r � -- _..... - .-...... .....

n

Systems

t

- - -

I

an

Sylvania Systems Group Communication Systems Division

GTE Products Corporation 77 A Street

Needham Heights, Mass. 02194 U.S.A.

I

a iliti

1402-81(A)

1r',

........ ... � ....... -.......

utline of Presentation

• ELF communications - Why is it needed?

• GTE - Who are we?

• ELF communications - An overview

• Key features of an ELF system

e Typical ELF transmission system concepts

• Planning for an ELF capability

� .........

�."i't ....... --

1JI' -- �

���<._;_,,.

1225-81

..,.,

-

--- i. !!"'

LF Communication for Improved

3 is Needea NO\N

• Increasingly complex threat environments and effective surveillance employed by enemy forces establishes urgent need for a secure transmission system to provide one-way C3 capability to the forces without compromising detection

• ELF communications can survive the link degradation resulting from ECM and disruption by nuclear effects on the propagation path to establish or reconstitute C3 capability with hardened force command centers and remote survivable weaponry where all other means have been neutralized or destroyed

----- �"',sk,_ �-;· �--"'"" """' II'' ''1'! !(:' P'-""' "i'"l ""!!iil 11'!!�,.� ......._ -- -- ......... ...... .............

7689-82

�. --- _......_ ' . � _..... - � �� --.,..

ornrnunication to

uDrnarines is eeae OV\1

• Submarines are an essential element of national defense and vital to deterrence of nuclear war

• Dependable command communication is essential if submarines are to be effectively utilized for ASW, antishipping or as missile platforms

• Non-ELF communication techniques require an antenna above or near the ocean surface, and thereby compromise a submarine's most important asset- its ability to remain hidden

• A submarine whose position is known at the onset of hostilities may be effectively neutralized

• A submarine that can be neutralized does not contribute to deterrence of a conflict

• ELF communications allows command reception by submarines while they remain deeply submerged, undetected and invulnerable

1239-81

i li

Application

Submarine C3

Mine Field Remote Control

Force Command Center c3

Enduring C3

(Transportable ELF Transmi� sion Systems)

...... ')!· �,,, .._

-,,

� r '

hts of

lrn

Ability to Penetrate Conductive Media Seawater

X

X

X

� -

Earth

X

X

X

f'' '!!! � ,.:.

F Advanta

rovernents

esand

Improved Com. Channel Resistance Improved C3

Operational To Threat Environments Survivability &

Flexibilit� ECM Nuclear Effects Vulnerabilit�

X X X X

X X X

X X X

X X X X

!'!i''''� ""''' ':"'t �,,,, .

3·364-82

r -- --- � ,_,....

TE's ole in ornrnunication

• Developed ELF communications for the U. S. Navy

• Produced receivers installed on U. S. submarines

• Operates transmitter facility in U. S.

• Demonstrated message reception at depth and speed in the Mediterranean, Arctic, Western Pacific, North and South Atlantic

• Is able to provide U. S. Allies with a similar ELF submarine or landbased command and control communication capability

1222-81

GT ontracts for ELF

o�n�nunications

• 1973 - System design of nuclear survivable ELF transmitters and submarine receivers for Project Sanguine

• 1974- Operate and maintain ELF transmitter test facility

• 1974- Design, develop and field ELF Propagation Validation System (PVS)

• 15 Receivers and transmitter modulators

• 1974 - ELF Design Validation for Project Seafarer (DV)

+ Site surveys, environmental impact assessment, preliminary design for 2400-mile antenna, five transmitter sites, and sophisticated rece1ver

• 1981 - Continuation of PVS and DV contracts

• 1982 - Design and development for full-scale system

• Two transmitter sites and 20 receivers

<tf,J� �_i· 't'•o"

Ill$' �,,, -- 11..... --- ...._ --

,,.,.

