarrying anti-ship cruise missiles.

The contact continues inbound, headed toward theBattle Group. Within minutes, it is within range of yourship’s three-dimensional search and track radar. Thecontact’s bearing, range, and altitude are plotted togive an accurate course and speed. The rangeresolution of the pulse-compressed radar allows you todetermine that the target is probably just one aircraft.You continue totrack the contact as you ponder yournext move.

As the aircraft approaches the outer edge of itsair-launched cruise missile’s (ALCM) range, the ESMoperator reports that aircraft’s radar sweep haschanged from a search pattern to a single target trackmode. This indicates imminent launch of a missile.

According to the Rules of Engagement (ROE) ineffect, you have determined hostile intent on the part ofthe target and should defend the ship against imminentattack. You inform your CIC team of your intentions,andselect a weapon, in this case a surface to air missile(fig. 2-21), to engage the target. You also inform theAnti-Air Warfare Commander of the indications ofhostile intent, and he places you and the other ships inAir Warning Red, “attack in progress”.

As the target closes to the maximum range of yourweapon system, the fire control or tactical computerprogram, using target course and speed computes apredicted intercept point (PIP) inside the missileengagement envelope. This information and the reportthat the weapon system has locked-on the target isreported to you. You authorize “batteries release” and

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Figure 2-20. —Display consoles in the Combat Information Center (CIC).

Figure 2-21. —Surface-to-Air missile.

the missile is launched toward the PIP (fig. 2-22). Asthe missile speeds towards its target at Mach 2+, theship’s sensors continue to track both the aircraft andthe missile. Guidance commands are sent to the missileto keep it on course.

On board the enemy aircraft, the pilot is preparingto launch an ALCM when his ESM equipmentindicates he is being engaged (figure 2-23). Thiswarning comes with but precious few seconds, as themissile enters the terminal phase of its guidance. In a

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Figure 2-22.—Missile launch.

Figure 2-23.—Enemy aircraft.

desperate attempt to break the radar lock, the pilot usesevasive maneuvering. It’s too late though. As themissile approaches its lethal “kill radius,” theproximity fuze on the missile’s warhead detonates themissile’s explosive charge, sending fragments out inevery direction,destroying or neutralizingthe target(figure 2-24). This information is confirmed by yourship’s sensors. The radar continues to track that targetas it falls into the sea and the ESM equipment goessilent.

THE FIRE CONTROL PROBLEM

The above scenario is not something out of a warnovel, but rather an example of a possible engagementbetween a hostile force (the enemy attack aircraft) anda Naval Weapons System (the ship). This scenarioillustrates the concept of the “detect-to-engage”sequence, which is an integral part of the modern FireControl Problem. Although the scenario was one of asurface ship against an air target, every weapon systemperforms the same functions:target detection,resolution or localization, classification, tracking,weapon selection, and ultimately neutralization. Inwarfare, these functions are performed by submarines,aircraft, tanks, and even Marine infantrymen. Thetarget may be either stationary or mobile; it may travelin space, through the air, on the ground or surface of the

sea, or even beneath the sea (figure 2-25). It may bemanned or unmanned, guided or unguided,maneuverable or in a fixed trajectory. It may travel atspeeds that range from a few knots to several times thespeed of sound.

The term weapons systemis a generalizationencompassing a broad spectrum of components andsubsystems. These components range from simpledevices operated manually by a single person tocomplex devices operated by computers.

To accomplish one specific function, a complexarray of subsystems may be interconnected bycomputers and data communication links. Thisinterconnecting allows the array to perform severalfunct ions or to engage numerous targetssimultaneously. Although each subsystem may bespecifically designed to solve a particular part of thefire control problem, having these components operatein concert that allows the whole system to achieve itsultimate goal — the neutralization of the target.

COMPONENTS

All modern naval weapons systems, regardless ofthe medium they operate in or the type of weapon theyuse, consist of the basic components that allow thesystem todetect, trackandengagethe target. Sensorcomponents must be designed for the environments inwhich the weapon system and the target operate. Thesecomponents must also be capable of coping withwidely varying target characteristics, including targetrange, bearing, speed, heading, size and aspect.

Detecting the Target

There are three phases involved in target detectionby a weapons system. The first phase is surveillanceand detection, the purpose of which is to search apredetermined area for a target and detect its presence.This may be accomplished actively, by sending energyout into the medium and waiting for the reflectedenergy to return, as in radar, or passively, by receivingenergy being emitted by the target, as by ESM in ourscenario. The second phase is to measure or localizethe target’s position more accurately and by a series ofsuch measurements estimate its behavior or motionrelative to ownship. This is done by repeatedlydetermining the target’s range, bearing, and depth orelevation. Finally, the target must be classified; that is,its behavior must be interpreted to estimate its type,number, size and most importantly identity. Thecapabilities of weapon system sensors are measured by

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Figure 2-24. —Successful engagement of a missile.

the maximum range at which they can reliably detect atarget and their ability to distinguish individual targetsin a multi-target group. In addition, sensor subsystemsmust be able to detect targets in a medium clutteredwith noise, which is any energy sensed other than thatattributed to a target. Such noise or clutter is alwayspresent in the environment due to reflections from rainor the earth’s surface or because of deliberate radiointerference or jamming. It is also generated within theelectronic circuitry of the detecting device.

Tracking the Target

Sensing the presence of a target is an essential firststep to the solution of the fire control problem. Tosuccessfully engage the target and solve the problem,updates of the target’s position and velocity relative tothe weapon system must be continually estimated.This information is used to both evaluate the threatrepresented by the target and to predict the target’sfuture position and a weapon intercept point so theweapon can be accurately aimed and controlled. Toobtain target trajectory information, methods must bedevised to enable the sensor to follow or track thetarget. This control or “aiming” may be done by acollection of motors and position-sensing devicescalled aservo system. Inherent in the servo process is aconcept calledfeedback. In general, feedback providesthe system with the difference between where thesensor is pointing and where the target is actuallylocated. This difference is calledsystem error. Thesystem takes the error and, through a series ofelectro-mechanical devices, moves the sensor orweapon launcher in the proper direction and at a ratethat reduces the error. The goal of any tracking system

is to reduce this error to zero. Realistically this isn’tpossible, so when the error is minimal the sensor is saidto be “on target.” Sensor and launcher positions aretypically determined by devices that are used toconvert mechanical motion to electrical signals.Synchro transformers and optical encoders arecommonly used in servo systems to detect the positionand to control the movement of power drives andindicating devices. Power drives move the radarantennas, directors, gun mounts, and missilelaunchers.

The scenario presented in the beginning of thissection was in response to a single target. In reality, thisis rarely the case. The modern “battlefield” is one inwhich sensors are detecting numerous contacts,friendly and hostile, and information is continuallybeing gathered on all of them. The extremely highspeed, precision, and flexibility of modern computersenable the weapons systems and their operators tocompile, coordinate, and evaluate the data, and theninitiate an appropriate response. Special-purpose andgeneral-purpose computers enable a weapons systemto detect , t rack, and predict target mot ionautomatically. These establish the target’s presenceand define how, when, and with what weapon the targetwill be engaged.

Engaging the Target

Effective engagement and neutralization of thetarget requires that a destructive mechanism, in thiscase a warhead, be delivered to the vicinity of the target(see figure 2-24). How close to the target a warheadmust be delivered depends on the type of warhead andthe type of target. In delivering the warhead, the

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Figure 2-25. —Enemy submarine.

aiming, launch, type of weapon propulsion system,and the forces to which the weapon is subjectedenroute to the target must be considered. The weapon’scapability to be guided or controlled after launchdramatically increases its accuracy and probability ofkill. The use of guidance systems also dramaticallycomplicates system designs. These factors as well asthe explosive to be used, the fuzing mechanism, andwarhead design are all factors in the design andeffectiveness of a modern weapon.

Q9. What is the sequence of events in fire control thatbegins with the initial detection of an enemytarget and ends with the destruction of thattarget?

Q10. What phase of target detection estimates thetype, number, size, and identity of a target?

SUMMARY

This chapter has given you an overview of many ofthe radar systems used in today’s Navy. The goal ofthis chapter was not to tell you about every radarsystem or every detail of every radar system, but tosimply explain what radar systems are found on whichships in the Navy and on what types of ships you willfind various radar systems.

One of the key tools used for the “detect-to-engage” scenario is radar systems. Understandinghow your ship accomplishes the detect-to-engage

scenario is extremely important to every FireControlman. Doing so will give you a clear, firm graspof what your ship does in a battle scenario and how youfit in the big picture of naval warfare for your ship.You should also understand the fire control problem inrelationship to this scenario. The detect-to-engageprocess and fire control problem work together toaccomplish the goal of destroying an enemy target.Each ship has its own, unique configuration ofweapons and radar systems; it is your responsibility asa Fire Controlman to learn how these work together inthe detect-to-engage sequence and the fire controlproblem.

ANSWERS TO CHAPTER QUESTIONS

A1. Variation in frequency .

A2. TICONDEROGA class cruisers and ARLEIGHBURKE class destroyers.

A3. The AN/SPG-62 radar.

A4. Air, surface, and beacon.

A5. The Mk 91 Guided Missile Fire Control System..

A6. The Perry class frigate.

A7. Non-AEGIS ships.

A8. A shipboard electro-optical system.

A9. Detect-to-engage.

A10. The classification phase.

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CHAPTER 3

RADAR SAFETY

INTRODUCTION

Throughout your military career, you will be“bombarded” with safety slogans, rules, andprocedures concerning almost every job that you do.There is a reason for this. Your command is trying tokeep you alive and well. Your part in this process is tobecome safety “conscious” to the point that youapproach every job from the safety point of view. Inthis chapter, we will address the specific safetymeasures and devices associated with operating andmaintaining radar equipment.

RADIATION SAFETY

One of the hazards associated with maintainingradar equipment is exposure to RFR (Radio FrequencyRadiation). Radar peak power may reach a millionwatts or more. Therefore, you must remain aware ofthe RFR hazards that exist near radar transmittingantennas. These hazards are present not only in front ofan antenna but also to its sides and sometimes evenbehind it because of spillover and reflection. Exposureto excessive amounts of radiation can produce bodilyinjuries ranging from minor to major (Think of howfood is cooked in a microwave oven.). The extent ofinjuries depends on the RFR frequency and the time ofexposure. At some frequencies, exposure to excessivelevels of radiation will produce a noticeable sensationof pain or discomfort to let you know that you havebeen injured. At other frequencies, you will have nowarning of injury. If you suspect any injury, see yourship’s doctor or corpsman. Be sure to acquaint yourself

with the actual radiation hazard zones of the radar onyour ship.

Whenever you work around radar equipment,observe the following precautions to avoid beingexposed to harmful RFR:

• Do not inspect feedhorns, open ends ofwaveguides or any opening emitting RFR energyvisually unless you are sure that the equipment isdefinitely secured for that purpose.

• Observe all RFR hazard (RADHAZ) warningsigns (fig. 3-8). They point out the existence ofRFR hazards in a specific location or area.

• Ensure that radiation hazard warning signs areavailable and used.

• Ensure that radar antennas that normally rotateare rotated continuously or that they are trainedto a known safe bearing while they are radiating.

HAZARDS OF ELECTROMAGNETICRADIATION

Studies have shown that humans cannot easilysense electromagnetic radiation (EMR), also referredto as radio frequency radiation (RFR). Furthermore,EMR at frequencies between 10 kilohertz (kHz) and300 gigahertz (GHz) presents a hazard to humans andto some materials. Since radiation at these frequenciesis common in the Navy’s e lect romagnet icenvironment, its presence must be detected andannounced to ensure the safety of personnel involved

3-1

LEARNING OBJECTIVES

Upon completing this section, you should be able to:

1. Identify and explain the radiation hazards associated with maintaining andoperating radar.

2. Identify the safety precautions associated with maintaining radar equipment.

3. Identify safety devices associated with maintaining radar equipment.

4. Identify other hazards associated with maintaining radar equipment.

in various activities within the electromagneticenvironment. A discussion of the various methodsused to detect electromagnetic energy is beyond thescope of this TRAMAN. However, we must emphasizethe importance of remaining alert to the danger ofoverexposure to electromagnetic radiation.

