AT-A146 251 DCS (DEFENSE COMMUNICA IONS Sy STEM N ETWORK 11fSYNCHRONIZATION D ESIGON CRTERIMA U DEFENSECOMMUNICATIONS ENGINEERING CENTER RESTSN VA

UNCLASSIFIED T L MCCRICKARD 01 MAY 64 DCEC-EP-3-83 FIG 17/2 NL

L3.11 36

MICROCOPY RESOLUTION TEST L IARTNATIONAL BUREAU OF STANDARDS 1963 A

AD-A 146 251

1P 3-83

DEFENSE COMMUNICATIONS ENGINEERING CENTER

ENGINEERING PUBLICATION NO. 3-83

DCS NETWORK SYNCHRONIZATION

DESIGN CRITERIA

MAY 1984

DTICAELE'CTE

1-SEP 27 S941

43

Approved for public release; distribuon unl ie4 09 4

UnclassifiedSECURITY CLASSIFICATION OF THIS PAGE

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DCEC EP 3-83 vOiTO lcRA1ZTO6. NAME OF PERFORMING ORGANIZATION b. OFFICE SYMBOL 7*. NAME OF MONITORW ORGANIZATIONDefense Communicati ons ,I~p~ iEngineering Center

SO. ADDRESS (CIty. State nd ZIP Code 7b. ADDRESS (City, Ste and ZIP Codei

1860 Wiehle AvenueReston, VA 22090 g4ill-

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DCS Network Synchronization Design Criteria12. PERSONAL AUTHORIS)

Thomas L. McCrickard. III13. TYPE OF REPORT 13b. TIME COVERED 14.'DATE OF REPORT (Yr. .o., Day) 15. PAGE COUNT

Enoineerina Pub, FROM O__ TO 1, 84/5/1 8316. SUPPLEMENTARY NOTATION

17. COSATI CODES 18. SUBJECT TERMS (Continue on reuee if neceuary and identify by block nulberI

FIELO GROUP SUB. GR. Network Synchronization Clock Distribution SubsystemBuffer

1S. ABSTRACT (Con tinue on uttitr$e If-neI uaPY O.d identify by. block number)

This publication describes the proposed network synchronization capability for the near-term Defense Communications System (DCS), and in particular the methodology for developingthis capability. The basic network synchronization capability using existing technology,followed by major and minor transmission node implementations, are described. Finally,a detailed implementation plan for the OCS is given, with the admonition that the dynamicnature of timing and synchronization will cause update and revision of the plan. <

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ENGINEERING PUBLICATION NO. 3-83

DCS NETWORK SYNCHRONIZATIONDESIGN CRITERIA

MAY 1984Prepared by:T. McCrickard

Technical Content pprov d: Approved for release-

Are. ao, oon Warren P. Hawrylko

USAF, Deputy Director forN-) Acting Principal DeputyTransmission Engineering Director

FOREWORD

The Defense Communications Engineering Center Engineering Publications(EP's) are published to provide engineering guidance to DoDDepartments/Agencies and their contractors engaged in engineering, RDT&E,procurement, installation, testing, acceptance, and O&M of specific DCSProjects and Programs. Before using EP's as, or as part of, procurementspecifications, coordination should be accomplished with DCEC or the cognizantDCA Program Office to insure currency and the propriety of the application.

Comments or technical inquiries concerning this document are welcome, andshould be directed to:

DirectorDefense Communications Engineering Center1860 Wiehle AvenueReston, Virginia 22090

Distribution/

Availability Codes

Avail and/orDist Special

ii

EXECUTIVE SUMMARY

This engineering publication describes the criteria and rationale used indeveloping the network synchronization capability for the near-term DefenseCommiunications System (DCS). Not only are there near-term requirements forthis network synchronization capability, but there also exist long-termbenefits to be derived from an improved timing capability. The purpose ofthis report is to provide the methodology for applying this networksynchronization capability in the OCS.

For the near-term network synchronization capability within the DCS, noresearch and development is necessary since state-of-the-art technology isavailable. Chapter III describes in generic terms the basic configuration ofthe equipment used to provide network synchronization. This basicconfiguration is composed of a station clock, clock distribution subsystem,and the digital data buffer. The performance characteristics of this systemas well as the performance characteristics of the individual equipments arestated in Chapter III.

Chapter IV defines the criteria by which the implementation of networkstation timing is determined for each of the two types of transmission node,called major and minor. The major node typically has a heavy concentration oftraffic, several incoming and outgoing links, perhaps switching equipment, andperhaps interfaces with another major system such as the DSCS or TRI-TAC. Aseparate, self-contained timing subsystem is proposed for the major node. Theminor node has none of the attributes of the major node and typically is asimple repeater or a terminating site off the major backbone. For the minornode, loop timing will be used to provide the required clock.

In Chapter V the application of the previously developed network design tothe OCS is presented. Based on this network design, a detailed networkimplementation description is provided, defined in terms of OCS area as wellas digital transmission upgrades (e.g., DEB, DTN, DSN, DSCS).

Since the timing and synchronization project is dynamic in nature, it mustbe recognized that as future requirements are identified, the planning andimplementation strategies will need to be adjusted. Therefore, it isanticipated that future updates/revisions of this engineering publication willbe necessary.

TABLE OF CONTENTS

Page

EXECUTIVE SUMMARY iiiI. INTRODUCTION 1II. BACKGROUND 2III. TIMING AND SYNCHRONIZATION CONFIGURATION 3

1. Station Clock 3

a. LORAN C Receiver 5

b. Frequency Multiplexer 5

c. Oscillators 6

d. Distribution Amplifier 6

2. Clock Distribution Subsystem (CDS) 6

a. Frequency Synthesizer 8

b. Distribution Amplifier II

3. Buffers II

IV. STATION TIMING 16

1. Major Node Timing 18

2. Minor Node Timing 18

V. APPLICATION OF NETWORK DESIGN TO THE DCS 24

1. Data Transmission Network Timing and Synchronization 24

2. Defense Switched Network Timing and Synchronization 29

a. European Telephone System Synchronization 30

b. ETS Switch Synchronization Characteristics 32

c. Timing Interface Between International Systems 33

3. Frequency Standard Extension (DSCS/Terrestrial DCS) 33

REFERENCES 44TERMS AND DEFINITIONS 45ACRONYMS 46APPENDIX A Electrical Characteristics A-iAPPENDIX B Timing and Synchronization Configuration for the DCS B-iAPPENDIX C Timing and Synchronization Configuration for the Data

Transmission Network (DTN) C-iAPPENDIX 0 Timing and Synchronization Configuration for the ETS D-iAPPENDIX E OSCS Interconnect Facility Data E-1

iv

LIST OF FIGURES

Figure Title Page

1 DCS Station Clock and Clock Distribution Subsystem 4

2 Functional Diagram of the Station Clock 7

3 Functional Schematic of Clock Distribution Subsystem 9

4 Receive Timing for OCS Major Node 14

5 Transmit Timing for Major Node 19

6 External T&S Configuration (Transmit Timing) 20

7 Transmit Timing for Minor Node 22

8 Receive Timing for Minor Node 23

9 Timing and Synchronization Configuration for 25Troposcatter Radio Equipment

10 DCS Digital Transmission Equipment 26

11 DCS Interface with Digital Switch 31

12 Generic ETS Switching and DCS Transmission Node 34

13 Frequency Standard Extension from Earth 36Terminal to Technical Control Facility

14 Case I Interconnect Facility 37

15 Case II Interconnect Facility 38

16 DRAMA Digital Radio Solution Alternatives 39

17 Case III Interconnect Facility 41

18 Case IV Interconnect Facility 42

v . . , . ... . .

LIST OF FIGURES (CONT'D)

Figure Title Page

B-1 Proposed Tining and Synchronization Configuration B-2for DCS in Europe

B-2 Proposed Timing and Synchronization Configuration B-3for DCS in the Pacific

B-3 (sheet 1) Proposed Timing and Synchronization Configuration B-4for DCS in the Western Hemisphere (Outside CONUS)

B-3 (sheet 2) Proposed Timing and Synchronization Configuration B-5for OCS in The Western Hemisphere (CONUS)

C-i Timing and Synchronization Configuration Proposed C-2for the Data Transmission Network (DTN) InitialImplementation State IA

D-1 PCM-30 Lease Connections D-2

D-2 Timing and Synchronization Configuration Proposed D-3for the European Telephone System (ETS)

vi

LIST OF TABLES

Table Title Page

I Clock Frequency Families 10

II DRAMA Equipment Buffer Lengths 12

III DRAMA Equipment Synchronous Channel Capabilities 17

B-I Timing and Synchronization European Area B-6

B-II Timing and Synchronization Pacific Area B-lO

B-Ill Timing and Synchronization Western Hemisphere Area B-12

D-I ETS Timing and Synchronization Near-Term D-4(Pre CY85) Requirements

E-1 DCS-DSCS Interconnect Facility Data E-2

vii

I. INTRODUCTION

This technical report describes the criteria and rationale used inplanning the network timing and synchronization (T&S) capability for theplanned digital portion of the Defense Communications System (DCS). Thistiming and synchronization capability will be required for certain equipments,subsystems, and system interfaces.

The interface of synchronous data channels between the terrestrial DCS andthe Defense Satellite Communications System (DSCS) will requiresynchronization of these two subsystems. Widespread application of the LowSpeed Time Division Multiplexer (LSTDM) and its synchronous data channelcapability will require this timing and synchronization capability. Theintroduction of digital troposcatter will require synchronization ofassociated equipment. The network of digital switches and interconnectingdigital trunks being implemented as the European Telephone System (ETS) mustalso be synchronized.

In addition to these near term requirements described above, there existlong term requirements for, and benefits to be derived from, a timing andsynchronization subsystem. Benefits to be derived are improved performance,efficiency, and availability of digital transmission links, and the potentialfor dissemination of precise time/frequency to other users. An improvedtiming capability will also aid in establishing or reestablishingcommunications, reduce the time to acquire synchronization of a spreadspectrum signal that is being jammed, and facilitate the synchronization ofcrypto equipment.

The purpose of this report is to provide the methodology for applying thistiming and synchronization equipment in the DCS, both generically and tospecific areas of the DCS.

II. BACKGROUND

Prior to implementation of the proposed timing and synchronization (T&S)equipment, the OCS digital transmission subsystems will be timed by clocksintrinsic to the transmission equipment (e.g. clocks within the DRAMA radio)and by use of pulse stuffing and buffering, also intrinsic to the transmissionequipment. However, with the introduction of certain subsystems, such as theLow Speed Time Division Multiplexer (LSTDM) and digital troposcatter, a timingsubsystem was also determined to be required to: (1) allow synchronoustransmission within the low speed digital data network, (2) provide acceptableperformance of digital troposcatter by using synchronous interfaces for alllevels of multiplex, and (3) provide extension of satellite derivedsynchronous circuits into the terrestrial DCS.

DCEC TR 23-77, [1] described the technical performance aspects of thetiming subsystem proposed for implementation to support the aforementionednear-term synchronous subnetworks in the Defense Communications System. Thisrequirement was originally submitted for Military Department consideration inthe DCA Five Year Program (FYP 76) and has since been updated annually in eachyear's FYP.

The U.S. Army has been tasked by DCA to acquire the tiP j andsynchronization subsystem. Because of the widespread avai ility ofcommercial timing components, the required equipment is be .g "ocuredoff-the-shelf.

2

III. TIMING AND SYNCHRONIZATION CONFIGURATION

The proposed configuration of the timing and synchronization (T&S)subsystem consists of the station clock, clock distribution subsystem, anddigital data buffer. A functional diagram of the station clock and the clockdistribution subsystem is shown in Figure 1, while their electricalcharacteristics are defined in Appendix A. For terrestrial nodes collocatedwith DSCS sites, existing cesium beam standards used in the DSCS may be usedas the primary reference for the DCS station clock. The two precisionoscillators provided as backup will have an initial accuracy equal to thereference and a long term stability of + 2 x 10-10 (according to AFCCEPS-82-012, 27 Aug 82). For non-DSCS sTtes, Loran C will be used as theprimary reference source for the station clock. Both the DSCS atomic clocksand the LORAN C navigational system have transmit frequency sources that aresynchronized to UTC.

