unclassified 6/26/2015 huntsville, alabama slide 1 stab propation analysis status summary &...

UNCLASSIFIED

UNCLASSIFIED04/18/23

Huntsville, Alabama

Slide 1

STAB Propation AnalysisStatus Summary &Emerging Results

James Dawson

6/1/01

UNCLASSIFIED


Huntsville, Alabama

Slide 2

(U) STAB Communication Assessment Objectives:

Assess the capability of STAB and related laser technologies for basis of battlefield communication network

Determine to what degree will rain, fog, smoke, dust, terrain, and other obscurants degrade laser communications

Define & compute the probability of “successful communication” under varying weather data

Period of Performance: 6 Mar 2001 - 18 Dec 2001

Resources:

2435 Labor Hours ($138,721.95)

Travel ($6,600)

ODCs ($4678.05)

Total: $150,000

COTR: Mr. Brian Matkin, Smart Weapons Management Office

Deliverables:

Final Technical Report (Communications Study)

IPRs

Final Briefing

Monthly Performance and Cost Reports

Technical and Management Work Plan

UNCLASSIFIED


Huntsville, Alabama

Slide 3

(U) ESSENTIAL ELEMENTS OF ANALYSIS

Determination of Link Parameters

Characterization of “Reasonable” Technological Capability

Impact of Complex Atmospheric Phenomenology:

Atmospheric Turbulence and Corrective Techniques

Natural and Induced Aerosol (Smoke, Dust, Fog, Cloud)

Terrain Effects

Mitigation Techniques

Determination of Appropriate Models

Availability of Propagation Measurements for Model Verification

Communication Topology Implications

Requirements for Nearest Neighbor Maximum Separation

Determination of Link Parameters

Characterization of “Reasonable” Technological Capability

Impact of Complex Atmospheric Phenomenology:

Atmospheric Turbulence and Corrective Techniques

Natural and Induced Aerosol (Smoke, Dust, Fog, Cloud)

Terrain Effects

Mitigation Techniques

Determination of Appropriate Models

Availability of Propagation Measurements for Model Verification

Communication Topology Implications

Requirements for Nearest Neighbor Maximum Separation

UNCLASSIFIED


Huntsville, Alabama

Slide 4

PARAMETERS

• Laser Power

• Wavelength

• Receiver Sensitivity

• Beam Dispersion

• Terrain Data

• Geographic Location

• Weather Data

• Grid Altitude

• Separation Distance

MOEs/MOPs

• Propagation Range Limits for Various Conditions

• Network Robustness

• Link Availability

• Probability of Successful Communication

• Percent of Grid that Can Communicate

(U) KEY PARAMETERS AND MOEs/MOPs

UNCLASSIFIED


Huntsville, Alabama

Slide 5

Coordination With DARPA, SMDC, & STAB Contracts Will Be Coordination With DARPA, SMDC, & STAB Contracts Will Be MaintainedMaintained

Coordination With DARPA, SMDC, & STAB Contracts Will Be Coordination With DARPA, SMDC, & STAB Contracts Will Be MaintainedMaintained

• Review, survey, and select appropriate models

• Obtain models and make operational

• Refine appropriate Essential Elements of Analyses (EEAs) and MOEs/MOPs

• Obtain weather & terrain data for appropriate regions such as NEA and SEA

• Obtain all needed parameters for laser communication links and network

• Determine appropriate weather states and probabilities of occurrence

• Develop definitions of weather states including spatial structure

• Determine operational configuration of network

• Identify and model all mechanisms for SNR degradation

• Solve for maximum range for successful communication for each weather state and altitude

• Determine probability of successful communication given operationally constrained separation distances

• Perform limited sensitivity study by varying laser parameters

• Document assessment in briefing and final report

(U) METHODOLOGY

UNCLASSIFIED


Huntsville, Alabama

Slide 6

Review, survey, and select models

Obtain models and make operational

Obtain weather & terrain data

Determine laser link parameters

Determine weather states & probabilities

Develop definitions of weather states including spatial structure

Determine operational configuration

Identify and model SNR degradations

Solve for max range for successful communication

Determine prob. of successful comm.

Constrain separation based on operational requirements

Perform limited sensitivity study by varying laser parameters

Refine EEAs and MOEs/MOPs

Document assessment in briefing and final report

(U) METHODOLOGY

UNCLASSIFIED


Huntsville, Alabama

Slide 7

Atmospheric PhenomenologyAtmospheric PhenomenologyAtmospheric PhenomenologyAtmospheric Phenomenology

(U) Models/Data To Be Considered

HITRAN: Compilation of spectroscopic parameters used by models to predict

transmission & emission of light in the atmosphere Hi-resolution, supports analysis of molecular absorption of laser lines

FASCODE: First principles, line-by-line atmospheric radiance and transmittance code

PROTURB: Developed by the Battlefield Environment Directorate of Army Research

Laboratory Calculates an estimate of optical turbulence strength Effects on laser system performance