1364-81

GENERAL TELEPHONE & ELECTRONICS

CORPORATION

• Annual sales and revenues, 9.9 billion

• 227,000 employees

• Ninth largest USA company

• Operations in 41 states and 16 countries

• Creatively develops and utilizes new technology

• A world-wide leader in communication products, systems, and services

....... ....... ..... � - ---

1223-81

� ;.. . r �

I COMMUNICATIONS PRODUCTS- JAPAN

l LICATA

PRESIDENT

� r

I GTE AUTOMATIC

ELECTRIC

J. M. KIRKER

PRESIDENT

� ........... -

J L GTE ELECTRICAL

GTE INTERNATIONAL PRODUCTS

J. C. AVALLON R. J. GRESSENS

PRESIDENT PRESIDENT

I L EUROPE, AFRICA,

GTE LENKURT MID EAST GROUP

M. X. GARVEY A. CARDARELLI PRESIDENT SR. V. P.

I I SYLVANIA TRAINING STRATEGIC

OPERATION SYSTEMS DIVISION

A. DER MARDEROSIAN R. R. FIDLER

V. P. & G. M. V. P. & G. M.

I I

GENERAL TELEPHONE & ELECTRONICS

T. F. BROPHY

CHAIRMAN

AND CHIEF EXECUTIVE

OFFICER

GENERAL TELEPHONE GENERAL TELEPHONE & ELEaRONICS LABORATORIES

T. A. VANDERSLICE D. 0. KISER PRESIDENT AND PRESIDENT

CHIEF OPERATING OFFICER

I GTE COMMUNICATIONS TELEPHONE

GTE TELENET PRODUCTS OPERATIONS

A. L RAYFIELD J. L. JOHNSON J.D. HANN

GROUP PRESIDENT PRESIDENT PRESIDENT

I I SYLVANIA LATIN AMERICA- GTE BUSINESS

SYSTEMS GROUP FAR EAST GROUP COMMUNICATION GTE MICROCIRCUITS

H. E. PATTERSON SYSTEMS

D. 0. WOLKINS W. H. HEFLIN SR. V. P. SR. V. P. & G. M.

J. E. DONNELLY PRESIDENT

PRESIDENT

I I COMMUNICATION WESTERN INTERNATIONAL

SYSTEMS DIVISION DIVISION SYSTEMS CORP.

F. A. GICCA C. G. FIESTER G. H. SACRA

V. P. & G. M. V. P. & G. M. PRESIDENT 159-82 REV, 8/82

I MCC

A. Der Morderosion

-- � -

I BUSINESS

DEVELOPMENT

A.J. Macleod

., -

!!f!'

-.....

SYLVANIA SYSTEMS GROUP

COMMUNICATION SYSTEMS DIVISION

SPECIAL STAFF

R.W. Smartt

I CONTRAaUAL

RELATIONS

R.K. Hillegass

I ADVANCED

SYSTEMS

J.W. Page

"'·

- �

F.A. GICCA

VICE PRESIDENT &

GENERAL MANAGER

A. DER MARDEROSIAN

ASSISTANT

GENERAL MANAGER

(Bus. Acquisition & Bus. Areas)

I CONTROLLER

I

T.F. Warren

I TRI-TAC

SYSTEMS

A.l. Hersh

ENGINEERING

B. Resnick

STAFF

I PRODUa

ASSURANCE

I. Shapiro

DIGITAL SYSTEMS

E.G. Crone

FUNCTIONAL : '

OPERATIONS

A. Kimura

!!!·· ,.,,

l HUMAN

RESOURCES

J.T. Turner

I NETWORK SYSTEMS

R.A. Jolicoeur

ELECTRONIC SYSTEMS

& SERVICES

R.J. Schaffner

'II

I SECURE

SYSTEMS

C.F. Onthonk

''!II;

BUSINESS

I ELF

SYSTEMS

D.A. Newcombe

6542-81 REV. 7/82

r � li,

-- ��� --· -­t

CSD Talent and Facilities

Provide complete turnkey implementation from conception to installation ...

CSD Skills

• Systems engineering

• Architectural studies

• Program management

• Equipment design and installation

CSD Systems Experience

• Satellite terminals

• Digital data systems

• Secure voice arrangements

• Custom-designed systems

• Maintenance operations and training • Special station arrangement

• Fiber optics

• Architectural studies

• Cable transmission

• Microwave transmission

• Wideband switching

• Packet switching 1400-81

TECHNICAL SPECIAL TIES

• Communication systems analysis and design

• Radio equipment design, HF modems, signal processing equipments, COMSEC equipment

• Transmission systems design, antenna design, site surveys, antenna and tower erection

• Computer analysis, programming, digital data terminals

• Facilities design, power systems, security systems

• Training, installation support, site administration and logistics support

- ..... -- �

"

.......... -- .__

1224-81

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82,2060

7667,82

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ELECTROMAGNETIC SPECTRUM USAGE