Radiation hazards can be broken down into threecategories:

• Hazards of Electromagnetic Radiation toOrdnance (HERO)

• Hazards of Electromagnetic Radiation to Fuel(HERF)

• Hazards of Electromagnetic Radiation toPersonnel (HERP)

We will discuss each of these categories in moredetail in the following paragraphs.

Hazards of Electromagnetic Radiation toOrdnance (HERO)

The high intensity radio frequency (RFR) fieldsproduced by modern radio and radar transmittingequipment can cause sensitive electroexplosivedevices (EEDs) contained in ordnance systems toactuate prematurely. The Hazards of ElectromagneticRadiation to Ordnance (HERO) problem was firstrecognized in 1958. The prime factors causing theproblem have been increasing ever since. The use ofEEDs in ordnance systems has become essential. Atthe same time, the power output and frequency rangesof radio and radar transmitting equipment have alsoincreased.

RFR energy may enter an ordnance item through ahole or crack in its skin or through firing leads, wires,and so on. In general, ordnance systems that aresusceptible to RFR energy are most susceptible duringassembly, disassembly, loading, unloading, andhandling in RFR electromagnetic fields.

The most likely results of premature actuation arepropellant ignition or reduction of reliability bydudding. Where out-of-line Safety and Arming (S+ A)devices are used; the actuation of EEDs may beundetectable unless the item is disassembled. If theitem does not contain an S+ A device, or if RFR energybypasses the S+ A device, the warhead may detonate.

Ordnance items susceptible to RFR can beassigned one of three HERO classifications, basedupon the probability that they will be adversely

af fected by the RFR envi ronment . Thoseclassifications are:

1. HERO Safe. An ordnance item sufficientlyshielded or protected to make it immune toadverse effects from RFR when used in itsexpected shipboard RFR environments.

2. HERO susceptible. Ordnance containing EEDsproven by tests to be adversely affected by RFRenergy to the point that safety or reliability maybe in jeopardy when the ordnance is used in RFRenvironments.

3. HERO unsafe. Any electrically initiatedordnance item that becomes unsafe when:

a. Its internal wiring is physically exposed.

b. Tests being conducted on the item requireadditional electrical connections to be made.

c. Electroexplosive devices (EEDs) havingexposed wire leads are present, handled, orloaded.

d. The i tem is being assembled ordisassembled.

e. The item is in a disassembled condition.

f. The item contains one or more EEDs and hasnot been classified as HERO safe orsusceptible by either a test or designanalysis.

To ensure the HERO safety and HERO reliabilityof ordnance systems, the Naval Sea SystemsCommand sponsors an extensive testing program todetermine their susceptibility to RFR energy. HEROrequirements and precautions are provided inNAVSEA OP 3565/NAVAIR 16-1-529/NAVELEX0967-LP-624-6010/Volume II,ElectromagneticRadiation Hazards (U) (Hazards to Ordnance) (U).You will find your ship’s specific requirements in itsHERO Emission Control (EMCON) bill.

The commanding officer of each ship or shorestation is responsible for implementing HEROrequirements. He or she must also establish aprocedure to control radiation from radio and radarantennas among personnel handling ordnance andpersonnel controlling radio and radar transmitters. Thecommanding officer does this through a commandinstruction based on the ship’s mission and specialfeatures. This instruction is usually part of the Ship’sOrganization Manual and is the basis for departmentand division instructions.

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Hazards of Electromagnetic Radiation

to Fuels (HERF)

Many studies have been done about fuel vaporsbeing accidentally ignited by electromagneticradiation. Tests aboard ships and in laboratories haveshown that the chances of this happening are lowbecause of other conditions that must exist at the sametime to support combustion of the fuel. Althoughaccidental ignition of fuel by RFR is unlikely, you stillneed to be aware of the potential hazards. The mostlikely time this might occur is during a ship’s refuelingevolutions, commonly called UNREPs (UnderwayReplenishment). Many ships also carry at least onehelicopter or have the ability to refuel a helicopter and,therefore, carry fuel to support helo operations. All ofthese operations are inherently dangerous bythemselves and require the utmost attention andalertness. As a junior Fire Controlman you most likelywill be personally involved in these refuelingoperations. You need to be aware of the potentialhazards associated with Fire-Control radar and fuel.As a senior Fire Controlman, you need to know thehazards of electromagnetic radiation to fuel, so youcan ensure that your division personnel are working ina safe environment.

RADAR RESTRICTIONS .—ElectromagneticRadiation Hazards (U) (Hazards to Personnel, Fueland Other Flammable Material) (U),NAVSEA OP3565/NAVAIR16-1-529/NAVELEX 0967-LP-624-6010/Volume I specifies the safe distances fromradiating sources at which fueling operations may beconducted. Figure 3-1 indicates safe distances betweenfueling operations and a conical monopole antenna,based on transmitter power. Each type of antenna hasits own chart. Refer to your ship’s Emissions Control(EMCON) bill for specific guidance concerningfueling operations.

FUEL RESTRICTIONS .—As the RFR energyradiated from high-powered communications andradar equipment installed on ships increased in recentyears, the Navy shifted to less volatile fuels. Undernormal operating conditions, volatile mixtures arepresent only near aircraft fuel vents, open fuel inletsduring over-the-wing fueling, and near fuel spills.

Before fuel vapors can ignite, three conditionsmust exist simultaneously:

1. For a given ambient temperature, the mixturemust contain a specific ratio of fuel vapor to air.

2. There must be enough energy in the arc or sparkto produce the appropriate temperature forignition.

3. The length of the arc must be sufficient tosustain the heat in the arc for the time required toinitiate a flame.

Each of these conditions is likely to vary for everysituation, and two of the conditions may exist at anygiven time. Although all three conditions will probablynot occur simultaneously, the consequences of anaccidental explosion make it very important to becareful.

Hazards of Electromagnetic Radiation toPersonnel (HERP)

The RFR hazard category of most immediateconcern to you is HERP. The heat produced by RFRmay adversely affect live tissue. If the affected tissuecannot dissipate this heat energy as fast as it isproduced, the internal temperature of the body willrise. This may result in damage to the tissue and, if thetemperature rise is sufficiently high, in death.

The Bureau of Medicine and Surgery hasestablished safe exposure limits for personnel whomust work in an electromagnetic field based on thepower density of the radiation beam and the time ofexposure in the radiation field. Before we discuss thesefurther, we must discuss some additional terms.

Specific Absorption Rate (SAR)—This is the rateat which the body absorbs non-ionizing RFR. Thethreshold at which adverse biological effects begin is 4watts per kilogram of body mass (W/kg). With a safetyfactor of 10 added, the accepted threshold is 0.4 W/kgfor the whole body, averaged over any 6-minute (0.1hour) period. A special limit for “hot spot” or limitedbody exposure has been set at 8.0 W/kg, averaged overany 1 gram of body tissue for any 6-minute period.Although this rate of absorption is very important indetermining whether or not a safety hazard exists, it isvery difficult to measure. Measuring this rate ofabsorption can also be dangerous since it requiresactual exposure of body tissue. A related measure thatgives an acceptable indication of SAR is “PermissibleExposure Limit”.

Permissible Exposure Limit (PEL)—This is alimit to RFR exposure based on measurements ofradiation’s electric field strength (E) or magneticfield strength (H) taken with instruments. You canuse available charts to determine whether the

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3-4

Figure 3-1.—Guidance Curve for Potential Fueling Hazards.

strength of the field presents abiological hazard topersonnel located at the point where the measurementswere taken. PEL readings are the basis for determiningRADHAZ safety boundaries.

Permissible Exposure Time (PET)—This is themaximum time of exposure to a specific power densityfor which the PEL will not be exceeded when theexposure is averaged over any 6-minute period. Table3-1 shows the PET for a variety of radars operated attheir normal power levels.

If you suspect that you or someone else has beenoverexposed to EMR, follow the flow chart in figure3-2. If you confirm your suspicions, the exposure isconsidered an incident and must be reported asrequired by Protection of DOD Personnel fromExposure to Radio Frequency Radiation, DODInstruction 6055.11.

RFR HAZARDS TO THE SKIN.— The energyimpinging on a person in an electromagnetic field maybe scattered, transmitted, or absorbed. The energyabsorbed into the body depends upon the dimensionsof the body, the electrical properties of the tissues, and

the wavelength of the RFR. Thus, the wavelength ofthe energy and its relationship to a person’sdimensions are important factors bearing on thebiological effects produced by RFR.

Significant energy absorption will occur onlywhen a personal dimension is equivalent to at leastone-tenth of a wavelength. As the frequency ofradiation increases, the wavelength decreases and theperson’s height represents an increasingly greaternumber of electrical wavelengths, increasing thedanger from RFR exposure. As the frequency isdecreased, the wavelength increases and the personbecomes a less significant object in the radiation field.Thus, the likelihood of biological damage increaseswith an increase in radiation frequency. Also, as theradiation frequency increases and the wavelengthbecomes progressively shorter, the dimensions of partsand appendages of the body become increasinglysignificant in terms of the number of equivalentelectrical wavelengths.

When a person stands erect in a RFR field, thebody is comparable to a broadband receiving antenna.

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Figure 3-2.—Personnel RFR exposure decision chart.

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Table 3-1.—Permissible Exposure Time Limits—Partial List

When any of the major body dimensions are parallel tothe RFR energy’s plane of polarization, the producedeffects are likely to be more pronounced than whenthey are oriented in other positions.

The depth of penetration and coincident heatingeffects of energy on the human body depend on theenergy’s frequency. The region of transition betweenmajor damage and minor or no damage is between 1and 3 GHz. Below 1 GHz, the RFR energy penetratesto the deep body tissues. Above 3 GHz, the heatingeffect occurs closer to the surface. At the higherfrequencies, the body has an inherent warning systemin the sensory elements located in the skin. Atfrequencies between 1 and 3 GHz, the thermal effectsare subject to varying degrees of penetration, with thepercentage of absorbed energy ranging from 20 to 100percent. The two microwave cooking oven frequenciesfall close to this range. The lower frequency, 915 MHz,produces a deeper heating effect on tissue (i.e., roasts)and is not as effective for surface cooking (browning)as the higher frequency, 2,450 MHz.

RFR HAZARD TO THE EYES .—Thetransparent lens of the eye may be damaged by radiatedenergy (ultraviolet, infrared, or radio frequency),causing the development of cataracts or opacities. Thelens is very susceptible to thermal damage, since it hasan inefficient vascular system to circulate blood andexchange heat to the surrounding tissues. Unlike othercells of the body, the cells of the lens cannot bereplaced by regrowth. When cells in the lens die orbecome damaged, a cataract may form. The damagedcells may lose their transparency slowly and,depending upon the extent of damage, cause theindividual to suffer impaired vision. Apparently, thepresence of even a relatively few damaged cells mayact upon other lens cells, either by releasing toxicsubstances or by preventing normal chemicaltransformation to take place within other cells.

RFR HAZARD TO THE TESTICLES .—Testicular reaction to heat injury from excessiveexposure to RFR radiation can be the same as thereaction to a high fever associated with many illnesses.Although a condition of temporary sterility may occur,the condition does not appear to be permanent and willultimately correct itself. However, injury to thetesticles may be permanent because of an extremelyhigh dosage or because of high exposures for extendedperiods of time (i.e., months to years).

SHIPBOARD RADIATION HAZARDZONES.—Because of the danger of radiation hazardsto personnel, the fire control radar is equipped with

cutout switches that turn off the transmitter for certaindirector bearings and elevations. The informationconcerning cutout zones for your part icularinstallation is located in the radar OPs(OperationalPublications). You should know the cutout zones foryour particular radar. The equipment OPs also give theradiation pattern and the minimum safe distance forpersonnel exposed to the mainbeam of the radar. Thesafe limit of radiation exposure to personnel,established by the Naval Medical Command, is 10mW/cm2 averaged over any one-tenth hour period (sixminutes). No exposure in a field with a power densityin excess of 100 mW/cm2 is permitted.

