NCSLI Measure 2007 Dec

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measure

NCSL INTERNATIONAL

The Journal of Measurement Science Vol. 2 No. 4 December 20

In This Issue:

Application of Simulation Software

to Coordinate Measurement

Uncertainty Evaluations

NIST Primary Frequency Standards

and the Realization of the SI Second

Leakage Effects in Microwave

Power Measurements

Electromagentic Metrology

Challenges in the U.S. DOD

and the Global War on Terrorism


2/100

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4/1002 | MEASURE www.ncsli.org

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Over a decade of archived technical/managerialarticles for today's metrologist

NCSLI Technical Publications Library

NCSLI Newsletter collection is available for articles

and information

Stay current with committee activities

Member Delegates can

register their entire staff,

allowing individual access.

NCSLI measure(ISSN #19315775) is a metrology journal published byNCSL International (NCSLI). The journal's primary audience is calibra-

tion laboratory personnel, from laboratory managers to project leaders

to technicians. measureprovides NCSLI members with practical and

up-to-date information on calibration techniques, uncertainty analysis,

measurement standards, laboratory accreditation, and quality

processes, as well as providing timely metrology review articles. Each

issue will contain technically reviewed metrology articles, new prod-

ucts/services from NCSLI member organizations, technical tips,

national metrology institute news, and other metrology information.

Information for potential authors, including paper format, copyright

form, and a description of the review process is available at

www.ncsli.org/measure/ami.cfm. Information on contributing Technical

Tips, new product/service submission, and letters to the editor is avail-

able at www.ncsli.org/measure/tc.cfm. Advertising information is avail-

able at www.ncsli.org/measure/ads.cfm.

Managing EditorRichard B. Pettit, Sandia National Laboratories (Retired), 7808 Hendrix,

NE, Albuquerque, NM 87110 USA. Email: [email protected]

NMI/Metrology News Editor:

Michael Lombardi,NIST, Mailcode 847.00, 325 Broadway, Boulder, CO

80305-3328 USA. Email: [email protected]

New Product/Service Announcements:

NCSLI Business Office,2995 Wilderness Place, Suite 107, Boulder, CO

80301-5404 USA. Email: [email protected]

Technical Support Team:

Norman Belecki,Retired, 7413 Mill Run Dr., Derwood, MD

20855-1156.

Belinda Collins,National Institute of Standards and Technology

(NIST), USA

Salvador Echeverria,Centro Nacional de Metrologia (CENAM), Mexico

Andy Henson, National Physical Laboratory (NPL), United Kingdom

Klaus Jaeger,Jaeger Enterprises, USA

Dianne Lalla-Rodrigues,Antigua and Barbuda Bureau of Standards,

Antigua and Barbuda

Angela Samuel, National Measurement Institute (NMI), Australia

Klaus-Deter Sommer, Physikalisch-Technische Bundesanstalt (PTB),

Germany

Alan Steele, National Research Council (NRC), Canada

Pete Unger,American Association for Laboratory Accreditation (A2LA),

USA

Andrew Walla rd,Bureau International des Poids et Mesures (BIPM),

France

Tom Wunsch,Sandia National Laboratories (SNL), USA

Production Editor:

Mary Sweet,Sweet Design, Boulder, CO 80304 USAEmail: [email protected]

Copyright 2007, NCSL International. Permission to quote excerpts or to reprint

any figures or tables from articles (Special Reports, Technical Papers, Review

Papers, or Technical Tips) should be obtained directly from an author. NCSL Inter-

national, for its part, hereby grants permission to quote excerpts and reprint

figures and/or tables from articles in this journal with acknowledgment of the

source. Individual teachers, students, researchers, and libraries in nonprofit institu-

tions and acting for them are permitted to make hard copies of articles for use in

teaching or research, provided such copies are not sold. Copying of articles for

sale by document delivery services or suppliers, or beyond the free copying

allowed above, is not permitted. Reproduction in a reprint collection, or for adver-

tising or promotional purposes, or republication in any form requires permission

from one of the authors and written permission from NCSL International.

measureNCSL INTERNATIONAL

The Journal of Measurement Science

www.MyNCSLI.orgOn-line resources for your organization


5/100MEA SURE | 3Vol. 2 No. 4 Decembe r 2007

Letter from the Editor

HOW TO REACH US: MAILletters to: NCSLI measureJournal, 2995 Wilderness Pl., Ste 107, Boulder, CO 80301-5404 USA

FAXletters to: 303-440-3384 E-MAILletters to: [email protected]

This issue marks the end of the second year publishing NCSLI measure. Over these two years, a total of 67

technical papers have been published, including ten Special Reports, eight Review Papers, and four Technical

Tips. As you may have noticed, we increased the journal size in 2007 to 96 pages, from 80 pages last year. As

always, I continue to receive wonderful support for each issue, including Mary Sweet and her staff who

convert each paper to electronic, publication form and then pull everything together, always on time and veryprofessionally done; Michael Lombardi, NIST, who collects and edits all the NMI News and Metrology News

items; Linda Stone, NCSLI, who collects and edits all the new product/service announcements; and Craig

Gulka, NCSLI, who always provides valuable ideas and suggestions.