I

10

<1: Y; i' r! �

q,o l 18

41 "'!to/ 4. ,.,

iJ' R! N� � !IJ s.§ �o s Jj

s�

r---��----1 t ( I I I

100 1 000 10,000 1 00,000 1M FREQUENCY IN CYCLES PER SECOND

I

10M T

1000M 1193-81

PROPAGATION OF ELF SIGNALS

ELF ENERGY

TRAPPED WITHIN

EARTH-IONOSPHERE

CAVITY

... ........ ...... ...... ��;;' �r·, ',� �,,, f* "->11;

... .... ...... L-,,,.

IONOSPHERE

IONOSPHERE HEIGHT

ABOUT 80 km - NIGHT

50 km- DAY

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1216-81

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L8-L6£L

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COMMUNICATIONS COVERAGE

COMPARISON

�-- --- -·- ----

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COMBINED

WISCONSIN/MICHIGAN

FACILITY J

1369-81

r t· ,.. ,_, .- - � - - -

PRESENT ELF TEST SERIES RECEPTION EXPERIENCE

1371-81

NAVY

HEADQUARTERS

e ORIGINATES MESSAGE

• SENDS TO ELF

ELF TRANSMITTER

CONTROL CENTER

e AUTHENTICATES MESSAGE

e FORMATS MESSAGE FOR ELF

e SENDS TO TRANSMITTER STATIONS

ELF USAGE CONCEPT

ELF TRANSMITTER

STATIONS

e AMPLIFY J----e..l ELF SIGNALS

e FEED SIGNAL TO ANTENNA

LINES

,�"t}\', q!i''

ELF TRANSMITTING

ANTENNA

e CONDUCTS ELF CURRENT

e RADIATES SIGNAL

_____ .... __ ...._. .�

SUBMARINE COMMANDER

TAKES

APPROPRIATE ACTION

0

ELF RECEIVER

e RECEIVES ELF SIGNAL

e DECODES MESSAGE

1370-81

-

Key Features of ELF

Cotnrnunication

• Penetrates sea water, ice and the earth

• Allows continuous communication reception by submarines at depth, and to hardened force command centers

• Assures submarines will remain undetected and invulnerable

• Maintains submarine's condition of readiness for mission response

• Provides near global coverage from a single transmitter site

• Can be crypto-secure and jam protected

• Is fully within current state-of-the-art

--- .... - - -- ....._ lilioa.- c �':

1226-81

�--------- --���-�'

ELF COMMUNICATIONS

APPROACH

LANDBASED SEGMENT SEABASED SEGMENT

CONTROL/ MONITOR

TRANSMITTER ELF ANTENNA

TRAILING WIRE PRE-AMP

CONTROL -

TRANSMITTER r- .I- 1--

1.....--.---- ··-� -- �---� -- � -ANTENNA

The Transmitter Control Segment and the ELF Transmitter can be separated by large distances and interconnected with appropriate communications

1-- RECEIVER

CONTROL/ MONITOR

1191-s·l

TRANSMITTER CONTROL

BLOCK DIAGRAM

CONTROL

&

MONITOR

t -- COMMUNICATIONS -- PROCESSOR 1--

TERMINALS -.....

t CRYPTOGRAPHIC I KEY GENERATOR i

.'�" �� . . '.''· t':· .,, I!''" . if;:"" ''�� if'' " '""' Iff!': ' '".'"ll! ..... ... -.- ...... .... .. ...... ....... ........

- ---- _ _j

TO

ELF

TRA.NSMITTER

1197-81

r r-�t;.

....-. .......- � ,........ __... - -

MODULATION, FREQUENCY & CODING

SELECTION MODULATION

• MSK GIVES A NEAR OPTIMUM BANDWIDTH AND IS EASILY IMPLEMENTED

80Hz 72Hz

FREQUENCY

• ELF SIGNALS PROPAGATE WITH VERY LITTLE ATTENUATION, e.g., PATH LOSS OF 1 dB PER 1000 km AT 100Hz

• ELF SIGNALS PENETRATE USEFUL DISTANCES DOWN INTO THE OCEAN, e.g., 0.09 dB/FT AT 75 Hz

CODING

• ORTHOGONAL (BLOCK)

• CONVOLUTIONAL

MESSAGE BITS

MESSAGE BITS

TAIL BITS 1215-81

ELF Transmitting Antenna

• A practical transmitting antenna for ELF consists of:

+ A long horizontal cable

+ Cable may be above, on or below the surface of the earth + Antenna must be grounded at each end + Antenna normally powered at or near its center

• The transmitting antenna excites electromagnetic waves in the spherical cavity bounded by the ionosphere and the surface of the earth

• Radiated power is a function of IL product

w2(1L)2 Pr =

2 watts

Be ha e

• Low conductivity areas are desirable to improve antenna efficiency

........ ...... - - ........ $¥> �

� L.:: .............

