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POSTGRADUATE SCHOOLMonterey, California

THESISARMY JTIDS: A C3 CASE STUDY

byRichard E. Volz, Jr

March, 1991

Thesis Advisor: Donald A. Lacer

Approved for public release; distribution is unlimited


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CLASSIFICATION OF THIS PAGEREPORT DOCUMENTATION PAGE

SECURITY CLASSIFICATION lb RESTRICTIVE MARKINGSCLASSIFICATION AUTHORITY

SCHEDULE3 DISTRIBUTION/AVAILABILITY OF REPORTApproved for public release; distribution is unlimited.

ORGANIZATION REPORT NUMBER(S) 5 MONITORING ORGANIZATION REPORT NUMBER(S)

OF PERFORMING ORGANIZATIONSchool

6b OFFICE SYMBOL(// applicable)

CC7a NAME OF MONITORING ORGANIZATIONNaval Postgraduate School

(City, State, and ZIP Code)CA 93943-5000

7b. ADDRESS {City, State, and ZIP Code)Monterey, CA 93943-5000

OF FUNDING/SPONSORING 8b OFFICE SYMBOL(If applicable)

9 PROCUREMENT INSTRUMENT IDENTIFICATION NUMBER

(C/ty. State, and ZIP Code) 10 SOURCE OF FUNDING NUMBERSProgram Element No Project No Tavk NO Work Unit Accession

Number

(Include Security Classification)JTIDS: A C3 CASE STUDY, UNCLASSIFIED

AUTHOR(S) Volz, Richard E. Jr.OF REPORT

Thesis13b TIME COVEREDFrom To

14 DATE OF REPORT (year, month, day)March, 1991

15 PAGE COUNT142

NOTATIONexpressed in this thesis are those ofthe author and do not reflect the official policy or position ofthe Department of Defense or the U.S.

CODESGROUP SUBGROUP

18. SUBJECT TERMS (continue on reverse if necessary and identify by block number)JTIDS, Command, Control, Communications, ATCCS, JSTARS

(continue on reverse if necessary and identify by block number)author examines the Army command, control, and communications aspects of the Joint Tactical

Distribution System (JTIDS). The developmental history ofJTIDS as a secure, jam-resistant, datasystem is discussed with emphasis placed on the acquisition process. An overview of the system,the key components, is also presented. Particular emphasis is placed on management of theand the current joint concept of operations. The potential ofJTIDS to pass other forms of surveillanceis examined. In particular, the Joint Surveillance Target Attack Radar System (JSTARS) produces

of information for all Army C2 elements. JTIDS can provide the means to transmit JSTARS grounddata to the Army Tactical Command and Control System (ATCCS), making this information

to users that would not ordinarily receive it. Total Battlefield Automated System integration is thecomponent for full exploitation of this information.

OF ABSTRACT] SAME AS REPORT ] DTIC USERS

21 ABSTRACT SECURITY CLASSIFICATIONUnclassified

OF RESPONSIBLE INDIVIDUALDonald A Lacer

22b TELEPHONE (Include Area code)(408)646-2772

22c. OFFICE SYMBOLCC1473, 84 MAR 83 APR edition may be used until exhausted

All other editions are obsoleteSECURITY CLASSIFICATION OF THIS PAGE

Unclassified


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Approved for public release; distribution is unlimited.

Army JTIDS: A C3 Case Study

byRichard E. Volz, Jr.

Captain, United States ArmyB.S., Siena College, 1983

Submitted in partial fulfillmentof the requirements for the degree of

MASTER OF SCIENCE IN SYSTEMS TECHNOLOGY(JOINT COMMAND, CONTROL, AND COMMUNICATIONS)

from the

NAVAL POSTGRADUATE SCHOOLMarch 1991


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ABSTRACT

The author examines Army command, control, andcommunications aspects of the Joint Tactical InformationDistribution System (JTIDS) . The developmental history ofJTIDS as a secure, jam-resistant, data distribution system isdiscussed with emphasis placed on the acquisition process. Anoverview of the system, highlighting the key components, isalso presented. Particular emphasis is placed on managementof the network and the current joint concept of operations.The potential of JTIDS to pass other forms of surveillanceinformation is examined. In particular, the JointSurveillance Target Attack Radar System (JSTARS) produces awealth of information for all Army C2 elements. JTIDS canprovide the means to transmit JSTARS ground surveillance datato the Army Tactical Command and Control System (ATCCS) ,making this information available to users that would notordinarily receive it. Total Battlefield Automated Systemintegration is the key component to full exploitation of thisinformation

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,/TABLE OF CONTENTS

CHAPTER I. HISTORICAL EVOLUTION 1A. INTRODUCTION 1

1 Purpose 12 Definition 13 Scope 14 Background 25 Joint Concept of Operations 5

B. PROGRAM HISTORY 61 Phase Development 6

a Phase I 7b. Phase II 9

2. Congressional Review 103. Multifunctional Information Distribution

System (MIDS) 11C. SYSTEM EVALUATION 13

1. Technology Risk 132 Program Cost 153. Schedule/Milestones 184. JTIDS and NATO 205. Test and Evaluation 21

CHAPTER II. SYSTEM OVERVIEW 25

IV


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A. SYSTEM DESCRIPTION 25B. SYSTEM TECHNOLOGY 2 6C. MESSAGE STRUCTURE 2 9D. INFORMATION DISTRIBUTION 31E. RELAY FUNCTION 33

1. Paired Slot Relay 332. Repromulgation Relay 34

F. ACCESS MODES 341 Dedicated Access 342. Contention Access 353. Distributed Reservation Access 35

G. VOICE 36H. POSITION LOCATION 37I. IDENTIFICATION 38J. CLASSES OF TERMINALS 3 8

1. Class 1 Terminal 3 92. Class 2 Full Scale Development Terminal . . 393. Class 2M Terminal 414. Class 2H Terminal 435. Class LV Terminal 43

CHAPTER III. NETWORK MANAGEMENT 46A. DEFINITION 46B. NETWORK MANAGEMENT OVERVIEW 4 6

1. Class 1 Terminal Network 472. Class 1 and 2 Terminal Networks 51

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C. NETWORK DESIGN FOR JTIDS JTAO 58D. ARMY NET MANAGEMENT 60

1 Means of Employment 602 Army JTIDS Network Employment 63

CHAPTER IV. CONCEPT OF OPERATIONS 66A. JCS JOINT CONCEPT OF OPERATIONS 66

1 Current Joint Tactical Air Operations ... 662. Information Exchange (Non-JTIDS) 69

a. Track and Track Management 70b. C2 Unit Status 71c. C2 Coordination 71d. Special Information Transfer 72e. Summary 73

3. JTIDS Equipped Joint Tactical Air Operations 73a. Position and Status Reporting 78b. Surveillance 7 8c. Target Selection and Coordination ... 79d. Navigation 7 9e. Digital Voice 79

B. ARMY CONCEPT OF OPERATIONS 801. Introduction 802. Airland Battle Doctrine 803. Army Command and Control Systems 824. Three Pillared Architecture 83

a. Area Common User System 84vi


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b. Combat Net Radio 85c. Army Data Distribution System 86

5. Army JTIDS/EPLRS Employment 88

CHAPTER V. PROPOSED APPLICATIONS FOR JTIDS INFORMATIONDISTRIBUTION 91A. INTRODUCTION 91B. AIRLAND BATTLE - FUTURE 91

1. Projected Doctrine 912 Communications Support 94

C. JTIDS - A VITAL LINK FOR ALB-F 951 Joint Surveillance Target Attack Radar

System 952. JTIDS - A Gateway to the Sigma Star .... 98

D. A PROPOSED JTIDS ALTERNATIVE 991. Maneuver Control 1012. Air Defense Artillery 1033. Fire Support 1044. Intelligence/Electronic Warfare 1055. Combat Service Support 106

E. HURDLES TO OVERCOME 1091. Data Fusion 1092. Decision Support Algorithms 1103. Multilevel Security Ill4. Doctrine 1125. Summary 114

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CHAPTER VI. CONCLUSIONS AND RECOMMENDATIONS 115A. SUMMARY 115B. CONCLUSIONS 115C. RECOMMENDATIONS 116

1. Timely Fielding 1162. Continued JTIDS Development 1163. NCS-J - The Joint Management Tool 1174. JTIDS Transmission of JSTARS Information . . 117

LIST OF REFERENCES 119INITIAL DISTRIBUTION LIST 123

Vlll


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LIST OF TABLESTABLE 1 System Requirements for Each Phase 8TABLE 2 JTIDS Family of Terminals 12TABLE 3 Projected JTIDS Program Development Costs . . 18TABLE 4 Projected Milestones 20TABLE 5 JTIDS Class 2 Cost Estimates as of February

1990 24TABLE 6 JTIDS Operational Requirements 25TABLE 7 JTIDS Terminal Capabilities 45

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LIST OF FIGURESFigure 1 Planned JTIDS Users 7Figure 2 JTIDS System Technology 11Figure 3 JTIDS Signal Structure 2 6Figure 4 JTIDS Time Slot Structures 28Figure 5 IJMS Message Structure 31Figure 6 TADIL J Message Structure 32Figure 7 JTIDS Voice 37Figure 8 JTIDS Multi-Purpose Color Display 42Figure 9 JTIDS Single Net Operations 4 8Figure 10 JTIDS Multinet Operations 54Figure 11 Terminal Initialization Load Generation . . 57Figure 12 Army JTIDS Communication System 62Figure 13 Division JTIDS Network Management 65Figure 14 Current Joint Air Operations 67Figure 15 JTIDS Concept of Operations 75Figure 16 The Army Command and Control System .... 83Figure 17 The Three Pillared Communication