LORAN C was selected as the clock source for the near-term DCS T&Ssubsystem primarily because of its low cost, off-the-shelf availability,commonality with existing DCS timing standards, and proven performance. LORANC is a pulsed, low-frequency (LF), radio navigational system operated by theUnited States Coast Guard. Use of LF provides propagation stability and lowattenuation of the groundwave with distance. Thus, highly stable, long rangetransmission is possible.

All LORAN C transmitting stations are equipped with cesium beam frequencystandards. Synchronization among these frequency standards is maintained bymonitoring and updating each standard in comparison to UTC as determined bythe U.S. Naval Observatory. LORAN C is currently available to nearly all DCSsites.

The LORAN C system as it operates today has demonstrated a 99.7 percentavailability, excluding scheduled off-the-air maintenance which reduces thatfigure to about 99 percent. Frequency accuracy of 1 part in 1012 is easilyattainable and accuracy of a few parts in 1014 is in fact typical. Suchperformance cannot be achieved with independent free-running atomic clocks.

1. STATION CLOCK

It should be noted that the JCS Master Navigation Plan (SM-266-83)proposes a phase out of the LORAN system in favor of the NAVSTAR GlobalPositioning System during the period 1987-1992. In the event that thisplanning is executed, available alternatives will be substituted to providerequisite UTC reference.

The station clock, as functionally depicted in Figure 2, will provide anaccurate and stable source of frequency and time standards at rates of 1 MHz,5 MHz, and 1 pps. The station clock has the option of being driven by theLORAN C receiver or by an external reference source (such as cesium beamstandard), dependent upon the best available reference. In priority order,first choice will be the primary reference; second choice, the alternatereference; and third choice, the two oscillators. The selection of the LORANC or the external reference source ds the primary or alternate reference is anoperator selectable function.

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When driven by the LORAN C receiver, a 3-foot loop antenna and a 9-footwhip antenna are provided for reception of the LORAN C 100 kHz carrier signal.

a. LORAN C Receiver. The LORAN C receiver provides automatic acquisitionand tracking of operao selec -,I LORAN C signals for use as a precisereference against which other frequency standards may be compared orcontrolled. After the Group Repetition Interval (GRI) and desired LORAN Cstation have been selected by the operator, no other intervention will beneeded. The receiver will automatically acquire the selected station of theLORAN C chain and then automatically go into the tracking mode. Withoutintervention, the receiver will continue to track until the incoming signalfades beyond the sensitivity of the receiver or the operator takes action tohalt the tracking process. In the event that this signal is lost, thereceiver will automatically reacquire the ground wave of the initiallyselected station.

Using the LORAN C ground wave, the receiver will provide a 1 MUz signaloutput which tracks the long term accuracy of the LORAN C signal, and a 1 ppsoutput. This 1 MHz signal is phase locked to the received LORAN C signalThe 1 MHz reference output will have an accuracy of at least 1 part in 1011in one hour, 1 part in 1012 in one day, and 1 part in 1013 thereafter,maintained with respect to the received signal. The 1 pps reference output asprovided by the receiver is tied to the received LORAN C signal. The 1 ppsoutput is accurate to 1 microsecond with respect to the received signal. The1 pps pulse, at least 20 microseconds wide, will be used as an unambiguoustiming pulse.

In order to satisfy the set of performance objectives (as defined inreference [1]) for timing subsystem availability, station clock accuracy,station clock stability, meantime between outage (MIBO), mean time to repair(MTTR), mean time to timing slips (MTTS), and buffer lengths, the stationclock has been specified to provide redundancy in the form of two precisionoscillators in order to compensate for any loss of LORAN C due to equipmentfailure or signal loss. The station clock is also capable of accepting anexternal reference (such as a cesium beam standard) when available.

b. Fr,.quency Multiplier. The frequency multiplier provides the functionsof frequency synthesis,-distribution, manual selection and failure modeoperation and all necessary interfaces within the station clock, to includethe LORAN C receiver, the external source, the primary and back up oscillatorsand the distribution amplifier.

Should the primary reference fail, the frequency multiplier willautomatically switch to the alternate reference. The frequency multiplierwill then continue to operate using the alternate reference until it ismanually reset. Should both the primary and alternate references fail, allreference input signals to the oscillators will discontinue, and theoscillators will operate unlocked (not phase and frequency locked to the 1 MHzprimary and alternate reference).

As depicted in Figure 2, the frequency multiplier (for monitoring) accepts5 MHz sinewave signals from each of the two oscillators. The oscillators aredesignated as primary and backup. Manual intervention shall be required to

5

restore either oscillator after failure. For steering purposes, the frequencymultiplier provides each oscillator with a 1 MHz sinewave. If either theprimary or backup signal from the oscillators fails, switchover to theremaining oscillator occurs automatically without changing the outputs to theLORAN C receiver or distribution amplifier.

c. Oscillators. Two oscillators are provided as separate independentcomponents. Each oscillator is locked to its respective input from thefrequency multiplier. Should the reference signal be lost, reacquisition ofphase lock will be automatic after the reference signal is restored.

The oscillators accept the reference input and provide outputs that assumethe long term stability of the reference. Upon removal of the referencesignal, the oscillators will continue to provide the output signals withoutimmnediate degradation greater than I part in 1012. Thereafter theoscillators will degrade in accuracy not more than 3 parts in 1011 per day.

d. Distribution Amplifier. The distribution amplifier provides the drivecapability to interface the frequency multiplier and the oscillators' 1 MHzoutput signals to remote equipment. In addition to its use within the StationClock, the distribution amplifier is also capable of independent operation.The distribution amplifier employs three separate synthesizers to synthesizethe 5 MHz output signals. The distribution amplifier has the capability todrive the 1 MHz output reference, a distance of at least 1000 cable feet.

The distribution amplifier as a minimum provides six 5 MHz and six 1 MHzsinewave outputs continuously that are individually adjustable from 0.5 to 5.0volts RMS into 50 ohms. The outputs are separated to provide two 1 MHz andtwo 5 MHz outputs from each of three synthesizer sections.

2. CLOCK DISTRIBUTION SUBSYSTEM (COS)

The clock distribution subsystem interfaces with the station clock togenerate and distribute timing signals to transmission and user equipments.In order to meet DCS availability criteria, triple redundant frequencysynthesis followed by majority vote logic is provided. Voting logic willselect one of the three frequency synthesized outputs and provide the selectedfrequency rate to the distribution amplifier. The distribution amplifier thenprovides an individually isolated output to each equipment as required.

The principal functions of the COS include:

(1) Accepting up to three independent frequency reference input

signals.

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(2) Providing redundancy in generating (synthesizing) clockingfrequencies for the required families of rates (to be discussed later).

(3) Distributing these clocking signals to individual transmissionand switching equipment.

(4) Providing alarm indications for failures.

A functional schematic of the COS, depicting the interrelationship of itselements, is shown in Figure 3.

The CDS and the associated frequency sources will provide timing to someor all the transmission and switching subsystems located at a DefenseCommunications System (DCS) communications node. The clock signals generatedby the CDS will be applied to external clock inputs of the transmission andswitching equipment consistent with the input interface parameters of eachequipment.

a. Frequency Synthesizer. The CDS frequency synthesizer accepts asinputs three I MHz or 5 MHz signals that may or may not be phase coherentsinusoidal or squarewave outputs from the Station Clock or other frequencystandard. The CDS also accepts as inputs three 1.544 MHz squarewave signalsthat may or may not be phase coherent inputs from external sources (e.g.,AN/FCC-98). Simultaneous inputs of any combination of 1.544, 1, or 5 MHzcannot be used. When available, the frequency synthesizer of the ClockDistribution Subsystem can also interface with the Hewlett Packard Model 5061AFrequency/Time Standard with option 004 (high performance cesium tube) andoption 001 (clock), of the type used in the Defense Satellite CommunicationSystem (DSCS). The frequency synthesizer is capable of synthesizing all clockrates listed in Table I. For each generated family of clock rates specifiedin Table I, the redundant frequency synthesizers will provide outputs to thevoting logic. The voting logic will then select one of these synthesizeroutputs and provide the selected frequency rate to the distributionamplifier. The voting logic determines which (if any) of the frequencysynthesizer outputs are in disagreement. If one frequency synthesizer isfound to disagree with the other two synthesizers, its output is removed fromthe input to the distribution amplifier, and will require operatorintervention for return to service. If all frequency synthesizers are foundto disagree, the voting logic will lock to any one of the synthesizeroutputs. If two or more of the frequency synthesizers are found to agree, thevoting logic will select any one of the synthesizers which agree for output tothe distribution amplifier.

The frequency synthesizer and voting logic are modul -ar, such that a givenmodule would only generate or vote upon a subset of the full complement ofrates specified in Table 1. A typical configuration of the COS would requireonly a few of the clock rates listed in Table 1.

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TABLE I. CLOCK FREQUENCY FAMILIES

1. 75 (2N) Hz family - N = 0 to 11

II. 600 (N) Hz family - N = 1 to 12

IIl. 8000 (N) Hz family - N = 1 to 8

IV. 2N kHz family - N = 6 to 1l

V. 192 (N) MHz family - N = 1, 2, 3, 8

VI. 1.544 (N) MHz family - N = i to 4

VII. 3.232 (N) MHz family N = 1 to 4

VIII. 5.0 (N) MHz family - N = l

10

b. Distribution Amplifier. The distribution amplifier accepts the outputof the frequency synthesizer voting logic and has the capability of deriving,for each family of rates, the specific frequency outputs required, which arethen provided as individually buffered outputs. Failure of any single outputwill not affect other buffered outputs. A typical DCS application wouldrequire one or two outputs for only a few of the frequencies specified. Forthis reason, the distribution amplifier is modularized so that each module ofthe distribution amplifier may have a number of outputs and a mix of frequencyrates.

The distribution amplifier of the Clock Distribution System providessquarewave signals at the clock rates listed in Table I.

The interface of the distribution amplifier of the clock distributionsystem includes but is not limited to the following transmission and switchingequipments at their respective external clock inputs:

AN/FRC-170 (Series) Digital RadioAN/FCC-99 MultiplexerAN/FCC-98 MultiplexerAN/FCC-1O0 MultiplexerCY-104(A) MultiplexerAN/FCC-97 MultiplexerMD-918 Tropo ModemGSC-36 Group Data ModemKG-81 Encryption DeviceKG-84 Encryption DeviceDSN Switch Digital SwitchDCS Channel Packing SwitchAUTODIN Switches SwitchAN/USC-26 Group Data ModemMP 96 VF ModemAN/GSC-24 Sat. MultiplexerKG-13 Encryption DeviceKG-34 Encryption DeviceTD 13XX MultiplexerCV 3511/TD 1220 MultiplexerDPAS Electronic PatchTropo Radio RF (Transmitter/Receiver) Local OscillatorsAN/USC-28 Spread Spectrum ModemLRM Low Rate Satellite MultiplexerTD 1303 MultiplexerC30 Packet Swi'-,h

3. BUFFERS

All received digital signals entering a digital transmission network nodefrom other nodes have clock accuracies and stabilities determined by thetransmitting node clock. These received signals also exhibit the transitiondelay variations introduced by the intervening link(s). Received digitalsignals will either be dropped at a particular node or through-routed.

11

TABLE II. DRAMA EQUIPMENT BUFFER LENGTHS

PORT PORT AGGREGATETRANSMISSION BUFFER BUFFERRATE (kb/s) LENGTH (BITS) LENGTH (BITS)

AN/FRC-170 (V) 12,928 + 11SERIES DIGITAL LOS 9,696 + 11RADIO 6,464 + H

3,232 + 11

AN/FCC-99 6,176 + 8SECOND LEVEL 3,088 7 8MULTIPLEXER 1,544 T 8

AN/FCC-98 512 + 64FIRST LEVEL 256 + 64MULTIPLEXER 128 + 64

64 76456 764

AN/FCC-100 (V)LSTDM + 1024 (Maximum)*SYNCHRONOUS PORTS 64 +6, -16

32 +6, -16

19.2 +4, -19

16.0 +3, -20

9.6 +2, -218.0 +2, -217.2 +2, -21

4.8 +1, -222.4 +1, -221.2 +1, -22.6 +1, -22.3 +1, -22.150 +1, -22.075 +1, -22

* The AN/FCC-100 is equipped with a programmable aggregate buffer at aggregate rates

through 64 kbps.

