US Navy RFID HERO Risk Mitigation Shipboard … · –navsea op 3565 vol. 2 minimum hero...

NAVAL SURFACE WARFARE CENTER

DAHLGREN DIVISION

16 April 2010

Mike SlocumE3 Assessment and Evaluation Branch

[email protected]

540-653-2212

Approving Authority: NSWCDD

Command

US Navy RFID HERO Risk Mitigation

&

Shipboard Demonstration

DISTRIBUTION STATEMENT “A"

Approved for Public release; Distribution is Unlimited

NSWCDD Electromagnetic Effects Division (Q50)

mailto:[email protected]

ELECTROMAGNETIC & SENSOR SYSTEMS DEPARTMENT

Agenda

HERO & E3 Stakeholders

HERO Governance

– Philosophy : Specification : Recommendations

– Certification Process

Electromagnetic Risk Assessment Tool (EMRAT)

Shipboard Demonstration of pRFID


RFID E3 Stakeholders

EMAC serves as the Lead E3 Engineering Agent for both

NAVSEA and NOSSA for AIT (RFID) and Wireless.

NOSSAOrdnance Safety

NSWCDDTechnical Development

EMACHERO & E3

OPNAVNAVSEA


HERO Philosophy

Conventional HERO evaluations are based on RF propagation in free space

– Safe operations are achieved by separation of transmitter and ordnance (direct line of sight)

In many/most cases RFID systems will be used in enclosed electrically reflective spaces– Free space attenuation is not always dominant

– RF reflections and multiple transmitters in enclosed spaces result in an additive effect Such spaces become low-power microwave ovens Resultant electric fields are dependent on construction

materials and volume

– A derivative of Reverberation Chamber Calibration methodology developed to characterize such spaces(1)(2)

(1) DoD E3 Symposium, San Diego, CA April 2008

(2) IEEE EMC Symposium, Detroit, MI August 2008


HERO E-Field Limits

Governing Specification

– NAVSEA OP 3565 Vol. 2

0.1

1

10

100

1000

0.01 0.1 1 10 100 1000 10000 100000

Frequency (MHz)

V/m

E=0.5 V/m

E=0.00625 fE=1/f

902 MHz = 5.6 V/m

928 MHz = 5.8 V/m

Figure 2-2, Maximum Allowable Environment for HERO Unsafe Ordnance


HERO E-Field Limits (cont.)

Governing Specification

– NAVSEA OP 3565 Vol. 2

HERO CLASSIFICATION MINIMUM SEPARATION

DISTANCE (FT.) SAFE SUSCEPTIBLE UNSAFE OR UNRELIABLE

> 10 General HERO

Requirements

Use Calculated Distance

per OP 3565

Use Calculated Distance

per OP 3565

5 0.5 < EIRP < 5 watts

All Frequencies

EIRP < 0.5 watts

Frequencies > 100 MHz

0.025 < EIRP < 0.1 watts

200 MHz < Freq < 1 GHz

1 0.1 < EIRP < 0.5 watts

All Frequencies

0.025 < EIRP < 0.1 watts


0.025 < EIRP < 0.1 watts

Frequencies > 1 GHz

0 EIRP < 0.1 watts All

Frequencies

EIRP < 0.025 watts All

Frequencies

EIRP < 0.025 watts


Table 3-1, Minimum Safe Separation Distance Exceptions


HERO E-Field Limits (cont.)

EMAC Recommendation to NOSSA

– Guidance to address interior spaces

0.0

50.0

100.0

150.0

200.0

250.0

300.0

350.0

400.0

450.0

0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000

Frequency (MHz)

uW

/Ft2

Ships

Shore

590367.0 fPA

90367.0 fPA

915 MHz = 92.58uW /Ft2

915 MHz = 42.58uW /Ft2


AIT HERO Certification Process

NSWCDD: Conducts technical evaluation of equipment to establish engineering constraints.

– SSD & TRP

Program Office/Installation Activity: Develops CONOPS which adheres to engineering constraints.

Program Office/Installation Activity : Submits usage plan (CONOPS) with associated engineering evaluation to NOSSA for certification.

– NOSSA will consult with DD as required

Joint services and industry not under Navy cognizance

– NSWCDD will provide engineering constraints in report Letter will state HERO compliance requires adherence with findings

to adequately mitigate risk of HERO

NOSSA will provide certification for government activities only.


Electromagnetic Risk

Assessment Tool (EMRAT)

Chamber

Measurements

Shipboard

Measurements

Statistical EM

Theory

EM Modeling

& Simulation

EM Below Deck

Risk Assessment

Tool

E-Field

Prediction(1)

(4)

(3)

(2)

Below-Decks Electromagnetic Environment


HERO Risk Mitigation Process

Space

Content

4)

Electromagnetic

Ray Casting

Simulation

3)

Statistical

EM

Space

Characteristics

Input

E < ELIMIT

2)

Load Q

Database

E < ELIMIT

1)

In-Situ

Measurement

Upper Bound

E-Field

N

N

Y

Upper Bound

E-Field

Upper Bound

E-Field

Y

“Tunable Accuracy”


Reverberant Spaces

Multi-path propagation

Statistical electromagnetic environment

Random walk properties

Electrically large, reflective spaces


Multi-Path vs. Direct PathIn

sert

ion

Lo

ss (

dB

)

0

-10

-20

-30

-40

-50

Tx – Rx Distance RC

Direct Path

Multi-Path

Critical Distance: c

volDDR rxtxC

2

1


Multi-Path Critical Distance

Example

Vol ~ 200 m3

~ 30 ns (Q ~ 500 at 2.4 GHz)

Antenna directivity ~ 1.6 (half-wave dipole)

Critical Distance for antenna separation RC ~ 3 m

R > RC Multi-Path is Dominant even if antennas are bore-sighted !