'-" ,,-,-

1390-81

r r---.......-�--- ·�..,..._

ELF TRANSMITTING ANTENNA

• If perpendicular lines are installed and the antenna currents suitably phased, the antenna pattern can be steered

• Attenuation rate of ELF propagation is on the order of 1 dB per 1 000 km of path length at 1 00 Hz

1233-81

L8-Z6L L

N�3ll 'f/ d NOll 'f/IO'f/�

r---- --- ----

Horizontal Grounds

• Resistance of grounds depends inversely on the product of installed length and effective ground conductivity

• Step potential is proportional to

d = burial depth L = length

• Installation factors

+ Multiple wires and feed points + Horizontal length + Burial depth + Long right of way requirements

(J = ground conductivity

+ Desirable to locate in relatively high conductivity surface layers + Wire size determined by mechanical handling and strength + Easy access to wire after burial + Large area to survey for conformance to safety requirements + Vertical rods

I (J Ld

1401-81

PROPAGATION MEASUREMENTS

o =DAY • =NIGHT

ex

-

E E :2:;

--

m "C -

tS

20 50 100

FREQUENCY (Hz)

PROPAGATION IS NOT UNIFORM IN POSITION, TIME OR DIRECTION DUE TO VARIATIONS OF THE LOWER STRUCTURE OF THE IONOSPHERE 1195-81

� ·*'fli,

..... ..... ..... ..... ..... ..... ...... ..... � -

r r ---�----

ELF Propagation and Excitation Characteristics

Propagation loss, dB per 1 000 km

Seawater penetration, db per ft

Relative transmitting antenna efficiency, dB

45Hz 76Hz 140Hz

0.75

.07

-4.4

1.2

.09

0

2.0

0.12

+2.5

1399-81

'-- 111111111111111 w�,

%�

� --

RECEIVING ANTENNA

BUOY ANT E FIELD TRAILING WIRE ANTENNA WITH ELECTRODES

SPACED 1000 FT APART

ANTENNA PATTERN

H FIELD ANTENNA

ELECTRODES

OPTIMUM DIRECTION FOR RECEPTION

DIRECTLY TOWARD OR DIRECTLY

AWAY FROM TRANSMITTER

• BEYOND CURRENT STATE OF THE ART

e OMNI-DIRECTIONAL 1214-81

�""-,•\lJt;' �"'"'

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.... �"

........

tr ' ·" ""; �

["�'l . "''" "''"'' !'*"' ,_

r r: r r r !!�"""""'" - -- -

RECEIVER FLOW DIAGRAM

I 1 ANTENNA

GAIN AID

AID - r---------- ANALOG f-------<- CONTROL r----- r----- GAIN

l PRE-AMPL. FILTERS AMPLIFIER CONVERTER CONTROL

SPEED, DEPTH, CONDUCTIVITY

DATA

l LOW OCEAN

PRE-EMPHASIS ADAPTIVE

L_. PASS COMPENSATION 1--- FILTER � NOTCH

1 FILTER FILTER FILTERS

GAIN

� KEY � DIVERSITY

� PHASE

CONTROL COMBINING ESTIMATOR

l NOISE

QUADRATURE AI PHASE

DEINTER-MESSAGE

l.....-CLIPPER 1--l...-oo MATCHED

SHIFTER f----- LEAVER & -DECODER 1--

FILTER � QUANTIZE A

GAIN � CONTROL

(OUTPUT)

I MESSAGE EXPANSION I TO 1/0 nFVIr.F

1187-81

RECEIVER GENERAL DESCRIPTION

• MSK modulated waveforms represent message chips

• Analog signals received by E field antenna

• The signal is digitized after filtering and AGC

• Receiver computer program performs signal processing to recover the original ELF message