12

Through-routing can be accomplished at the user rate, or the data trunk ordigroup levels. Through-routed circuits that are to be transmitted from thenode via synchronous transmission equipment must be brought intosynchronization with the local station clock. Synchronization is accomplishedusing data buffers, which are either built into the transmission equipment orare separate stand-alone units. As an example, Table II gives the bufferlengths intrinsic to the input ports of the DRAMA equipment. The stand-alonebuffers will be capable of buffering from a minimum of 64 bits to a maximum of32,768 bits with an upper speed of 2.048 Mb/s.

In the receive direction of the major node, as shown in Figure 4, receiveddata is buffered for synchronization purposes. Data is clocked into thebuffer by received timing derived in the radio or multiplexer, and clocked outby the local clock.

The buffers for the higher speeds (greater than 2.048 Mb/s) are built intothe transmission equipment and have sufficient length to compensate for clockdifferences and path delay variations for terrestrial transmission. Interfacewith satellite-derived synchronous circuits will require the additional bufferlength provided by the stand-alone digital data buffer to compensate forsatellite delay variations that are caused largely by satellite orbitinclination, orbit eccentricity, and atmospheric/ionospheric variations. Thesatellite is initially orbited with a maximum inclination in one direction andduring the satellite operational lifetime the orbital plane inclination shiftsthrough 00 and then in the opposite direction. The path length delayvariation due to orbital inclination varies with the inclination angle andranges from 1 to 4 ins. The delay variation is largest at the beginning andend of the satellite operational lifetime and is minimum during mid-life. Thepath delay variation is also a function of the orbital eccentricity, which isa daily variation. DSCS satellites are allowed a 1 percent eccentricity,which contribute as much as 5.6 mns additional delay variation. Future DSCSsatellites will be better controlled and thus reduce the orbit eccentricitydelay contributions. Propagation delay due to atmospheric and ionosphericvariations contributes an additional delay variation of approximately 1 ins.This results in a total maximum diurnal delay variation of approximately 10 ins.

The network synchronization system cannot be considered truly synchronousin that the network nodes are not always slaved to a single common timingsource. Even if they are, some data buffers are required to account for delayvariations of the transmission media. The most critical buffer designrequirement, however, is to accommodate the plesiochronous mode of operation.In a plesiochronous system, data and transmission system digital signalsgenerated under the control of one station clock may be at a slightlydifferent rate from those generated under the control of other station clockswithin the network. To maintain Bit Count Integrity (BCI), buffers are usedto compensate for the phase difference between these signals. Buffers arerequired also to compensate for small timing differences which may arisebecause of differences and perturbation in LORAN C transmission. By design,internal buffers have been included as an integral part of most of the inputcircuits for the digital transmission equipment that will be used to implementthe future DCS. The equipment input buffers have been designed to provide BCIfor 24 hours in a plesiochronous system when the station clock stability is10-9.

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In a plesiochronous system that has station clocks of 10-11, BCItheoretically would be extended to 2400 hours. For those stations slaved to asingle clock or coordinated with UTC, BCI will be maintained for an indefiniteperiod of time. Note, however, that buffer sizing is critical in that if abuffer reaches an underflow or overflow condition, it will reset to itsmidpoint, causing a loss of BCI.

The following is an example of the calculations required to determine theproper buffer lengths, both for the terrestrial and the satellite portions ofa circuit. For this example, a hypothetical, full-duplex 512 kb/s circuittraversing both satellite and terrestrial paths wi'l be analyzed. Thiscircuit originates at a DSCS site and is transmitted via satellite to anotherDSCS location where it is tandemed into a synchronous multiplexer fortransmission terrestrially to its termination site. To compensate for thesatellite path delay variation (design goal of +10 ms for DSCS paths) and toprovide a proper mean time between loss of syncFronization (design requirementof at least 24 hours), a stand alone buffer capability is required.

To determine the appropriate size of this buffer, both terrestrial andsatellite segment requirements must be taken into account. Terrestrially, amean time between loss of synchronization of 24 hours is required end-to-end.The buffer length required to accommodate this requirement can be determinedin two steps: first, by taking the number of seconds in 24 hours (86,400seconds/24 hours) multiplied by the circuit rate in bits/second (in thisexample: 512 kb/s) to determine the number of bits transmitted per day(4.42368 x 1010 bits/day), and then multiply the number of bits transmittedper day by the average clock accurai. of the circuit in question (in the DCSthe average design goal is +1 x 10-'). Thus,

(4.42368 x 1010 bits/day) (2 x lo-ll)= 8.84736 x 10-1 bits of buffer.

Therefore, terrestrial buffer requirements approximate I bit of buffer.

As would be expected, the major factor in determining the buffer size isthe satellite delay variation. This buffer length can be calculated bymultiplying the circuit rate (512kb/s in this example) by the (conservativedesign goal) maximum delay variation of approximately ±10m sec for DSCSpaths. Thus,

(512 kb/s) (20 x 10-3)= 10240 bits of buffer.

Therefore, the total buffer size is found by adding the terrestrialportion (I bit) and the satellite portion (10,240 bits) together: I + 10,240=10,241 bits of buffer.

15

IV. STATION TIMING

The implementation of the network does not require that every node have aLORAN C receiver or other primary reference standard. The allowableimplementation will be to provide these primary clock sources at major nodes,with minor nodes slaved (looped) to them.

The determination as to major versus minor node designation and hence thetiming and synchronization (T & S) configuration for each node is made using anumber of specific criteria.

Specific criteria for major nodes include:

(1) The widespread application of the Low Speed Time DivisionMultiplexer (LSTDM - AN/FCC-0) and its synchronous data channel capabilities(as shown in Table III) require in most cases separate timing andsynchronization capabilities. The exception to this rule is noted below.

(2) The introduction of digital troposcatter will requiresynchronization of associated equipment to include the MD 918 tropo modem andinternal oscillators.

(3) With the DCS evolving toward an all-digital conunicationssystem, there are T & S requirements for the application of digital switching(including the implementation of the European Telephone Systems (ETS)).Therefore, major nodes within the ETS realm will consist of those colocatedETS/DCS sites not defined as terminating nodes. These major nodes arespecifically identified in Appendix D.

(4) The interface of synchronous data channels between theterrestrial DCS and the Defense Satellite Communications System (DSCS) willrequire synchronization of these two systems. Buffers, station clocks, andclock distribution subsystems may be required for satisfying theseDSCS-terrestrial interface requirements and are discussed in more detail inSection V.

(5) Timing and synchronization systems have been allocated at thoserepeater locations (which are more than through-routed repeaters) branching inthree or more directions, in order to maintain the overall performancecharacteristics of the network.

Specific criteria for minor nodes include:

(1) Where LSTDM's are located at terminating sites, looped timingwill be used.

(2) Through-routed repeater locations are not provided separatetiming and synchronization subsystems.

16

TABLE III. DRAMA EQUIPMENT SYNCHRONOUS CHANNEL CAPABILITIES

AN/FCC-99 AN/FCC-98 AN/FCC-100

1.544 Mb/s 56 kb/s 75 b/s3.088 Mb/s 64 kb/s 150 b/s6.176 Mb/s 128 kb/s 300 b/s

256 kb/s 600 b/s512 kb/s 1.2 kb/s

2.4 kb/s4.8 kb/s7.2 kb/s8.0 kb/s9.6 kb/s

16.0 kb/s19.2 kb/s

32 kb/s64 kb/s

17

1. MAJOR NODE TIMING

For the major node, the distribution of clock lines for the transmitdirection can be accomplished by (1) synthesis of the transmission rates fromthe timing and synchronization subsystem and distribution of these appropriaterates to the radio, encryption equipment (e.g., KG-81), and each level ofmultiplex, using internal phase adjustment within the transmission equipment(as shown in Figure 5); (2) providing the highest transmission equipment level(usually the radio) its external timing at the appropriate rate from the T&Sequipment and then cascading the timing through the transmission hierarchy(shown in Figure 5), or (3) as shown in Figure 6, using the arrangementdescribed also in method (2) above with the exception that the timing isprovided to the FCC-99 level multiplex and then to the encryption equipment(e.g., KG-81).

Figure 5 represents an approach for dissemination of timing through theequipment hierarchy referred to as cascading. When used in conjunction withthe KG-81 encryption device, caution should be exercised. Preliminary resultsindicate that when the HNF-81-2-TSEC frame is placed into the bypass mode, thetransmit reference clock is triple terminated. This results in an impedancemismatch that causes signal reflections which oistort the timing signal andcause loss of bit count integrity. This problem is related to the length ofthe equipment interconnecting caole. With short enough cable lengthconfigurations, proper operation of the transmission equipment (even with theHNF-81-2-TSEC frame placed into the bypass mode) should result, but can not beguaranteed. For this reason, cascade timing directly from the radio (or MD918for troposcatter applications) to the KG-81 is not reconmmended.1

The alternative approach indicated by the broken lines in Figure 5 isacceptable; however, the recommended approach for dissemination of timingthrough the equipment hierarchy is depicted in Figure 6. This timingconfiguration alleviates the problems experienced when placing theHNF-81-2-TSEC into the bypass mode by eliminating the multiple terminations ofthe transmit reference clock. This preferred approach will also reduce thenumber of output modules (in the COS) and cable connections required. Thistiming configuration would appear to violate red/black criteria by using blacktransmit clock on the red side of the KG-81. However, the DCS application ofthe KG-81 is limited to bulk encryption, only, i.e., for encryption ofunclassified traffic, so that red/black criteria does not apply.

2. MINOR NODE TIMING

The minor transmission node has no free-standing timing system, but ratherutilizes the timing generation and distribution capability inherent intransmission equipments. Two options are available for this timing system.The first option uses received timing, derived by a master equipment (e.g.,radio), as a clock source for transmit timing. Timing derived from the master

1 This problem exists only when using the KG-81 with the HNF-81-2-TSEC framein the bypass mode for unclassified traffic. When the KG-81 is used with theHNF-81-1-TSEC frame for encryption of classified traffic this problem does notexist because the HNF-81-1-TSEC frame has no bypass mode. When theKG-81/HNF-81-l-TSEC is used for encryption of classified traffic, cascadedtiming is required.

18

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equipment is based on a timing system located at a remote major node withattendant accuracy of the major node station clock. This first option isutilized where the existence of synchronous users dictates the need for anaccurate timing source. The second option uses internal timing of the highestlevel transmission equipment (usually the radio) as the station master. Theinternal timing source of the radio, with accuracy of 1 part in 106, issuitable for applications where no requirement exists for synchronous users.

Figures 7 and 8 illustrate station layouts for transmit and receive timingfor digital radio applications of the minor node timing subsystem. Note thatFigure 7 shows two selectable options for transmit timing: (1) slaving thedigital radio to receive timing from a master radio, or (2) operating off theinternal clock of the radio. For either option, the digital radio generatesthe timing rates required for the associated multiplexers/cryptographicequipments. Each transmission equipment in turn generates and distributesrequired timing lines for the next equipment downstream. Receive timing asshown in Figure 8 is the straightforward distribution of timing derived in theradio to associated multiplex and cryptographic equipment.

The minor node timing system would typically be either at a terminatingsite at the end of some spur off the main backbone or at a repeater with no VFbreakout. This type of node does not have the capability to generatetransmission rates other than those inherent in the radio and multiplex, sinceno separate timing system would exist to generate other required rates.Additionally, this option presupposes no requirement to provide timing to anyother equipment.