RFR Burns

You can receive an RFR burn if your skin contactsa source of RFR voltage. This is because your skin’sresistance to the current flow in the area of contactproduces heat. The effect of this heat on your skin canrange from noticeable warmth to a painful burn.

Mild RFR burns are usually indicated by smallwhite spots on the skin and possibly the odor ofscorched skin. More severe burns may penetratedeeper into the flesh and produce painful and slowerhealing injuries. For our purposes, “hazardous” will beassociated with the RFR voltage level sufficient tocause pain, visible skin damage, or an involuntaryreaction. The termhazarddoes not include the lowervoltage that causes annoyance, a stinging sensation, ormild heating of the skin.The Naval ShipsEngineering Center has prescribed that an opencircuit RFR voltage exceeding 140 volts on anobject in an RFR radiation field be consideredhazardous.

A common source of potential RFR burns is cranehooks. Transmitting antennas can induce RFRvoltages in nearby crane structures and wire ropes.Figure 3-3 shows areas on a crane in which inductiveand capacitive charges may be induced by RFR. Somecrane/antenna problems can be eliminated byrelocating the associated antennas, but eachinstallation requires special considerations. Thelocations of ship’s antennas are based on the desiredradiation patterns, taking into account the physicallimitations imposed by the ship’s structure. Often, therelocat ion of antennas, al though physical lypermissible, is not feasible because of the location ofthe associated transmitters.

RFR voltages measured aboard ships show thatresonance effects may occur at frequencies between 2

3-7

and 30 Mhz. The careful use of frequency can reducethe coupling of RFR voltages induced in cranestructures and rigging. A better approach, however, isthe use of RFR high voltage insulator links, whichprovide protection for personnel against RFR burns.(Refer toLink RFR High Voltage Insulator for ShipCranes, MIL-L-24410 (SHIPS)). Two separate bandsof fiberglass filament wound on two zinc-coated steelsaddles provide the required high electrical resistance,low capacitance, high tensile strength, ruggedness andfail-safe features of the insulator links. While the innerband normally carries the full working load, the outerband can carry the full working load if the inner bandbreaks.

When proper precautions are taken, personnelhandling rigging will not be harmed as long as nearbyelectronic transmitting equipment is operated at anoutput of 250 watts or less, average (at any frequency).HOWEVER, PERSONNEL SHOULD BECONSTANTLY ALERT TO THE FACT THATEVEN UNDER THE ABOVE OPERATIONALLIMITS, ELECTRONIC TRANSMITTINGEQUIPMENT CAN CAUSE HAZARDOUSVOLTAGES TO BE INDUCED IN THE STAND-ING RIGGING AND OTHER PORTIONS OF ASHIP’S STRUCTURE, PARTICULARLYSTRUCTURES AND OBJECTS (i.e., AIRPLANES

AND HELICOPTERS) THAT PROTRUDE FROMTHE SHIP IN THE SAME PLANE AS THERADIATING SOURCE. The RFR voltage induced ina ship’s structures, rigging, or other objects will causeburns to personnel when they contact conductiveobjects. The burn hazard problem, its causes, andremedial techniques are discussed in chapter 3 (“RFRBurns”) of Electromagnetic Radiation Hazards (U)(Hazards to Personnel, Fuel and Other FlammableMaterial) (U), NAVSEA OP 3565/NAVAIR16-1-529/ NAVELEX 0967-LP-624- 6010/Volume I.

Q1. What do the letters RFR stand for whenassociated with radiation safety?

Q2. What are the three categories of electromagneticradiation hazards?

Q3. What are the three classifications of ordnancesusceptible to RFR?

Q4. What NAVSEA publication specifies safedistances from radiation sources for fueling?

Q5. If you confirm that someone has beenoverexposed to RFR, what instruction must youuse to properly report the incident?

Q6. According to the Naval Ships EngineeringCenter, what is the minimum RFR voltage in anopen circuit that qualifies as hazardous?

3-8

Figure 3-3.—Electrical equivalent of cargo handling equipment.

MAN ALOFT SAFETY

Since many areas on the exterior of a ship thatcontain radar equipment are inaccessible from decks orbuilt-in work platforms, someone must go aloft towork in these areas. We define “aloft” as any mast,kingpost, or other structure where the potential for afall exists. Probably the greatest hazard associatedwith working aloft is the danger of a fall. Other hazardsinclude electrical shock, radiation burns, asphyxiationfrom stack gasses, and the dropping of objects.

As long as nearby equipment is turned off, youshould not have to worry about receiving a shock fromcurrent generated by the equipment. However, youmustbe aware of the possibility of shock due to staticcharges. Static charges are caused by electricallycharged particles that exist naturally in the water.Under certain conditions these charged particlescollect on metallic objects such as wire antennas andproduce a shock hazard. You can eliminate this hazardby grounding these objects. Shocks from static chargeswill not harm you directly, but the surprise of such ashock may cause you to fall.

WORKING ALOFT CHECK SHEET

Because of the associated dangers, no one may goaloft on masts, stacks, or kingposts without firstobtaining permission from the Officer of the Deck(OOD), as prescribed by theNavy Occupational Safetyand Health (NAVOSH) Program Manual for ForcesAfloat, OPNAVINST 5100.19 series. Before grantingpermission, the OOD must ensure that the WorkingAloft Check Sheet (fig. 3-4) has been properlycompleted and routed. When the ship is underway, thecommanding officer’s permission is required to workaloft. The OOD will ensure that appropriate signalflags are hoisted. (KILO for personnel working aloft;KILO THREE for personnel working aloft and over theside.) Before the work begins and every 15 minutesthereafter, he will have the word passed over the 1 MC,“DO NOT ROTATE OR RADIATE ANYELECTRICAL OR ELECTRONIC EQUIPMENTWHILE PERSONNEL ARE WORKING ALOFT.”Additionally the OOD will inform the ships in thevicinity that personnel will be working aloft to ensurethat they take appropriate action on the operation oftheir electrical and electronic equipment. Departmentsconcerned must ensure that all radio transmitters andradars that pose radiation hazards are placed in theSTANDBY condition and that a sign reading“SECURED. PERSONNEL ALOFT. DATE _______

TIME _______ INITIALS ________ ” is placed onthe equipment.

You should always check your ship’s instruction(Man Aloft Bill) for specific guidance before you goaloft. Here are some general guidelines to follow whenyou go aloft:

1. Use a climber sleeve assembly in conjunctionwith the safety harness where a climber safetyrail is installed.

2. Attach safety lanyards to all tools, if practical.Never carry tools up and down ladders. Rig aline and raise or lower your tools in a safecontainer.

3. Stop work when the ship begins to roll in excessof 10 degrees, or to pitch in excess of 6 degrees,when wind speed is greater than 30 knots, andwhen an ice storm or lightning threatens.

4. Be sure the petty officer-in-charge has markedoff an area below the zone of work and keeps allunnecessary personnel clear. If the slightestchance of danger exists, have personnel in thearea moved to safety.

5. Read all safety placards posted in the area beforeyou begin the work.

6. Wear personal protective equipment, such ashearing protection, goggles, gloves, or arespirator for hazards other than RFR.

7. When you perform hot work, replace thepersonal safety and staging or boatswain chairfiber lines with wire rope. Personal safety linesmust consist of CRESS wire rope.

Most ships in today’s Navy are aviation capable.Any loose materials or tools that you leave in anoutside work area may become foreign object damage(FOD) material. FOD material can be sucked intoaircraft engines (causing extensive damage) or blownaround by engine exhaust or rotor wash (possiblyinjuring someone). You must learn the importance offoreign object damage (FOD) control. Supervisorypersonnel are responsible for ensuring that assignedpersonnel who work on the mast and other topsideareas receive training on the importance of FODcontrol. After completing any work topside, you mustensure that all tools and materials are removed from thework area. Metallic items left in these areas may alsocreate electromagnetic interference problems.

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SAFETY HARNESS

For your own safety, you should wear an approvedparachute-type safety harness (fig. 3-5) with a safetylanyard and a tending line (as required) with doublelocking snap hooks whenever you work aloft. (Thelineman-type safety belt is no longer authorized for

use.) Safety harnesses should be checked periodicallyas prescribed by the Planned Maintenance System.Place the tools that you will use on the job in a canvasbag and haul the bag up with a line to the job location.To guard against dropping tools and seriously injuringsomeone, tie the tool you are using to your safetyharness with a piece of line.

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Figure 3-4.—Sample Working Aloft Check Sheet.

The safety harness assembly consists of the

following components:

1. Safety harness with lanyards

(NSN-9G-4240-00-402-4514)

2. Working lanyard nylon

(NSN-9G-4240-00-022-2518)

3. Safety lanyard with dynabrake(NSN-9G-4240-00-022-2521)

4. Safety harness(NSN-9G-4240-00-022-2522)

5. Safety climbing sleeve(NSN-9G-4240-01-042-9688)

WARNING SIGNS

Warning signs and suitable guards should beposted conspicuously in the appropriate places for thefollowing purposes:

• To keep personnel from accidentally cominginto contact with dangerous voltages;

• To warn personnel about possible explosivevapors and RFR radiation;

• To warning personnel working aloft about thepoisonous effects of stack gases;

• To warn of other dangers that may cause injuriesto personnel.

Installation of equipment is not consideredcomplete unless appropriate warning signs are postedconspicuously.

HIGH VOLTAGE WARNING SIGN

High voltage and shock hazard warning signsshould be installed on or in the vicinity of equipment oraccessories having exposed conductors at potentials of30 volts (root mean square or dc) or above. Exposedconductors include those from which personnel mayreceive a shock by physical contact or by voltage arcover. The signs should be posted so that they areobvious and can be clearly read by personnel enteringthe area.

Compartments or walk-in enclosures containingequipment with exposed conductors presenting shockhazards in excess of 500 volts (root mean square or dc)should have a “Danger High Voltage” sign (fig. 3-6)posted conspicuously within each entrance.

Compartments or walk-in enclosures containingequipment with exposed conductors presenting shockhazards between 30 volts (RMS or dc) and 500 volts(RMS or dc) should have either a “Danger HighVoltage” sign or a “Danger Shock Hazard” sign postedconspicuously within each entrance.

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Figure 3-5.—Parachute-type safety harness.

STACK GAS WARNING SIGN

A warning sign to alert personnel working aloftnear smoke pipe (stack) gases is shown in figure 3-7.One sign should be mounted near the bottom of eachaccess ladder leading aloft. Another sign should belocated at the top of each ladder but mounted on thebase of the antenna pedestal.

RFR HAZARD WARNING SIGNS

There are six RFR radiation hazard (RADHAZ)warning signs (fig.3-8). Requisitioning information isprovided on the signs themselves. Consult with yourleading petty officer (LPO) to obtain the appropriatesigns if they are not posted in your workspace.

RADHAZ signs are made of anodized aluminumand come in two authorized sizes: large (14-inches by14-inches) and small (5-inches by 5-inches). The largesigns are reserved for shore use. The small signs maybe used either aboard ship or ashore.

The signs shown in figure 3-8 were approved foruse in 1990. Some old style signs may still be posted invarious work areas. If you find older style RADHAZsigns posted in an area, you do not have to replace themwith the new style signs unless they are damaged orillegible.

The purpose of each type of RADHAZ sign isexplained below.

Type 1—“WARNING RADIO FREQUENCYHAZARD . . . KEEP MOVING”

The type 1 sign advises personnel not to linger inan area surrounding HF antennas where RFRpermissible exposure limit (PEL) can be exceeded.There is no danger from exposure to HF radiation inthese areas for short periods. However, no one shouldremain within the area (defined by a 4-inch redline/circle on the deck) longer than 3 minutes within a 6minute period.

When type 1 signs are required, install them at eyelevel, or where they can be seen easily, outside the PELboundary.

Type 2—“WARNING RADIO FREQUENCYHAZARD . . . BEYOND THIS POINT”

The type 2 sign is used to keep personnel fromproceeding past a designated point unless they complywith established RADHAZ avoidance procedures.These procedures are discussed in ship’s doctrine, suchas the “MAN ALOFT BILL.” You will probably notfind deck markings in these areas.