• Decoded messages are provided to the operator

,,

..... ... ..... .... .... ..... ...... ....... a.-... .........___,

1231-81

r �

i - ,........ �

t � ,........... --

RECEIVER OPERATION

• Receiver segment is chip and keystream synchronized with the MIS/TS through the use of highly stable time and frequency standards located at each site

• Message synchronization between the MIS/TS and receiver is achieved through the definition and adherence to predefined times at which the end of the first block of any message will terminate

• The receiver and transmitter operates at Rc chips per second to provide noise and jam protection

1228-81

� 5.7 X 105 CC

EXISTING SUBMARINE RECEIVER

......... � ...... ...... ....... ........

rends in Receiver

eveloprnent

�.,__, �J-, ·:�.,-,

rro......- �

� 2.8 X 104 CC

DEVELOPMENT SUBMARINE

RECEIVER

'"'l\1'

1.2 X 103 CC

D DEVELOPMENT

MINE RECEIVER

3740-81

Typical ELF Transmitter and

Antenna Requirements for

Moderate Systems

System Short Range System Features 400 km

Application: • Reconstitute command center C3 connectivity in trans- and post-attack envi-ronment

• Mine reco

Coverage area: 400 km dipole pattern

Antenna length: 12 km line

Transmitter power: One 10 kw P.A.

.._... ..._ __ ___ _

Medium Range System long Range System 1400 km 3000 km

e Submarine comrnunica- • Submarine communica-tions tions

• Mine reco

1400 km dipole pattern 3000 km omni-pattern

15 km line 20 km crossed dipole

One 50 kw P .A. Two 200 kw P.A.

3446-82

�r - ,..-.. r-- r

- --

DERIVATION OF REQUIRED CURRENT MOMENT

PERFORMANCE MODULATION \ IMPLEMENTATION ATMOSPHERIC

REQUIREMENTS AND CODING �- AND

NOISE 1--

ALLOWANCE OCEAN NOISE

IDEAL Eb

iN0

\ IDEAL SIN

0 SIN

e AT DEPTH

\ I FRONT END I\

AT SURFACE EREQ

RQIL

REQUIRED CURRENT

MOMENT

.I

ANTENNA

FILTERING

-

I I

ROUND THE DIRECT i WORLD CHANNEL

f4-CHANNEL :

RQIL + MARGIN 1200-81

DERIVATION OF REQUIRED CURRENT MOMENTS CONSIDERING DIRECT WAVE ONLY

CURRENT MOMENT

~ � 1 -ad ��R).

h2o-e

cis e � 1 Lf sin (d/ lEvi = 2

"-. """ ATTENUATION "-. EXCITATION COEFFICIENT

SPREADING FACTOR

IN NEPERS/Mm FACTOR

1TEo 20 log (IL) = 20 log (EREQ) - 20. log f - 1 0 log 2R c

+ 10 log sin (d/R - 20 log 1

h2a e

C!v +ad

= 20 log (EREQ) - 20 log f + 261.38

+ 10 log sin (d/R) - 20 log � + ad

..... ..... ..... � ..... ---�

1217-81

r � � ..

- ......... r � ---

\' \ . Is �·

- - -�

SMOOTHED WORST CASE ATMOSPHERIC NOISE

USED FOR SYSTEM SIZING

l () -

a: w J: o..­cn::I: om :E� � ztJ)

0000 0400

,... -

/ / "- ..( MEDITERRANEAN

I I

/

.--.-/ PACIFIC \ I '

I ' I .._ __

0800 1200 1600 2000 2400

- TIME OF DAV -­

(GMT) 1201-81

Chief Paran�eters for IL

Reauirernent Esti�nate

• Data rate: 1/2 bit per minute (1 0 bits in 20 minutes)

• Receiving antenna • Performance similar to 300m electrode spacing (600m total length)

trailing wire submarine antenna towed at 10 knots (5.1 m/s) at 1OOm depth

• 1OOm of seawater produces the same attenuation as about 4 km of "average" earth

....... ...... .... �� ..... - - -

3445-82

r: ,........ � .

� _.. ............ ,......._ __..... .--., -

1 0 w 0:: ::;:) d w 0::

� "'--' ..J

�

(.!) 0 ..J

0 N

I

190

180

170

160

150

140

I

' I

�

'\.