I was recently reminded that October 4, 2007 was the 50th anniversary of the launching of the Sputnik

satellite by Russia. The satellite was an amazing 83 kilos (183 pounds) and broadcast a beeping radio signal

as it circled the earth. From a scientific viewpoint, Sputnik carried no research instruments but the gradual

changes in Sputniks orbit due to atmospheric drag forces allowed researchers to reconstruct the atmospheric

density at the satellites altitude. These observations lead to an increased investigation of the Earths outer

atmosphere. Sputnik sent shock waves of concern within the United States about the decline in scientific

leadership, so Congress initiated a science and math education push (National Defense Education Act). The

next year, 1958, Congress created the National Aeronautics and Space Administration (NASA), which started

the Apollo Program in 1961; as we all remember, this resulted in the landing (and returning) a man on the

moon July 20, 1969. I remember those events and was excited to be studying math and physics as I workedmy way through school. For several summers, I had a job working with scientists at NASAs Lewis Research

Center (now the Glenn Research Center) analyzing experimental data on the flow of liquid hydrogen, a

possible rocket fuel.

It was also 40 years ago that the unit of time, the second, was redefined in the International System of

Units (SI) so that it was based on the cesium atom. Prior to 1967, the second was based on astronomical time

scales. In this issue of measure, Michael Lombardi, Thomas Heavner, and Steven Jefferts of the National

Institute of Standards and Technology, have authored a review article on the 50-year history of NIST primary

frequency standards that realize the SI second. Besides the interesting photos and discussion, the paper

presents a plot of the uncertainty assigned to nine different NIST cesium primary frequency standards

covering the period from 1950 to today. The results show that there has been an improvement in the

uncertainty of the NIST primary frequency standards of a factor of 10 for every decade in time! This has

resulted in an uncertainty estimate for the new NIST-F2 standard that is under development of less than

1 1016 (k= 1). These rapid developments are certainly one of the most incredible achievements by

humans in the science of measurements!

There are several other metrology articles that should be of interest to NCSLI members. The article titled

Electromagnetic Metrology Challenges in the U.S. DOD and the Global War on Terrorism, by Larry Tarr,

U.S. Army Primary Standards Laboratory, discusses new developments in the RF and millimeter-wave

portions of the electromagnetic spectrum (up to 100 GHz) that present challenges to the metrology

community. These challenges include new imaging systems that can reveal concealed weapons, mines, and

explosives; radio frequency identification systems for identifying and tracking assets; antenna parameter

metrology for gain, pattern, and polarization data; development of synthetic instrumentation through the use

of software; and complex on-chip testing at RF and millimeter wave frequencies. Advances in these areas will

require coordination between government agencies, national metrology institutes, manufacturers, and

metrology organization, such as NCSLI.

Another paper by Brian Parry, Boeing, won a Best Paper Award at the 2007 NCSLI Conference is entitled

Overview of ASME B89 Standards with an Emphasis on B89.4.22Methods for Performance Evaluation

of Articulated Arm Coordinate Measuring Machines. This standard addresses evaluation of articulated

arm coordinate machines by specifying a minimum set of requirements that can be used to determine

machine performance.

Richard Pettit

Managing Editor

Sandia National Laboratories (Retired)


6/100



NMI NEWS

PTB Tests Quantum Voltmeter forAlternating Voltages

The quantum voltmeter for alternating voltages conceived at

the Physikalisch-Technische Bundesanstalt (PTB) has achieved

in its test phase an uncertainty of 5 108 during the measure-

ment of a 400 Hz signal, a value ten times lower than previously

obtained. The outstanding performance of superconducting

quantum standards, used so far for dc voltage calibrations, has

thus been extended for the measurement of alternating voltages.In the low frequency range, alternating voltages are measured

using sampling methods during which the time-varying voltage

is measured repeatedly (sampled) in rapid succession. The

amplification factor and the internal voltage reference of the

sampling voltmeter limits the attainable uncertainty. In practice,

this can be completely avoided if the sampled voltage is directly

compared with the voltage of a Josephson quantum standard,

which is known at 1 V to better than 0.1 nV.

This idea is realized in a method developed and patented at

PTB. For this purpose, alternating voltages are synthesized with

programmable Josephson-series-arrays. A chip, cooled down to

the temperature of liquid helium, contains 8 192 superconduct-ing Josephson tunneling junctions supplied with a microwave

frequency of 70 GHz. They are distributed over segments with

1, 2, 4, 8, 16, junctions. Switchable current sources control

the individual segments such that they produce quantized

partial voltages which add up to the total voltage. A transition

between quantized voltages requires less than 100 ns; thus, the

slowly changing voltage to be measured can be compensated. If

the two time-varying voltages and a sampling voltmeter are syn-

chronized, the differences between the two alternating voltages

can be measured with high resolution.