Type 2 signs are installed at eye level at the bottomof vertical ladders or suspended at waist level betweenthe handrails of inclined ladders. When type 2 signs areused as temporary barriers, such as when weaponsdirection radars are radiating, they are installed atwaist level on a nonmetallic line.

Type 3—“WARNING RADIO FREQUENCYHAZARD . . . BURN HAZ ARD”

The type 3 sign advises personnel to use specialhandling procedures when they touch a designatedmetallic object, or simply to not touch it. This object isan RFR burn source when it is illuminated by energyfrom a nearby transmitting antenna. Although thehazard may exist only at certain frequencies or powerlevels, personnel should regard the object as a hazardunless the transmitter is secured.

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Figure 3-6.—High voltage warning sign.

PERSONNEL ARE CAUTIONED TO GUARD

AGAINST POISONOUS EFFECTS OF SMOKE PIPE

GASES WHILE SERVICING EQUIPMENT ALOFT.

WHEN SERVICING EQUIPMENT IN THE WAY

OF SMOKE PIPE GASES USE OXYGEN BREATHING

APPARATUS AND A TELEPHONE CHEST OR

THROAT MICROPHONE SET FOR COMMUNICATION

WITH OTHERS IN WORKING PARTY.

OBTAIN NECESSARY EQUIPMENT BEFORE

GOING ALOFT.

Figure 3-7.—Stack gas warning sign.

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WARNIN

G

RADIO

FREQUENCY

HAZA

RD

WARNIN

G

HAZARD

TO

ORDNANCE

RADIO

FREQUENCY

HAZA

RD

WARNIN

GRADIO

FREQUENCY

HAZA

RD

BEYOND

THIS

POIN

T

WARNIN

GRADIO

FREQUENCY

HAZA

RD

PERSONNEL

HAZA

RD

KEEP

MOVIN

G

WARNIN

GRADIO

FREQUENCY

HAZA

RD

PRIO

RTO

FUELIN

GOPERATIO

NS

WARNIN

GRADIO

FREQUENCY

HAZA

RD

BURN

HAZA

RD

INTH

ISAREA

Figure 3-8.—Sample RADHAZ signs.

NOTE: Whenever possible, the RFR burn sourceshould be replaced with a nonmetallic substitute orrelocated or reoriented to eliminate the hazard beforeresorting to a type 3 sign for personnel protection.

A type 3 sign should be installed on the RFR burnsource or in the immediate vicinity where it can be seeneasily. When used on cargo handling running rigging,type 3 signs should be mounted on the hook insulator.Personnel should be warned to not touch thewire/rigging above the insulator. More than one type 3sign should be installed on larger burn sources that canbe approached from multiple directions.

Type 4—“WARNING RADIO FREQUENCYHAZARD . . . FUELING OPERATIONS”

The type 4 sign advises of the hazards ofelectromagnetic radiation to fuels (HERF). Thesesigns are normally used only on ships that carryaviation gasoline (AVGAS) or automotive gasoline(MOGAS). Marine diesel fuel and JP-5 jet fuel are notconsidered to have a HERF problem and require nospecial electromagnetic safety precautions duringfueling. Most naval ships do not carry gasoline. Anexception to this is amphibious ships carryinggasoline-powered landing vehicles. Aboard ships thatcarry AVGAS or MOGAS, personnel should observethe following precautions during fueling or fueltransfer operations:

1. Secure all transmitting antennas located withinthe quadrant of the ship in which fueling is beingconducted.

2. Ensure that RADHAZ cutouts for microwaveradiators are not overridden during fueling,which could result in the illumination of thefueling areas.

3. Do not energize any radar or communicationstransmitter on any aircraft or vehicle.

4. Do not make or break any electrical, staticground wire, or tie down connection, or anymetallic connection to the aircraft or motorvehicle while it is being fueled. Make theconnections before the fueling commences.Break them afterward.

Type 5—“WARNING RADIO FREQUENCYHAZARD (SPECIAL CONDITION)”

The type 5 sign has a blank area for filling inspecial safety precautions. Its purpose is to advisepersonnel of procedures to follow when other

RADHAZ warning signs are not appropriate.Examples of directions that can be filled in on a type 5sign include:

• “Inform OOD before placing system in radiate.”

• “In manual mode, do not depress below horizonbetween ______ and _______ degrees relative.”

• “Ensure temporary exclusion barriers are inplace before radiating.”

• “Do not stop antenna between _______ and_______ degrees while radiating.”

A type 5 sign is normally installed below decks in asystem operating room. It should be installed in thevicinity of controls such as a radiate switch or antennacontrol switch, where the person operating the gear innormal operation can see it. When mounted on systemcabinets or control panels, RADHAZ signs should notobscure switch labels, meters, indicators or nameplatedata.

Type 6—“WARNING RADIO FREQUENCYHAZARD . . . HAZARD TO ORDNANCE”

The type 6 sign advises of hazards ofelectromagnetic radiation to ordnance (HERO).NAVSEA OP 3565 explains the purpose of HEROsigns and where to place them.

ROTATION HAZARD WARNING

Rotating directors present a serious danger topersonnel near them. To guard against this hazard, besure the topside area near the directors is cleared of allpersonnel before you energize a director. “DANGERROTATION HAZARD” warnings should also beposted or painted in conspicuous places to alert unwarypersonnel.

Q7. What OPNAV instruction gives the OODguidance for the Working Aloft Check Sheet?

Q8. What size RADHAZ signs should be used onships?

Q9. What type of RADHAZ warning signs should beused when other RADHAZ signs are NOTappropriate?

OTHER RADAR HAZARDS

The hazards we discussed above occur primarilyon the exterior of the ship. We now need to discuss

3-14

some of the radar hazards you may encounter inside theship.

CATHODE-RAY TUBES (CRTs)

Cathode-ray tubes can be very dangerous andshould always be handled with extreme caution. Theglass envelope encloses a high vacuum, and because ofits large surface area, is subject to considerable forceby atmospheric pressure. (The total force on thesurface of a 10-inch CRT is 3,750 pounds or nearly 2tons; over 1,000 pounds is exerted on its face alone.)Proper handling and disposal instructions for a CRTare as follows:

• Avoid scratching or striking the surface.

• Do not use excessive force when you remove orreplace the CRT in its deflection yoke or itssocket.

• Do not try to remove an electromagnetic CRTfrom its yoke until you have discharged the highvoltage from the anode connector (hole).

• Never hold a CRT by its neck.

• When you set a CRT down, always place its facedown on a thick piece of felt, rubber, or smoothcloth.

• Always handle the CRT gently. Rough handlingor a sharp blow on the service bench can displacethe electrodes within the tube, causing faultyoperation.

• Wear safety glasses and gloves whenever youhandle a CRT.

RADIOACTIVE ELECTRON TUBES

Electron tubes containing radioactive material arecommon to radar equipment. These tubes are known asTransmit-Receive (TR), antitransmit-receive (ATR),spark-gap, voltage-regulator, gas-switching, andcold-cathode gas-rectifier tubes. Some of these tubescontain radioactive material that has a dangerousintensity level. Such tubes are so marked according tomilitary specifications. In addition, all equipmentcontaining radioactive tubes must have a standardwarning label attached where maintenance personnelcan see it as they enter the equipment.

As long as these electron tubes remain intact andare not broken, no great hazard exists. However, if they

are broken, the radioactive material may become apotential hazard.

The radioactivity in a normal collection of electrontubes in a maintenance shop does not approach adangerous level, and the hazards of injury fromexposure are slight. However, at major supply points,the storage of large quantities of radioactive electrontubes in a relatively small area may create a hazard. Ifyou work in an area where a large quantity ofradioactive tubes is stored, you should becomethoroughly familiar with the safety practices containedin Radiation Health Protection Manual, NAVMEDP-5055. By complying strictly with the prescribedsafety precautions and procedures of this manual, youshould be able to avoid accidents and maintain a workenvironment that is conducive to good health.

The hazardous materials information system(HMIS) contains a listing of radioactive tubes, alongwith proper stowage techniques and disposalprocedures.Afloat Supply Procedures, NAVSUPP-485 contains detailed custody procedures. Be sureyou use proper procedures whenever you dispose of aradioactive tube. Also, be aware that federal and statedisposal regulations may vary.

Any time you handle radioactive electron tubes,take the following precautions:

1. Do not remove a radioactive tube from its cartonuntil just before you actually install it.

2. When you remove a tube containing aradioactive material from equipment, place it inan appropriate carton to keep it from breaking.

3. Never carry a radioactive tube in your pocket, orelsewhere on your person, in such a way thatcould cause the tube to break.

4. If you do break a radioactive tube, notify theappropriate authority and obtain the services ofqualified radiological personnel immediately.The basic procedures for cleaning the area arecovered in the EIMB,General, Section 3. If youare authorized to clean the area, get a radioactivespill kit with all the materials to clean the areaquickly and properly. The ship must have at leastone radioactive spill disposal kit for itselectronic spaces. It may have more, dependingon the number and location of spaces in whichradioactive tubes are used or stored. Each kitshould contain the following items:

• Container—Must be large enough to hold allcleanup materials and pieces of broken

3-15

radioactive tubes and must be airtight. Athree-pound coffee can with a plastic lid or30/50 caliber ammo box is an acceptablecontainer. The container must be clearlymarked “RADIOACTIVE SPILLDISPOSAL KIT.”

• Rubber gloves—Two pairs of surgical latexgloves to prevent contact with contaminatedmaterial.

• Forceps or hemostats—Used for picking uplarge pieces.

• Masking tape—One roll of 2-inch-wide tapefor picking up small pieces.

• Gauze pads or rags—One stack of 4-inchgauze pads (50 pads or more) for wiping downthe area.Do NOT use sponges.

• Container of water—A small container ofwater (approximately 2 ounces) in anunbreakable container, for wetting the gauzepads or rags.

• Boundary rope and appropriate signs—Usedfor marking the contaminated area.

• Respirator—With filters that are specific forradionuclides.

• Radioactive material stickers—For labelingthe material to be disposed of. (These can bemade locally).

• Two 12-inch plastic bags—For containing theused material.

• Procedures—Step-by-step cleanupprocedures.

• Other items recommended by the typecommander and the fleet training group.

5. Isolate the immediate area of exposure to protectother personnel from possible contaminationand exposure.

6. Follow the established procedures set forth inNAVMED P-5055.

7. Do not permit contaminated material to contactany part of your body.

8. Avoid breathing any vapor or dust that may bereleased by tube breakage.

9. Wear rubber or plastic gloves at all times duringcleanup and decontamination procedures.

10. Use a HEPA filtered vacuum cleaner (with anapproved disposal collection bag) to remove thepieces of the tube. The vacuum cleaner shouldbe designated for “Spill Response” or “ForCleanup of Radioactive Materials ONLY” anduse the standard magenta/yellow markings forlabeling. If a vacuum cleaner is not available,use forceps and/or a wet cloth to wipe theaffected area. In this case, be sure to make onestroke at a time. DO NOT use a back-and-forthmotion. After each stroke, fold the cloth in half,always holding one clean side and using theother for the new stroke. (Dispose of the cloth inthe manner stated in item 14.)

11. Do not allow any food or drink to be brought intothe contaminated area or near any radioactivematerial.

12. Immediately after leaving a contaminated area,if you handled radioactive material in any way,remove any contaminated clothing. Also washyour hands and arms thoroughly with soap andwater and rinse them with clean water.

13. Immediately notify a medical officer if yousustain a wound from a sharp radioactive object.If a medical officer can not reach the sceneimmediately, stimulate mild bleeding byapplying pressure about the wound and usingsuction bulbs. DO NOT USE YOUR MOUTH.If the wound is a puncture type, or the opening issmall, make an incision to promote freebleeding, and to enable cleaning and flushing ofthe wound.