Architecture 84Figure 18 Deployment of Army Communication Systems . . 88Figure 19 The PLRS /JTIDS Hybrid System 8 9Figure 20 Airland Battle - Future Concept 93Figure 21 Communications on the Non-Linear Battlefield 96Figure 22 The JSTARS Radar Platform 98


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Figure 23 The JTIDS Alternative 100Figure 24 Integrated Information Flow 108Figure 25 Potential ATCCS Management 113

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TABLE OF ABBREVIATIONS

ABMOCACCSACUSADAADDSADSOAFATDS

AFPALBALB-FASASAS ITATCCSATDL-1AWACSBASBDEFDCBITBFABNFDCCACC2

CCSK

Air Battle Management Operations CenterArmy Command and Control SystemArea Common User SystemAir Defense ArtilleryArmy Data Distribution SystemAssistant Division Signal OfficerAdvanced Field Artillery Tactical DataSystemAssault Fire PlatoonAirland BattleAirland Battle-FutureAll Source Analysis SystemAdaptable Surface Interface TerminalArmy Tactical Command and Control SystemArmy Tactical Data Link-1Airborne Warning And Control SystemBattlefield Automated SystemBrigade Fire Direction CenterBuilt-in-TestBattlefield Functional AreaBattalion Fire Direction CenterCombined Arms CenterCommand and ControlCyclic Code Shift Keying

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CIPCNRCONOPSCONUSCPSMCRCCRPCSSCSSCSCVSDDABDCADJRUDMEDTDMADTMEACECMEPLRS

EPUUEWFAADFACPFAADC 2 IFM

Communication Improvement ProgramCombat Net RadioConcept of OperationsContinental United StatesContinuous Phase Shift ModulationControl and Reporting CenterControl and Reporting PostCombat Service SupportCombat Service Support Control SystemContinuous Variable Slope DeltaDefense Acquisition BoardDefensive CounterairDedicated JTIDS Relay UnitDistance Measuring EquipmentDistributed Time Division Multiple AccessData Transfer ModuleEchelons Above CorpsElectronic Counter MeasuresEnhanced Position Reporting LocationSystemEPLRS User UnitElectronic WarfareForward Area Air DefenseForward Area Control PostFAAD Command, Control, and IntelligenceField Manual

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FSFSDGAOGSMHFHICHIMADHIUICPIEWIHFRIJMSITNSJCSJINTACCS

JMSWGJOPMJORJPOJSTARS

JTAOJTIDS

Kbs

Fire SupportFull Scale DevelopmentGovernment Accounting OfficeGround Station ModuleHigh FrequencyHigh Intensity ConflictHigh to Medium Air DefenseHost Interface UnitInterface Control PanelIntelligence/Electronic WarfareImproved High Frequency RadioInterim JTIDS Message SpecificationIntegrated Tactical Navigation SystemJoint Chiefs of StaffJoint Interoperability Program forTactical Command and Control SystemsJTIDS Message Standards Working GroupJTIDS Operational Performance ModelJoint Operating RequirementJoint Program OfficeJoint Surveillance Target Attack RadarSystemJoint Tactical Air OperationsJoint Tactical Information DistributionSystemKilobits per Second

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LICLNOLRIPMCSMICMIDS

MLSMPCMPCDMSEMSRTNATONCSNCS-JO&COSDPCDPPJHIPLRSPPLIPTRATTRLRSCSACP

Low Intensity ConflictLiaison OfficerLow Rate Initial ProductionManeuver Control SystemMedium Intensity ConflictMultinational Information DistributionSystemMultilevel SecurityMessage Processing CenterMulti-Purpose Color DisplayMobile Subscriber EquipmentMobile Subscriber Radio TelephoneNorth Atlantic Treaty OrganizationNet Control StationNet Control Station-JTIDSOperations and ControlOffice of the Secretary Of DefensePilot Control and Display PanelPLRS-JTIDS Hybrid InterfacePosition Location Reporting SystemPrecise Position Location IdentificationEnhanced PLRS TerminalRadio TeletypeRapid LoadRadio Set ControlStand Alone Control Panel

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SAMSDSSINCGARS

SYSCONTACANTACSTADILTADIL JTCTTDMATRADOCTRI-TACUROWAN

Surface to Air MissileSoftware Development StationSingle Channel Ground and Airborne RadioSystemSystem ControlTactical Air NavigationTactical Air Control SystemTactical Data Information LinkTactical Data Information Link JTIDSTactical Computer TerminalTime Division Multiple AccessTraining and Doctrine CommandTri-service Tactical CommunicationsUser ReadoutWide Area Network

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ACKNOWLEDGMENTSThe author wishes to express his appreciation to Colonel

William Guerra, Director of Combat Developments, United StatesArmy Signal Center, Fort Gordon for his sponsorship.Professor Donald A. Lacer and Professor Michael G. Sovereignprovided invaluable support and advise throughout thedevelopment of this thesis. Special thanks are provided toCaptain James Kohlman, Captain David S. Velasquez, and CaptainDavid J. Sacha for their invaluable assistance in researchingthis thesis.

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CHAPTER I. HISTORICAL EVOLUTION

A. INTRODUCTION1 . Purpose

This chapter presents an introduction to the JointTactical Information Distribution System (JTIDS) . It willexamine JTIDS' s mission requirements and its history ofdevelopment to meet those needs . The system' s procurementhistory and current procurement status will be discussed.

2 . DefinitionJTIDS is a secure, jam-resistent data and voice

communications system. The system enables the exchange ofreal-time tactical information between joint forces concerningfriend and foe alike. The information exchange includes forceidentification, location, and command and control data. [Refl:p 11]

3 . ScopeThis thesis will present JTIDS under its command and

control aspects. An examination of JTIDS potentialapplications for information distribution on futurebattlefields will also be performed. Chapter I examins thehistory of JTIDS development as a data distribution system forjoint air operations. Chapter II presents an overview ofJTIDS and highlights key components in the system. The


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components will include the major terminals and theirinterfaces with various platforms. Chapter III reviewscurrent concepts to plan and manage a JTIDS network. ChapterIV discusses the current Joint CONOPS for JTIDS employment.The communication architecture planned by the U.S. Army willalso be presented. Chapter V presents potential JTIDSinterfaces into the ATCCS . A number of proposals aredeveloped for use of JTIDS provided information. Primaryamong the information sources is the U.S. Air Force JSTARSground surveillance aircraft. The last portion of the chapteris devoted to the problems inherent in the integration ofautomation devices on the battlefield.

4 . BackgroundThe war in Vietnam, particularly the air war,

demonstrated U.S. forces' inability to effectively employcombat power. Much of this ineffectiveness was due toinadequate command and control (C2 ) capabilities. Aircraftand weapon systems have dramatically increased both theircapabilities and lethality, while C2 has lagged behind. Theair war over North Vietnam is a case in point. [Ref . 2:p 25]

In 1972 the U.S. was withdrawing it's land forces fromthe Asian land mass . The North Vietnamese viewed this as anopportunity to capture South Vietnam with limited U.S.opposition. It was decided by then-President Richard Nixon tocommit U.S. air power over North Vietnam to stem the flow of


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arms to the South. The ensuing air war over North Vietnamclearly displayed our command and control weaknesses

North Vietnam was divided into geographical areas ofresponsibility that were under the control of only oneservice, namely the Navy or Air Force. This was done toeliminate confusion due to incompatible C 2 systems . Eachservice had its own surveillance capability and intelligencereports . Lack of interoperability of the command and controlsystems prevented information sharing and all sourceinformation processing. Invaluable information was notshared, though both services could have benefitted from itIn addition, aircraft from different services could notcommunicate with each other. Frequencies, call signs andradio procedures differed for each service. Navigation andposition reporting were also extremely difficult and differedbetween the services. Hanoi was often used as a centralreference point. Each pilot had to be aware of his locationwith reference to Hanoi . Any hostile aircraft detected werereferenced in the same manner. In a combat situation, thepilots often became confused and misoriented. It became clearthat some form of data distribution system would be requiredto fuse this data. The requirement to share informationthroughout the theater of operation, as a joint network wasself-evident. [Ref. 2:p 13]

The 1973 Mideast War between Israel and Egypt pointedout, in a rather dramatic manner, a major weakness in U.S.


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communication systems. Israeli intelligence reported thatEgyptian forces used Soviet-developed jammers during theconflict that virtually blocked all inter-aircraftcommunications. This threat was viewed in it's implicationsfor a land war in Central Europe, and a need for jam-resistentcommunications was given a greater priority. [Ref. 3:p 25]

In 1974, the Joint Chiefs of Staff issued a service-wide directive that outlined the potential threat to U.S.forces . It also directed that a new command and controlsystem be developed. This system was to be jam resistant witha method for the distribution of shared data to allparticipants. [Ref. 4:p 3]

The Air Force and Navy were both directly affected bythe JCS directive. Fortunately, both had previously begundevelopment of tactical information distribution systems . TheNavy was developing the Integrated Tactical Navigation System(ITNS) that was a distributed form of Time Division MultipleAccess (DTDMA) . The Air Force was concurrently working on aposition, location, reporting and control system, known asPLRACTA. This system later evolved into the SEEK BUS system.The SEEK BUS placed it's emphasis on incorporating manysubscribers into a single network. Both developmental effortswere pursued in order to evaluate technical requirements andpotential concepts of operation.