IL REQUIREMENTS VS FREQUENCY AND RANGE

-� 1,400km

400km

DATA RATE= 1/2 bpm Ne = -139dBHo AT 76Hz 600m/300m TRAILING WIRE 10 KNOTS AT 100m

if I I I I I I '.1 50 100 150 200 250 300

---- FREQUENCY (Hz) ----

3449-82

Assumptions for Esti�natin

O\Ner Reauirernents

• Antenna length: 20 km (plus ground assemblies)

• Site effective conductivity: 5x1 0- 4Sfm

• Antenna cable: 1 os circular mils (25.4mm effective diameter) aluminum

• Terminal grounds: 1.5 n each (two per antenna line)

• One antenna line

• Coverage will not be omniazimuthal unless two orthogonal lines are used

• Double ELF power for two lines

'!'' f'' '!iii ""t----1� ----- lillilllllip --. ........ ... ..... � �-

3442-82

� ,.....,

t -� al "0 -

u. ...J w

c..

(!) 0 ...J

0 �

� � ..

,......., ."'

70 (10Mw)

60 (1Mw)

50 {100kw)

I

40 (10kw)

.....,... �

� .-..... -....,_ ,.....

J

ELF POWER REQUIREMENTS VERSUS FREQUENCY AND BANGE FOB EXAMPLE SYSTEM (SINGLE ANTENNA)

' � 1,400\<m

400km

� 300 50 200 250 100 150

- FREQUENCY (Hz) --. 3441-82

ELF POWER REQUIRED FOR EXAMPLE SYSTEM VERSUS LINE LENGTH AND RANGE (SINGLE ANTENNA)

f =150Hz

60 + (1Mw)

t -

:5: 50+ (100kw) CQ

� u.. + (50kw) -' w

0..

(!) 0 ..J

0

40 + (10kw) .....

30 -1- (1kw)

'-"""'

5f I I I I I I I I I 5 10 15 20 25 30 35 40 45 50

ANTENNA LENGTH (kw) .. 3440-82

--... ......... -- � ...... - -- -- -

,.,� �� ,...... �� '? \}0. ;(-\ )I!

FRANCE

- -

AUSTRIA

COVERAGE AREA FOR POSTULATED

400km ELF COMMUNICATIONS SYSTEM

POLAND

HUNGARY

3450-82

... ......

�<e­�...,o

& CJ *S'

� �

D

COVERAGE AREAS FOR POSTULATED 1400km AND 3000km ELF COMMUNICATIONS SYSTEMS

-- ...... ....... ...... -- ...... ....__

·�

- AREAS OF FAVORABLE BEDROCK RESISTIVITY

3439-82

zs·Lvv£

L::l ooo'oL

t L::l 00£

1:13MOd ::113

31:1011\1 S3li\IIL OOL

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AL IAILSIS3l:l >I�Ol:I038

SA

A�N31�1::1::13 ::113

-

TRANSMITTER AND ANTENNA SENSITIVITY

TO SITE LOCATION

PARAMETER SITE A SITE B

SITE CONDUCTIVITY 10·5 MHOS/m 10-3 MHOS/m

RQIL 106 A-m 107 A-m

LINE LENGTH 6 km 6 km- 60 km

TRANSMITTER POWER 152 kw 15,200 kw - 523 kw

1227-81

..... ......... -- � -- - ........., - .._ .........

�� � _.....,. � r i

,,

,__ -

� �,,

�

Summary Table of Applications

For ELF Communications

Application Force Elements Basing Location Major Improvements

1. Submarine • SSBNs Undersea • Improved S&V communica- • SSNs • Resistance to jamming and tions • SSGs nuclear effects

• SSs • ASW detection • Surveillance vehicles • Covert operation flexibility

• Maintain station depth and speed

2. Undersea • Mines Undersea • Establish C2 where none oth-weapons C2 • Captor mines erwise existed

• Flexibility in mine deployment • Recovery

3. Land based • Missile CPs Underground • Reconstitute C3 during severe weapons C3 • Command and control ECM and nuclear stressed en-

centers vironment • Mine fields • Mine field C2 and recovery • Tactical fusion cen- • Improved mission planning C31

ters

4. Survivable/ • Land mobile transmit- Land, sea • Establish or reconstitute C3 transportable ter post attack ELF transmit- • Shipboard transmitter • Resistant to jamming and nu-ters to sup- clear effects port enduring C3

3365-82

.:113 NV' l:l

rr ,......, �·

� !'