14. When you clean a contaminated area, seal alldebris, cleaning cloths, and collection bags in acontainer such as a plastic bag, heavy wax paper,or glass jar. Place the container in a steel canunt i l i t can be disposed of proper ly.Decontaminate, using soap and water, all toolsand implements you used to remove aradioactive substance. Monitor the tools andimplements for radiation with an authorizedradiac set. They should emit less than 0.1MR/HR at the surface. (MR/HR is theabbreviation for milliroentgen/hour,which isdefined as a unit of radioactive dose ofexposure.)

3-16

References to Consult Concerning Radioactive

Tubes

The following is a basic list of publicationsconerning the handling and use of radioactive tubes.

– Department of Defense Hazardous MaterialsInformation System (HMIS), DOD 6050.1-L

– Radiat ion Health Protect ion Manual,NAVMED P-5055

– Afloat Supply Procedures,NAVSUP P-485

– EIMB, General

– EIMB, Radiac

– Safety Precautions for Forces Afloat

– Naval Ships’ Technical Manual, Chapter 400

Technical Assistance

For technical assistance and advice regardingidentification, stowage, or disposal of radioactivetubes, contact:

Officer In ChargeNaval Sea Systems Command DetachmentRadiological Affairs Support Officer(NAVSEADET, RASO)Naval Weapons StationYorktown, VA 23691-5098

X-RAY EMISSIONS

X-rays may be produced by high-voltageelectronic equipment. X-rays can penetrate humantissue and cause both temporary and permanentdamage. Unless the dosage is extremely high, therewill be no noticeable effects for days, weeks, or evenyears after the exposure.

The sources of these x-rays are usually confined tomagnetrons, klystrons, and CRTs. Where these typesof components are used, you should not linger near anyequipment on which the equipment covers have beenremoved. Klystrons, magnetrons, rectifiers, or othertubes that use an excitation of 15,000 volts or moremay emit x-rays out to a few feet, thus endangering youor other unshielded personnel standing or workingclose to the tubes.

If you must perform maintenance on x-rayemitting devices, take the following precautions:

• Observe all warning signs (fig. 3-9) on theequipment and all written precautions in theequipment technical manual.

• Do NOT bypass interlocks that prevent theservicing of operating equipment with the x-rayshield removed, unless the technical manualrequires you to do so.

• Be sure to replace all protective x-ray shieldingwhen you finish the servicing.

Q10. What publ icat ion gives basic cleanupprocedures for a broken, radioactive tube?

SUMMARY

This chapter has presented radar safety measuresyou are expected to practice in your daily work. Aswith electrical and electronic safety, the greatestdanger you will face as a Fire Controlman is becomingtoo familiar with the safety hazards you will face.COMPLACENCY KILLS! Radio frequency energy isnot the only hazard associated with working aroundradar. Working aloft has its own set of hazards. Be

3-17

CAUTION

X-RAY

Figure 3-9.—X-ray caution label.

aware of your environment and other evolutions thatare happening around you. It is your responsibility toknow what warning signs mean and where they shouldbe posted. Remember, as a Fire Controlman, you havea responsibility to yourself and to your shipmates toalways be alert to detect and report hazardous workpractices and conditions.

ANSWERS TO CHAPTER QUESTIONS

A1. Radio Frequency Radiation.

A2. Hazards of Electromagnetic Radiation toOrdnance (HERO), Hazards of ElectromagneticRadiation to Fuel (HERF), and Hazards ofElectromagnetic Radiation to Personnel(HERP).

A3. HERO safe, HERO susceptible, and HEROunsafe.

A4. NAVSEA OP 3565, Volume 1.

A5. DOD Instruction 6055.11. Protection of DODPersonnel from Exposure to Radio FrequencyRadiation.

A6. 140 volts.

A7. OPNAVINST 5100.19 series, Navy OccupationalSafety and Health (NAVOSH) Program Manualfor Forces Afloat.

A8. Small (5 inch by 5 inch).

A9. Type 5, Warning Radio Frequency Hazard(Special Condition).

A10. EIMB, General, Section 3.

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APPENDIX I

REFERENCES

NOTE: Although the following references were current when this NRTCwas published, their continued currency cannot be assured. Therefore, youneed to be sure that you are using the latest version.

Chapter 1

Combat Systems Technical Operations Manual (CSTOM)

Electronics Installation and Maintenance Book-General, NAVSEASE000-00-EIM-100, Electronics Installation and Maintenance Book (EIMB),Naval Sea Systems Command, Washington, DC, 1983.

Navy Electricity and Electronics Training Series (NEETS), Module 9,Introduction to Wave-Generation and Wave-Shaping Circuits, NAVEDTRA172-09-00-83, Naval Education and Training Professional Development andTechnology Center, Pensacola, FL, 1983.

Navy Electricity and Electronics Training Series (NEETS), Module 10,Introduction to Wave Propagation, Transmission Lines, and Antennas,NAVEDTRA B72-10-00-93, Naval Education and Training ProgramManagement Support Activity, Pensacola, FL, 1993.

Navy Electricity and Electronics Training Series (NEETS), Module 11,Microwave Principles, NAVEDTRA 172-11-00-87, Navy Education andTraining Program Management Support Activity, Pensacola, FL, 1987.

Navy Electricity and Electronics Training Series (NEETS), Module 15,Principlesof Synchros, Servos, and Gyros, NAVEDTRA B72-15-00-93, NavalEducation and Training Program Management Support Activity, Pensacola,FL, 1993.

Navy Electricity and Electronics Training Series (NEETS), Module 18,RadarPrinciples, NAVEDTRA 172-18-00-84, Naval Education and TrainingProgram Development Center, Pensacola, FL, 1984.

Chapter 2

A1-F18AC-744-100,Forward Looking Infra Red (FLIR) System, Chapter 3,Principles of Operation(0801-LP-020-9610)

OP 3541,Volume 1, Revision 2, AN/SPG-51D(0610-LP-354-1129)

OP 4350,Transmitter, Control and Power Supply for AN/SPG-51D

SE213-UE-MMO-010,Radar Set AN/SPS-48E; Volume 1 Part 1, Radar set,Chapter 1, General Information(0910-LP-586-4200)

SE213-VC-MMO-010,Radar Set AN/SPS-52C; TM Volume 1, Chapters 1 and 2(0910-LP-064-5800)

SW221-JO-MMO-010,Close-In Weapon System, Mk 15, Mod 11-14(PHALANX); Introduction to CIWS, Volume 1(0640-LP-167-5800)

AI-1

SW230-AO-SOM-060,Target Acquisitioning System (TAS) Mk 23; OperationsManual for CV/CVN class, Integrated with CDS(0640-LP-168-1900)

SW261-SA-GYD-010,Ship Self Defense System (SSDS); Mk 1 Mod 0,Installation and Checkout Support Guide(0640-LP-021-6420)

SW272-AM-AEG-010,AEGIS RADAR SYSTEM for SPY-1D; Description,Operation and Maintenance(0640-LP-013-4590)

SW272-AJ-AEG-020,AEGIS RADAR SYSTEM HANDBOOK for SPY-1B/D; B/L5.3/3A(0640-LP-021-7570)

SW279-EJ-AEG-010,AEGIS ANTENNA GROUP for SPY-1D; Description andOperation(0640-LP-013-4490)

TE660-AX-PDD-230, AN/SYS-2 (V) 1 Radar Satellite Simulation Program;Program Descr ip t ion Document , Volume 23; AN/SPS-48E(0910-LP-148-2900)

TW210-AA-GYD-010, Thermal Imaging Sensor System (TISS); AN/SAY-2;Installation and Checkout Support Guide(0910-LP-017-6120)

TW271-T2- IDS-010, MK 92 Mod 2 Combined Antenna System(0910-LP-019-9580)

Chapter 3

Department of Defense Directive 4715.1, “Environmental Security,” February 24,1996.

Department of Defense Instruction 6055.11, “Protection of DoD Personnel fromExposure to Radiofrequency Radiation and Military Exempt Lasers,”February 21, 1995.

Electromagnetic Radiation Hazards (Hazards to Ordnance), NAVSEA OP 3565,Volume II, Naval Sea Systems Command, Washington, DC, April 1995.

Electromagnetic Radiation Hazards (Hazards to Personnel, Fuel, and OtherFlammable Material), NAVSEA OP 3565, Volume I, Naval Sea SystemsCommand, Washington, DC, 1979.

Executive Order, 12196, “Occupational Safety and Health Programs for FederalEmployees,” February 26, 1980.

Contributing Commands/Facilities

Commander Operational Test and Evaluation Force (COMOPTEVFOR), SurfaceWarfare Division, Code 70

FC “A” School

Naval Air Warfare Center (NAWC) Weapons Division, Point Mugu

Naval Air Warfare Center Weapons Division (NAWCWD), Fleet Help Desk, ChinaLake

Naval Research Laboratory (NRL)

Naval Sea Systems Command (NAVSEASYSCOM) NAVY SEA Test andEvaluation Office

AI-2

Naval Surface Warfare Center, Carderock Division (NSWCCD) Smart ShipProgram

Naval Surface Warfare Center, Dahlgren Division (NSWCDD)

Surface Warfare Officer School (SWOS)

AI-3

INDEX

A

Accelerometers, 1-16Acquisition, 1-18, 2-15Acquisition phase, 1-19, 2-15Active homing, 1-17Air-search radar, 1-12, 2-1AN equipment indicator system, 1-12AN/ZPG-51 Radar, 1-21AN/ZPG-60 radar, 1-21, 2-6AN/ZPG-62 radar, 1-21, 2-6AN/SPQ-9 antenna, 1-21, 2-7AN/SPS-48, radar, 1-21, 2-2AN/SPS-52 radar, 1-21, 2-1AN/SPY-1 radar, 1-22, 2-4Antenna lenses, 1-9Antenna system, 1-7

array types, 1-10feedhorns, 1-9horn radiators, 1-9lens antenna, 1-9parabolic reflectors, 1-8

Array antennas, 1-10Atmospheric conditions, 1-5

B

Basic radar systems, 1-1, 1-5Beam deflection, 1-10Beam-rider guidance, 1-16Beam-riding missile, 1-16Bearing, 1-3Bearing resolution, 1-5Boost phase, 1-14

C

Cathode-ray tubes (CRTs), 1-3, 1-6, 3-15Close-in weapon system (CIWS), 1-11, 1-22, 2-10Combined antenna system (CAS), 1-21, 2-10Conducting (acceleration) lens, 1-9Continuous wave illumination (CWI), 1-4, 1-11Control group, 1-11Control systems, missile, 1-14

D

Designation phase, 1-18Detect-to-engage sequence, 1-19, 2-15

Detection, 1-19, 2-15acquisition and tracking, 1-19guidance (missiles), 1-16launcher/gun positioning, 2-16prediction, 1-19

Detection, 1-19, 2-15, 2-18Dielectric (delay) lens, 1-9Dielectric material, 1-9Displays, 1-6

type A, 1-6type B, 1-6type E, 1-6type P, 1-7

Doppler effect, 1-4Dry air systems, 1-11Ducting effect, 1-5Duplex, 1-4, 1-6

E

Electromagnetic radiation, 3-1Engaging, 2-19Evaluation, 1-20

F

Feed horns, 1-9Fire-control problem, 1-19

detect to engage sequence, 1-19, 2-15Fire-control radar, 1-21, 2-3Forward looking infra-red radar (FLIR), 1-22Frequency-modulated continuous wave (FM-CW),

1-4

G

GMFCS, 1-20Guidance (missiles), 1-14, 1-20

phases, 1-14types of, 1-16

Guided missile fire control system, 1-14Gyroscopes, 1-11

H

HARPOON missile, 1-14, 1-17Hazards of electromagnetic radiation to fuels (HERF),

3-3Hazards of electromagnetic radiation to ordnance

(HERO), 3-2

INDEX-1

Hazards of electromagnetic radiation to personnel(HERP), 3-3

permissible exposure limit (PEL), 3-4permissible exposure time (PET), 3-5specific absorption rate (SAR), 3-3