The Office of the Secretary of Defense (OSD) combinedboth efforts in 1974 by selecting the Air Force as the lead


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service . DTDMA and TDMA technologies were each viewed ashaving potential. The Navy was to continue its efforts underDTDMA technology with new requirements for security and jam-resistance. Their system was designed for use over existingTactical Data Information Links (TADIL) links. The Air Forcecontinued its development of the already proven potential ofTDMA. [Ref. 4:p 3]

In 1976, a Joint Operating Requirement (JOR) waspublished. It further outlined the development of a secure,anti-jam, digital data distribution system. It also separatedfurther development into two phases, with differentrequirements. The phases, as determined by the UnderSecretary of Defense for Research and Engineering, differedunder the criteria of system capacity, multiple netting, andthe number of voice channels per net. [Ref. 4:p 4]

5. Joint Concept of OperationsJoint operations are the norm today rather than the

exception. An integrated data distribution system is vital tocommand and control of air, ground, and sea assets in theAirland Battle. The JTIDS system incorporates all air andground sensor information into a coherent picture that canthen be filtered to meet unique user requirements.

Sensors, such as the Air Force E-3A AWACS and the NavyE-2C Hawkeye, with other air and ground sensors, can create anintegrated air picture. This snapshot of the air battle is


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sent to all the net participants in near real-time. One ofthe primary recipients is the Air Force Control and ReportingCenter (CRC) . The CRC is responsible for the conduct of airdefense and air space control over the area designated by theJoint Force Commander. The CRC will perform a managementfunction over subordinate Control and Reporting Posts (CRPs)and U.S. and NATO E-3As. When Army surface-to-air missiles(SAMs) are assigned to operate in a joint air defenseenvironment, the CRC provides operational control over the SAMemployment. The CRC establishes an air picture of its area ofresponsibility. This is accomplished through local radar andthe cross telling of track information among all the elementshaving track data in the designated air space. Figure 1depicts planned JTIDS users. [Ref. 5:p 24]

In the past, these vital command and control functionswere performed manually between systems. The JTIDS networkautomates this process providing near real-time distributionof surveillance and C2 information to all users . A fullydeployed JTIDS network will greatly enhance combateffectiveness in the air battle. [Ref. 5:p 26]

B. PROGRAM HISTORY1 . Phase Development

The Joint Operating Requirement (JOR) for a datadistribution system set the goals for future development. Thephased development of the system was designed to meet short


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USAFMPC USMC/USArTAOC-85/MCE

Figure 1 Planned JTIDS Users

and long term goals. Phase I established minimum essentialrequirements to meet the Air Force's desperate need for a datalink between the E-3A AWACS and ground C 2 centers. Phase II-was to produce a terminal with a greatly enhanced datacapacity and netting capability. Table 1 depicts the specificdigital requirements for each phase.

a . Phase IThe first priority for the Air Force was to develop

a data distribution terminal for the E-3A AWACS and NATO E-3As . The Hughes Aircraft CO., under a $20 million contract,


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TABLE 1 System Requirements for Each Phase

Phase I Phase II

Data Rate 20 kbs 300 kbsNetting

Capability 4 nets 15 netsVoiceChannels perNet 3 voice 7 voice

developed the Class 1 terminal . This first generation JTIDSterminal met the anti- jam requirement under the JOR. TheClass 1 JTIDS terminal could be used in both versions of theE-3A AWACS aircraft, but its weight and size requirements madeit incapable of use in any Air Force fighter aircraft . TheClass 1 terminal had a limited capacity, which lackedflexibility, and could employ limited netting. Additionally,an agreed upon standard message format had not yet beendeveloped [Ref . 6:p 54] . The interim JTIDS MessageSpecification (IJMS) was developed to meet the needs of theClass 1 terminal until a final message format could beapproved. [Ref. 7:p 3]

The Advanced Surface Interface Terminal (AS IT) wasdeveloped to meet the need to communicate with ground systemsThe ASIT enabled communications with Air Force ground commandand control centers and Army air defense assets with theprimary function of translating the IJMS message format intoTADIL B. In 1987, the Class 1 terminal successfully passedits operational test. [Ref. l:p 57]

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b . Phase IIThe development of the first generation JTIDS

terminal (Class 1) established the operational capability ofthe TDMA technology. The Class 1 terminal was too large andheavy and had limited capabilities to be used in tacticalaircraft. Phase II development began well before Phase Irequirements were met. It focused on reduction in terminalsize, weight, and greatly enhanced data capability. The AirForce and Army continued with development of TDMA technology.The Navy was allowed to continue development of DTDMAtechnology providing it was compatible with the Air Forceprogram. With the understanding that TADIL J was to be thejoint message format standard, both technologies were fundedfor Full Scale Development (FSD) in 1981. [Ref. 8:p 7]

The Class 2 terminal was developed through TDMAtechnological advances. The terminal developed was smaller,had a much greater data capability, and an improved capacityfor netting; however, it also had its share of problems. TheClass 2 terminal was still too large to fit into smallertactical aircraft such as the Air Force F-16. The Army haddifficulty interfacing the Class 2 terminal with its Position,Location, and Reporting System (PLRS) . A single type ofterminal would not be able to perform all the assignedmissions; therefore, several different versions were developed


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to meet specific requirements of individual services. [Ref.l:p 87]

One version was the Army's Class 2M terminal. Thisterminal was designed to meet the needs of the Army AirDefense community. The Class 2M terminal differed in that ithad a data-only capability. Voice capability was determinedto be unnecessary and its elimination would reduce theterminal's size. The Army opted for the trade-off ofcapability for size. [Ref 9:p 7]

A high power version of the Class 2 terminal, the2H is under development to meet a system requirement forgreater range. This new requirement was established to meetthe needs of:

The Marine Corps Tactical Air Operations Module. Air Force Modular Control Equipment Navy E-2C surveillance aircraft. Class 1 terminal upgrades for E-3A AWACS . [Ref. 4:p 19]

2 . Congressional ReviewThe JTIDS program came under Congressional review in

August of 1985. A joint meeting of both the Senate and HouseArmed Services Committees directed then-Secretary of DefenseCasper Weinberger to select one system that would meet theneeds of all services. The evaluation by OSD determined thatthe Naval development of DTDMA technology was yielding aproduct that was too complex and required costly unique micro-

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circuitry. The Secretary of the Navy, John Lehman, canceledall DTDMA development in October 1985. He directed that allfuture naval fighters were to use the Class 2 terminals[Ref. 8:p 3] The selected system technology is depicted inFigure 2

9BK 1TIME SLOTSEPOCH = 12.8MINUTES98KTIMESLOTS

98K/12.8min = 1536/12 sec

TDMA9 FREQUENCY HOPPINGQ 128 TIME SLOTS/SECOND/NET

INFO/TIME SLOTS VARIES225 BITS W/EDC1860 BITS W/OEDCQ PROPAGATION RANGE300 nml NORMAL500 nml EXTENDED

PROP-MESSAGE J AGATION1

_ Figure 2 JTIDS System Technology3. Multifunctional Information Distribution System (MIDS)

A team of experts were brought together by NATO alliesin 1979. Their purpose was to recommend to the NATO alliancecurrent technologies available for development of a secure,anti-jam, data distribution system. This system had to meetmission needs for all aspects of the NATO battle plan. The

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team recommended that TDMA technology developed under theJTIDS program had the greatest potential to meet those missionneeds; hence the MIDS program was established.

The MIDS program is currently in the conceptdevelopment phase. U.S. services are working concurrentlywith their NATO counterparts to develop JTIDS-type terminalsthat would be adaptable to a variety of NATO aircraft . The AirForce hopes to develop a terminal that will fit into thecockpit of their smaller tactical aircraft (i.e., F-16 and F-18) . The Navy as the lead service represents the UnitedStates in the MIDS program. [Ref . l:p 129-132] The family ofJTIDS terminals are depicted in Table 2TABLE 2 JTIDS Family of Terminals

CLASS 1 CLASS 2 CLASS 3

POTENTIALAPPLICATIONSC2 CENTERS

* E-3A* AF TACS* NATO C2* ARMY TSQ-73

SMALL PLATFORMS* F-15* F-16* HAWK* ARMY AIRDEFENSE* ARMY C2

VERY SMALL PLATFORMS* TRANSPONDER* RPV* MISSILE* MANPACK

PERFORMANCEMULT INETCAPACITYAJ PROTECTIONPOWER OUTPUTREL NAVRELAYINTEGRATE CNIVOICE

* Ya* 30/60 kb/a* High* 200W 1000N* Rfrnoa Only* Yta* No* Ya

* Ya* 30/238 kb/a* High* 200W* Yaa* Yaa* TACAN* Ya

TO BE DEFINED

CHARACTERISTICSWEIGHTSIZE * 400 lb* 6.4 ft' * 125 lb1.7 ft J TO BE DEFINED

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C. SYSTEM EVALUATION1 . Technology Risk

The development of a JTIDS system to meet the missionrequirements for a secure, anti-jam, data distribution systemmade large assumptions about available and potentialtechnologies. A comprehensive assessment of the risks to theprogram with a common baseline for the level of technology wasnever performed. The technological risk was compounded due tothe number of new technologies required to implement the JTIDSprogram.