It is now possible, with new programmable Josephson cir-

cuits currently only produced at PTB, to synthesize alternating

voltages with amplitudes of even 10 V, making possible a range

of additional applications. In addition, the attainable relative

measurement uncertainty should, due to the improved signal-

to-noise ratio, decrease by an additional order of magnitude.

For more information, contact R. Behr,

email: [email protected]

PTB Utilizes Robot Goniophotometers forMeasurement of the Luminous Flux

A worldwide unique goniophotometer with three long-armed

robots has now been put into operation at the Physikalisch-

Technische Bundesanstalt (PTB). With its newly developed pho-

tometer heads, the goniophotometer can simultaneously detect

photometric, radiometric and colorimetric quantities, as well as

relative spectral distributions, by means of a charged-coupled

device (CCD) array spectrometer.

PTB has the task of distributing to industry the lumen unit

of the luminous flux; which is fundamentally derived from the

SI base unit candela for the luminous intensity. To calibrate

transfer standards used for this purpose, a goniophotometer in

a fully gimballed suspension construction was developed in the

1970s and used at PTB. Metrological limitations and an out-

dated computer technology led to the need to redesign the

system, making it more modern and at the same time reducing

the measurement uncertainties.

The new goniophotometer of completely novel design, whose

concept is protected by an international patent, was developed

at PTB and has now been put into operation. It is composed ofthree robots, each having seven controlled axes for moving the

slim arms having a length of more than 6.4 m. One robot

carries the light source in a freely selectable burning position,

aligns it in the instrument center and holds it in position during

the measurement. The other two robots each align a photome-

ter head with the light source and divide the room into hemi-

spheres. They can move on any paths at distances of 1 m to 3 m

and with measurement periods of typically 10 min to 1 h. The

orientation of the robots in the room, as well as their kinematic

characterization, is determined by means of a laser tracker

system. This results in path deviations of the photometer head

of < 0.6 mm, and on average only 0.2 mm. The movable pho-

tometer heads and a monitor-photometer head are each

designed as a tristimulus colorimeter head with four channels.

In addition, they contain an unfiltered Si-photodiode for radio-

metric measurements and a CCD array spectrometer. Thus,

light, color and optical radiation are measured through the

same light-entry window, all photo currents are measured in

parallel and converted to frequencies. This allows the simulta-

neous measurement of all 18 channels with synchronous trig-

gering and any integration times whatsoever, optimally adapted

to the motion sequences of the robots and the modulations of

NMI NEWS

Part of a Josephson-series-array. From the left, the microwave

striplines appear; from below the control leads for the individual seg-

ments.

Continued on page 6

If you would like your news item to appear in a future issue

ofmeasure, contact Michael Lombardi at [email protected].



NMI NEWS

the light.

With the new robot goniophotometers, it is now possible to

determine both the photometric and chromaticity data of lightsources at considerably reduced measurement periods. By using

the freely programmable robots, nearly any near-field and far-

field measurements are possible. The ozone-proof version of the

goniometer also allows the measurement of UV lamps, and, due

to the adjustable temperature range of 25 C to 35 C, lumines-

cent lamps can also be measured at the respective luminaire

temperature.

For more information, contact M. Lindemann, email:

[email protected]

NIST Light Source Illuminates Fusion

Power DiagnosticsUsing a device that can turn a tiny piece of laboratory space into

an ion cloud as hot as those found in a nuclear fusion reactor,

physicists at the National Institute of Standards and Technology

(NIST) are helping to develop one of the most exotic yard-

sticks on earth, an instrument to monitor conditions in the

plasma of an experimental fusion reactor. Their measurement

tool also is used in incandescent light bulbs, the element tungsten.

The intended beneficiary of this research is ITER

(www.iter.org), a multinational project to build the worlds

most advanced fusion test reactor. ITER, now under construc-

tion in Cadarache, France, will operate at high power in near-

steady-state conditions, incorporate essential fusion energy

technologies and demonstrate safe operation of a fusion power

system. It will be a Tokamak machine, in which a hot

250 000 000 C plasma of hydrogen isotope ions, magneti-

cally confined in a huge toroidal shape, will fuse to form helium

nuclei and generate considerable amounts of energy, much the

same way energy is generated in the sun.

One major issue is how to measure accurately the tempera-

ture and density of the plasma, both of which must reach crit-

ical values to maintain the fusion process. Any conventional

instrument would be incinerated almost instantly. The usualsolution would be to use spectroscopy: monitor the amount and

wavelengths of light emitted by the process to deduce the state

of the plasma. But light comes from electrons as they change

their energies, and at Tokamak temperatures the hydrogen and

helium nuclei are completely ionized no electrons left. The

answer is to look at a heavier element, one not completely

ionized at 250 000 000 degrees, and the handy one is tungsten.

The metal with the highest melting point, tungsten is used for

critical structures in the walls of the tokamak torus, so some

tungsten atoms always are present in the plasma.