High frequency surface wave radar, 1-22, 2-14HOJ mode, 1-18Home-on-jamming, 1-18Homing guidance, 1-16

active, 1-17passive, 1-18semiactive, 1-17

Horizontal plane, 1-2, 1-11Horn radiators, 1-8, 1-9

I

Inertial guidance, 1-16Infrared search and track (IRST), 2-14Initial phase, 1-14Intermediate frequency (IF), 1-6

J

Jamming, 1-18JETDS, 1-12Joint Army-Navy nomenclature system, 1-12Joint electronics type designation system, 1-12Joint-service standardized classification system, 1-12

L

Lens antenna, 1-9

M

Man aloft, 3-9Maximum range, 1-3Midcourse phase, 1-15Minimum range, 1-3Missile axes, 1-14Missile guidance radar, 1-14Mk 7 Aegis fire control system, 2-4Mk 23 target acquisitioning system (TAS), 1-10, 1-21,

2-8Mk 34 gun weapon system, 1-22, 2-4Mk 45 light weight gun, 1-21, 2-7Mk 74 fire control system, 1-21Mk 75 light weight gun, 1-21, 2-9Mk 86 gun fire control system (GFCS), 1-10, 1-21,

2-4, 2-6Mk 91 fire control system, 1-21, 2-5, 2-9

Mk 92 combined antenna system (CAS), 1-10, 1-19,1-21, 2-9

Mk 92 fire control system, 1-21Mk 95 radar, 1-21, 2-9Mk 99 missile fire control system, 1-21, 2-4Moving target indicator (MTI), 1-6, 2-2Multi-dimensional radar, 1-13Multi-function radar, 2-14

O

Optical sighting system (OSS), 1-22Optronics systems, 1-22; 2-14

thermal imaging sensor system (TISS), 1-22, 2-14

P

Parabolic reflectors, 1-8Passive homing, 1-18Phases of missile guidance, 1-14

initial (boost), 1-14midcourse, 1-15terminal, 1-15

Phases of radar operation, 1-18acquisition, 1-15designation, 1-18track, 1-18

Plan position indicator (PPI), 1-7Planar array antenna, 1-10Prediction, 1-19Pulse modulation, 1-4Pulse-repetition frequency (PRF), 1-3Pulse-repetition rate (PRR), 1-3

R

Radiation hazard zones, shipboard, 3-7Radar safety, 3-2

cathode-ray tubes (CRTs), 3-15HERF, 3-3HERO, 3-2HERP, 3-3RFR hazards, 3-12x-ray emissions, 3-17radioactive electron tubes, 3-15warning signs, 3-11working aloft, 3-9

Radar system block diagram, 1-5antenna, 1-8control group, 1-11display, 1-6duplexer, 1-6radome, 1-10

INDEX-2

receiver, 1-6stable element, 1-11support systems, 1-11synchronizer, 1-6transmitter, 1-6

Radar guidance beam, 1-16Radar measurements, 1-2

altitude, 1-3bearing, 1-3range, 1-3

Radar operation, 1-5, 2-7, 2-15phases of, 1-18, 2-7

Radar system accuracy, 1-4atmospheric conditions, 1-5bearing resolution, 1-5other factors, 1-5range resolution, 1-5

Radar transmission methods, 1-4continuous wave, 1- 4pulse modulation, 1-4

Radomes, 1-10Range, 1-3

minimum range, 1-3maximum range, 1-3range accuracy, 1-3

Range accuracy, 1-3Range resolution, 1-5Receiver, 1-6Receiver recovery time, 1-6Reference coordinate terms, 1-1Reflected power, 1-10Reflectors, 1-8Relative bearing, 1-3Remote optical sighting system (ROS), 1-22RF, 1-3RF interference, 1-18RFR hazards, 3-12

burns, 3-7eyes, 3-7shipboard radiation hazard zones, 3-7skin, 3-5testicles, 3-7

S

Safety harness, 3-10Search radar, 1-21, 2-1SEASPARROW missile system, 1-14, 1-17, 1-22, 2-9

Secondary effects, 1-10Semi-active homing, 1-17SSDS Mk 1 (Ship Self-Defense System), 1-22, 2-5,

2-9, 2-12, 2-13Stable elements, 1-11STANDARD ARM (missiles), 1-18STANDARD SM-1, 1-14, 1-17, 1-21STANDARD SM-2 missiles (MR & ER), 1-14, 1-17,

1-22, 2-5STIR (Separate Target Illuminating Radar), 1-19,

1-21, 2-10Support systems, 1-11Surface angular measurements, 1-2Synchronizer, 1-6

T

Temperature inversion, 1-5Terminal phase, 1-15Thermal imaging sensor system (TISS), 1-22, 2-14Three-dimensional (3-D) radar, 1-12, 1-14Track phase, 1-18Tracking, 1-19, 2-19Tracking radar, 1-18Transmission lines, 1-7Transmission loss, 1-10Transmitter, 1-6True bearing, 1-2Types of guidance, 1-14Types of radar, 1-12

W

Warning signs, 3-11high voltage, 3-11RF, 3-12stack gas, 3-12

Waveguide, 1-7Working aloft, 3-9

check sheet, 3-9safety harness, 3-10

WSN-2, 1-11WSN-5, 1-11

X

X-ray emissions, 3-17

INDEX-3

Assignment Questions

Information: The text pages that you are to study areprovided at the beginning of the assignment questions.

ASSIGNMENT 1

NOTE: I N THI S ASSIGNMENT, FIGURESMENTIONE D IN THE QUESTIONSARE FOUNDIN THE TEXT.

1-1. The term “radar” is an acronym made from thewords

1. radio, detection, and roaming2. radio, distance, and ranging3. radio, detection, and ranging4. radio, detection, or ranging

1-2. Radar surfaceangular measurements arenormally made from which direction?

1. North/south2. East/west3. Counter-clockwise from truenorth4. Clockwise from truenorth

1-3. Theanglemeasured clockwise from truenorthin thehorizontal planedefines which of thefollowing terms?

1. Truebearing/azimuth2. Truehorizontal plane3. Line-of-sight range4. Truenorth

1-4. What is theprimary limiting factor formaximum rangeof apulse-radar system?

1. Carrier frequency2. Peak power of transmitted pulse3. Receiver sensitivity4. Pulse-repetition frequency

1-5. Theanglebetween thecenterlineof theshipand alinepointed directly at a target is knownby what term?

1. Relativebearing2. Truebearing3. Anglenorth4. Angular bearing

1-6. What is themost common method used totransmit radar energy?

1. Continuous-wave2. Pulse-modulation3. Doppler-wave4. Frequency-modulation

1-7. What characteristic of continuous-wave radarmakes it difficult, if not impossible, to getaccurate rangemeasurements?

1. Doppler effect2. Missileguidance3. Illumination4. No specific stop time

1-8. Range resolution is defined as theability of aradar to perform what action?

1. Separateobjects at thesamerange, butslightly different bearings

2. Distinguish between two targets on thesamebearing, but at slightly differentranges

3. Separateobjects at different ranges, butslightly different bearings

4. Distinguish between two targets ondifferent bearings, but at thesamerange

1-9. Which of the following factors affect(s) radarperformance?

1. Operator skill2. Electronic Attack activity3. Weather conditions4. Al l of theabove

1-10. According to figure1-4, what is consideredtheheart of a pulse radar system?

1. Synchronizer2. Antennasystem3. Transmitter4. Duplexer

1

Textbook Assignment: “Introduction to Basic Radar Systems,” chapter 1, pages 1-1 through 1-23 and“Fire-Control Radar Systems,” chapter 2, pages 2-1 through 2-11.

1-11. A certain amount of time is required for aduplexer to disconnect the antenna from thereceiver and connect it to the transmitter.What is this switching time called?

1. Receiver recovery time2. Fast reaction time3. Detection time4. Transmitter recovery time

1-12. What radar subsystem is used to convert RFechoes to a lower frequency?

1. Superheterodyne receiver2. Antenna system3. Duplexer4. Transmitter

1-13. Figure 1-5 shows four basic radar displays.Which of the displays uses your own ship asthe center of the display?

1. Type A2. Type B3. Type P4. Type E

1-14. An automobile headlight is similar, in shape,to what type of radar reflector?

1. Truncated2. Parabolic3. Orange peel4. Banana peel

1-15. Radar antennas are designed using well-known optical design techniques. Which ofthe following radar characteristics allows aradar antenna to be designed in this way?

1. Radar operates in the microwave region ofthe electromagnetic spectrum

2. Radar operates in the ultraviolet region ofthe electromagnetic spectrum

3. Radar operates in the VLF region of theelectromagnetic spectrum

4. Radar operates in the infrared region of theelectromagnetic spectrum

1-16. What general characteristic of a horn radiatoris determined by the size of its mouthopening?

1. Symmetry2. Relativity3. Conductivity4. Directivity

1-17. Which of the following design actions can beused to eliminate feedhorn shadows?

1. Making the horn smaller2. Putting the horn behind the reflector3. Offsetting the horn from the center of the

reflector4. Making the reflector smaller

1-18. Which of the following antennas are lens typeantennas?

1. Conducting and dielectric2. Optical and electro-optical3. Flatplane and spherical plane4. Microwave and plane wave

1-19. In a delay lens, the amount of delay isdependent on what characteristic?

1. Thickness2. Dielectric constant3. Angle of reflection4. Angle of incidence

1-20. Which of the following elements can be usedin an array antenna?

1. Slots2. Dipoles3. Horns4. Each of the above

1-21. In an array antenna, what determines theposition of the beam?

1. The relative phase between the elements2. The relative amplitude between the

elements3. The total amplitude of the elements4. The scan motor

1-22. Which of the following adverse effects in asmall radome is caused by reflected power?

1. Beam deflection2. Transmission loss3. Antenna mismatch4. Secondary effects

1-23. What level of maintenance do FC’s normallyperform on radomes?

1. Ship’s 2M2. Factory repairs3. Technical repairs4. Preventive maintenance

2

1-24. Which of the following equipment is NOT partof the control group for a radar system?

1. AN/UYK-43 computer2. AN/BPS-15 radar group3. RD-358A(V)/UYK magnetic tape unit4. OJ-535 data terminal set

1-25. Every radar system requires a certain amountof support equipment to operate properly.Which of the following equipment is supportequipment?

1. SF6 gas canister2. Step-down transformer3. Frequency converter4. Each of the above

1-26. What is the primary purpose of a stableelement?

1. To measure any deviation of a directorfrom the vertical plane

2. To measure approximate deviation fromany optical equipment

3. To measure any deviation of a launcherfrom the horizontal plane

4. To measure approximate deviation fromany radar antenna

1-27. What equipment listed below does NOTcomply with the Joint Electronics TypeDesignation System (JETDS)?

1. AN/SPF-402. AN/SPS-48E3. AN/SPG-604. AN/SPQ-9B

1-28. What is the primary function of air-searchradar?

1. To maintain a 360-degree surveillance2. To provide security against attacks3. To provide information for aircraft control4. To determine aircraft altitude

1-29. The AN/SPY-1 series radar is a multi-dimensional radar. How does it differ fromair-search radar?

1. It has a wider vertical beamwidth2. It has a narrower vertical beamwidth3. It has a lower transmitting frequency4. It has a lower output power

1-30. Missile guidance systems consist of twoseparate systems. An attitude control systemis one of those systems. What is the othersystem?

1. Rocket motor control system2. Rocket motor thrust system3. Flight yaw control system4. Flight path control system

1-31. According to figure 1-17 which of thefollowing components is NOT part of thecontrol subsystem?

1. Computer detector2. Servo motor3. Receiver4. Control surface

1-32. The Standard SM-2 missiles use three phasesof guidance. What are they?

1. Boost, dropoff, terminal2. Boost, midcourse, terminal3. Guided, midcourse, terminal4. Unguided, midcourse, terminal

1-33. Which of the following missiles should followthe guidance path shown in figure 1-18B?

1. Standard SM-1 (ER)2. Standard SM-13. Standard SM-2 (MR)4. Standard SM-2 (ER)

1-34. The initial phase of a missile flight lasts howlong?