The need for a data distribution system was thedriving force behind JTIDS development. In the early stagesof the program, the Air Force and Navy had developed twodifferent technologies to meet the data distributionrequirement . The Air Force was developing TDMA and the Navywas developing DTDMA. The development of these twotechnologies created two levels of risk for the program. Therewas a great deal of duplication in the research anddevelopment involved with the two approaches. Congressionalreview of the program resulted in the cancellation of DTDMAdevelopment. Naval development of DTDMA only lasted as longas it did because of the potential savings in the long termgoal of using existing TADIL B links. [Ref. 10 :p 36]

The JCS requirement for an anti-jam capability addedtechnical risk to the program. In 1974 this technology was in

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its infancy. Two methods under development to overcomepotential Soviet jamming were frequency hopping and spreadspectrum technology. Frequency hopping involves signaltransmission on a randomly selected frequency within apredetermined frequency band. Spread spectrum technologyentails spreading the message signal over a broad frequencyband. This would ensure that enough of the message signal isreceived at the receiver to be accurately reproduced.Additionally, both anti- jamming technologies added greaterrisk to the program. The frequency hopping technique wasselected for incorporation into the Class 1 and Class 2terminals. [Ref. 5:p 44]

The final technical risk is one that was neveradequately assessed. Software development for the JTIDSterminals has continually lagged behind hardware. Over onemillion lines of code have been written for eight versions ofthe terminal . A standard message format for the system wasstill undecided during initial testing of the Class 1terminal . The Air Force directed the development of aninterim message format known as Interim JTIDS MessageSpecification (IJMS) . This format evolved in order tocontinue development of the JTIDS system. IJMS was incapableof directly interfacing with existing service command andcontrol centers that currently use TADIL B data links (i.e.Air Force CRCs and MPCs) . The development of the AdaptableSurface Interface Terminal (ASIT) was driven by the IJMS,

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enabling ground users to translate message formats. [Ref . l:p21]

The TADIL J message format was developed by the JTIDSMessage Standards Working Group (JMSWG) of the JointInteroperability Program for Tactical Command and ControlSystems (JINTACCS) . This message format has been accepted byeach service for employment in the JTIDS systems. The TADILJ format was employed in all JTIDS terminals in the late1980s. JTIDS message formats will be described in detail inChapter II. [Ref 7:p 6]

2 . Program CostProgram cost estimates have continually risen since

JTIDS' s conceptional development. Initial life cycle costestimates in 1974 varied between $3 billion and $4 billion tomeet data distribution needs for the U.S. in NATO. The JointProgram Office (JPO) increased this estimate in 1979 to $7billion. This new life cycle cost estimate had defects. TheJPO did not perform a separate cost estimate based upon theentire joint program; rather, it totalled all the services'individual cost estimates to determine the joint programfigure. Further investigation reveals that the Air Forcebased their estimate on current and anticipated TDMAtechnology. The Air Force also included a cost escalationfactor to account for anticipated inflation rates . The Navybased it's cost estimate on DTDMA technology under their

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development. Naval program managers also didn't include aninflation factor, basing their estimate solely on 1978dollars. The Army's estimate was based on fielding the Class2 terminal with their PLRS system in command posts only. Thisestimate did not include any figure for advanced thirdgeneration terminals to be employed with ground units . It isalso important to note here that as of 197 9 the Army stilllacked approval of a mission need for JTIDS within theirservice. [Ref 8:p 7]

No common baseline upon which to determine systemcosts was established. In 1979, the JTIDS program was jointin name only. Each service was maintaining its own program andcost estimates were based on vastly different sets ofcriteria. Thus, there was no basis for an accurate estimateof the cost of the program from cradle to grave . Currentestimates call for the procurement of 1700 terminals throughthe year 1997. The cost of production of these terminals isapproximately $1.7 billion. [Ref. 8:p 5]

The lead-follow contract method was employed in lowrate initial production of the Class 2 terminal. It was hopedthat this method of contracting would enhance competition andhelp drive down unit cost . The lead contractor for Air Forceprocurement of the Class 2 terminal is Plessey ElectronicsSystem Corporation. The Plessey Corporation was awarded aLRIP contract worth $90 million dollars for 47 Class 2terminals. The first 20 terminals were designated for

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installation in Air Force F-15 tactical fighters. Theadditional 27 Class 2 terminals will be installed into Navy F-14s and several command and control vessels. The followcontract for low rate initial production was awarded toRockwell Collins, Inc. at $42 million dollars. The Class 2terminals produced under this contract will be installedsolely on Air Force F-15s. [Ref. 9:p 10]

Current cost figures for each Class 2 terminal isapproximately $800,000 to $1 million. This estimate includesthe cost of production and initial logistical support.Contractors, in conjunction with the JPO estimate the per unitcost could possibly be reduced by as much as one half. A costreduction to $400,000 per terminal could be achieved throughexperience gained on the production line and competitionbetween Plessey and Rockwell Collins. The cost of investmentin test equipment and tooling may be recouped by thecontractor by 1992. Unit cost reductions should then follow.The JPO has a number of product improvement programs to aid inlife cycle cost reduction. These are as follows:

1. State of the art off-the-shelf mini processors.2. Increase reliability of the system.3. Bulk purchase of replacement parts.

In summary, the original developmental estimate of $3to $4 billion was highly optimistic. Software development wasnot estimated nor was the cost of having to develop twomessage formats included. JTIDS software development

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dramatically contributed to the already exceeded developmentalcost, currently over $2 billion. [Ref . 3:p 47] Recent budgetinformation is found in Table 3.TABLE 3 Projected JTIDS Program Development Costs

BUDGET(000) FY 1988 FY 1989 FY 1990 FY 1991 FY 1992 PGM TOT(TOCOMPL)

MAJORCONTRACT 78,603 61,120 87,130 87,808 72,317 TBD(SS5 in Thousands

)

3 . Schedule/MilestonesProgram managers are required to submit an acquisition

strategy within ninety days of appointment in accordance withthe Defense Management Review. This was never done for JTIDSacquisition. The Air Force, as the lead service, establishedfew milestones, which were regularly pushed back due to a lackof results in technological development.

Forces outside the JPO also contributed to delays inthe developmental process. The Class 1 terminal experienceddelays for several reasons . Congressional review of the JTIDSprogram discovered the services were developing systems thatwere not frequency compatible nor did they incorporate TACANfrequencies. Congress then mandated that the JTIDS systemmust be interoperable and TACAN frequency compatible beforefurther development. Additionally, the developmental phasewas extended two years, based on the Hughes Aircraft Co . 'recommendation that added development time would enable them

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to substantially reduce unit cost of first generationterminals. [Ref. 8:p 5]

Development of the Class 2 terminal also suffered fromdelays . Singer Kearfott and Rockwell Collins had developednewer micro computer chips that would process data at a muchhigher rate. Incorporation of these chips into the Class 2terminal design would greatly reduce the size of the terminalBased on the inherent advantage in size reduction andincreased capability, OSD approved a 14 month delay inawarding a production contract. [Ref. 8:p 15]

Development of the third generation of JTIDS terminalshas been repeatedly delayed. The Class 3 terminals were to bedesigned to meet the needs of Army air defense units andsmaller fighter aircraft. This generation of terminals hasexperienced many delays due to repeated lowering of itspriority through the Defense budgeting process . There hasbeen continued lack of service support, due to the large costinvolved, for JTIDS development and no clear definition ofmission requirements. At this time, the future of the Class3 terminal is uncertain. Current schedule information is foundin the Table 4

Current estimates show that the first low rate initialproduction Class 2 terminals will be delivered to the Navy inDecember 1991. Delivery of low rate initial productionterminals to the Air Force will occur in April 1992. TheArmy's Class 2M terminal is still in the developmental stage,

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TABLE 4 Projected MilestonesSchedule 1988 1989 1990 1991 1992 ToCompleteProgramMS IIIA9/89F-15CLS2

IIIA 2/91Navy CLS2 IOCF-15 IOC Army/Navy

EngrMS

Rel.Verif ArmyTerminalIntegr

.

NavyTerminalIntegr

.

TSEMS DT-IIF-15 Pre DABTeat OTF-15 OT-IINavy 9/91 DT/OTEval.ContractMS BLK 1Navy BLK IINavy F-15Prod Unit Prod.UnitArmy/Navy

due to an Army-unique data only requirement. The Class 2Mterminal is expected to undergo Defense Acquisition Board(DAB) Milestone IIIA review in October 1991. [Ref. 9:p 45]

4. JTIDS and NATOThe NATO MIDS program selected JTIDS technology for

its development in Europe. Cooperative agreements with theUnited States, the United Kingdom, and France are planned topurchase JTIDS terminals for each countries' own E-3A AWACSaircraft . The terminals will be bilingual and fullyinteroperable with existing Class 1 terminals . Memorandums ofUnderstanding with the U.K. and France were signed by the AirForce in 1989. The Plessey Corp. will deliver 20 Class 2H,high power terminals to the U.K. and ten Class 2H terminalsto France in 1990. Plessey is the lead contractor of all NATOcontractors involved in MIDS development . Other NATO membernations involved in the program are Germany, Spain, and Italy.[Ref. ll:p 89]

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5 . Test and EvaluationTesting and evaluation of the JTIDS system has been

on-going throughout the developmental phases of the program.The Air Force conducted the first operational test on theClass 1 terminal in April 1973 on board an E-3A AWACSaircraft . The operational test concluded that the Class 1terminal did not meet defined requirements. As late as 1978,the Class 1 terminal still fell short of establishedrequirements. At this time, the Class 1 terminal is the onlyterminal undergoing operational tests. The Air Force'sassessment of the terminal's operational capability is thatsome requirements are being met by the system, (anti-jam anddata rate) , and others were not (multi-netting) . The criteriaused by the Air Force are outlined in the Joint OperatingRequirement (JOR) for JTIDS published by the JCS in March1976, under Phase 1 developmental requirements. The firstfull scale development model test of the Class 2 terminal tookplace in 1979. This test was to include an operationalassessment of the terminal's ability to enhance command andcontrol functions between the E-3A aircraft and ground supportC2 centers. At the time of the evaluation, the ASIT was theonly ground terminal used in the test. A true groundenvironmental test of the system, including C 2 elements, wasdelayed until the mid 1980s. [Ref . 9:p 20-21]