To gather accurate data on the spectrum of highly ionized

tungsten, as it would be in the Tokamak, NIST physicists use an

electron beam ion trap (EBIT), a laboratory instrument which

uses a tightly focused electron beam to create, trap and probe

highly charged ions. An ion sample in the EBIT is tiny a

glowing thread about the width of a human hair and two to

three centimeters longbut within that area the EBIT can

produce particle collisions with similar energies to those that

occur in a fusion plasma or a star. In a pair of papers, 1 the NIST

researchers uncovered previously unrecognized features of the

tungsten spectrum, effects only seen at the extreme tempera-

tures that produce highly charged ions. The NIST team has

reported several previously unknown spectral lines for tungsten

atoms with 39 to 47 of their 74 electrons removed. One partic-

ularly significant discovery was that an anomalously strongspectral line that appears at about the energies of an ITER

Tokamak is in fact a superposition of two different lines that

result from electron interactions that, under more conventional

1 Yu. Ralchenko, Density dependence of the forbidden lines in Ni-like

tungsten, J. Phys. B: At. Mol. Opt. Phys., vol. 40, pp. F175-F180,

2007.

Yu. Ralchenko, J. Reader, J.M. Pomeroy, J.N. Tan and J.D. Gillaspy,

Spectra of W(39+)-W(47+) in the 12-20 nm region observed with

an EBIT light source,J. Phys. B: At. Mol. Opt.Phys., vol. 40, pp.

3861-3875, 2007.A tiny human figure indicate s t he scale of the ITER toroid

View inside the robot gonioph otometer with an LED array as light

source in the equipment centre and the two measuring robots in basic

position. The group of people provides a size comparison.



NMI NEWS

plasma conditions, are too insignificant to show up.

Team member John Gillaspy observes: Thats part of the fas-

cination of these highly charged ions. Things become very

strange and bizarre. Things that are normally weak become

amplified, and some of the rules of thumb and scaling laws that

you learned in graduate school break down when you get into

this regime. The team has proposed a possible new fusion

plasma diagnostic based on their measurements of the superim-

posed lines and supporting theoretical and computational

analyses.

New NIST Calibration Service SupportsPower Grids

The new calibration service for phasor measurement units

(PMUs) offered by the National Institute of Standards and

Technology (NIST) benefits the operators of Americas electri-

cal power gri d, as well as everyone who values

uninterrupted electrical power. The service provides calibra-

tions for the instruments that measure the magnitude and phase

of voltage and current signals in a electrical power system, acombined mathematical entity called a phasor, and report the

data in terms of Coordinated Universal Time (UTC, also known

as the official world atomic time). Use of absolute time

enables measurements called phase angles taken at one location

on a power grid to be comparable to others across different

systems. Phase angles and their derivations allow grid managers

to know the operating condition of their portion of the system

and determine if action is needed to prevent a power blackout.

The new NIST calibration service has already yielded two

additional benefits. First, a major PMU manufacturer reports

that using the calibrations during the manufacture of its instru-

ments has improved their accuracy by a factor of five. Secondly,

some PMUs that have been calibrated using the NIST service

have revealed incompatibilities in the message format they send

out, leading to corrections that have improved interoperability

between PMUs across power grids.

This project is partially funded by the U.S. Department of

Energy (DOE), and is operated in conjunction with DOE and

the North American Synchrophasor Initiative (NASPI). NASPI

is a joint government and utility collaboration supporting the

North American Electric Reliability Corporations efforts to

improve the reliability of the nations power grids.

For more information on the NIST PMU calibration service,

contact Jerry Stenbakken, [email protected],(301) 975-2440.

More News on page 9


10/100

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METROLOGY NEWS

EURAMET Calibration Guides Updated

Ten EURAMET (European Associ-

ation of National Metrology Insti-

tutes) calibration guides (formerlyEuropean Co-operation for Accredi-

tation, EA, guides) have been recently updated. They are all

available for downloading from the EURAMET web site at:

www.euromet.org/docs/calguides/

The EURAMET documents cover various temperature cali-

brations, inductive voltage dividers, vector network

analyzers, static torque measuring devices, digital multimeters,

hardness measurements, electromechanical manometers, and

non-automatic weighing instruments. A summary of each cali-

bration guide is provided below:

1. Calibration of Thermocouples,EURAMET/cg-08/v.01, July

2007. This guide serves as a basic advisory document for

laboratories that calibrate thermocouples. It is primarily for

thermocouple types standardized in accordance with tem-

perature-emf reference tables produced at NIST and

adopted by the International Electrotechnical Commission

(IEC) and later by the European Committee for Standardi-

zation (CEN) as EN 60584-1:1996. It covers the tempera-

ture range -200 C to +1600 C, the calibrations being

carried out in terms of the International Temperature Scale

of 1990 (ITS-90). Most of the topics covered in this guide

are also applicable to non-standard thermocouples.

2. Measurement and Generation of Small AC Voltages with

Inductive Voltage Dividers, EURAMET/cg-09/v.01, July

2007. This guide applies to the generation and measure-ment of small AC voltages from 1 mV to 1 V in the fre-

quency range from 50 Hz to 100 kHz depending on the

selected procedure and the measuring method used. The

accreditation of the measurand AC voltage for voltages of

more than 1 V is presupposed.