...,._ ,......_ l.J,

� - -..... ..

Planning an ELF Program

• Establish requirements for ELF utilization in defense planning

• Perform an ELF site optimization study to determine the following planning objectives:

1. Determination of a site location for an ELF transmitting antenna

2. Size the transmission system and define requirements for the transmitter, antenna, grounds, and receiver

3. Develop construction and implementation plans for the initial and final operating capability

7690-82

�

GIVEN INPUTS e UTILITY/TELEPHONE MAPS

e GEOLOGY/CONDUCTIVITY DATA

o PERFORMANCE REQUIREMENTS

e TERRAIN & FORESTRY MAPS

Site Optimization Study

Functional Activities Diagram

PERF. REQMTS. PERFORMANCE EVAL.

AGAINST REQMTS.

SELECT NEW SITE

I I PRELIMINARY DESIGNS

INPUTS � DATA BASE I SITE

, DEVELOPMENT DATA SITE I SITE

SURVEY LOCATIONS

SYSTEM �REQUIREMENTS! •1

DEFINITION

• CONSTRUCTION FACTORS • COST DATA

• GTE DEV. INPUTS

....... ..... � --- ---'!" --

MIT. DATA

--r . '!!.

MITIGATION STUDIES

OPTIMIZATION STUDY DOCUMENTATION e SITE CHARACTERIZATION

REPORT

• ANTENNA CONSTRUCT. &

INSTALLATION PLAN

e SYSTEM SIZING REPORT

• MITIGATION STUDY REPORT

1199-81

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ite Optimization Stuay

Task Development

TASK 1

PERFORM SITE SURVEY

INPUTS

o GEOLOGIC MAPS

o MAPS OF TERRAIN

• MAPS OF NATIONAL GRID

o GROUND CONDUCTIVITY DATA

SUBTASKS

• DEVELOP PRELIMINARY SITING PARAMETERS

• PERFORM CONDUCTIVITY MEASUREMENTS

• SELECT CANDIDATE EX. SITES

• PERFORM ANTENNA SYSTEM

REQUIREMENTS ANALYSES

• CONDUCT ANTENNA AND GROUND PERFORMANCE ANALYSIS

• DEVELOP BEDROCK GEOLOGICAL DATA

• DEVELOP SURFICIAL GEOLOGICAL LAND USE AND SOILS DATA

• DEVELOP ANTENNA CONSTRUCTION AND

INSTALLATION PLAN

PRODUCTS

• RECOMMENDED FULL SCALE ELF

ANTENNA SYSTEM LOCATION

• RECOMMENDED EXPERIMENTAL ANTENNA SYSTEM LOCATION

• GEOGRAPHICAL DATA

• CONDUCTIVITY DATA

• ANTENNA INSTALLATION PLAN

OUTPUT

• TECHNICAL REPORT

e BRIEFING --- ---

TASK2

SYSTEM REQUIREMENTS DEFINITION

INPUTS

• ANTENNA LOCATIONS

• COMMUNICATIONS REQUIREMENTS

• CONDUCTIVITY

• GEOGRAPHICAL DATA

SUBTASKS

• DEVELOP SYSTEM PERFORMANCE REQUIREMENTS

o DEVELOP TRANSMITTER

REQUIREMENTS

• DEVELOP ANTENNA REQUIREMENTS

• DEVELOP ANTENNA GROUND

REQUIREMENTS

• DEVELOP TEST REQUIREMENTS

PRODUCTS

o COMMUNICATION SYSTEM DEFINITION

• MODULATION, CODING AND MESSAGE FORMATS

o TRANSMITTER, ANTENNA AND GROUND DESIGN

' • POWER REQUIREMENTS

I o SITE SELECTION I

I OUTPUT

I I o TECHNICAL REPORT I

o BRIEFING

TASK3

CONDUCT MITIGATION STUDIES

INPUTS

o MAPS OF POWER DISTRIBUTION SYSTEM

• COMMUNICATIONS CHARACTERISTICS

• MAPS OF TELEPHONE NETWORK

SUBTASKS

o DEFINE MITIGATION THRESHOLDS

• DEFINE POWER SYSTEM MITIGATION CONTOURS

• DEFINE TELEPHONE SYSTEM MITIGATION CONTOURS

• DEFINE TELEPHONE AND POWER SYSTEM TECHNIQUES

o DEFINE SPECIFIC CUSTOMER MITIGATION REQUIREMENTS

PRODUCTS

• MITIGATION TECHNIQUES

• MITIGATION REQUIREMENTS

• COMPUTER PROGRAMS FOR

MITIGATION PREDICTION

• DESIGN GUIDELINES

OUTPUT

• TECHNICAL REPORT

• BRIEFING

5980-SOE

DEVELOP

PRELIMINARY

SITING PARAMETERS FROM:

• GEOLOGY MAPS

• ROCK TYPE CHARACTERIZATION

f-• AVOIDANCE AREAS

• EXISTING a DATA

• GOVERNMENT OWNED LAND MAPS

...... --- - ......... .......,

ELF SITE SURVEY APPROACH AND EVALUATION METHODOLOGY

PERFORM

CONDUCTIVITY

MEASUREMENTS c.-...,

...... .�>·

........

ANTENNA SYSTEM

REQUIREMENTS

ANALYSIS

DEVELOP SELECT

AREA FULL

a MAPS SCALE

• CONTOUR ANTENNA

e LAYERED EARTH LOCATIONS f--

r.-J PERFORM SITE

:_____.,. SELECT CANDIDATE SPECIFIC a

EXPERIMENTAL r-f----. MEASUREMENTS

SITES

.._____

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.........

• ANTENNA

• GROUNDS

SELECT

ALTERNATE

SITE IF

REQUIRED

f' �, 1!"- -� �

PERFORMANCE

ANALYSIS

• ANTENNA SIZING 1--• TERMINAL GROUNDS

• PREDICTED IL

RE-EVALUATION RECOMMEND ELF

OF SITE SELECTION �

ANTENNA SYSTEMS

AND DESIGN 1. FULL SCALE

OBJECTIVES 2_ EXPERIMENTAL

5965-SOE

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CONDUCTIVITY MEASUREMENT TECHNIQUE

• Audio frequency magnetotelluric (AMT) method is used.

• AMT technique measures the impedance of natural electro­magnetic energy propagating into the ground.

• The energy source is generated by world-wide thunderstorms.

• The propagated energy is refracted into the earth and depth of penetration is dependent on conductivity and frequency.

• Instrumentation measures the horizontal magnetic (H) and electric (E) fields as a function of frequency.

f • Conductivity = 5 2 MHOS/M

1.26 X 10 x (E/H)

• Instrumentation consists of horizontal dipole E-field sensor, a coil H-field sensor, and a variable frequency receiver

• Frequency range from 1 0 Hz to 1 0,000 Hz provides information on earth conductivity as a function of depth into the earth.

1218-81

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SCHEMATIC DIAGRAM OF AMT DETECTION EQUIPMENT

ELECTRIC FIELD SENSOR

Ex,y

,----

-- -,

I I I I I I LOW PASS

H FILTER I x,y I 10kHz CUTOFF

I I

ILRECEIVING COIL _jl ------

MAGNETIC FIELD SENSOR

-- --- ........ � - --- w;.·; [;�""' ............

50/60Hz

REJECT FILTER

-.w-���....M.

LOW PASS FILTER

E INPUT TO t • INTERFERENCE

10 kHz CUTOFF ANALYZER

50/60Hz

REJECT FILTER

H INPUT TO �---------.INTERFERENCE

ANALYZER

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CONDUCTIVITY CHARACTERIZATION

BASED ON GEOLOGY ANALYSIS

a a � 2.1 X 10- 4

� 2.1 X 10- 4 � a � 10-3

[IJ] 10-3 �a� 10-2

EL] 10-2 �a

CONDUCTIVITY IN MHOS/METER

1204-81

Suggested ELF Develop�nent

Program

• Phase 1 -Site optimization study (8 months) • Site survey

• System requirements definition

• Mitigation studies

• Full-scale system site location

• Develop construction and implementation plans

• Phase 2 -Full-scale system • Detail design for antenna and grounds

• Facilities design for transmitter and tuning

• Site construction and antenna installation

• System checkout and test

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ELF Con�n�unications

• ELF provides continuous communication to deeply submerged submarines and hardened force command centers

• Assures mission readiness

• Assures invulnerability

• ELF has proven "world wide" performance

• GTE provides off-the-shelf system and equipment designs and turn-key operational capability

1447-81

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