In 1980, two reviews of JTIDS procurement wereconducted. The first of these reviews was the Welsh Study,

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conducted by the JCS . The second review was known as theCritical Evaluation Study under the direction of the AirForce. Both studies concluded that employment of the JTIDSsystem would significantly increase the combat effectivenessof both tactical fighter and surveillance aircraft. In 1983,Boeing Aerospace was awarded a contract to upgrade command,control and communication elements of the E-3A AWACS,including the Class 1 terminal in the upgrade. [Ref. 4:p 4 6]

A Class 2 terminal installed in a F-15 tacticalfighter was tested in 1985. The test included threecommunication terminals: two ground and one airborne. Thetest was conducted by the Air Force Electronics SystemsDivision. A second test was conducted in 1986. This testevaluated the JTIDS system within a combat scenario . Five F-15s with Class 2 terminals, 1 E-3A AWACS with a Class 1terminal, and Army Air Defense Artillery (ADA) units, alsowith Class 2 terminals, were involved in the test. Both testswere viewed as highly successful by all services involved.[Ref. 6:p 62-63]

Independent evaluations of the system were conductedby McDonnell-Douglas Astronautic Co. in 1979 and 1986. Bothstudies concluded that combat effectiveness was increased forboth fighter and surveillance aircraft. The Plessey Corp.conducted a reliability verification demonstration in August1988. Five hundred fifty sorties were flown with JTIDSequipped aircraft under a variety of climatic conditions . The

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mean time between failure of the terminals tested was 316hours. The report stressed that none of the failures effectedthe combat mission. [Ref. 9:p 51]

Computer simulations have also been used to determinecombat effectiveness. The JTIDS Operational Performance Model(JOPM) was developed to assess the operational performance inthe F-15 theater defensive counterair mission (DCA) . Theassessment was performed by the DOD JOPM Supervisory WorkingGroup and Teledyne Brown Engineering. The report, publishedin November 1988, concluded that one JTIDS-equipped F-15 isworth 1.35 non-JTIDS F-15s in the DCA role. The reportfurther stated that JTIDS dramatically enhances F-15 defensivecounterair combat effectiveness against a hostile forceheavily superior in numbers. [Ref. 12 :p 4-11]

A GAO report to Congress in February 1990 stated thatalthough the Class 2 terminal is currently below itslaboratory and field reliability requirements, it has achievedat least the threshold values for other performancerequirements established by the 1981 Secretary of DefenseDecision Memorandum. Nevertheless, in October 198 9 the UnderSecretary of Defense for Acquisition approved low rate initialproduction (LRIP) for the Class 2 and 2H terminals. Approvalof low rate initial production for the Army Class 2M terminalis scheduled for Defense Acquisition Board (DAB) review inOctober 1991. The Under Secretary had segmented Class 2 and2H LRIP into three consecutive annual production lots.

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However, the Under Secretary has identified specific criteria,such as reliability improvements that must be satisfied beforethe final two production contracts are awarded. [Ref . 9:p 55]

The GAO report also stated that the services and DODwill continue to share the $2 billion cost of developing theClass 2 terminal. The JPO estimates that development willcontinue through 1995. The services will purchase productionterminals with their own funds. As of February 1990, totalprogram costs through production are estimated at $3.9billion. [Ref. 9:p 56] A breakdown of JTIDS Class 2 costestimates from the 1990 GAO report are listed in Table 5.

TABLE 5 JTIDS Class 2 Cost Estimates as of February 1990Escalated Dollars in MillionsFunding Category CostDeve1opment $2,032.1Procurement $1,861.6Total $3,893.7

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CHAPTER II. SYSTEM OVERVIEW

A. SYSTEM DESCRIPTIONThe Joint Tactical Information Distribution System (JTIDS)

is an advanced radio system which provides a wide range ofinformation distribution, position location andidentification. The system can distribute information at ahigh rate in a manner that is both secure and jam resistant ina hostile EW environment . JTIDS links together dispersedusers and sensors yielding a position grid , position locationwith a common reference point, and provides a uniqueidentification capability. [Ref. l:p 11] Operationalrequirements are summarized in Table 6.TABLE 6 JTIDS Operational Requirements

JTIDS Joint Operational Requirements1 . INFORMATION DISTRIBUTIONBroadcast and Point-to-pointJam ProtectionNon-NodalSecureHigh Capacity

2. POSITION LOCATIONCommon Grid (Relative & Geodetic)High Accuracy3 . IDENTIFICATIONDirectIndirect

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B. SYSTEM TECHNOLOGYJTIDS utilizes a bit oriented message form of information

which enables the use of extremely efficient digital messagestructure as in TADIL J, digital voice, or character orientedmessages. The system operates within the 960 to 1215 MHzradio frequency band. This insures compatibility with civilDistance Measuring Equipment (DME) , Military Tactical AirNavigation equipment (TACAN) . JTIDS uses Time DivisionMultiple Access (TDMA) technology to meet integratedoperational requirements. [Ref. l:p 11] The structure ofTDMA design is depicted in Figure 3.

// DOUBIF PULSESYMBOLi

'ill- i ii

SINGLE PULSE SYMBOLDOUOLE PULSE SYMBOL 13 itc76 ,.wc

JTIOSPULSE

CHIP

6 6 >ec

SYMBOL CAN BE SINGLE OR DOUBLE PULSE

PULSES EREOUENCY HOPPEO 32 PM CHIPS -5 MHf RATE ENCODES5BITSOF DATA CCSK5BITS = 3?CHIPS 32 CHIPS ARE CPSM

Figure 3 JTIDS Signal Structure

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TDMA technology is used to produce a time slot multinetstructure. A 12.8 minute epoch is divided in 7.8125millisecond time slots, yielding 128 time slots/second/net.The 7.8125 millisecond time slot is divided into a variabletime slot (jitter), a synchronization preamble, theinformation transmitted, and a propagation time period. Thepropagation time allows a maximum transmission range of 300nautical miles or 500 nautical miles in the extended relaymode. The extended range is achieved by decreasing the sizeof the jitter in order to increase propagation time. Timeslot nets may then be stacked using frequency hopping patternof code division techniques. A total of 128 separate netswith 98,304 time slots/net can then be achieved within asingle geographic area of operations. [Ref. l:p 16] Figure4 depicts the time slot structure.

A time reference for all nets or individual nets is madeby designating one terminal as the Net Time Reference. Thisis determined based on the user's operational requirements.The selected Net Time Reference terminal will maintainalignment of the time slots within each net. Up to 200 fullyassigned nets can exist in one geographic area before mutualinterference seriously degrades the network. The same numberof nets can be employed in non-overlapping geographic areas[Ref. l:p 16]

The JTIDS signal, within a single time slot, consists ofa train of pulses organized into symbols. One pulse consists

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STANDARDDOUBLEPULSE

PACKED2SINGLE PULSE

PACKED 2DOUBLEPULSE

PACKED 4SINGLE PULSE

INFORMATION BITS PER SLOT(TERMINALCAPACIT Y = Kb/s|WITH EDC W/OEDC

225 465J S M D P 1288]

450

159.5]

930|1 19 0]

930(119 0]

1860(238.0)

J S H D D P |57.6J

450 H D D P 157.6)900 H D D D D P P15.2]

DCORRECTIONS = SYNC JH = HEADER PD = DATA EDC

= JITTER= PROPAGATION= ERROR DETECTION AN

Figure 4 JTIDS Time Slot Structuresof 5 bits of data in one 6.4 microsecond unit of time in a 13microsecond symbol or 2 pulses in each 26 microsecond symbol.The latter method still contains 5 bits of data within the twopulses. Each pulse containing the 5 bits are represented bya 32-chip Cyclic Code Shift Keying (CCSK) pattern. Theresulting pulse is then Continuous Phase Shift Modulated(CPSM) at a rate of 5MHz . The resultant signal symbols arethen interleaved on transmission. Employment of the frequencyhopping mode (Mode 1) dictates that each successive pulse israndomly transmitted using one of the 51 availablefrequencies. In the non-frequency hopping mode (Modes 2, 3and 4) all pulses are transmitted on 969 MHz. [Ref. 13 :p 6]

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C. MESSAGE STRUCTUREDifferent information capacities are obtained through the

use of differing message structures. The differinginformation capacities can then be matched to the type ofinformation desired for transmission. The standard is thedouble pulse structure which is the most rugged foroperational performance. Some structures enable the time slotto be packed with two or four messages through the use of thesingle pulse structure or deletion of the jitter or both.Error detection and correction is accomplished through use ofthe Reed-Solomon method. The error and correction portion ofthe transmission may be deleted if considered unnecessary,thereby providing additional bits for operational information.[Ref. l:p 17]

JTIDS currently uses two message formats. The InterimJTIDS Message Specification (IJMS) and TADIL J message weredeveloped by the JTIDS Message Standards Working Group (JMSWG)of the Joint Interoperability Program for Tactical Command andControl Systems (JINTACCS) . Both message formats providefixed format and free text messages. Additionally, TADIL Jprovides a variable message format structure. Reed-Solomondata code words are used to embed information for both messagespecifications. A shortened Reed-Solomon code word isincorporated into the header yielding a 35 bit informationheader. The header includes the type of message, the source

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address of the originator, and security information to decodethe transmission. [Ref. 7:p 3]