3. Guidelines on the Calibration of Temperature Indicators

and Simulators by Electrical Simulation and Measurement,

EURAMET/cg-11/v.01, July 2007. This guide applies to the

calibration, by electrical simulation and measurement, of

temperature indicators and temperature simulators intended

for use with resistance thermometers or standardized ther-

mocouples. It also applies to the calibration of simulators

which are intended to emulate the electrical outputs of

resistance thermometers or standardized thermocouples.

4. Guidelines on the Evaluation of Vector Network Analyzers

(VNA), EURAMET/cg-12/v.01, July 2007. This guide

describes how to evaluate some of the important character-

istics of VNAs. It describes measurement procedures that

can be used to assess whether or not a VNA meets the

accreditation requirements of EN45001. The principles

given in this guide apply to any frequency range for which

VNAs can be used, and to any transmission medium;

however, some of the techniques given for the assessment of

uncertainties are only applicable to coaxial lines at frequen-

cies above 500 MHz. Although the calibration of a VNA

must, by definition, cover phase as well as magnitude capa-

bilities, the uncertainties produced using this document are

only applicable to magnitude. Phase uncertainty will be

covered in a future edition.

5. Calibration of Temperature Block Calibrators,

EURAMET/cg-13/v.01, July 2007. This guide applies to

temperature block calibrators where a controllable temper-ature is realized in a solid-state block, with the aim of cali-

brating thermometers in the borings of this block. A

temperature block calibrator comprises at least the solid-

state block, a temperature-regulating device for the block,

and a temperature sensor with an indicator (the built-in con-

trolling thermometer) to determine the block temperature.

These components are either combined to form a compact

unit, or kept separate. This guide is valid in the temperature

range from 80 C to +1300 C, but the temperature ranges

stated by the manufacturer shall not be exceeded.

6. Guidelines on the Calibration of Static Torque Measuring

Devices, EURAMET/cg-14/v.01, July 2007. This guideapplies to torque measuring devices where the torque is

obtained by the measurement of the elastic deformation of

a body or of a measurand proportional to it. This guide

applies to the static calibration of torque measuring systems

using supported beams or the comparison method with ref-

erence transducer and includes an example for calculation of

the uncertainty of measurement. A diagram showing an

example of the calibration steps and series is given in Annex

D. The guide defines the torque measuring device s the com-

plete instrument comprising all parts, from the torque trans-

ducer to the indicating device.

7. Guidelines on the Calibration of Digital Multimeters,

EURAMET/cg-15/v.01, July 2007. This document providesguidelines on the calibration of Digital Multimeters (DMM)

for accredited calibration laboratories (ACL). In the absence

of specific international written standards on DMMs, this

document supplements the manufacturers recommenda-

tions and the calibration procedures of the ACLs. Even

though this guide is not intended to cover the question of

judging whether or not a DMM is compliant with a specifi-

cation, it suggests a suitable calibration method on which a

statement of compliance can be based.

8. Guidelines on the Estimation of Uncertainty in Hardness

Measurements, EURAMET/cg-16/v.01, July 2007. In the

field of hardness measurement a wide variety of methods

and equipment is applied which may differ according to the

material. A hardness measurement is useful when the results

obtained at different sites are compatible to within a deter-

mined interval of measurement uncertainty. This guide

demonstrates and applies the concepts of measurement

uncertainty to this special field.

9. Guidelines on the Calibration of Electromechanical

Manometers, EURAMET/cg-17/v.01, July 2007. Scope:

This guide discusses the calibration of electromechanical

manometers, excluding dial gauges. It provides the users of

METROLOGY NEWS

Continued on page 10



METROLOGY NEWS

electromechanical manometers with the fundamentals nec-

essary for establishing and applying calibration procedures.

The guide applies to all electromechanical manometers for

measuring absolute, gauge or differential pressures, exclud-

ing vacuum devices measuring pressures below 1 KPa.

10. Guidelines on the Calibration of Non-Automatic Weighing

Instruments,EURAMET/cg-18/v.01, July 2007. This docu-

ment provides guidance for the static calibration of self-indi-

cating, non-automatic weighing instruments. It covers the

measurements to be performed; the calculation of the meas-

uring results; the determination of the uncertainty of meas-

urement; and the contents of calibration certificates. The

object of the calibration is the indication provided by the

instrument in response to an applied load. The results are

expressed in units of mass. This guide does not specify lower

or upper boundaries for the uncertainty of measurement.

The calibration provider and customer must agree on an

appropriate level of uncertainty of measurement; based on

the use of the instrument and the cost of the calibration.

New EUROLAB Documents on Uncertaintyand ISO 17025 Computer Guidance

EUROLAB (European Federation of

National Associations of Measure-

ment, Testing and Analytical Labora-

tories) has recently published several documents dealing with

the uncertainty of measurement and ISO/IEC 17025 guidance

for computers and software. These documents are available on

the EUROLAB web site (www.eurolab.org/pub/i_pub.html)

and are described below:

1. Measurement Uncertainty Revisited: Alternative Approaches

to Uncertainty Evaluation, EUROLAB Technical Report #1/2007, March 2007. This report focuses on reviewing and

comparing the currently available approaches for evaluating

measurement uncertainty of quantitative test results, provid-

ing a range of examples. After more than ten years, the ISO

Guide to the Expression of Uncertainty in Measurement,

known as the GUM, is acknowledged as the master docu-

ment on measurement uncertainty throughout the testing

community. This report applies the term measurement

uncertainty to all types of quantitative test results, and the

GUM principles are fully accepted.