EOSAEL: e.g. COMBIC: Combined Obscuration Model for Battlefield Induced

Contaminants

HITRAN: Compilation of spectroscopic parameters used by models to predict

transmission & emission of light in the atmosphere Hi-resolution, supports analysis of molecular absorption of laser lines

FASCODE: First principles, line-by-line atmospheric radiance and transmittance code

PROTURB: Developed by the Battlefield Environment Directorate of Army Research

Laboratory Calculates an estimate of optical turbulence strength Effects on laser system performance

EOSAEL: e.g. COMBIC: Combined Obscuration Model for Battlefield Induced

Contaminants

UNCLASSIFIED


Huntsville, Alabama

Slide 8

(U) Propagation Effects

Turbulence Molecules Particulates Water DropletsFocus &Aperture

Sensitivity& Aperture

Transmitter/Receiver Separation (Range)

Alignment Errors

• oxygen• nitrogen• water vapor• carbon dioxide• trace gases

UNCLASSIFIED


Huntsville, Alabama

Slide 9

AEROSOLS

(SMOKE,

DUST,CHAFF)

DRY WET FROZEN

GROUND CLUTTER

EVAPORATION

(HUMIDITY)

(RAIN)

WIND

VEGETATION SNOW COVER

SOLAR LOADING

SIGNATURE(ALTERATION)

TURBULENCE

PRECIPITATION

(SNOW)

CONDENSATION

(CLOUDS/FOG)

(U) Propagation Issues

UNCLASSIFIED


Huntsville, Alabama

Slide 10

M A M J J A S O N D

PERIOD OF PERFORMANCEACTIVITY/ACTION

Contract Award

Kick-off Meeting

Develop EEAs andMOPs/MOEs

Obtain Req’d Data & Models

Develop Network Operational Config.

Define & Evaluate Weather States

Parametric Analysis

In-Process Reviews

Develop Solutions for Max. Prop. Range

Technical Report Draft Final

(U) SCHEDULE

UNCLASSIFIED


Huntsville, Alabama

Slide 11

(U) Network Communication Studies NRC did laser propagation

study

4 types of links (sat/blimp/ground)

Times of 5 min to 6 hrs.

Limited by dense fog data available supports 4 km

range determination

Any “better” condition than fog can be handled How often is that the case?

Need to look at intervisibility as “random” effect independent of weather effect spatially uncorrelated?

Choose Grid “Size” (spacing) 3 - 4 km in fog expected size

Vary height relative to terrain+vegetation Need DTED and Vegetation data

Recommend platforms for gridded network aerostat

aircraft

masted ground stations

Topology with Smart Controllers Seeking 95% operability

UNCLASSIFIED


Huntsville, Alabama

Slide 12

0.0001

0.001

0.01

0.1

1

10

100

1000

0 2 4 6 8 10Exit & Entrance Aperture Diameter (cm)

Re

qu

ire

d T

ran

sm

itte

d P

ow

er

(mW

)

10

100

1000

10000

Div

erg

en

ce (

rad

)

Trans. Power

Beam Divergence

Output Power Requirements, Ideal Environment

• Assumptions– Uniform Beam– Diffraction Limited– Shot-Noise Limited– No Background

2R

2T

2

22

RT aa

RPP

hc

SNRPR

• Parameters– Bandwidth: Dn=1 GHz– Wavelength: l=1.55 mm– Signal-to-noise: SNR=10– Range: R=4 km– Transmit Aperture Radius: aR (varies)– Receive Aperture Radius: aT (varies)– Constraint: aR = aT

Diffraction LimitBeam Propagation

Shot-LimitedPhoton Detection

• Assumptions (cont)– No Attenuation– No Turbulence– Perfect Alignment

UNCLASSIFIED


Huntsville, Alabama

Slide 13

0

5

10

15

20

25

30

1.00E-15 1.00E-14 1.00E-13

Cn2 (m -2/3)

r 0 (c

m)

Turbulence Effects on Beam Divergence

53

2n

560 RC

8

3185.0r

Weak Moderate Strong

Fried’s Coherence Diameter(Determines maximum effective

size of output aperture)

0.0001

0.001

0.01

0.1

1

10

100

1000

0 2 4 6 8 10Exit & Entrance Aperture Diameter (cm)

Re

qu

ire

d T

ran

sm

itte

d P

ow

er

(mW

)

10

100

1000

10000

Div

erg

en

ce (

rad

)

Trans. Power (max turb)

Trans. Power (no turb)

Beam Divergence (max turb)

Beam Divergence (no turb) Beam DivergenceNot Degraded by Turbulence

For Aperture Diameters < ~2 cm

Effects of Turbulence on Pointing (jitter) and Fading

(scintillation) Remain Significant Issues

Effects of Turbulence on Pointing (jitter) and Fading

(scintillation) Remain Significant Issues

UNCLASSIFIED


Huntsville, Alabama

Slide 14

0.986

0.986

0.986

0.986

0.987

0.987

0.987

0.987

0.987

0.988

-10 0 10 20 30 40 50 60

Temperature (C)