The IJMS message contains 225 bits within a standard timeslot. Message labelling provides 128 possible messageformats, only 36 of which have been defined. These messagesinclude position reports, track reports, strobes, specialreports and command and control messages. There are a limitednumber of net management messages available. The entire menuof messages available are based on the JCS Publication 10 setof messages. The data field portion of the messagecorresponds directly to the JCS Publication 10 data fields,but have been expanded to allow future use . There are onlytwo major exceptions here. The first is the positionreference which uses longitude and latitude rather than therectanglinear coordinate system. The second exception is thebasic reference number which is 5 octal digits rather than 4 .[Ref. 13 :p 8] Figure 5 contains a breakdown of the IJMSStructure

TADIL J messages consist of one or more 75 bit messagewords. Four error detection bits, 70 information bits and 1spare bit are contained in one word. This compositionprovides a modular message structure allowing single ormultiple messages to be transmitted in one time slot.Messages include position reports, track reports, specialreports, strobes, weapons control and command and controlmessages. Message labelling permits 256 message types

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TIME SLOT

S = SYNCHH HEADERD - DATA

1/ DEFINESCONTENT OF MESSAGE NCONTENT

I BITS/FIELDMSGCAT

SUBCAT DATAFIELDS PARITY

4 3 206 12

Figure 5 IJMS Message Structureincluding a full set of net management messages. The JCSPublication 10 is also the model for TADIL J messages. Thereis also a variable message format which allows the user tocompose messages of varied content and format. [Ref. 7:p 8]Figure 6 contains a breakdown of the TADIL J message format.Interoperability of the two message formats is achievedthrough a bilingual capability for all Class 2 terminals

D. INFORMATION DISTRIBUTIONJTIDS' unique architecture and signal structure provide a

large number of information distribution techniques which canbe designed to meet specific user requirements . Participationgroups are formed by pooling time slots . Nets are created byassigning these groups various net access and relay modes

.

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TIME SLOTs M D^ ' \

**'.-

s SYNCHHEADER*

'

H .^ \^- DATA \wr . WOROFORMAT** 1 INITIAL WORDE EXTENSION WORDr C CONTINUATION WORD N

wr WF WFPARITY DATAFlELOS I.EORC PARITY OATA FIELDS I.EORC PARITY OATA FIELDS 1

5 (1 2 s ( 2 5 (S 22 25 15 1 1 so 7j 75 1

3 MODULAR WOROS

Figure 6 TADIL J Message StructureInformation is thereby distributed to users in the portionrequired. Information transfer needs are met by creatingblocks of 2 n time slots . Various combinations of thesestructures are designed to meet specific needs.

The system is based on a broadcast receiver orientedstructure or a circuit oriented structure. The broadcastreceiver oriented structure transmits information without a-specific address. Users then listen to all time slots andselect only the desired portion of information required. Thecircuit oriented structure provides a link between two usersover specified time slots . These time slots then function asa virtual circuit . The number of time slots employed must

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match the desired bit rate of the virtual circuit. [Ref . l:p24]

E. RELAY FUNCTIONBasic coverage of the JTIDS network can be extended from

300 nautical miles to a maximum range of 500 nautical miles byretransmitting the message content of the time slots. This isaccomplished by retransmitting messages received in one timeslot into another specific time slot. This function, whenselected, is automatic and is transparent to the user. Tworelay techniques may be employed to extend the range of thenetwork. The two methods are paired slot relay andrepromulgation relay. [Ref. l:p 25]

1 . Paired Slot RelayIn this relay method one or more sets of time slots

are designated as blocks. These blocks are then paired withother blocks of the same size for retransmission. Additionalblocks can be linked together when more than one relay hop isdesired. Each terminal so assigned can then relay on aconditional or unconditional basis. In the unconditionalmode, the designated terminal relays continuously in thedesignated time slots. In the conditional mode, the terminalrelays messages received in the slots designated to be relayedonly if that terminal has the best coverage. If there isanother terminal with better net coverage, it will serve asthe relay terminal. [Ref. 13 :p 12]

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2 . Repromulgation RelayThe originator of the message determines how often the

particular message will be relayed and the pattern of timeslots that will be used in the repromulgation method. Allother designated receivers will be assigned to listen to thepool of slots designated for transmission. The number ofsuccessive relay hops is then determined by the receiver. Ifthe designated number of hops has not been reached, thereceiving terminal will retransmit the message in theappropriate time slot. If the last hop has been attained, thereceiving terminal stops transmission. Within three timeslots, the originator can transmit over the same sequence oftime slots. Messages transmitted over a given sequence oftime slots may be stacked one immediately following another.[Ref. 13:p 13]

F. ACCESS MODESA variety of access modes are provided for the JTIDS

system. These modes define which terminal can transmit in agiven time slot. Access modes are designed to matchpredetermined information distribution needs . There are threeaccess modes available to network planners

1 . Dedicated AccessIn this access mode, specific users are assigned

specific time slots for transmission of messages. The timeslot remains vacant when the designated user is not

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transmitting. The number of slots assigned to a given userwill depend upon that user's particular needs. Thesedesignated time slots may only be reused in a differentgeographical area

2 . Contention AccessA block of time slots is designated, in this method,

to be shared by a number of users . Each user randomly selectsa time slot from the block for transmission. All users withinthe group listen to the entire block of time slots when nottransmitting. The amount of information to be transmitted orthe rate at which the information is to be transmitted willdetermine the number of time slots utilized.

3 . Distributed Reservation AccessThe final access mode again determines a block of time

slots to be shared by a group of users. Sequentially, theusers determine how many time slots they will need in thefuture. Reservation messages are used to identify each user'sfuture requirements. These messages are transmitted in thededicated access mode. The previous reservation is used todetermine the number of time slots remaining for use withinthe block. In turn, the remaining users transmit theirreservation message to the reservation group. This is acyclic, ongoing process and provides the opportunity for allusers to adjust reservations based on changing needs. [Ref

.

l:p 27]

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VOICEDIGITIZERiOOOOO-OOOO'OO'OO ou-'00 >00 '000 00 00 00 0'

TIME SLOTBLOCKVOICECHANNEL

NUMBEROFTIMESLOT - TOVOICE DATA RATEiO>'00 iiiimO


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and itself. The propagation time and the transmitter'sreported position permits the terminal to determine its rangefrom the transmitter. Similar measurements are taken fromother transmitters or subsequent transmissions from the firsttransmitter. These measurements are used to triangulate theterminal's position. Once the terminal's position locationhas been accurately determined, it will periodically transmitposition reports for other platforms to use. [Ref . l:p 35]

I . IDENTIFICATIONPeriodic secure position and identification messages are

transmitted to provide direct identification among allplatforms equipped with JTIDS . Position location and commandand control functions are also supported with these messagesJTIDS position and identification messages that are receivedcan be verified against radar tracks and/or intelligenceinformation. The periodicity of reporting can be varied tocoincide with the needs of the platform. An aircraft will berequired to broadcast its identification and position muchmore often than a ground station. [Ref. l:p 37]

J. CLASSES OF TERMINALSThere are three classes of terminals that are each

designed to meet the requirements of a general grouping ofusers:

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Command and Control Users. The Class 1 Terminal isdesigned for use in large airborne and ground basedcommand and control elements. Small Platform Users. The Class 2 Terminal is designedfor use in small command and control elements and sometactical aircraft Missile and Manpack Users . The Class 3 Terminal is beingdesigned for use with very small units including manpacks,missiles and voice-only uses. [Ref. l:p 41]

1 . Class 1 TerminalThe Class 1 command and control terminal is designed

for use in U.S. and NATO E-3As, NATO air defense C2 systemsand in the JTIDS Adaptable Surface Interface Terminal (ASIT)The terminal can operate in all four JTIDS modes . Itprocesses only the standard JTIDS message format . Both thenormal and extended range modes may be employed. The Class 1terminal can operate as a Net Time Reference station, but doesnot have a position location function. It may function as aposition reference station with an external position datasource . The terminal can transmit in only one net and canreceive on a maximum of three different nets . The messageformat used is the Interim JTIDS Message Standard (IJMS) . Theunit weighs 400 pounds and occupies 6.5 cubic feet of space.It is rack mounted to enable employment with the various usersit supports. [Ref. 14]

2 . Class 2 Full Scale Development TerminalThe Class 2 (FSD) terminal is designed for small

platform users. The terminal contains an Interface Unit (IU)

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JTIDS information is displayed on the Multi-PurposeColor Display (MPCD) , a five inch, four color graphic screenlocated in the combat aircraft's cockpit. The unit presentsJTIDS data, armament data, and Built-in-Test (BIT) informationbased on the pilot's selection. A graphic air situation ispresented with a choice of six display options (net, subnet,identification, hostile SAM, corridor and route) . Anycombination of options may be selected. JTIDS displays are incolor to identify the data presented. Green representsfriendly objects, white represents text, red representshostile objects, and yellow indicates points and paths. Atypical display consists of friendly and hostile tracks witha range scale determined by the pilot. [Ref. l:p 104-110]Figure 8 depicts the MPCD.

3 . Class 2M TerminalThe Class 2M terminal is being designed to meet

specific requirements of the Army's air defense C2 elements.The terminal will replace the TADIL B link between the Controland Reporting Center (CRC) and the Brigade Fire DirectionCenter (BDEFDC) . This terminal will also replace all ATDL-1data links between Army air defense C 2 units.