1. Until the target is destroyed2. Until the booster recharges3. Until the booster burns up its fuel4. Until the target manuevers

1-35. What is unique about the Harpoon missileguidance phase?

1. It is the shortest phase, in both time anddistance

2. It is the longest phase, in time only3. It is the longest phase, in distance only4. It is the longest phase, in both time and

distance

1-36. What phase of missile guidance requires fastresponse to guidance signals?

1. Final phase2. Boost phase3. Initial phase4. Midcourse phase

3

1-37. In an inertial guidance system, what devicescontrol the missile?

1. Accelerometers2. Accelerators3. Fin stabilizers4. Yaw stabilizers

1-38. A beam-rider missile is most effective againstwhich of the following types of targets?

1. Outgoing and long-range2. Incoming and long-range3. Incoming and medium-range4. Outgoing and long-range

1-39. Homing guidance is the most accurate methodof missile guidance. What gives it this ability?

1. RF waves2. Reflected energy3. Magnetic field energy4. Guidance error signals

1-40. According to figure 1-21, which of thefollowing terms best describes guidance for aHARPOON missile?

1. Passive homing2. Semi-active homing3. Active homing

1-41. Which of the following factors is a drawbackof semi-active homing?

1. During its use, the ship is not free to useSMS missiles

2. Its use keeps the system tied to a singletarget

3. It can only be used with SEASPARROWmissiles

4. It can only be used with STANDARDSM-1 missiles

1-42. Figure 1-21 illustrates the different homingguidance methods. Which method is used fora STANDARD ARM missile?

1. Passive homing2. Semi-active homing3. Active homing

1-43. What type of data is primarily used infire-control radar?

1. Continuous positional data2. Intermittent horizontal data3. Target resolution data4. Continuous ship position data

1-44. Which of the following is the correct sequencefor modes of radar operation?

1. Designation, acquisition, and search2. Designation, direction, and search3. Designation, direction, and track4. Designation, acquisition, and track

1-45. Search radar is used for what operation of thefire-control problem sequence?

1. Track phase2. Detection3. Prediction4. Evaluation

1-46. Continuous, accurate target position isavailable during what stage of fire-controlproblem sequencing?

1. Acquisition and tracking2. Launcher positioning3. Missile guidance4. Evaluation

1-47. Which of the following operations is NOTperformed after target detection andacquisition?

1. Establishing a track LOS2. Determining launcher position angle3. Positioning the gun mount4. Establishing a targets initial position

1-48. During the acquisition and tracking phase,why are radar indications of a targetconsidered as instantaneous, present targetpositions?

1. RF energy travels at the speed of light2. Target ranges are relatively small3. Both 1 and 2 above4. Target speed is fast

1-49. According to Table 1-2, which of thefollowing radar systems should be used duringthe designation phase of the fire-controlproblem sequence?

1. Mk 95 radar2. 52C3. Mk 14. HF Surface Wave

4

1-50. During the acquisition and tracking phase, afire control radar director is aligned with thesearch radar’s target position. Which of thefollowing radar systems should be used as thefire control radar in this process?

1. SPY 1 Series2. SPS 48E3. SPS 52C4. FLIR

1-51. Although fire-control radar is more accurate,initial detection of a target is done with searchradar. Which of the characteristics listedbelow enable(s) search radar to initially detecta target?

1. Narrow beam width2. Wide beam width3. Long-range 360 degree coverage4. Both 2 and 3 above

1-52. Which system below is a search radar that anFC might work with in today’s Navy?

1. AN/SPS-40(V)2. SLQ-32(V)33. AN/SPS-494. AN/SPS-48E

1-53. What is the function of the 25-degree tilt in theAN/SPS-52 radar antenna?

1. It provides access for preventivemaintenance

2. It enables four modes of operation3. It enables solar alignment4. It provides high-elevation coverage

1-54. The AN/SPS-48E radar is a long-range, three-dimensional radar that FC’s work with. Howdoes this radar provide contact range, height,and bearing information?

1. By using D/E band frequency scanning2. By using E/H band short-dwell time3. By using E/F band frequency scanning4. By using D/E band short-dwell time

1-55. Which of the following modes is NOT anSPS-48 radar mode?

1. Equal Angle Coverage2. Maximum Frequency Management3. Maximum Energy Management4. Adaptive Energy Management

1-56. The AN/SPS-48 radar is found on what type(s)of ship?

1. NIMITZ class carriers2. LCC class amphibious ships3. ENTERPRISE class carriers4. All of the above

1-57. Fire-control radar is normally part of largersystems. Which of the following systems arelarger gun or missile systems that areassociated with fire-control radar?

1. GFCS2. FCCS3. GMCM4. MFCC

1-58. Which of the following systems is/are foundon board the USSPaul Hamilton?

1. SPY-1 radar system2. Mk 99 MFCS3. Mk 86 GFCS4. All of the above

1-59. The Mk 7 Aegis FCS is found on boardARLEIGH BURKE class destroyers andTICONDEROGA class cruisers. Which of thefollowing radar systems should you find onboard one of these ships?

1. SSDS2. SPY-13. Mk 924. CAS

1-60. What radar system is the heart of the AEGISsystem?

1. SSDS2. AN/SPY-1 radar3. MFCS4. GFCS

1-61. In reference to figure 2-6, which of thefollowing is NOT a weapon or sensor foundon an AEGIS class cruiser?

1. AN/SPS-49 radar2. Mk 41 vertical launching tubes3. AN/SPS-40E radar4. AN/SPG-62 illuminators

5

1-62. The Mk 99 MFCS provides terminal guidancecontrol for which of the following missiles?

1. TOMAHAWK cruise missile2. SM-2 anti-air missile3. SM-1 extended range missile4. Stinger missile

1-63. What type of radar is the AN/SPG-62?

1. Long-range search radar2. Short-range tracking radar3. Missile guidance radar4. Gun illumination radar

1-64. Which of the following weapons is controlledby the Mk 86 GFCS?

1. Mk 45 5-inch gun2. Mk 75 3-inch gun3. Mk 13 missile launcher4. Mk 45 8-inch gun

1-65. Which of the following radar systems enablethe Mk 86 GFCS to support AW gunengagements?

1. CAS and Mk 23 TAS2. STIR and CAS3. AN/SPG-9B and AN/SPQ-9A4. AN/SPQ-9 and Mk 23 TAS

1-66. The AN/SPQ-9B radar can track air andsurface targets simultaneously. Whatcharacteristics allow it to do this?

1. Real-time signal and data processing2. Low resolution and narrow beam radar3. Raw video and azimuth video reference4. Variable-time signal and beam processing

1-67. What modes of operation does theAN/SPQ-9B have?

1. Air, surface, and beacon2. Air, surface, and beam3. Detection and acquisition4. High scan and low scan

1-68. What mode of the AN/SPQ-9B radar uses thepulse-doppler radar?

1. Surface2. Detection3. Air4. Beam

1-69. The AN/SPQ-9B radar is found on boardwhich of the following ship types?

1. SPRUANCE class destroyers2. TICONDEROGA class cruisers3. SAN ANTONIO class amphibious ships4. All of the above

1-70. The Mk 23 TAS integrates varioussubsystems. Which of the followingsubsystems is NOT part of that integration?

1. Two-dimensional air-search radar2. Long-range threat evaluation console3. IFF subsystem4. Display subsystem

1-71. What is the primary weapon controlled by theMk 91 missile fire control system?

1. SEASPARROW missile2. Mk 45 gun3. HARPOON missile4. Close-in weapon system

1-72. The Mk 91 missile fire control system useswhich of the following consoles?

1. Firing officer console only2. Signal data processor console only3. Radar set console only4. Advanced display system console

1-73. Which of the following radar systems is NOTpart of the Mk 91 fire control system?

1. Mk 95 illuminator2. Mk 23 target acquisition system3. Mk 157 discriminator4. AN/SPQ-9 series radar

1-74. Which of the following ship classes uses theCombined Antenna System?

1. TICONDEROGA class cruisers2. LHA class amphibious ships3. PERRY class frigates4. SEAWOLF class submarines

1-75. In reference to figure 2-14, where is the STIRantenna located on a PERRY class frigate?

1. On the forward bullnose2. On the aftship O-2 level3. On the forecastle main deck4. On the midship O-2 level

6

ASSIGNMENT 2

2-1. TheMk 15 Phalanx Close-In Weapon Systemhas two primary modes of operation. What arethey?

1. Autonomic and manual2. Recommend fireand manual3. Remotecontrol and manual4. Automatic and manual

2-2. What is theprincipal air threat to U. S. navalsurfaceships?

1. Anti-ship cruisemissiles2. Low, slow, or hovering aircraft3. Low altitudeenemy aircraft

2-3. TheShip Self-DefenseSystem (SSDS)integrates and coordinates what equipment onboard non-AEGIS class ships?

1. Existing sensors and weapons2. Special computer programs3. Operator stations4. Al l of theabove

2-4. SSDS is the integration element of theentirecombat system program, including allweapons and sensors. Which of the followingis NOT apurposeof SSDS?

1. To improve reaction time from detect toengagement in less than 60 seconds

2. To improve theperformanceofweapons/sensors beyond normalstand-alonecapability.

3. To improve the integration andcoordination of all weapons and sensors inorder to providequick reaction combatcapability

4. To improve thecapability to engagemultiple targets and quick responseagainstanti-ship cruisemissiles

2-5. Which of the following systems is an SSDSinterfaceon anon-AEGIS class ship?

1. AN/SPS-49 air search radar2. AN/SPG-62 illuminator3. AN/SPQ-9B firecontrol radar4. AN/SPY-1 multi-dimensional radar

2-6. Which of the following systems uses heat orlight as asource for target detection?

1. Firecontrol radar2. Close-in weapon system3. Optronic system4. Ai r search radar

2-7. TheThermal Imaging Sensor System (TISS)provides surfaceand air target data to combatsystems viaan electro-optical system. TISSalso has which of the following capabilities?

1. Good night detection and identification2. Minedetection3. Both 1and 2above4. Aid to navigation

2-8. Which of the following sensors is/areapart ofupcoming developments in radar?

1. High frequency surfacewave2. Multi-function radar3. Volumesearch radar4. Al l of theabove

QUESTIONS 2-9 THROUGH 2-19 REFER TO THEDETECT-TO-ENGAGE SCENARIO.

2-9. What is thedefinition of a warning status ofyellow?

1. Hostilities probable2. Hostilities imminent3. Hostilities detected4. Hostilities displayed

2-10. TheTactical Action Officer (TAO) isresponsible for which of the following actionsin theabsenceof thecommanding officer?

1. Theproper employment of theship’sweapons systems

2. Theproper navigation of theship throughfriendly waters

3. Theproper employment of theship’sauxiliary systems

4. Theproper useof consoles in thecombatinformation center

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Textbook Assignment: “FireControl Radar Systems,” chapter 2, pages 2-11 through 2-20 and “Radar Safety,”chapter 3, pages 3-1 through 3-18.

2-11. During aDetect-to-Engagescenario, what isthe first equipment to detect and identify athreat?

1. A wideband ESM receiver2. A firecontrol radar3. An IFF interrogator4. A narrow band navigation radar

2-12. Theship’s 2-D air search radar, with thehelpof theESM receiver, helps to localize theincoming threat. What tactical informationdoes localizing the threat giveyou?

1. An accuratebearing only2. An accurate rangeand bearing3. An accurate rangeonly4. An accurate range, bearing, and altitude

2-13. What featureof theship’s 3-D radar leads youto believe that the threat consists of only oneaircraft?

1. Thebearing resolution of thepulse-compressed radar

2. Theelevation resolution of thepulse-compressed radar

3. The resolution of theESM sensors4. The range resolution of the

pulse-compressed radar

2-14. According to theRules of Engagement (ROE)in effect, you havedetermined hostile intentbased on atarget’s action. At this point youshould prepare to defend your ship againstwhat typeof attack?

1. Probable2. Conceivable3. Comprehensible4. Imminent

2-15. After you inform theAnti-Ai r WarfareCommander of a target’s hostile intent, heplaces your ship in Ai r Warning Red. Whatdoes Air Warning Red mean?