2. Guide to the Evaluation of Measurement Uncertainty for

Quantitative Test Results, EUROLAB Technical Report

# 1/2006, August 2006. This document offers technicalguidance on the evaluation of measurement uncertainty for

quantitative test results. While fully compliant with the prin-

ciples of the GUM, this document also includes alternative

approaches to the bottom-up approach, based on a com-

prehensive mathematical model of the measurement

process, as emphasized in the GUM. These alternative top-

down approaches utilize performance data from inter-lab-

oratory comparisons and from within-laboratory validation

and quality control data. Various annexes in the document

provide information about frequently occurring uncertainty

sources and data evaluation problems.

3. Guidance for the Management of Computers and Software

in Laboratories with Reference to ISO/IEC 17025/2005,

EUROLAB Technical Report # 2/2006, October 2006. This

succinct and comprehensive guideline focuses on managing

the requirements specific for computers and software with

respect to ISO/IEC 17025 requirements. This document

identifies neither best practice nor a total solution, but pro-

vides advice and guidance with no mandatory parts. It is

assumed that a laboratory will have measures to comply

with the general requirements of ISO 17025. Therefore this

guidance focuses on the special requirements concerning

software and computer system validation, including: identi-

fication and interpretation of computer and software

clauses in ISO 17025; implementing computing systems in

the lab.; different categories of software; risk assessment;

verification and validation of software; electronic docu-

ments handling, transmission and archiving; usage of com-

puter networks in connection with the measurement

process; and security.

ILAC Celebrates 30 years (1977-2007)

ILAC (International Laboratory Accreditation Cooperation) is

the international cooperation of laboratory and inspection

accreditation bodies which this year celebrates its 30th

anniversary. One of the primary aims of ILAC is the removal of

technical barriers to trade.

Imagine you are importing toys

from another country. The toys

have been tested in that country

by a laboratory which says it

meets international safety stan-

dards. But how do you convinceyour authorities that the tests

and results are genuine? That

dilemma was a major impediment

to international trade 30 years ago, but

today, thanks to a handful of pioneers, things have changed for

the better.

The ability of authorities to trust technical standards and pro-

cedures from different countries reaches an important mile-

stone this year, with ILAC celebrating 30 years of helping the

worlds economies overcome technical barriers to trade.

ILACs evolution was prompted by the Tokyo round of inter-

national trade negotiations under the General Agreement on

Tariffs and Trade (GATT). The outcome was the GATT Stan-dards Code, an agreement between a number of the member

states encouraging recognition of the equivalence of different

standards, and the variety of testing and accreditation regimes.

ILACs Chair, Daniel Pierre said: The first conference on

International Laboratory Accreditation, was convened in

Copenhagen in 1977 by Mr. Per Lund Thoft of the Ministry of

Trade, Denmark with the support of Dr. Howard Forman of the

US Department of Commerce. Twenty countries from around

the world, the EEC Commission and ISO accepted their invita-

tion.

The conference gave countries that already had, or were plan-


13/100MEASURE | 11Vol. 2 No. 4 Decembe r 2007

METROLOGY NEWS

ning accreditation schemes an opportunity to compare notes

and experiences. The delegations with practical experience were

The National Testing Board of Denmark (1977), NVLAP U.S.

Department of Commerce (1976), BSIs System of the Registra-

tion of Test House, UK (1977), NATA Australia (1947), and

TELARC - New Zealand (1973).

The outcome of that first ILAC conference was the idea that

mutual recognition agreements between accreditation bodies

meant any laboratory, anywhere could have their test results

recognized as reliable. ILAC from its inception has worked to

create an international framework to support international

trade through the removal of technical barriers. This is now rec-

ognized through the ILAC Mutual Recognition Arrangement

(MRA).

Fifty eight signatories, representing 46 economies have now

signed the ILAC Mutual Recognition Arrangement, enhancing

the acceptance of products and services across national

borders.

Further information about ILAC is available from:

www.ilac.org/aboutilac.html

ISO 9001 Celebrates Its 20th Birthday

This year, 2007, marks the twentieth anniversary of ISO 9001,

the International Standard for quality management systems

from the International Organization for Standardization (ISO).

ISO 9001:2000 is the principal standard in the ISO 9000

family, a suite of sixteen standards

that provide guidance on topics such

as performance improvement, audit-

ing and training. Now used in more

than 160 countries around the globe,

ISO 9001 has become an interna-tional reference for quality manage-

ment requirements, and a benchmark

for improving customer satisfaction and achieving continual

improvement of an organizations performance in pursuit of

these objectives. ISO 9001 can be applied to any organization,

in any sector of activity, whether it is a business enterprise,

public administration, or government department.