The Class 2M terminal is bilingual and processes boththe IJMS and TADIL J message protocols . It has an automaticrelay capability, relative navigation feature and an over-the-air rekeying capability. The terminal generates 200 watts of

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OOQiDOFigure 8 JTIDS Multi-Purpose Color Display

output power, has a volume of 1.3 cubic feet and weighs 93pounds

This version of the JTIDS Class 2 terminal has anumber of unique characteristics. The Class 2M terminalutilizes the X.25 protocol to control all input and outputinterfaces. A broadcast connect status indicator is alsounique to the 2M terminal . The TACAN function was eliminatedfrom the terminal as the Army had no requirement for thisfunction. The most significant difference associated with the

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Class 2M terminal is its lack of the digital voice capability.The terminal has no ability to participate on the digitalvoice channel of the JTIDS net to which it is assigned. [Ref15]

4 . Class 2H TerminalThe Class 2H terminal is under development to meet the

needs of the Navy E-2C and C 2 elements. It will also replacereplace Class 1 terminals previously fielded to Air Force E-3AAWACS aircraft . The terminal was approved to meetrequirements for extended transmission range.

The 2H terminal has a transmission output power of1000 watts. This increased power capability greatly extendsthe terminal's range of transmission. The terminal processesboth message protocols. It has an automatic relay capabilityand relative navigation feature. The navigation featureprovides a new capability to the E-3A AWACS. The terminal hasa TACAN capability and over-the-air rekey function. It'svolume is 5.2 cubic feet and weighs 34 pounds. [Ref. 15]

5 . Class LV TerminalThe Low Volume terminal is currently in the concept

development stage. It is being designed to meet requirementsunder the third phase of JTIDS development. This terminal isto be employed with manpacks, missiles and very small C 2elements

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The LV terminal has the same basic capabilities as theClass 2 series of terminals. These capabilities include 200watts of output power, bilingual message protocal processing,automatic relaying, digital voice, TACAN and over-the-airrekeying. The major difference in this terminal is its size.The LV terminal's volume is 0.6 cubic feet and weighs 64pounds. It also has a lower data processing capability.[Ref. 15] Table 7 contains a summary of terminalcapabilities

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TABLE 7 JTIDS Terminal CapabilitiesTERMINAL CLASS DESIGNATOR

CHARACTERISTIC 1 2 2H 2M LVVOLUME(Cu. ft.)

6.5 1.6 5.2 1.3 0.6

WEIGHT(lbs)

400 130 340 93 64

OUTPUT POWER(watts) 200 &1000 200 1000 200 200BIT RATE (kbps) 30/60/11

5115/238 115/238 115/238 115/238

MESSAGEPROTOCOL IJMSONLY IJMS &TADIL J IJMS &TADIL J IJMS &TADIL J IJMS &TADIL JI/O INTERFACE 1553A 1553B 1553B X.25 1553 &OTHERSBROADCASTCONNECT STATUS No No No Yes NoAUTO RELAYCAPABILITY Yes Yes Yes Yes YesINTEGRATEDVOICE Yes Yes Yes No YesRELATIVENAVIGATION No Yes Yes Yes YesTACANCAPABILITY Yes Yes Yes No YesKEY VARIABLEQUANTITY 4 8 8 8/64 TBDKG INSTALLATION External External External Internal InternalOVER-THE-AIRINITIALIZATION TSA TSA TSA FULL TSA

OTAR CAPABILITY Yes Yes Yes Yes YesPACKAGING 3 BOX 2 BOX 3 BOX 1 BOX 1 BOX

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CHAPTER III. NETWORK MANAGEMENT

A. DEFINITIONNetwork management of JTIDS is the process of directing

the use of specific terminal capabilities and netconfigurations to meet mission requirements . Appropriateterminal parameters are selected for each member terminalTransmission requirements for each platform are met throughassignment of appropriate time slots. Compatibleinitialization parameters are determined to ensure terminalcommunications. In addition, network support functions mustbe assigned (i.e. Terminals designated to serve as Net TimeReferences) . This broad scope of activities is referred to asNetwork Management. [Ref. l:p 33]

B. NETWORK MANAGEMENT OVERVIEWThe required exchange of information among network

participants is met through the development of networkdesigns, by the JTIDS system manager. These network designscan range from simple Class 1 terminal networks to morecomplex networks containing both Class 1 and 2 terminals . Anetwork involving only Class 1 terminals is described,followed by a description of network management of a morecomplex system incorporating both terminal types.

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1 . Class 1 Terminal NetworkCurrent implementation of Class 1 JTIDS networks

involve E-3A AWACS and Control and Reporting Centers (CRCs) .The operation of a JTIDS network can be conceptualized as adata bus in the sky. This analogy represents the technologyof Time Division Multiple Access (TDMA) . Under TDMA, eachuser is assigned specific time slots in which to transmitComputers, internal to each terminal, receive their time slotassignments through the loading of software parameters . Thesoftware directs time slots that will be used for transmissionby the terminal. Every time slot contains a series of pulses,each of which can encode 225 bits of formatted data or 4 65bits of free text information. 128 time slots are availableevery second to users in a JTIDS net. All terminals listen tothe net when they are not transmitting. This reception occursautomatically and is the default condition of the Class 1terminal . The JTIDS Class 1 network is a receiver orientedcommunications system. Each terminal receives all transmittedinformation on the network. The individual user then filterthe information as necessary to meet their requirements[Ref. l:p 16]

A Class 1 terminal only network contains a single netIt is not capable of participating in networks where multiplenets are operating simultaneously. Multiple nets aredeveloped through the use of frequency division multiplexing.All members of a Class 1 network operate on a single

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frequency, therefore multiple nets are not possible. [Ref.5:p 2] Figure 9 represents JTIDS single net operations.

usAr cnc

ASH

UK NIMMOU

MPC -jj^ USMC/USAr1AOC-85/MCE

Figure 9 JTIDS Single Net Operations

The Class 1 network makes use of a cryptovariablepair. This is the normal mode of operation, although anyterminal may operate without encrypting transmitted messages.

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All messages are encrypted for transmission and decrypted forreception through use of the current cryptovariable . Thetransmission frequency appears to be a random series of pulsesto any receiver not possessing the cryptovariable. Class 1terminals are loaded with only two cryptovariables . The firstcryptovariable is used for the first day of operation. At theend of the 24 hour period, the first variable is destroyed bythe terminal and the second variable is selected for the nextday's use. The terminal is loaded with a new pair ofcryptovariables upon completion of the second day. There isno confusion on the Class 1 net as to which variable is in useduring any given time period. [Ref . 5:p 3]

Messages are segregated by the transmitting Class 1terminal . Only three classes of messages exist for thispurpose. The message classes are P messages which carry thetransmitter's identity, status and position, all other datamessages, and voice messages. Each class of message isdesignated for transmission in specific time slots . Anyreceiver in the net can select a specific class of messagesand ignore the rest. The terminal must listen to all incomingmessages and then screen them for the desired information.[Ref. 13:p 12]

Time slots are assigned to a specific Class 1 terminalin groups called time slot blocks . The number of time slotscontained in a time slot block must be an integral power oftwo. A terminal can be alloted a time slot block which may

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contain one time slot, two slots, four slots, eight slots,etc. For example, if a terminal requires 24 time slots per 12second JTIDS frame for data transmissions it would be assignedone time slot block of 16 time slots and one block of 8 timeslots. A terminal may be assigned a total number of timeslots not equal to a power of two by assigning several timeblocks whose sum of time slots is greater than or equal to thedesired number of slots. Terminals requiring 22 time slotsper frame, which is not a power of two, would be assigned thesame blocks of time slots as above. This would result in twoextra slots per frame. Class 1 terminals may be assigned atotal of four time slot blocks, one is for P messages and theremaining three for data transmission. Additionally, theterminal can be assigned one block for digital voice and asmany as six pairs of smaller blocks for transmission relay.Each time slot block requires only four initializationparameters . The first three parameters identify a specifictime slot block. The final parameter identifies the class ofmessage that will be transmitted in that block. [Ref . l:p 43]

Class 1 terminals have relatively few features whichneed to be enabled or disabled during initialization.Selection of normal or extended range mode is an example ofone of these features . The net manager may select theextended range mode which would reduce that terminal's anti-jam capability due to a reduction in the anti-jam provision ofthe transmitted signal. This assignment of terminal

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capabilities requires that choices be made by the networkmanager of initialization parameters that will result in thedesired JTIDS network. The default condition of the Class 1terminal is receive only. This condition reduces theworkload for the metwork manager because each time slot notspecifically assigned will automatically default to thereceive conditions. There are only 15-20 parameters that mustbe selected to implement this network. [Ref . 5:p 13]

In summary, the network manager' s tasks to implementa Class 1 network are as follows:

Allocation of time slots to terminals. Selection of implemented features. Assignment of initialization parameters

The network manager must ensure that all parametersare distributed to terminal operators, that they are properlyloaded and validated, and that the network performs properlyduring operation. Any changes are made on the ground by thenetwork manager and are loaded into individual terminals asthe users return to base or are couriered to other groundunits. These responsibilities will remain consistent formultiple nets involving Class 1 and 2 terminals

2 . Class 1 and 2 Terminal NetworksA Class 1 terminal only network provides increased

capabilities to air battle participants over non-JTIDSequipped participants . The network is receiver oriented and

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is therefore highly flexible. This network configurationallows significantly reduced preplanning regarding design ofa JTIDS network. Data distribution requirements at thetheater level have dramatically increased the demand for JTIDScommunication capabilities . Numerous capabilities have beenincorporated into the Class 2 series of terminals to meetthese increased requirements . The complexity of networkdesign has increased with each new capability. [Ref . 5:p 5]

Employment of Class 2 terminals in a JTIDS networkmeets the required increase in network capacity. A JTIDSterminal is assigned specific time slots in which to transmit.Narrow band jamming is defeated by pseudo-randomly selectinga new frequency for each pulse transmitted. The process ofselecting frequencies is part of the encryption process,preventing the enemy from ascertaining the pattern offrequency hopping. Selection of different frequency hoppingpatterns allows the simultaneous operation of multiple JTIDSnets. [Ref. l:p 16]