21

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32

V. APPLICATION OF NETWORK DESIGN TO THE DCS

Based on the rationale developed in Section IV, Appendix B illustrates thetiming and synchronization configuration for the worldwide DCS. Includedwithin Appendix B is an alphabetized listing of all the major nodes within theDCS European, Pacific, and Western Hemisphere areas. The information inAppendix B should be viewed as a "snapshot in time" due to the dynamic natureof the digital upgrade plans.

Initially, the European Timing and Synchronization project is intendedto: (1) provide an operational evaluation phase of both equipments andconcepts for DCS network timing and synchronization in Europe; and (2)support initial implementation of various other subsystems including the LSTDMpilot program, initial digital troposcatter upgrades, synchronous interfacesbetween the DCS and DSCS, and digital switching applications. As futureefforts continue to evolve, the knowledge derived from the Europeanimplementation will form the basis for the other areas (Pacific and WesternHemisphere) as their various projects develop (to include KIP and HAWS in thePacific area and the WAWS in the Western Hemisphere).

1. DATA TRANSMISSION NETWORK TIMING AND SYNCHRONIZATION

During the 1980-1990 time frame, the DCS will be rapidly transitioningfrom a system based on analog transmission and switching facilities to onebased on digital technology. This transition, which is driven by the need forsecurity and the economic and operational benefits of digital processing, willbe accompanied by the growth and restructuring of the digital datarequirements to be satisfied by the DCS. To accommodate changes in digitaldata requirements and to capitalize on the evolution of the DCS to digitaloperation, a Data Transmission Network (DTN) is being planned to achieve amore efficient and effective transmission of data. This DTN is an extensionof other digital transmission upgrades (e.g., the Digital European Backbone(DEB)) which are introducing multiplex and radio equipment using PCM, TDM, anddigital LOS and troposcatter radio equipment into the DCS.

Figure 9 depicts the timing and synchronization configuration fortroposcatter radio equipment. Transmit timing will be provided by externalclock at a frequency of 5 MHz. The troposcatter radio equipment requires sixseparate 5 MHz frequencies, two for each of the MD 918 tropo modems(redundancy), transmit frequency synthesizers (diversity), and receivefrequency synthesizers (diversity). It is recommended that in troposcatterapplication, the 5 MHz frequencies be provided directly from the stationclock. The 5 MHz frequencies can also be provided from the clock distributionsubsystem although the signals may not be quite as stable as those of thestation clock. The troposcatter modem will cascade clock to the next level inthe transmission hierarchy.

Figure 10 depicts the predominant, internodal, Government-ownedtransmission facilities that will be used to implement the Data TransmissionNetwork (OTN). Digital channels are provided for the DTN by the Low Speed

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The AN/FCC-98 and AN/FCC-99 multiplexers and the AN/FRC-170 Series (V)digital radio are currently being used to upgrade and digitize overseasDefense Communications System (DCS) analog transmission facilities. (TheEuropean portion of the digitization program is known as the Digital EuropeanBackbone (DEB)). The AN/FCC-99 (second level multiplexer) uses pulse stuffingto maintain bit synchronization between the first and second levelmultiplexers. As the timing and synchronization system is implemented,synchronous operation of the LSTDM with the multirate digital data module inthe AN/FCC-98 and CY-104 will also be implemented. In higher levels of thenetwork, the AN/FCC-99, using its pulse stuffing capability, could continue to

27

operate nonsynchronously; however, the AN/FCC-99 multiplexer has thecapability of operating synchronously and will be converted to the synchronousmode to provide improved network performance. This will eliminate twoproblems, pulse stuffing errors which cause loss of bit count integrity (BCI),and pulse stuffing jitter which reduces bit synchronization performance.

In the synchronous mode of operation, all transmitted signals from a DCSdigital terrestrial facility are timed by the station clock and are thereforewithout long-term frequency error. The encryption equipment and themultiplexing equipment are slaved, in turn, to the transmitter as shown by thedashed clock lines in Figure 10. Received signals at each digital level inthe hierarchy are slaved to the source clocks at their originating nodes.

Figure 10 shows a generalized configuration of nodal equipment depictinghow the mission bit streams, digroups, digital data groups, and low speed datacircuits can be either dropped and inserted or through-routed at theappropriate level of the digital hierarchy. A digital circuit provided by theDTN and passing through the DCS digital transmission system will be processedat each node as illustrated in the figure. There are also repeater andbranching repeater configurations where the mission bit stream is received,regenerated, and retransmitted. In a synchronous network, with accuratetiming sources at each transmission node, these configurations are specialcases of the one shown.

The DTN implementation will be phased over a long period of time.Appendix C depicts the proposed configuration of the initial DTNimplementation. Sites were selected such that interfaces with all types oftransmission facilities will be encountered. The various types oftransmission facilities in the initial implementation include:

* DCS terrestrial digital transmission facilities using representativedigital multiplexers. The timing and synchronization configurationfor this various transmission equipment (including FCC-I00, FCC-99,FCC-98) has previously been described.

0 DSCS digital transmission facilities that provide both non-ECCM andECCM capabilities. DSCS facilities are provided Cesium beam frequencystandards for their timing and synchronization requirements. As newrequirements are identified, other timing and synchronization ratesmay need to be provided and thus may necessitate the use of a clockdistribution system.

* Leased digital facilities (WAWS, HAWS, etc). In most digital leasedfacilities, the contractor's equipment provides its own clock with thesame performance as that of the government system described here. Asan alternative if desired, their equipment is capable of accepting theGovernment external reference.

28

* Undersea cable systems. Cable systems, whether in the external,internal, or looped timing mode, may necessitate the usage of linedrivers/repeaters to provide the appropriate clock signals to thevarious transmission equipment.

* Analog and leased analog (FDM) transmission facilities using VF and/orGroup modems. Synchronous transmission is accomplished via timingprovided by an internal source, external source, or the data source.

* Tactical/NATO interface. The synchronism between the DCS and tacticalor NATO digital signals (e.g., 16, 32, 64, 128, 256, 512, and 2,048kb/s) is plesiochronous. A more detailed explanation is given in DCECTR 23-77.

The DTN implementation is being further developed under the auspices ofthe DTN working group.

Note that in order to operate the initial implementation of the DTNsynchronously, timing and synchronization systems are required. The MilitaryDepartment with prime site operations and maintenance (O&M) responsibilitywill provide a timing and synchronization system for each site (identified inFYP 86) within the DTN initial implementation. Certain locations have timingand synchronization equipment for various programs already in place. Some ofthese include DSCS sites and AUTODIN locations. Although in some cases theT&S equipment has been in the field for quite a few years (therefore notnecessarily state-of-the-art) an effort will be made to use this existingequipment where feasible.

For those sites in the DTN in which low speed time division multiplexers(AN/FCC-lO0) are to be located, timing and synchronization systems arerequired. The exception to this rule is for locations which have no drop andinsert function (termination or minor nodes). These LSTDM's will use cascadedclock derived from the higher level transmission equipment via the incomingmission bit stream.

2. DEFENSE SWITCHED NETWORK TIMING AND SYNCHRONIZATION

The Defense Switched Network (DSN) will evolve from the existing AUTOVONnetwork and other circuit switched projects, including all DoDteleconnunications (voice and data, common-user, and dedicated) from userterminal to user terminal across all connectivity means (government owned andleased, terrrestrial and satellite transmission paths, and switchingfacilities). The present DSN architecture permits this evolution to proceedincrementally.

Each military department as well as DCA has been proceeding with switchingprograms designed to improve telecommunications effectiveness, reduce costs,meet user demands for new and improved service, and replace obsolete andinefficient plants. The DSN provides the means to integrate these switchprograms into a coherent focused effort. The majority of work within the DSNto date has been under the European Telephone System (ETS) program, which isthe only portion of DSN discussed in depth here.

29

a. European Telephone System Synchronization. The European TelephoneSystem (ETS) is to be the common user, general purpose, direct dial telephonecommunications network for the United States forces in the European theater,providing cost effective, reliable, and survivable switchedtelecommunications. The ETS design is based on the use of off-the-shelfcommercially available digital switching systems employing PCM technology.These switches are to be connected by a mix of U.S. government-owned andleased transmission media.

The ETS when initially implemented will have digital switches connectedvia both analog and digital transmission media. By the time the complete ETShas been implemented much of the European DCS transmission network will bedigital, hence permitting direct digroup interfacing between the digitalswitch and the digital transmission systems. Such evolution will eventuallyproduce an integrated digital transmission and switched network in whichinformation, once digitized, can be transmitted through the switched networkand not be converted back to analog form until it reaches its finaldestination. A major design requirement within such an all digital network issynchronization of transmission and switching equipment.

ETS implementation will require the installation of highly accuratestation clocks (described earlier) at the switching nodes and buffers designedinto the switch of sufficient size to absorb timing differences betweenstation clocks. Specific buffer sizing and clock accuracy requirements willbe discussed later. A typical network connectivity with DCS interface anddigital switch timing requirements is shown in Figure 11. Although externalbuffers are shown, these normally will be incorporated as part of the digitalinterface unit (DIU) on the switch. In addition, the digroup interface mayoccur at either 1.544 Mb/s or 2.048 Mb/s. Specific DCS transmission equipmentwith which the switch must interface and the timing subsystem are described inSection 11 of the DCA European Telephone System (ETS) System EngineeringArchitecture [6], and summarized below.

In the transmit configuration, the timing subsystem supplies timing to theETS switch and to each transmitting transmission equipment. Alternatively,the switch may operate on its internal clock if it does not directly connectto digital facilities on either the trunk or the loop side. The digitaloutputs of the switch will be at 1.544 Mb/s to interface with U.S. owneddigital systems and at 2.048 Mb/s to interface with leased (DeutscheBundespost) PCM-30 systems. The 1.544 Mb/s interface with U.S. systems willemploy a bipolar format. All U.S. multiplex equipments will use externalclock, supplied from the T&S subsystem to provide synchronization with the ETSswitch, although a pulse stuffing interface can be used for those DCSlocations where station clocks are not yet installed. On the receive side,the second level multiplex is synchronized to the received timing derived fromthe mission bit stream. Both data and timing are transferred downstream inthe multiplex hierarchy to the lowest level multiplexers. The establishedswitch performance objective for the ETS digital switched network conforms tothe CCITT Recommendation G811 [3], which specifies one slip or less in 70 days(1680 hours). Station cloc'. performance and buffer size requirements arederived based on the switch-to-switch performance objective. The clockperformance required to meet the ETS system timing objectiy7 will have a longterm frequency inaccuracy of not greater than 1 part in 10', which is alsopart of CCITT Recommendation G.811.

30

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b. ETS Switch Synchronization Characteristics. The ETS switch includesa Central Clock Generated (CCG)/Reference Clock Interface (RCI) unit whichaccommodates one primary and one backup source for external synchronization.Both the primary and backup sources are constantly monitored for loss orinstability. Each of these have a range of frequencies, waveforms, andlevels with the following specifications:

(1) Frequency range: 1000 Hz to 16.384 MHz in integer steps of 250

Hz

(2) Waveform: Sine or Square wave

(3) Level: O.3V RMS to 3V RMS (load impedance = 50 ohms)

The CCG/RCI is based on a microprocessor (8086) controlled intelligentphase locked loop control system which processes digital phase measurementsand controls a highly stable, double ovenized, voltage controlled crystaloscillator (OVCXO) via a high stability, ultra linear, 16 bit digital toanalog converter (DAC). The intelligent phase locked loop system provides thecapability of rapid acquisition of lock by adaptive bandwidth control andphase normalization techniques.

Synchronization in a master-slave network is made possible by the CCG/RCIability to operate with very narrow bandwidths which allow for attenuation ofboth jitter and diurnal wander. Synchronization accuracy is better thanlxlO -il under all worst case conditions, and error decreases with time. TheETS switch is also capable of deriving its clock from incoming PCM digroups orusing its own internal clock. When the external synchronization sources failor have become unreliable, a "Coast Mode" is effected and the overall accuracyand stability of the coast mode (internal clock) frequency is better than+ lxlO-9 per 24 hours.