1. Attack is imminent2. Attack is probable3. Attack is on hold4. Attack is in progress

2-16. Oncea target is closeenough to bedetected byyour weapons system, the firecontrolcomputer uses the target’s courseand speed tocomputewhereyour missilewil l engage thetarget. What is the term used for this placeofengagement?

1. Predicted engagement envelope2. Predicted intercept envelope3. Predicted intercept point4. Predicted engagement point

2-17. What verbal command authorizes thelaunching of amissileat ahostile target?

1. “Batteries release”2. “Batteries charged”3. “Fireall batteries”4. “Fireall weapons”

2-18. From which of the following sources do youconfirm that the target has been destroyed orneutralized?

1. Ship’s lookouts2. Ship’s sensors3. Anti-air warfarecommander4. ESM equipment only

2-19. Which of the following functions is part of themodern firecontrol problem?

1. Informing thewarfarecommander of thethreat

2. Confirming target resolution3. Making aweapon selection4. Making equipment ready for tracking

2-20. What is theultimategoal of all subsystemcomponents in solving the firecontrolproblem?

1. To quickly locate the target2. To neutralize the target3. To detect the target4. To select the right weapon

2-21. Thereare threephases involved in targetdetection by aweapon system. What is thesecond phase?

1. Surveillanceand detection2. Interpret thebehavior of the target3. Measuring or localizing the target’s

position4. Classifying the target

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2-22. Which phase uses either reflected energy orreceived energy emitted from the target todetect a target?

1. First2. Second3. Third4. Fourth

2-23. In tracking a target, a collection of motors andposition-sensing devices called a servo systemhelps to successfully engage a target. Theoperation of such a system is based on whatinherent concept?

1. Error reduction2. Feedback3. Zeroing4. Rate reduction

2-24. What is the definition of “system error”?

1. The difference between where the sensor islocated and where the target is going

2. The difference between where the target ispointing and where the target is actuallygoing

3. The difference between where the sensor ispointing and where the sensor is located

4. The difference between where the sensor ispointing and where the target is actuallylocated

2-25. What devices are used in servo systems todetect the position of and to control themovement of power drives?

1. Gun mounts2. Missile launchers3. Optical encoder4. Radar antennas

2-26. The effective engagement and neutralizationof a target requires that a destructivemechanism, such as a missile warhead, bedelivered to the vicinity of the target. Whichof the following factors should be consideredin the design of an effective destructivemechanism?

1. Propulsion system2. Fuzing mechanism3. Warhead design4. All of the above

2-27. What is at the functional center of everyweapon system?

1. A human being2. A complex computer3. A large RF power supply4. A planned maintenance system

2-28. What is the purpose of your command’sbombarding you with safety slogans, rules,and procedures?

1. To keep you alive and well2. To improve your morale3. To keep you busy4. To give you something to do

2-29. Being safety conscious means to approachevery job from a safety point of view.

1. True2. False

2-30. Radio Frequency Radiation (RFR) is one ofthe hazards associated with radar operation.Which of the following areas around a radarantenna should you consider to be an RFRhazard?

1. The front2. The sides3. The rear4. All of the above

2-31. If you suspect any injury or excessiveexposure to radiation which of the followingindividuals should you contact?

1. Your leading petty officer2. Your ship’s doctor or corpsman3. Your division chief4. All of the above

2-32. Whenever you work around radar equipment,you should observe which of the followingsafety precautions?

1. Do not inspect feedhorns when they areemitting RFR

2. Observe all RADHAZ warning signs3. Ensure that radiation hazard warning signs

are available and used4. All of the above

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2-33. Scientific studies have shown that peoplecannot easily sense electromagnetic radiation(EMR). What EMR frequency range presentsa hazard to humans?

1. 10 Hz to 300 Hz2. 10 kHz to 300 GHz3. 10 THz to 300 THz4. 1000 Hz to 3000 Hz

2-34. Hazards of Electromagnetic Radiation toOrdnance (HERO) is one category of radiationhazards. What are the other two categories?

1. HERP and HERD2. HERF and HERR3. HERD and HEED4. HERP and HERF

2-35. What type of devices can actuate prematurelyin ordnance systems due to RFR?

1. Electro-optical devices2. Electromagnetic devices3. Electroexplosive devices4. Electromechanical devices

2-36. When are ordnance systems most susceptibleto RFR energy?

1. During loading only2. During unloading only3. During assembly4. During disassembly only

2-37. The radiation hazard HERO can be brokendown into three classifications. In which ofthe following conditions is an item consideredto be HERO unsafe?

1. The item is being assembled2. The item contains3. The item is sufficiently shielded from4. The item, through testing, has been proven

to be adversely affected by

2-38. Which of the following publications will listyour ship’s specific requirements for HEROsafety?

1. Naval Sea Systems Command instruction2. EMCON bill3. NAVSEA OP 35654. NAVAIR 16-1-529

2-39. Who is responsible for the implementation ofHERO requirements?

1. Commanding officer2. Executive officer3. Safety officer4. All hands

2-40. Which of the following publications listsspecific guidance about fueling operations andradar on your ship?

1. EXCON bill2. NAVSEA OP 35653. NAVELEX volume I

2-41. According to table 3-1 in the text, what is themaximum permissible exposure time limit fora fixed-beam hazard with the AN/SPY-1 radartransmitter?

1. 0.023 minute2. 0.23 minute3. 3.2 minutes4. 6 minutes

2-42. Which of the following changes in frequencyincreases the likelihood of biological damagefrom RFR?

1. A decrease in frequency only2. An increase in frequency only3. Either an increase or decrease in frequency

2-43. A navigational radar with a frequency of 900MHz may cause what type of damage, if any,to body tissues?

1. Minor damage2. Damage to surface skin3. Deep tissue damage4. None

2-44. Which of the following parts of theelectromagnetic spectrum can cause damage tothe transparent lens of the eye?

1. Ultraviolet2. Infrared3. Radio frequency4. All of the above

2-45. Permanent injury to the testicles can happenbecause of which of the following hazardconditions?

1. An extremely high dosage of RF2. High exposure of RF for many years3. Both 1 and 2 above

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2-46. Shipboard radar has cutout switches forpersonnel safety due to radiation. Which ofthe following is a function of cutout switches?

1. They turn off the transmitter for certainbearings and elevations

2. They turn off the transmitter for certainbearings only

3. They turn off the transmitter for certainelevations only

2-47. The specific cutout zones for your radar areidentified in which of the followingpublications?

1. NAVSEA OP 35652. Operational publications3. DOD instruction 6055.114. Bureau of Medicine and Surgery

publications

2-48. Which of the following is a symptom of a mildburn?

1. Slow healing injury2. Odor of scorched skin3. A tingling sensation4. Hair standing up

2-49. A common source of RFR burns is cranehooks. Which of the following factors is thebasis of these burns?

1. The location of the crane2. Induced RFR voltage3. The location of transmitters4. The location of wire ropes

2-50. The careful use of frequency can reduce theRFR voltages induced into crane structuresand rigging. Which of the following is abetter approach for the prevention of RFRinduced voltage injuries to personnel?

1. The use of RFR high voltage insulatorlinks

2. The use of RFR personnel protectors3. The use of RFR insulated gloves4. The use of RFR cable

2-51. Which of the following is considered thegreatest hazard associated with working aloft?

1. Dropping of objects2. Asphyxiation from stack gasses3. Electrical shock4. Falling

2-52. Which of the following is a danger associatedwith static charges encountered by personnelworking aloft?

1. RFR burns to the skin2. High-voltage shock3. Surprise of the shock may cause a fall4. Electrical arcing

2-53. Because of the associated dangers, no one maygo aloft without the permission of which ofthe following personnel?

1. Chief petty officer2. Officer of the deck3. Division officer4. Department head

2-54. Which of the following documents must beproperly completed before permission is givento go aloft?

1. Working check sheet2. Working aloft check sheet3. Under way check off list4. In port work list

2-55. When your ship is underway, who must grantpermission to go aloft?

1. Commanding officer2. Safety officer3. Officer of the deck4. Master chief of the command

2-56. How often should the announcement “DONOT ROTATE OR RADIATE ANYELECTRICAL OR ELECTRONICEQUIPMENT WHILE PERSONNEL AREWORKING ALOFT” be made over the 1MC?

1. Every 15 minutes2. Every 20 minutes3. Every 30 minutes4. Every 45 minutes

2-57. What document gives you specific instructionsfor your ship with regard to man aloftprocedures?

1. Under way check off list2. Master work list3. Ship’s Organization and Regulation

Manual4. Man Aloft Bill

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2-58. Which of the following is NOT a generalguideline for going aloft?

1. Stop work if the ship rolls more than 10degrees

2. Make sure the climber sleeve is attached toa safety harness when the wind speed is inexcess of 30 knots

3. Read all posted safety placards before youbegin work

4. Wear personal protective gear for hazardsother than

2-59. After working aloft, FC3 Smith leaves somerags and tools unsecured and then goes tolunch. You are his supervisor and learn thatthe ship’s helo will be flying right after lunch.What, if anything, should you be concernedabout, knowing the above facts?

1. FOD2. Rescheduling maintenance3. Nothing

2-60. For your safety when going aloft you shouldwear an approved parachute type harness.Which of the following components is/areassociated with this type of safety harness?

1. Safety lanyard2. Tending line3. Double lock snap hooks4. All of the above

2-61. A “Danger High Voltage” warning sign shouldbe posted at the entrance to compartments thatcontain which of the following equipment?

1. Equipment with shock hazards in excess of30 volts

2. Equipment with shock hazards in excess of500 volts

3. Equipment with exposed conductors withshock hazards in excess of 500 volts

4. Equipment with exposed conductors withshock hazards less than 30 volts

2-62. In which of the following locations should youpost stack gas warning signs?

1. Near the bottom of each access ladderleading aloft

2. At the top of each ladder leading aloft3. At the base of the antenna pedestal4. All of the above

2-63. Your radar equipment has a 4-inch red linecircling it. What type of sign should be postedfor your equipment?

1. Type 12. Type 23. Type 34. Type 4

2-64. A RADHAZ safety sign is mounted on a hookinsulator and warns personnel not to touch thewire/rigging above the insulator. What typeof RADHAZ safety sign is it?

1. Type 12. Type 23. Type 34. Type 4

2-65. Which of the following types of fuel is NOTconsidered to have a HERF problem?

1. AVGAS2. MOGAS3. JP-5

2-66. The type 6 RADHAZ sign advises of hazardsof electromagnetic radiation to ordnance.Which of the following publications givesguidance on type 6 signs?

1. EMCON bill2. NAVSEA OP 35653. SORM4. NAVSEA OP 4134

2-67. Which of the following instructions is NOT aproper instruction concerning a CRT?

1. Discharge the high voltage from the anodeconnector before removing the CRT fromits yoke

2. Wear safety glasses and gloves whenlifting the CRT by its neck

3. Always place CRT face down on a thickpiece of felt, rubber, or smooth cloth

4. Avoid scratching or striking the surface

2-68. On a ship, each electronics space is supposedto have one radioactive disposal spill kit.Which of the following items should be in thespill kit?

1. A container, rubber gloves, and forceps2. Masking tape, gauze pads, and a container

of water3. Respirator, radioactive material stickers,

and procedures4. All of the above

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2-69. If an approved HEPA filtered vacuum is NOTavailable for cleaning up the broken pieces ofa CRT, what is the approved alternate methodfor clean up?

1. Use forceps and a wet cloth with a firmback and forth motion

2. Use forceps and dry cloth with a carefulpatting motion

3. Use forceps and dry cloth with a circularmotion

4. Use forceps and a wet cloth, making onestroke at a time

2-70. If you sustain a wound from a sharpradioactive object whom should youimmediately notify?

1. Safety officer2. Commanding officer3. Medical officer4. Officer of the deck

2-71. X-ray emissions can penetrate human tissueand cause both temporary and permanentdamage. Which of the following types ofequipment are sources of x-rays?

1. Magnetrons2. Klystrons3. CRTs4. All of the above

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