Tra

ns

mis

siv

ity

Molecular Absorption Effects

Computations Based on LZTRAN Module from EOSAEL-

92

Computations Based on LZTRAN Module from EOSAEL-

92

• Parameters– Pressure: 1013.3 mb– H20 Vapor: 2.596 mb– Range: 4 km– Wavelength: 1.54 mm

UNCLASSIFIED


Huntsville, Alabama

Slide 15

NEA Terrain Analysis

SOUTHERN

KOREA

WEST

EAST COAST

126° E

126° E

128° E

128° E

40° N

38° N

36° N

40° N

38° N

36° N

Northeast Asia Climatic Zones

Northeast Asia Climatic Zones

DTED Level 1(1 deg x 1 deg)

DTED Level 1(1 deg x 1 deg)

Sample Terrain Relief Profile

Sample Terrain Relief Profile

Analysis Tool For Terrain Intervisibility Utilized to Determine

Grid Performance

Analysis Tool For Terrain Intervisibility Utilized to Determine

Grid Performance

UNCLASSIFIED


Huntsville, Alabama

Slide 16

Example Terrain Intervisibility ResultsLOS Vs. Terrain

(Off-set = 60m)

0

50

100

150

200

250

300

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44

Pixels

Ele

vati

on

(m

)

LOS Vs. Terrain (Off-set = 0m)

520

540

560

580

600

620

640

660

680

700

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44

Pixels

Ele

vati

on

(m

)

Effects of Sensor Off-set on LOS(4km Range)

0

10

20

30

40

50

60

70

80

90

100

0 20 40 60 80 100 120 140 160

Sensor Off-set (m)

Per

cen

t L

OS

Effects of Range of LOS(60 m Sensor off-set)

0

10

20

30

40

50

60

70

80

90

100

0 5 10 15 20 25

Range (km)

Per

cen

t L

OS

UNCLASSIFIED


Huntsville, Alabama

Slide 17

Terrain Intervisibility Results: Regional Comparisons

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

0.1 1 10 100 1000

Height Offset

Pro

bab

ility

of

LO

S 0.5 km1.0 km1.5 km2.0 km2.5 km3.0 km3.5 km4.0 km4.5 km5.0 km

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

0.1 1 10 100 1000

Height Offset

Pro

bab

ility

of

LO


0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

0.1 1 10 100 1000

Height Offset

Pro

bab

ility

of

LO


0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

0.1 1 10 100 1000

Height Offset

Pro

bab

ility

of

LO

S

0.5 km1.0 km1.5 km2.0 km2.5 km3.0 km3.5 km4.0 km4.5 km5.0 km

Ft. Hunter Liggett

National Training Center

NorthEast Asia

SouthWest Asia

UNCLASSIFIED


Huntsville, Alabama

Slide 18

Terrain Intervisibility Results: Regional Summaries

0

20

40

60

80

100

120

140

0 1 2 3 4 5 6

Range

Off

se

t H

eig

ht

for

PL

OS=5

0%

NEA

SWA

FHL

NTC

0

50

100

150

200

250

0 1 2 3 4 5 6

Range

Off

se

t H

eig

ht

for

PL

OS=7

0%

NEA

SWA

FHL

NTC

0

50

100

150

200

250

300

350

0 1 2 3 4 5 6

Range

Off

se

t H

eig

ht

for

PL

OS=9

0%

NEA

SWA

FHL

NTC

Offset Height Required for PLOS=70%






SWA and NEA represent extreme conditions for achieving accept LOS conditions for LaserCom

SWA and NEA represent extreme conditions for achieving accept LOS conditions for LaserCom

UNCLASSIFIED


Huntsville, Alabama

Slide 19

(U) Statistical Grid Analysis: No “Controllers”

N

M

Number of nodes with 4 neighborss is (M-2)(N-2)=12Number of nodes with 3 neighborss is 2(M+N-4)=16Number of nodes with 2 neighbors is 4Total of M*N nodesProbability of successful link is PFor grid to work, each node must have at least one

good link to a neighboring node

Number of nodes with 4 neighborss is (M-2)(N-2)=12Number of nodes with 3 neighborss is 2(M+N-4)=16Number of nodes with 2 neighbors is 4Total of M*N nodesProbability of successful link is PFor grid to work, each node must have at least one

good link to a neighboring node

2N2M4link

4NM23link

42linkgrid P11P11P11P

Simple MxN Grid Topology

Simplified prediction of grid performance based on statistical independence

UNCLASSIFIED


Huntsville, Alabama

Slide 20

(U) Prediction of Grid Performance vs. Link Reliability

0

0.2

0.4

0.6

0.8

1

0 0.2 0.4 0.6 0.8 1

Link Reliability

Ne

two

rk R

elia

bili

ty

16x16

32x32

8x8

4x4

16x4

• The network will be less sensitive to low-altitude link degradations if there are fewer nodes (covers less area)

• Slant links to elevated “controllers” or relay nodes could tie teams (mini grids) together– Less likely to have terrain

blockage since grid size is reduced

– Controller need only “see” one node in each team

– One issue is cloud coverage problem

unclassified 6/26/2015 huntsville, alabama slide 1 stab propation analysis status summary &...

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