Buffer requirements are stated in terms of buffer lengths and arespecified to provide synchronism over a specified period in accordance withthe Mean Time to Timing Slip objective. The MTTS gives an estimate of thetime before buffer underflow or overflow occurs, a condition which results ina bit slip. Factors which influence choice of buffer length include (a) clockaccuracy and stability, (b) time-varying propagation delays (see reference[1]), and (e) allowed slip rate. The buffer lengths required to meet the ETSperformance criteria are stated below for PCM-24 and PCM-30 type systems.

PCM-30: 64 Bytes (512 bits)

PCM-24: 48 Bytes (384 bits).

The equipment components of the ETS external timing and synchronizationsubsystem described earlier include the station clock and the clockdistribution subsystem. It is envisioned that the clock distributionsubsystem, or the station clock directly, will provide the ETS switch a 1 MHzfrequency reference.

32

c. Timing Interface Between International Systems. As shown inFigure 12, the ETS must be capable of interfacing with U.S. owned and DBPleased transmission facilities. As presently proposed, the ETS switches willbe capable of interfacing at the digital group level (e.g., 1.544 and 2.048Mb/s port rates) via digital interface units (DIU). These units shall becapable of establishing phase compensation, frame alignment, clocksynchronization, and buffering. The ETS switch will be capable of operationin the plesiochronous mode as governed by CCITT Recommendation G.811, timinginterface between international systems, where it has been assumed the PTTleased transmission facilities will employ a timing reference different fromthat of the United States.

The criterion applied to determine which sites receive timing andsynchronization systems in support of the ETS is to provide station clocks atall tandem switch centers and intermediate switch centers (TSC and ISC) and tothose DCS sites collocated with ETS end office switches (EO). Appendix Ddefines the timing and synchronization configuration of the ETS.

3. FREQUENCY STANDARD EXTENSION (DSCS/TERRESTRIAL OCS)

The interface of synchronous data channels between the terrestrial DCS andthe Defense Satellite Communications System (DSCS) will requiresynchronization of these two subsystems. Where atomic clocks already exist inthe DCS, such as with DSCS earth terminal locations, the oscillators withinthe station clock may be disciplined to the atomic clock rather than LORAN Cif such an approach proves economically and technically acceptable.

Interfaces between the terrestrial DCS and DSCS require buffers tocompensate for relatively large path delay variations. Satellite path delayvariations are caused largely by satellite orbit inclination, orbiteccentricity, and atmospheric/ionospheric variation. These result in a totalmaximum diurnal delay variation of approximately 10 ms. To compensate forthis satellite path delay variation (doppler), a + 10 ms stand-alone satellitebuffer capability is required.

Since the number of bits of buffering required to compensate for thesatellite path transmission delay variation is a function of data rate, aseparate buffer is not always required. For example, since a much smallerbuffer is required for low data rate circuits, it is possible to compensatefor satellite delay variation in the output circuits of certain transmissionequipment (e.g., the Low Speed Time Division Multiplexer (LSTDM)). The LSTDMbuffer will compensate for satellite delay variations for aggregate rates upto 64 kb/s.

The possible use of existing DSCS earth terminal frequency standards asstation clock references for the synchronous data interface betweenterrestrial and satellite systems has been identified. All but three (seeAppendix E) DCS DSCS earth terminal locations are equipped with the HewlettPackard Model 5061A Frequency/Time Standard with Option 004 (high performancecesium tube offering increased short term stability and greater immunity toeffects of shock and vibration) and Option OO (digital clock providingprecise I pulse-per-second outputs and an equally readable LED display ofhours, minutes, and seconds), and therefore are candidates for frequency andtime extension.

33

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Extension of the I MHz or 5 MHz reference frequencies provided by theearth terminal standard to the serving Technical Control Facility (TCF) (asshown in Figure 13) to provide a TCF frequency reference is constrained by theInterconnect Facility (ICF) connecting the two.

The ICF consists of the cable and/or microwave radio, digitalmultiplexers, and associated equipment necessary to interface the earthterminal and the TCF. Appendix E provides a listing of current DSCS earthterminal locations, responsible MILDEP, ICF media type, case type, and ICFmedia length. The general ICF configurations and the associated viablesolutions fall into four categories, referred to as cases, and will bediscussed separately.

Figure 14 is a block diagram of a Case I ICF. The TCF and earth terminalare located near each other, but in two separate buildings or vans. Themodulation and multiplex equipment is located in the earth terminalbuilding/van. The TCF supplies VF line conditioning. The transmission linesbetween the TCF and the Earth Terminal Complex (ETC) can be coaxial cable,multipair cable, or a combination, depending on the data rate to betransmitted between the two sites. Data rates of 9.6 kb/s and above utilizecoaxial cable, while those of 4.8 kb/s and below use multipair cable. ThisICF configuration is used for distances where adequate cable exists or can beprovided most economically, and where the location of multiplex equipment atthe ETC is operationally acceptable. Fiber optic cable may also be used forthis type ICF. The distances involved are nominally 7000 feet and below. Itis possible to extend the DSCS frequency standard in this case usingoff-the-shelf equipment in combination with the DCS timing and synchronizationsystem components. The available off-the-shelf 1 and 5 MHz line drivers forcable applications are capable of driving signals approximately 3000 feet.For distances greater than 3000 feet, line drivers used in tandem can be used.

Figure 15 is a block diagram of a Case II digital radio ICF. The trafficmaking up each RF link to be transmitted via satellite, together with the SSMAbaseband traffic, will be combined in the TDM equipment at the TCF. All suchlink basebands will be further combined in a final stage of TDM to form asingle digital ICF baseband. At the ETC Patch and Test Facility (PTF), acorresponding TDM stage will separate the ICF baseband into its componentlinks, one per RF link. The SSMA baseband will, where applicable, be thedigital radio link that is amplitude or frequency, modulated in the RF or IFcarrier. This ICF configuration is used where, because of distance or othergeographical considerations, a microwave system is more economic than awideband cable system. In Case II, the TCF and earth terminal are located inseparate buildings and interconnected by analog or digital microwave radio.

A requirement to distribute a precise time or frequency standard overdigital microwave links has three possible solutions. The alternativesolutions 1, 2, and 3 are depicted in Figure 16. To accomplish this extensionof a time standard over existing DCS digital microwave links would requiremodifications of the DRAMA digital radio and use of a disciplined oscillatorthat accepts a timing signal as opposed to a frequency standard. Thismodification would involve manipulation of the overhead bits provided in theaggregate bit stream of the radio. Because a multiplexing function existswithin the radio, overhead (frame) bits are present at a 64 kb/s rate for all

35

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I PPSCLOCK(I) DISTRIBUTION 0I

S YSTEM c

3.232, 6.4814, 9.696,OR 12.928 MHZ(2.3) ____ ____

DRAMA

RADIO

L-

(3)3.232,*6.464,9.696. OR 12.928MW RM

3.232,6.464. I (PPS)9.696, OR(I

FCC 1.2 ~ 2

1.544MHZ U

CLOCK

DISTRIBUTION I OR 5 MHZSYSTEM (3)

VIABLE DRAMA DIGITAL RADIO SOLUTION IN PARENTHESES.

FIGURE 16. DRAMA DIGITAL RADIO SOLUTION ALTERNATIVES

39

versions of the DRAMA radio. A timing code could be superimposed on the framebit pattern to allow transmission of a timing standard (probably 1 pulse persecond). Such a time code could then be used to discipline a remote (e.g., atDCS Tech Control Facility) time or frequency standard, although it must bepointed out that most existing disciplined oscillators require synchronizationby a frequency standard and are not capable of synchronization from a timestandard. The performance and cost of this radio modification are currentlybeing investigated with the DRAMA contractor. Because of the anticipated costand uncertainty of performance, the results of this investigation may indicatea better solution to be the use of a stand alone station clock at such DCSsites or one of the other two alternatives described below, both of whichinvolve extension of a frequency standard.

A second alternative would be a modification to the disciplined oscillator(part of station clock) which would allow the acceptance of the DRAMA rates(3.232, 6.464, 9.696, and 12.928 MHz) by the oscillator. This modificationwas not defined in the oscillator description within the station clockperformance specification and therefore can be dismissed.

The third and recommended alternative requires that the clock distributionsystem accept a 1.544 MHz signal as a stanaard frequency. This 1.544 MHzfrequency would be derived from the output of an FCC-99 multiplexer whichwould produce the rate from the standard DRAMA rates of 3.232, 6.464, 9.696,or 12.928 MHz. This capability is aefined in the performance specificationfor the clock distribution system.

Another option for providing precise time dissemination would be the useof an FM analog microwave radio link for time transfer via the Naval ResearchLaboratories Time Transfer Unit (TTU). The TTU as described in NAVELEX0967-425-2010 Technical Manual for Time Transfer Unit CM-427 (XB-I)/URC 1 Aug.1971, can be used to extend a 1 pps signal from the Earth Terminal to theTechnical Control Facility. Other applications of the TTU exist. The TTU isinterded for use in comparing time standards through various communicationssystems and has provisions for synchronizing communications equipment and forcalibrating other local time standards. For DCS applications, the TTU wouldrequire use of a disciplined oscillator capable of frequency synchronizationfrom a time standard (a capability not normally found with disciplinedoscillators), so that the TTU is not a viable solution to the requirement forfrequency standard extension.

Figure 17 is a block diagram of a Case III ICF. In this case, the earthterminal is located in the same building with, or in a van adjacent to, theTCF, and no drivers, extra multiplexers, or microwave radios are required forinterconnection. The cable lengths generally used are no greater than 250feet.

Figure 18 is a block diagram of a Case IV wideband cable ICF. The trafficmaking up each RF link baseband is combined in the TDM equipment at the TCFand then either (1) combined in a final stage of TDM with other RF linkbasebands via an ICF multiplexer or (2) connected directly to PSK modemswithout intervening multiplex equipment, utilizing tubes in a multitubecoaxial cable. The method used at each terminal location will be determinedon a site-by-site basis. The SSMA baseband shall, where applicable, utilize

40

OZ

00

(NOli±Od aNV9USYS) AVG H3IVd 1WIXVO00 a

zo*~ 0 S0" ;: a

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0 (13A31 MOI) AVG H~lVd IVJ.IDIG**

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41

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TDM equipment at the ETC PTF to derive separate channels for the several SSMAinterstitial pairs occupying the spaces between the coaxial tubes. Thesepairs shall be used for orderwire channels ana low speed digital access to theSSMA equipment. Other coaxial tubes in the same cable may be used for TDMbasebands during the transitional period when only a portion of the links at anodal terminal have been converted to digital operation. This ICFconfiguration shall be used where, because of distance or other geographicalconsiderations, a coaxial or fiber optic cable installation will be moreeconomical than a microwave system. Using fiber optic cable with theappropriate fiber optic line drivers, it is possible to extend a frequencystandard from the earth terminal to the technical control facility. Thus,over multipair and coaxial cable as well as fiber optic cable, frequencystandard extension appears acceptable.

Certain questions are raised not only as to the feasibility of frequencyextension but also as to the lengths possible for the extensions and theavailability of repeaters that might be required. These subjects will beaddressed during testing by the Navy at their facility at NAVCAMS EASTPAC tocommence during CY84. Test media expected to be used will include multipairand coaxial cable, fiber optic cable, and digital microwave.

Engineering studies of the interconnects between satellite nodes andserving technical control facilities will determine the exact equipmentrequired to extend the DSCS clocks. The timing and synchronization capabilityis predicated on the assumption that access to the cesium standard will beavailable to the serving TCF. It is anticipated that not all DSCS clocks canbe extended back to the serving tech control due to interconnect limitations;therefore, new timing and synchronization requirements would be identified atthat time. Where technical control facilities have access to two or moreCesium beam frequency standards, separate cesium standards would be used tosupply the references (primary and alternate) to the station clock. It mustbe stressed, however, that it is not advisable to base the TCF communicationscapability on the supposition that reliable frequency extension will bemaintained continuously. For this reason, it is recommended that sites usingDSCS frequency extension also be equipped with LORAN C receiver capabilitiesto serve as a backup.