Reverberant Space Equations

Gain G

Quality Factor Q

Receive Power Probability

Binomial Trials for Random Walk

Q

Volf

c

P

PGain rxtx

input

locantrec 1

16

13

3

2

..

)(3 MHzf

AreaSurface

VolQ

r

xnx pp

x

nx

)1(}{Prob

x – number of successes

n – number of trials

p – probability of success per trial

thresholdP

thresholdrec ePP

}{Prob 2

2 Distribution:


Random Walk Receive Power

Power samples are separated in space by a distance greater than the

decorrelation length ld ~ l

-30

-25

-20

-15

-10

-5

0

5

10

0 20 40 60 80 100 120 140 160 180 200

Random Walk Sample

Me

an

No

rma

lize

d R

ec

eiv

e P

ow

er

(dB

)

Pthreshold

Complex Standing Wave Pattern


Random Walk Power Distribution

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

0 1 2 3 4 5 6 7

Mean Normalized Power

Cu

mu

lati

ve

Dis

trib

uti

on

Sample Distribution

Theoretical Chi-squared

2

2


Single Sample Probability

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

-30 -25 -20 -15 -10 -5 0 5 10

Mean Normalized Receive Power (dB)

Pro

bab

ilit

y

Probability that Prec Pthreshold per single sample location

Pthreshold


pRFID Application Of EMRAT

Interrogator to Tag

– Power delivery

– Ray Casting (EMRAT) is effective

Tag to Interrogator

– Data communications

– Multi-path can be considered noise

Ray Casting may be appropriate in

defining volumetric amplitudes

(Noise)

Ray Tracing expected to be more

accurate (Signal to Noise)

– Will require further development

Currently working with ONR and

Drexel University


Shipboard Demonstration

of pRFID

Objective

– Demonstrate effective and HERO safe shipboard use of pRFID.

Participating members

– NAVSUP, Sponsor

– NOLSC, Program Management

– XIO Strategies, Project Lead

– Alien Technologies, Equipment Supplier

– North Dakota State University, Read Range Assessment

– NSWCDD Q52, HERO Assessment

Execution

– Determine HERO SSD at selected transmit power levels.

– Evaluate read range & reliability at the selected transmit levels.

– Develop system configuration based on above.

– Install system at selected points aboard ship.

– Pass materials through read point and assess functionality.

– Electric eye triggered portal; tags read and data captured by GlobeRanger iMotion software


SSD (in.) Read Range (in. 100 of 100) ERR* (in.) Read Aperature# (in.)

0 10 10 20

6 24 18 36

12 40 28 56

24 66 42 84

~72 Not Conducted

* Effictive Read Range (ERR) = Read Range - SSD

# Read Aperature Width = 2*ERR

% Based on typical NOT WORST CASE

Hardware Preparation / Tuning

HERO SSD Evaluation

Amp Pwr (dBm) Att (dB) Tx Pwr (dBm) Tx Pwr (W) (Pt) Antenna Gain (dBi) Antenna Gain (Linear) (Gt) EIRP (W) (PtGt) SSD (in)

30 24 6 0.003981072 6 3.981071706 0.015848932 0

30 17 13 0.019952623 6 3.981071706 0.079432823 6

30 13 17 0.050118723 6 3.981071706 0.199526231 12

30 9 21 0.125892541 6 3.981071706 0.501187234 24

30 0 30 1 6 3.981071706 3.981071706 ~72

Read Range Evaluation 50mW / 42.58uW

= 1175 ft2

13 dB Attenuation

12” SSD Selected


Tagged Assets

MK 46 Torpedo container 54 Inert 5” projectiles MK 82 500lb bomb rack

Partially filled Tri-wall Partially filled “war wagon” Pallet of supplies w/liquids


Instrumented Areas

Port side clearway

Elevator access


Test Results

Port side clearway Container reads 100% (36 of 36) runs on 5 of 6 containers 97% realized on 5” projectile w/diesel forklift

– 100% w/electric forklift….Anomaly??

Cargo Hold / Magazine No diesel lift used below deck 100% (35 of 35) runs on 3 of 5 containers 81% on 500lb bomb rack 69% on tri wall container (suspected instrumentation issue)

Additional opportunity to collect data in elevator 3 most challenging containers selected

– Door open» 100% (20 of 20) reads on 2 of 3 containers

» 40% on war wagon

– Door closed» 100% (20 of 20) reads on all 3 containers


Demonstration Take Away

Observations

– Occasional stray tag reads picked up from

nearby containers.

– More reflective spaces provided greater read

probability of both containers and items within.

Conclusions

– HERO safe implementation of pRFID in a

shipboard environment is possible.

Business case will depend on desired degree of

asset visibility.


Q & A

Electromagnetic Risk Assessment Tool

EMRAT

Assessing Tomorrow’s Risk Today

US Navy RFID HERO Risk Mitigation Shipboard … · –navsea op 3565 vol. 2 minimum hero...

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