The ISO 9000 standards originated as quality assurance stan-

dards in the military, nuclear and construction fields. They grew

through civilian use into national standards before being sub-

mitted to ISO in 1979. Today, there are more than 800,000

ISO 9001 certifications worldwide.

New EURACHEM-CITACUncertainty Guides 2007

A new (2007) EURACHEM-CITAC Guide titled Use of Uncer-

tainty Information in Compliance Assessment has been pub-

lished. The guide applies to compliance with regulatory or

manufacturing limits, where a decision is made on the basis of

a measurement result and its associated uncertainty. The guide

covers cases where the uncertainty does not depend on the

value of the measurand, and cases where the uncertainty is pro-

portional to the value of the measurand. The guide assumes

that the uncertainty has been evaluated by an appropriate

method that takes all relevant contributions into account.

A second new (2007) EURACHEM-CITAC Guide titled

Measurement Uncertainty Arising from Sampling: A Guide to

Methods and Approaches,has also been published. The guide

describes two main approaches to the estimation of uncertainty

from sampling: (1) The Empirical Approach uses repeated sam-

pling and analysis under various conditions, (2) The Modeling

Approach uses a predefined model that identifies each of the

component parts of the uncertainty, makes estimates of each

component, and combines them into an overall estimate. Exam-

ples from both approaches are given, covering a wide range of

different application areas.

For a PDF copy of the new EURACHEM-CITAC guides,

visit: www.eurachem.org

Jeff Gust joins Bagan, Inc.

as VP of Metrology ServicesFormer NCSLI President Jeff Gust joined Bagan, Inc. in Sep-

tember 2007, as the Vice President of Metrology Services. Gust

brings his extensive knowledge of measurement science and cal-

ibration quality system requirements to Bagan, and will

manage their in-lab and on-site metrology operations.

Jeff Gust has a bachelors degree in Physics from Purdue Uni-

versity and over twenty years of experience in the metrology

industry. He began his career in 1985 as a TMDE repair tech-

nician in the United States Marine Corps. Upon leaving the

Marines, he was employed by Tektronix as a Calibration Tech-

nician and Quality Manager for the Irvine CA Tektronix service

facility. In 1990, Jeff joined Verizon and served as a MetrologyTechnician until 1995, when he was promoted to Staff Engineer

and Technical Manager for Verizons Fort Wayne IN metrology

laboratory. There he developed Verizons corporate metrology

quality system and numerous calibration processes. He then

became the VP and Director of Quametec Proficiency Testing

Services, where he developed their quality system and estab-

lished A2LA accredited measurement proficiency testing pro-

grams to support the metrology industry. Gust served as

President of NCSL International in 2006 and continues to serve

on the Board of Directors. He is also a lead assessor for the

A2LA Calibration Accreditation Program, a NACLA evaluator,

and the author of a number of metrology related publications.

Bagan is A2LA accredited to ISO/IEC 17025:2005 for in-laband on-site calibration and specializes in calibration programs

for automotive, aerospace, pharmaceutical, and manufacturing

industries, as well as testing labs, and military installations.

For more information, contact Lydia McDevitt,

[email protected], or visit: www.rjbagan.com

More News on page 12



METROLOGY NEWS

EUROLAB and JRC-IRMM SignCooperation Agreement

Cooperation among testing laboratories is key for the harmo-

nization of test methods and the mutual acceptance of test

results. Optimizing the use of resources is also one of the corner

stones of the strategy of European Federation of National Asso-

ciations of Measurement, Testing and Analytical Laboratories

(EUROLAB) and the Joint Research Centre (JRC) of the Euro-

pean Commission. The representatives of the two organizations

signed a Memorandum of Understanding (MoU) on September

11, 2007 at the JRC Institute for Reference Materials and Meas-

urements (IRMM), in Geel, Belgium. The MoU establishes the

principles and guidelines of their cooperation. The two organ-

izations intend to:

Ensure information exchange in relevant matters, e.g.,

between the JRCs Community Reference Laboratories and

the EUROLAB community.

Coordinate workshops and seminars of mutual interest,

Exchange views and, wherever possible, find consensus posi-

tions on policy matters of interest to the European trade andinnovation community, such as prestandardization research

activities or quality assurance standards.

Coordinate European and international participation for the

standardization and conformity assessment of measurements.

The MoU was signed by the President of EUROLAB, Jean-

Luc Laurent, and the Director of JRC-IRMM, Alejandro

Herrero. Both Mr. Laurent and Mr. Herrero stressed that this

cooperation strengthens the roles EUROLAB and IRMM play

in harmonizing the European measurement system. The

concept of mutual recognition for instance, is very important

for the society as it has economical implications in trade, said

Mr. Herrero.

The President of EUROLAB, Jean-Luc Laurent, and the Director of JRC-

IRMM, Alejandro Herrero, sign the Memorandum of Understanding.

The new Fluke 9640ARF Reference Source

helps you cut RFcalibration time in half.

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Built-in signal leveling andattenuation.