43

REFERENCES

1. DCEC TR 23-77, "DCS II Timing Subsystem," December 1977.

2. U.S. Army Technical Manual, TM 11-5895-822-14.

3. CCITT Yellow Book, Vol.III.3, "Digital Networks Transmission Systems andMultiplexing Equipment," ITU, Geneva, 1981.

4. DCEC TR 12-76, "DCS Digital Transmission System Performance," Nov. 1976.

5. TRW Report SM 33753, "Drama Equipment System and Compatibility Analysis,"Apr 1979.

6. DCA Circular, "European Telephone System (ETS) System EngineeringArchitecture," Sep 1981, Draft.

7. OCEC TR 8-81, "System Design Plan for a DCS Data Transmission Network,"July 1981.

8. U. S. Air Force, EPS-82-012, "Equipment Performance Specification forStation Clock," Aug 1982.

9. U. S. Air Force, EPS-82-013, "Equipment Performance Specification forDigital Data Buffer (DDB)," Aug 1982.

10. U. S. Air Force, EPS-82-014, "Equipment Performance Specification forClock Distribution System," Aug 1982.

44

TERMS AND DEFINITIONS

ACCURACY - A term used to define how well a frequency agrees with itsdesignated standard value.

AGING - The process whereby crystals change their characteristics (e g.,resonance).

DIURNAL PHASE SHIFT - The phase shift (diurnal meaning daily) associated withsunrise or sunset.

DOPPLER EFFECT - An apparent change in frequency caused by motion of eitherthe transmitter or receiver.

FREQUENCY - The number of events per unit of time.

FREQUENCY DRIFT - The change in frequency of a source caused by aging orenvironmental fluctuations.

SETTABILITY - The degree to which the frequency of an oscillator can beadjusted to correspond with a reference frequency.

STABILITY - A term used to specify the rate at which a clock will change fromsome nominal frequency over a selected period of time. Short-termstability typically refers to frequency changes over periods oftime less than or equal to one second. Long-term stability refersto frequency changes which occur over times greater than onesecond.

STANDARD - A universally accepted reference.

45

ACRONYMS

ICF Interconnect FacilityTDM Time Division MultiplexerETC Earth Terminal ComplexTTU Time Transfer UnitCDS Clock Distribution SubsystemLSTDM Low Speed Time Division MultiplexerETS European Telephone SystemT & S Timing and SynchronizationUTC Universal Coordinated TimeGRI Group Repetition IntervalMTBO Mean Time Between OutagesMTTR Mean Time To RepairMTTS Mean Time To Timing SlipBCI Bit Count IntegrityKIP Korean Improvement ProjectHAWS Hawaiian Area Wideband SystemDTN Data Transmission NetworkFDM Frequency Division Multiplex0 & M Operations and MaintenanceDIU Digital Interface UnitCCG Central Clock GeneratedRCI Reference Clock InterfacePTT Public Telephone and TelegraphTCF Technical Control FacilityPSK Phase Shift KeyingDEB Digital European BackboneDAC Digital To Analog Converter

46

APPENDIX A

ELECTRICAL CHARACTERISTICS

The station clock is composed of four major equipments. The electricalcharacteristics defined in terms of input and output for each equipment are asfollows:

SECTION INPUT OUTPUT

LORAN C Receiver 0 MHz sinewave.5-5 volts RMSinto 50 ohms

Frequency Multiplier I MHz sinewaveinterface with .5-5 volts RMS intoLORAN C Receiver 50 ohms

or1 MHz squarewave.5-5 volts peak-to-peak

Frequency Multiplier 5 MHz sinewave 1 MHz sinewaveinterface with 5.5 volts RMS >1 volt peak-to-peakOscillators Tnto 50 ohms

Frequency Multiplier I MHz sinewaveinterface with .5-5 volts RMS intoDistribution Amplifier 50 ohms

Oscillators interface 1 MHz sinewave I MHz sinewavewith Frequency Multiplier >1 volt peak-to-peak 1-5 volts RMS into

Tnto 50 ohms 50 ohms

Oscillators interface 1 MHz sinewavewith Distribution 1-5 volts RMS intoAmplifier 50 ohms

Distribution Amplifier 1 MHz sinewaveinterface with Frequency .5-5 volts RMS intoMultiplier 50 ohms

Distribution Amplifier I MHz sinewaveinterface with Oscillators .5-5 volts RMS into

50 ohms

Distribution Amplifier 1 MHz sinewaveinterface with Clock .5-5 volts RMSDistribution Subsystem into 50 ohms

or5 MHz sinewave.5-5 volts RMSinto 50 ohms

A-i

The clock distribution subsystem electrical characteristics are as follows:

SECTION INPUT OUTPUT

Clock Distribution Subsystem I MHz sinewave/squarewave squarewave outputs.5-5 volts RMS into 50 strappable for 50,ohms 78, or 124 ohms

or1.544 MHz squarewave+3v +.5 to -3v +.5 into78 olms

or5 MHz sinewave.5-5 volts RMS into50 ohms

A-2

APPENDIX B

TIMING AND SYNCHRONIZATION CONFIGURATION FOR THE DCS

Based on the rationale developed in Section IV, Figures B-1, B-2, and B-3(sheets I and 2) depict the timing and synchronization configuration for theOCS in Europe, the Pacific, and the Western Hemisphere (Outside CONUS andCONUS). The implementation of this configuration is to be spread across anumber of years (beginning late 1983 and scheduled for completion inpre-1990's). It must be recognized that as future requirements areidentified, the implementation strategies will need to be adjusted.

Alphabetized listings of all the major nodes within the worldwide DCS ineach area (Europe, Pacific, and Western Hemisphere) are provided in TablesB-I, B-I, and B-Ill. Included in these tables for each major nodes is therequired timing and synchronization equipment, country code, the militarydepartment responsible for providing the T&S equipment, and the funding year(for implementation purposes). Due to the dynamic condition of the digitalupgrade plans, this information is continually changing. The timing andsynchronization project in the Defense Communications Agency Five Year Program(published each year) provides a means for updating these requirements. Thenumbers in each equipment and subsystem column are the quantities required.

Included under the required timing and synchronization equipment headingare two columns not previously discussed. Both "DISCIPL. OSCILL." and "FREQ.INTERCON." are associated with DSCS sites where their Cesium Beam Standard(located at the Earth Terminal) is within 300 cable feet of the TechnicalControl Facility (TCF) and can be used as the primary reference for thestation clock. Where this is possible, the "DISCIPL. OSCILL." (disciplinedoscillators) of the station clock are slaved directly to the Cesium beamfrequency standard, and thus no requirement for the LORAN C Receiver andantennae exists. However, other equipment (denoted as "FREQ INTERCON."meaning Frequency Interconnect) may be required to transfer the Cesium beamfrequency standard output over the media (cable) to the TCF. Typicalequipment includes the distribution amplifier and the media itself. It shouldbe pointed out that currently only four sites (Landstuhl, Ge.; Diego Garcia,Br; H.E.Holt, Aust.; and Camp Roberts, Cal.) in the entire DCS use thisarrangement. However, future testing to be conducted by the Navy in this areamay lead to an expansion of the number of sites using frequency extension asthe primary timing source for the Station Clock as well as to a betterdefinition of the exact equipment required for the extension.

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TABLE B-I. TIMING AND SYNCHRONIZATION EUROPEAN AREA

CLOCK DIGITALSTATION DISTRIB. DISCIPL. FREQ. DATA

CTY MILDEP CLOCK SUBSYSTEM OSCILL. INTERCON. BUFFER

Adenau GE AF 1 1 0 0 0Alconbury UK AF 1 1 0 0 0Aviano IT AF 1 1 0 0 0Bad Kreuznach GE A 1 1 0 0 0Bad Munder GE AF 1 1 0 0 0Bann GE AF 1 1 0 0 0Barkway UK AF 1 1 0 0 0Baumholder GE A I 1 0 0 0Berlin GE A 1 1 0 0 2Bitburg GE AF 1 1 0 0 0Bocksberg GE A 1 1 0 0 0Boerfink GE AF 1 1 0 0 0Bonstetten GE A 1 1 0 0 0Botley Hill Farms UK AF 1 1 0 0 0Breitsol GE A I 1 0 0 0Bremerhaven GE A 1 1 0 0 0Brize Norton UK AF 1 1 0 0 0Bruggen GE A 1 1 0 0 0Brunssum GE A 1 1 0 0 0Chicksands UK AF I 1 0 0 0Chievres BE A 1 1 0 0 0Colchester UK AF 1 1 0 0 0Coltano IT A 1 1 0 0 2Comiso IT AF 1 1 0 0 0Croughton UK AF 1 1 0 0 7Darmstadt GE A I 1 0 0 0Diyarbakir TU AF 1 1 0 0 1Donnersberg UK A I 1 0 0 0Edzell UK N 1 1 0 0 0Erp NL AF 1 1 0 0 0Eskishir TU AF 1 1 0 0 0Fairford UK AF 1 1 0 0 0Farnburough UK AF 1 1 0 0 0Feldberg GE AF 1 1 0 0 0Flobecq BE AF I 1 0 0 0Fylingdales UK AF I 1 0 0 0Frankfurt GE A 1 1 0 0 0Gablingen GE A 1 1 0 0 1Garlstedt GE A 1 1 0 0 0Giessen GE A 1 1 0 0 0Goeppingen GE A I 1 0 0 0Greenham Common UK AF 1 1 0 0 0

B-6

awj w iiAas ,i . -No. fL..

TABLE B-I (CONT'D)

EUROPEAN AREA

CLOCK DIGITALSTATION DISTRIB. DISCIPL. FREQ. DATA

CTY MILDEP CLOCK SUBSYSTEM OSCILL. INTERCON. BUFFER

Hahn GE AF 1 1 0 0 0Hanau GE A 1 1 0 0 0Heidelberg GE A 1 1 0 0 0Heilbronn GE A 1 1 0 0 0Helmstedt GE A 1 1 0 0 0Herongen GE A 1 1 0 0 0High Wycombe UK AF 1 1 0 0 0Hillingdon UK AF 1 1 0 0 0Hohenstadt GE A I 1 0 0 0Honington UK AF 1 1 0 0 0Hessiche Oldendorf GE AF 1 1 0 0 0Humosa SP AF 1 1 0 0 1Inoges SP AF 1 1 0 0 0Iraklion GR AF 1 1 0 0 0Kaiserslautern GE A 1 1 0 0 0Kalkar GE AF 1 1 0 0 0Karatas TU AF 1 1 0 0 0Karlsruh GE A 1 1 0 0 0Kato Souli GR N 1 1 0 0 0Katterbach GE A 1 1 0 0 0Keizersveer NL AF I 1 0 0 0Kindsbach GE AF 1 1 0 0 0Koenigstuhl GE A I 1 0 0 0Koterberg GE AF 1 1 0 0 0Lago Di Patria IT N 1 1 0 0 3Landstuhl GE A 0 1 1 1 6Langerkopf GE AF 1 1 0 0 0Le Chenoi BE AF 1 1 0 0 0Levkas GR AF 1 1 0 0 0Linderhofe GE A I 1 0 0 0Lindsey GE A 1 1 0 0 0London UK N 1 1 0 0 0Mainz GE A 1 1 0 0 0Malatya TU AF 1 1 0 0 0Mannheim C GE A 1 1 0 0 0Mannheim F GE A 1 1 0 0 0Maastricht GE A I 1 0 0 0Menwith UK AF 1 1 0 0 1Mildenhall UK AF I 1 0 0 0Minorca SP AF 1 1 0 0 0Moenchen Gladbach GE A 1 1 0 0 0Moehringen GE A 1 1 0 0 0

B-7

TABLE B-I (CONT'D)