Multiple nets are produced by assigning unique timeslots to each terminal with a unique frequency hoppingpattern. A terminal transmits data pulses during its assignedtime slots under its frequency hopping pattern. A secondterminal transmits its data pulses over a second frequencyhopping pattern. Any terminals desiring receipt of the firstterminal's transmission are set to the first terminal'sfrequency hopping pattern. The same requirement exists for

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those terminals wanting to receive the second terminal'stransmission. Each frequency hopping pattern is referred toas a net. Class 2 terminals can select up to 128 differentnets (0-127) for transmission or reception. Net 127 isusually designated for network management. [Ref. 13 :p 32]

Class 2 terminals are capable of transmission orreception on any net in any time slot. However, the terminalcan only be on one net during one time slot at any givenperiod in time. It is therefore imperative that networkmanagers ensure that no terminal needs to be on two netsduring the same time slot. In this event, network designerswill determine which data on the network is of interest tosmall groups of users. If more than one such informationexchange requirement exists, different nets will beestablished during those same time slots. For example,seperate nets will be established for surveillance, Army ADAtrack status, aircraft engagement status, etc. [Ref. 4:p 21]

Design of multi-net operations makes it vital forClass 2 terminals to have the same frequency hopping pattern.The terminals must therefore be initialized with the same netnumber for the desired time slot and the same cryptovariableto be used in that time slot. The cryptovariable keyrandomizes the frequency hopping pattern so that whenterminals select the same net but are using differentcryptovariables the terminals will be following a differentpattern for frequency hopping. The network designer can then

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assign a specific terminal to operate on a particular netduring time slots in which information is available that thehost platform can utilize. The terminal can then operate onother nets during the remaining time slots. [Ref. l:p 43]Figure 10 represents multiple net operations.

NETSOTO 126

Figure 10 JTIDS Multinet Operations

It is important to note that Class 1 terminalstransmit all of their data during blocks of time slots. TheClass 1 terminal will transmit messages, regardless of theirtype, during the next available time slot block. Thesemessage categories can include surveillance, control andmission management messages . Any user requiring only a

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specific category of messages would have to listen to allClass 1 transmissions to ensure reception of the desiredinformation. This limitation was eliminated in the Class 2series terminal design by having each message categoryassigned to a specific time slot. [Ref. 5:p 6]

Eighteen different subject categories were designedinto the Class 2 terminal to overcome Class 1 limitations.The subject categories are referred to as NetworkParticipation Groups. There are also 480 categories ofpotential message distributions, known as NeedlineParticipation Groups. The Class 2 terminal initializationprocess directs time slots to be selected specifically foreach category of messages to be transmitted. For example,surveillance information is directed to be transmitted inspecific time slots on net and control messages are to betransmitted on net 5 during a different set of time slots.Any terminal requiring receipt of this surveillanceinformation must be directed to listen to net during theappropriate set of time slots. All terminals that arerequired to transmit surveillance information are assignedtime slots on net for this purpose. All JTIDS members thatrequire surveillance information will be assigned to listen toall time slots on net which contains surveillanceinformation. These time slots will coincide with the set oftime slots assigned for surveillance transmission.

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Transmitting terminals will also be directed to listen to allother surveillance transmissions on net 0. [Ref. 5:p 7]

This design process continues for the development ofsubsequent nets. It is the network designer's responsibilityto ensure that each JTIDS participant is able to transmit andreceive all assigned information in time slots that aremutually exclusive. This higher level network is no longerreceiver oriented. Each terminal must know when it is totransmit and on which net . The terminal must also be toldwhen and where it is to listen. [Ref. 13 :p 29]

The Class 1 terminal is of a simpler design and onlyuses one cryptovariable pair for transmission. Multiplecryptovariables are available on the Class 2 terminal duringany given time slot . Therefore the Class 2 terminal must knowwhich cryptovariable is to be used in which time slot . Inaddition, the Class 2 terminal has a great many more featuresthan the Class 1 terminal. The Class 1 terminal's defaultcondition has widespread utilization in a Class 1 terminalonly network. The Class 2 terminal's default condition hasvery limited utilization in the mixed terminal network. [Ref.13:p 55]

The increased number of features on the Class 2terminal facilitates more initialization parameters. Theparameters enable the terminal to determine which function isto be performed in any given time slot. Initializationparameters will assign appropriate time slots for

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transmission, preset selected Class 2 features and establishself-test functions. [Ref. 13:p 9-2]

The parameters are divided into three categories basedon the support group that is responsible for theirimplementation. Working parameters involve feature selectionand selection of options available to the network designer.They are the only parameters under the control of the networkdesigner/manager. Test parameters tell the terminal whichtest data is to be collect during operation and where it is tobe stored. The third category consists of fixed parameters.Fixed parameters are associated with a particular hostplatform and are predetermined by the development community.[Ref. 5:p 8] Figure 11 displays the process ofinitialization parameter generation.

NETWORKDESIGNER

TESTCOMMUNITY

DEVELOPMENTCOMMUNITY

WORKINGPARAMETERSnTESTPARAMETERS

FIXEDPARAMETERS

COMPLETEINITIALIZATIONLOADS

SACPBDEFOC

ICP

SACP

CPNFDC ARMY'CLASS 2TERMINALS

SACP

ICP -> AFP

SDS 3JCLASS 1TERMINALSSCi

Figure 11 Terminal Initialization Load Generation

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Numerous devices are used to load initializationparameters into each of the terminals . The Stand AloneControl Panel (SACP) and the Interface Control Panel (ICP) areused to load the Army's Class 2M terminal. The SoftwareDevelopment Station (SDS) is used to set initializationparameters which are loaded into a number of Data TransferModules (DTMs) . The DTMs have battery powered memories whichstore the designated parameters. Tactical aircraft pilotscarry the DTM to their aircraft and load the parameters intothe aircraft's control panel. The Class 1 terminal is loadedthrough operator entries on the Radio Set Control (RSC) panel.[Ref. 5:p 8-9]

Multiple net operations are now possible with theintroduction of the Class 2 terminal. A great deal offlexibility in network design has also been achieved, but thishas been accomplished at the cost of greatly increasedcomplexity of design. The network designer must understandthe information requirements of the users he is supporting.The designer must also know who must communicate with whom andwhat type of information is to be exchanged. Correct networkdesign choices will ensure all appropriate communicationchannels are established.

C. NETWORK DESIGN FOR JTIDS JTAOA JTIDS network is designed to support the tactical

communication requirements of the joint air defense system,

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known as the Joint Tactical Air Operations (JTAO) system. AirForce command and control elements receive JTIDS servicethrough Class 1 terminals located in Adaptable SurfaceInterface Terminals (ASITs) . The ASIT can be deployeddirectly to a Command and Reporting Center (CRC) or to aMessage Processing Center (MPC) which services the CRC via aTADIL B data link. The E-3A AWACS also contains a Class 1terminal, but the ASIT is not required. The Army C 2 portionof the JTAO is the HAWK Brigade Fire Direction Center(BDEFDC) . These C2 elements employ the Class 2M terminal todirect accomplishment of the defensive counterair (DCA)mission. The Air Force CRC is the primary player in jointtactical air operations. The CRC generates and receivessurveillance data, assigns engagement missions to organicaircraft, and coordinates with Army HAWK missile elements.The E-3A aircraft provides surveillance information and mayact as the CRC when the situation warrants. The BDEFDCassigns engagement missions to its Assault Fire Platoons(AFPs) via the Battalion Fire Direction Center (BNFDC) (Thiswill be discussed in detail in Chapter IV) . [Ref . 14]

The JTIDS Main Net, designated as net 0, is the medium forexchange of surveillance information. Since Air Force C 2elements are equipped with Class 1 terminals, IJMS is themessage format used on the Main Net . Tactical aircraftmonitor the Main Net to establish an air situation picture.All JTIDS members transmit P messages into the Main Net

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Control messages, status reports and assignmentacknowledgements are also exchanged on the Main Net . A subnetis established for tactical aircraft to exchange organic datatrack data and to provide digital voice. [Ref . 13 :p 11-2]

Information exchange can occur between tactical aircraftand Army air defense elements . The TADIL J message format cannow be used because a subnet can be established without Class1 terminal participants. Use of TADIL J permits the expansionof multinet operations. [Ref. 13 :p 11-7]

D. ARMY NET MANAGEMENT1 . Means of Employment

Army development of JTIDS surfaced a unique deploymentdifficulty that was not encountered by other services. JTIDScommunication means require line of sight transmission. Thisfactor was not a significant problem to airborne platformsHowever, ground army air defense units often encounter terrainthat requires precise engineering to ensure a proper signal tonoise ratio (i.e. Europe and Korea) . The Army has developedtwo automated tools to meet engineering requirements . Thesetools will enable network managers to surpass anti-jammargins, site relays for maximum effectiveness and managecryptovariable keys. [Ref. 15]

The Net Control Station JTIDS (NCS-J) was designed toprovide automated net management and technical control . TheNCS-J generates initialization data and cryptovariables for

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automatic over the air initialization and rekeying. It canimplement alternate routing schemes and can support physicaldistribution of either initialization or cryptovariable data.The NCS-J will provide an interface to its parent SystemControl (Syscon) organic to the division signal battalion.[Ref. 16:p 6]

The second net management tool developed by the Armyis the Dedicated JTIDS Relay Unit (DJRU) . The DJRU wasspecifically developed to enhance network connectivity indifficult terrain. It relays JTIDS line of sighttransmissions between Army Clas

jtids applications

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