EUROPEAN AREA

CLOCK DIGITALSTATION OISTRIB, DISCIPL. FREQ. DATA

CTY MILDEP CLOCK SUBSYSTEM OSCILL. INTERCON. BUFFER

Molesworth UK AF 1 1 0 0 0Mormond Hill UK AF 1 1 0 0 0Moron SP N 1 1 0 0 0Martina Franca IT AF I 1 0 0 0Mt. Hortiatis GR AF 1 1 0 0 0Mt. Pateras GR AF 1 1 0 0 0Mt. Camadoli IT N 1 1 0 0 0Mt. Edheri GR AF I 1 0 0 0Mt. Limbara GR AF 1 1 0 0 0Martlesham Heath UK AF 1 1 0 0 0Mt. Parnis GR AF 1 1 0 0 0Mt. Vergine IT AF I 1 0 0 0Muhl GE AF 1 1 0 0 0Munich GE A 1 1 0 0 0Naples IT N 1 1 0 0 0Nea Makri GR N 1 1 0 0 0Nellingen GE A I 1 0 0 0North Point GE A 1 1 0 0 0Norvenich GE A 1 1 0 0 0Nuernberg GE A 1 1 0 0 0Pirmasens GE A 1 1 0 0 0Ramstein GE AF 1 1 0 0 0Reese GE A 1 1 0 0 0Rheinmain GE AF 1 1 0 0 0Rhine Ord Barracks GE A 1 1 0 0 0Roetgen GE AF 1 1 0 0 0Sahin Tepesi TU AF 1 1 0 0 0Samsun TU AF 1 1 0 0 0Savona IT A 1 1 0 0 0Schoenfeld GE AF 1 1 0 0 0Schwetzingen GE A 1 1 0 0 0Sembach GE AF 1 1 O, 0 0Shape BE AF 1 1 0 0 0Sinop TU A 1 1 0 0 0Soller SP AF 1 1 0 0 0Spangdehlem GE AF 1 1 0 0 0Stuttgart GE A I 1 0 0 0Swarzwald GE A 1 1 0 0 0Templehof GE AF 1 1 0 0 0Thurso UK N 1 1 0 0 2Torrejon SP AF 1 1 0 0 0

B-8

TABLE B-I (CONT'D)

EUROPEAN AREA

CLOCK DIGITALSTATION DISTRIB. DISCIPL. FREQ. DATA

CTY MILDEP CLOCK SUBSYSTEM OSCILL. INTERCON. BUFFER

Twisteden GE A 1 1 0 0 0Vaihingen GE A 1 1 0 0 0Vicenza IT A 1 1 0 0 0Vilseck GE A 1 1 0 0 0Vught NL AF I 1 0 0 0Weisbaden GE A 1 1 0 0 0Woensdrecht GE AF 1 1 0 0 0Worms GE A I 1 0 0 0Wethersfield UK AF 1 1 0 0 0Wueschheim GE A 1 1 0 0 0Wurzburg GE A 1 1 0 0 0Yamanlar TU AF 1 1 0 0 0Zaragoza SP AF I 1 0 0 0Zweibrucken GE A 1 1 0 0 0Zweibrucken GE AF 1 1 0 0 0

B-9

TABLE B-II TIMING AND SYNCHRONIZATION PACIFIC AREA

CLOCK DIGITALSTATION DISTRIB. DISCIPL. FREQ. DATA

MILDEP CLOCK SUBSYSTEM OSCILL. INTERCON. BUFFER

AF 4 AF 1 1 0 0 1Barbers Point, Hawaii N 1 1 0 0 0Bucket, Korea A 1 1 0 0 0Canberra, Australia N 1 1 0 0 0Changsan, Korea A 1 1 0 0 0Chiran, Japan AF 1 1 0 0 0Clark Daw, Philippines AF I 1 0 0 0Clark, Philippines AF I 1 0 0 0Camp Ames, Korea A 1 1 0 0 0Camp Casey, Korea A 1 1 0 0 0Camp Courtney, Japan A 1 1 0 0 0Camp Long, Korea A 1 1 0 0 0Camp Smith, Hawaii N 1 1 0 0 0Camp Zama, Japan AF 1 1 0 0 3Diego Garcia, BR N 0 1 1 1 1Embassy, Philippines AF 1 1 0 0 0Finegayen, Guam N 1 1 0 0 1Ford Island, Hawaii N 1 1 0 0 0Ft. Buckner, Japan A 1 1 0 0 2Fuchu, Japan AF 1 1 0 0 0H. E. Holt, Australia N 0 1 1 1 0Hakone, Japan AF I 1 0 0 0Hickam, Hawaii AF 1 1 0 0 0High Point, Korea A 1 1 0 0 0Iwakuni, Japan AF 1 1 0 0 0Kadena, Japan A 1 1 0 0 0Kamiseya, Japan AF 1 1 0 0 0Kwajalen Island A 1 1 0 0 1Makalapa, Hawaii N 1 1 0 0 0Namsan, Korea A 1 1 0 0 0Nimitz Hall, Guam N 1 1 0 0 0Osan, Korea A 1 1 0 0 0Owada, Japan AF 1 1 0 0 0Pearl Harbor, Hawaii N 1 1 0 0 0Pusan, Korea A 1 1 0 0 0Pyongtak, Korea A 1 1 0 0 0Richmond, Korea A 1 1 0 0 0Rizal, Philippines A I 1 0 0 0Rokko, Japan AF 1 1 0 0 0San Migul, Philippines N 1 1 0 0 0Santa Rita, Philippines N 1 1 0 0 0Seburiyama, Japan AF 1 1 0 0 0

B-1O

TABLE B-II (CONT'D)

PACIFIC AREA

CLOCK DIGITALSTATION DISTRIB. DISCIPL. FREQ. DATA

MILDEP CLOCK SUBSYSTEM OSCILL. INTERCON. BUFFER

Seoul, Korea A 1 1 0 0 0Shemya, Alaska AF 1 1 0 0 2Sofu, Japan AF 1 1 0 0 0Song So, Korea A 1 1 0 0 1Taegu, Korea A 1 1 0 0 0Tango, Korea A 1 1 0 0 1Totsuka, Japan AF 1 1 0 0 0Wahiawa, Hawaii N 1 1 0 0 9Wheeler, Hawaii AF 1 1 0 0 0Woomera, Australia AF I 1 0 0 0Yaedake, Japan AF 1 1 0 0 0Yokohama, Japan N 1 1 0 0 0Yokosuka, Japan N 1 1 0 0 0Yokota, Japan AF 1 1 0 0 0

B-il

TABLE B-Ill TIMING AND SYNCHRONIZATION WESTERN HEMISPHERE AREA

CLOCK DIGITALDISTRIB. DISCIPL. FREQ. DATA

MILDEP CLOCK SUBSYSTEM OSCILL. INTERCON. BUFFER

Adak, Alaska N 1 1 0 0 0Adcom (Colorado Springs) AF 1 1 0 0 2Alameda, California N 1 1 0 0 0Andrews, Maryland AF I 1 0 0 0Ascensin AF 1 1 0 0 2Barter Island, ALS AF I 1 0 0 0Bolling, Maryland AF I 1 0 0 0Broughton Island, Canada AF 1 1 0 0 0Byron Bay, Canada AF 1 1 0 0 0Cambridge, Canada AF I 1 0 0 0Cape Oyer (M), Canada AF 1 1 0 0 0Cape Dyer (TRM), Canada AF 1 1 0 0 0Cape Hooper, Canada AF I 1 0 0 0Cape Parry, Canada AF I 1 0 0 0Cape Young, Canada AF I 1 0 0 0Clinton Point, Canada AF I 1 0 0 0Corozal, Panama A I 1 0 0 0Camp Roberts, California A 0 1 1 1 2Dahlgren, Virginia N I 1 0 0 0DCA, Virginia A 1 1 0 0 0Dewar Lakes, Canada AF 1 1 0 0 0Driver, Virginia N 1 1 0 0 0Dye 1, Greenland AF 1 1 0 0 0Dye 2, Greenland AF I 1 0 0 0Dye 3, Greenland AF I 1 0 0 0Dye 4, Greenland AF I 1 0 0 0Dye 5, Iceland AF I 1 0 0 0Elmendorf, Alaska AF I 1 0 0 2Ft. Belvoir, Virginia A 1 1 0 0 0Ft. Detrick, Maryland A 1 1 0 0 7Ft. Leavenworth, Kansas A 1 1 0 0 6Ft. Lee, Virginia A 1 1 0 0 0Ft. Meade, Maryland A 1 1 0 0 0Ft. Eustis, Virginia A 1 1 0 0 0Ft. Ritchie, Maryland A 1 1 0 0 0Gladman Point, Canada AF 1 1 0 0 0Guantanamo, Cuba N 1 1 0 0 1Hall Beach, Canada AF I 1 0 0 0Hofu, Iceland AF I 1 0 0 0Howard, Panama A 1 1 0 0 1Isabella, Puerto Rico N 1 1 0 0 0Jenny Lind Island, Canada AF 1 1 0 0 0

B-12

TABLE B-Ill (CONT'D)

WESTERN HEMISPHERE AREA

CLOCK DIGITALDISTRIB. DISCIPL. FREQ. DATA

MILDEP CLOCK SUBSYSTEM OSCILL. INTERCON. BUFFER

Keflavik, Iceland N 1 1 0 0 0Komakuk Beach, Canada AF 1 1 0 0 0Lajes, Azores AF 1 1 0 0 1Langley, Virginia AF 1 1 0 0 0Lady Franklin Point, Canada AF 1 1 0 0 0Lonely, Alaska AF 1 1 0 0 0Longstaff Bluff, Canada AF 1 1 0 0 0Los Angeles, California N I 1 0 0 0Mackar Inlet, Canada AF I 1 0 0 0McClellen, California AF 1 1 0 0 0Moffett, California N 1 1 0 0 0Nato Site, Iceland AF 1 1 0 0 0Naval Security Station, DC A 1 1 0 0 0Nicholson Peninsula, Canada AF 1 1 0 0 0Norfolk, Virginia N 1 1 0 0 4Northwest, Virginia N 1 1 0 0 0Norton, California AF I 1 0 0 0Oakland, California N 1 1 0 0 0Offutt, Nebraska AF 1 1 0 0 4Olitok, Alaska AF 1 1 0 0 0P. Mountain, Greenland AF 1 1 0 0 0Paris, Virginia A I 1 0 0 0Pelly Bay, Canada AF 1 1 0 0 0Pentagon, Virginia A 1 1 0 0 0Pentagon, Virginia AF I 1 0 0 0Point Lay, Alaska AF I 1 0 0 0Point Barrow, Alaska AF I 1 0 0 0Quantico, Virginia N 1 1 0 0 0Quarry Heights, Panama A 1 1 0 0 0Richmond, Virginia A 1 1 0 0 0Roosevelt Rds., Puerto Rico N I 1 0 0 0Sabana Seca, Puerto Rico N 1 1 0 0 0San Diego, California N 1 1 0 0 0Shepard Bay, Canada AF I 1 0 0 0Shingle Point, Canada AF I 1 0 0 0Skaggs Island, California N 1 1 0 0 0San Francisco, California N 1 1 0 0 0Sondrestrom, Greenland AF I 1 0 0 0Stockton, California N 1 1 0 0 0Sunnyvale, California AF 1 1 0 0 5Tuktoyaktuk, Canada AF 1 1 0 0 0Wainwright, Alaska AF 1 1 0 0 0White Oak, Maryland N 1 1 0 0 0

B-13

Appendix C

TIMING AND SYNCHRONIZATION CONFIGURATION FOR THE DATA TRANSMISSION NETWORK (DTN)

The implementation of the DTN will occur gradually, phased over a longperiod of time. Figure C-1 depicts the proposed configuration of the initialDTN implementation defined as stage IA. The DTN initial implementation willserve as a field trial and will provide a basis for development of a finalizedoperations and maintenance concept for the mature DTN. The initialimplementation will also enable a detailed analysis of specific userrequirements to be provided by the DTN, and will serve as a test bed to obtainperformance data.

C-1

UNCLASSIFIED 6 7 64

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5 4 32 iJKLASSIFIED

APPENDIX D

TIMING AND SYNCHRONIZATION CONFIGURATION FOR THE ETS

At present, the near-term (pre-1986) ETS locations requiring timing andsynchronization will be at sites with PCM-30 (2.048 Mb/s) lease connectivityas shown in Figure 0-1. Table D-1 depicts the PCM-30 sites by initialoperation requirement date, and defines either the date for which T&S muste beavailable, or suggests a possible interim loop timing arrangement. The ETSswitches within the PCM-24 (1.544 Mb/s) connectivities may be satisfied by theT&S systems employed in the Digital European Backbone (DEB) upgrades as theyare cutover.

The timing and synchronization configuration for the European TelephoineSystem is shown in Figure D-2. As was discussed previously, those ETS sitesthat are not equipped with station clocks and clock distribution subsystems(designated as minor nodes) will use looped timing from the T&S system locatedat the nearest major node.

D-1

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TS)

g 3 I I(LASIFED

TABLE D-I. ETS TIMING AND SYNCHRONIZATION NEAR-TERM (PRE-CY85) REQUIREMENTS

T&S REQ'D TO SUPPORTSITE MILDEP ETS/IOC DEB IOC ETS/PCM 30 IOC

FRANKFURT (FKT) A 5/84 5/84

STUTTGART (SGT) A 8/84 8/84

GIBBS 3/84 LOOP FROM FKT (5/84)

HAHN AF 11/84 11/84

HEIDELBERG A 10/84 10/84

NELLINGEN A 9/84 9/84

HANAU A 12/84 12/84*

MAINZ (MNZ) A 1/85 1/85

WACKERNHEIM 1/85 LOOP FROM MNZ (1/85)

WIESBADEN A 1/85 1/85*

RAMSTEIN AF 2/85 2/85

DRAKE 3/85 LOOP FROM FKT (5/84)

OBERURSEL 3/85 LOOP FROM FKT (5/84)

BAD CANNSTATT 2/85 LOOP FROM SGT (8/84)

MUNICH A INSTALLED 6/84

*LOOP TIMING POSSIBLE ON INTERIM BASIS

D-4

plGEumm ftaO B.L-mO!C FlJu=

TABLE D-I (CONT-D)

T&S REQ'D TO SUPPORTSITE MILDEP ETS/IOC DEB IOC ETS/PCM 30 IOC

GARLSTEDT A lNSTALLED 84 84

KAISERLAUTERN A 6/84 83/85 83

LANDSTUHL A 9/84 IN/83 83

SCHWETZINGEN A 10/84 IN/87 83*

KATTERBACH A 10/84 85 85*

NUERNBERG A 9/84 85 85

VAIHINGEN A 11/84 IN 83*

SEMBACH AF 12/84 85 85

MOEHRINGEN A 9/84 83 83*

GEOPPINGEN A 6/84 83 84*

HEILBRONN A 7/85 88 88

PIRMASENS A 5/85 83 84

ZWEIBRUCKEN A 6/85 86 86

BITBURG AF 8/85 85 85

*LOOP TIMING POSSIBLE ON INTERIM BASIS

D- 5

APPENDIX E

DSCS INTERCONNECT FACILITY DATA

Table E-I provides a listing of the current earth terminal locationswithin the Defense Satellite Communications System. Along with the earthterminal location, the responsible MILDEP, type of media connecting the earthterminal and technical control facility (denoted "ICF"), case type (definedearlier in the text), and the distance between earth terminal and technicalcontrol facility (denoted "Distance") are provided.

E-1

I

TABLE E-I. DSCS INTERCONNECT FACILITY DATA

LOCATION MILDEP ICF CASE TYPE DISTANCEAUGSBURG A 22 Gauge/Multipair 1 2300/2500 Ft.CAMP ROBERTS A 22 Gauge Cable I1 100 Ft.COLTANO A Std. Cable 1 500 Ft.BERLIN A 22 Gauge Cable 1 3 MilesFT. BUCKNER A 22 Gauge Cable I1 250 Ft.

22 Gauge Cable 500 Ft.KWAJALEIN A 19 Gauge Cable I 2400 Ft.LANDSTUHL A 22 Gauge Cable 1 200 Ft.TANGO* A Std. Cable 600 Ft.FT. MEADE A Fiber Optic IV 5000 Ft.FT. DETRICK A 22 Gauge Cable IV 850 Ft.SONG SO A Line of Sight II 7 Miles

22 Gauge Cable 400 Ft.H. E. HOLT N Cable Il 200 Ft.DIEGO GARCIA N Cable Il 200 Ft.

WAHIAWA N Fiber Optic IV 7000 Ft.GUAM N Fiber Optic IV 7000 Ft.

NAVY No. 2 N Cable Il 200 Ft.NAVY No. 3 N Cable I 600 Ft.ELMENDORF AF 19/24 Gauge Cable I 2000 Ft.CROUGHTON AF 19/24 Gauge Cable I 5000 Ft.CAMP ZAMA AF 19 Gauge Cable I 7000 Ft.AZORES AF 19 Gauge Cable I 5000 Ft.SHEMYA AF 19 Gauge Cable 1 2500 Ft.

E-2

TABLE E-I (CONT'D)

DSCS INTERCONNECT FACILITY DATA

LOCATION MILDEP ICF CASE TYPE DISTANCE

HUMOSA AF 18 Gauge Twisted I 300 Ft.Pair Cable

OIYARBAKIR AF TBD TBD TBD

GEODSS I* AF TBD TBD TBD

GEODSS 11* AF TBD TBD TBD

NORTHWEST N Line of Sight (2 hops) II 30 Miles

ASCENSION AF 19 Gauge Twinax Cable I 1 Mile

THURSO N Line of Sight II 15 Miles

LAGO DI PATRIA N Line of Sight II 30-35 Miles

GUANTANAMO N Cable 1 500 Ft.

AF No. 4 AF TBD TBD TBD

SUNNYVALE AF Cable I 100 Ft.Cable 8000 Ft.

OFFUTT AF Fiber Optic I 5000 Ft.22 Gauge Cable 200 Ft.

HOWARD A Fiber Optic I 5000 Ft.

NEW BOSTON AF TBD I TBD

19 Gauge Cable I 7000 Ft.

CLARK AF Line of Sight II 6 Miles

WOOMERA AF Cable I 5000 Ft.

AF No. 1 AF TBD I TBD

AF No. 2 AF TBD I TBD

* Three locations with earth terminals not equipped with Cesium beam frequency standards

are Tango, GEODSS I, and GEODSS II, and therefore, will not be addressed further inthis analysis.

E-3

DISTRIBUTION LIST

(I copy unless noted)

STANDARD:

DCA: NCS-TS - I CommanderCode 632 OCA - Northwest Pacific Region

312 APO San Francisco 96328BIOB300 ChiefB400 DCA-Korea Field OfficeB600 APO San Francisco 96301B627B710 ChiefB770 DCA-Okinawa Field Office8780 FPO Seattle 98773B790

ChiefCCTC: DCA-Guam Field OfficeCode C610 Box 141, NAVCAMS WESTPAC

C660 FPO San Francisco 96630

PSI: ChiefCode JllO DCA-Athens Field Office

J300 APO New York 09223J700J800 Chief

OCA-United Kingdom Field OfficeDCEC: APO New York 09378Code RlOO/RlOl

R11O Director (2 copies)Rl20 U.S. Defense Communications OfficeR141 (12 copies) Brussels (NICSMA)R200 (10 copies) APO New York 09667R400 (10 copies)R600 (5 copies) CommanderR800 U.S. Naval Shore Electronic308c Engineering Activity Pacific

Box 130, ATTN: Code 420Commander (2 copies) Pearl Harbor, HI 06860Defense Communications AgencyEuropean Area CommanderATTN: Technical Library Naval Electronic Systems EngineeringAPO New York 09131 Center Portsmouth

ATTN: Technical LibraryCommander (2 copies) P.O. Box 55DCA-Worms Field Office Portsmouth, VA 23705APO New York 09056

ChiefCommander (3 copies) DCA Field Office Italy, Box 166Defense Communications Agency AFSOUTH (NATO),Pacific Area FPO New York 90524Wheeler AFB, HI 96854

~3GK~iPPAGE BIAaIM1,09 FILM

Commander CommanderOCA-Southwest Pacific Region Department of the Air ForceAPO San Francisco 06274 Headquarters 485th Engineering

Installation Group (AFCC)ATTN: Standards/Review BranchGriffis AFB, New York 13441

DTN WORKING GROUP MEMBERS

DirectorDefense Communications AgencyATTN: B780 (Mr. Richard Moriarty)

B790 (Col. Ed Henderson)B710 (Mr. Wes Perkins)

Washington, D.C. 20305

CommanderDefense Communications Agency - European AreaATTN: E400 (Mr. Sam Richardson)APO New York 09131

CommanderDefense Communications Agency - Pacific AreaATTN: P300 (Mr. B. Takano)

P400 (Mr. John Olsen)P41ON (Mr. L. R. Wical)P600 (Mr. Luther Chong)

Wheeler AFB, HI 96854

CommanderDefense Communications Agency Operation Center AEDATTN: N420R (Mr. Ray Parris) (6 copies)

N412 (Mr. Don Spangler)Scott AFB, IL 62225

Department of the ArmyOffice of the Deputy Chief of Staff for Research,Development and Acquisition

ATTN: DAMA-CSCWashington, D.C. 20310

Department of the ArmyAssistant Chief of Staff for Automation andCommunications

ATTN: DAAC-NIS-SCWashington, D.C. 20310

CommanderU.S. Army Communications CommandATTN: CC-OPS-TT (Mr. Harold L. Snellen)

CC-PA-PT (Mr. B. Bess)Ft. Huachuca, AZ 85613

CommanderU.S. Army Communications-ElectronicsEngineering Installation Agency

ATTN: CCC-CED-XEMCCC-CED-XET (Mr. J. Locke)

(Mr. D. Bennett)CCC-CED-STO (Mr. August Jaxel)

Ft. Huachuca, AZ 85613

CommanderU.S. Army Communications Systems AgencyATTN: CCM-CCS (Mr. John Gladis)

(Mr. John Flis)CCM-LG-SI-S (Mr. L. Creameans)

Ft. Monmouth, NJ 07703

CommanderU.S. Army Communications System AgencyATTN: CCM-TT-(H)-TC (Capt. Richard R. Dillon)

(Mr. James Usery)Ft. Huachuca, AZ 85613

CommanderNaval Telecommunications CommandATTN: 623 (Mr. Billy Addison)

(Ms. K. Arellano)4401 Massachusetts Ave., NWWashington, D.C. 20390

CommanderNaval Electronics Systems CommandATTN: PME ll0-241L (Mr. Arne Larson)

PME 110-242M (Mr. Dave Morris)Washington, D.C. 20390

Director of Command Control and CommunicationsHqs U.S. Air ForceATTN: XOKCWashington, D.C. 20330

CommanderAir Force Communications CommandATTN: EPP/XOD (Capt Kirby Austin)

XODTLGMBR

Scott AFB, IL 62225

CommanderElectronics System Division (AFSC)ATTN: DCF-lHansc(i AFB, MA 01731

bJj

CommanderAir Force Logistics CommandATTN: LOWEWright Patterson AFB, OH 45433

Commander1842 Electronics Engineering GroupATTN: EETS

EETTC (Mr. Dennis Janicek)Scott AFB, IL 62225

CommanderDIR MAT MGMTATTN: MMCMMcClellan AFB, CA 95652

CommanderAir Training CommandATTN: TTYKRandolph AFB, TX 28148

Commander-in-ChiefU.S. Army EuropeATTN: C-E DivisionAPO New York 09403

Commander-in-ChiefU.S. Pacific CommandATTN: C3STMHonolulu, HI 96813

Commander-in-ChiefU.S. Southern CommandATTN: Director C-EAPO New York 09827

Director, National Security AgencyATTN: (S-3) (Mr. Dick Brokenshire)

(S721) (Mr. John Massey)(T436) (Mr. Gary Pearlman)

9800 Savage RoadFt. Meade, MD 20755

I