Level accuracy up to 0.05 dBfrom 10 Hz to 4 GHz, whichgives you performance andprecision equal toor betterthanthe HP 3335A over awider frequency range.

Easy integration withMET/CALPlusCalibrationManagement Software forhigher throughput can reducecal time even more.

See the Fluke 9640A atwww.fluke.com/9640A.

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METROLOGY NEWS

For more information contact: Jean-Marc Aublant, email:

[email protected], www.eurolab.org or Doris Florian,

email: [email protected], www.irmm.jrc.be,

www.jrc.ec.europa.eu

12th IMEKO Symposiumon Man, Science & Measurement

The International Measurement

Confederation (IMEKO) Joint

Symposium on Man, Science

& Measurement will explore emerging challenges and novel

concepts in Measurement Science from an anthropocentric

viewpoint and will highlight education and training in these

areas. The Symposium, which is sponsored by IMEKO commit-

tees TC1 (Education and Training in Measurement and Instru-

mentation) and TC7 (Measurement Science), will be held in

Annecy, France, September 3-5, 2008, and is being organized

by the University of Savoie.

The Symposium will focus on the role of Measurement

Science in human activity. The official language of the confer-ence is English. Topics will include:

Measuring systems as a way for helping human perception of

the world

Measurement as a way for helping perception of human activity

General Issues of Measurement Science

Logical and Mathematical Fundamentals of Measurement

Science

Emerging Fields of Measurement Science and Technology

Intelligent and Virtual Instrumentation

Education and Training

Potential authors are invited to submit an extended abstract

of up to four pages in PDF format by uploading the file to the

symposium web site, which contains detailed instructions. The

deadline for extended abstracts is February 15, 2008; notifica-

tion of acceptance will be by April 14, 2008; and the camera-

ready paper submission date is June 1, 2008.

For more information, please visit: imeko2008.scientific-

symposium.com

16th IMEKO Symposium on Electrical andElectronic Measurements

The 16th International Measurement Confederation (IMEKO)

TC-4 Symposium Exploring New Frontiers of Instrumentation

and Methods for Electrical and Electronic Measurements will

be held in Florence, Italy on September 22-24, 2008.

The Symposium is a venue for the presentation of new ideas,

methods, principles, instruments, standards and industrial

applications on electric and magnetic quantities as well as their

diffusion across the scientific community. Participants will have

an excellent opportunity to exchange scientific and technical

information with specialists around the world and to enhance

Continued on page 14



METROLOGY NEWS

their international co-operation. The topics include:

Direct Current and Low Frequency Measurements

Radio Frequency, Microwave and Millimeter Wave

Measurements

Optical Wavelength Metrology

Calibration, Metrology and Standards

Traceability and International Compatibility of Measurements

Advanced Instrumentation Based on Micro and Nano Tech-

nologies

Digital and Mixed Signal Processing

Waveform Analysis and Measurement

Software Measurements

Biomedical Measurements

Dielectric Measurements

Power and Energy Measurements

Power Quality Assessment

Time and Frequency Measurements

Automated Test and Measurement Systems

Sensors and Transducers

Measurement for System Identification and Control

Virtual Measurement Systems E-learning and Education in Measurements and Instrumen-

tation

Original contributions are warmly welcome in the form of

three to four page length extended abstracts.

The deadline for the submission of abstracts is February

29, 2008.

For more information, please visit the conference web site:

www.imeko2008.org

2008 Measurement Science Conference

The 2008 Measurement Science Conference (MSC) will be held

at the Disneyland Hotel in Anaheim, California from March 10

to 14, 2008. The following is from the

2008 Presidents Message by Miguel

Cerezo: As people across the nation,

and indeed the world, continue to

benefit from advances in measurement

technology, MSC progressively seeks to

improve on its programs and opportunities. This years theme,

Measure for Success builds on this concept and provides the

framework for goal achievement within the context of a contin-

uously improving and dynamic learning and business environ-

ment. Whether you come to learn the latest in measurement

techniques from NIST and industry professionals, seek toimmerse yourself in the most up to date information regarding

laboratory management or accreditation, wish to pursue

becoming an ASQ Certified Calibration Technician or simply

conduct a business meeting with your peers, suppliers or

clients, the Measurement Science Conference promises to offer

you a memorable and satisfying experience.

The annual Measurement Science Conference was founded in

1970 to promote education and professionalism in measure-

ment science and related disciplines. MSC has grown and

matured to meet the needs of dynamic measurement technolo-

gies as well as to address pertinent national and global measure-

ment issues. Based in California, the MSC has attracted experts

from around the world as speakers, exhibitors and attendees.

For more information on the Technical Program, Tutorial,and Workshop, please visit: www.msc-conf.com

ANAB Expands to Offer Lab Accreditation

The ANSI-ASQ National Accreditation Board (ANAB)

announced on September 25, 2007, that they have acquired

Assured Calibration and Laboratory Accreditation Select Serv-

ices, LLC (ACLASS). This acquisition

expands ANABs range of conformity

assessment services to include accred-

itation of testing and calibration labo-

ratories. ANAB is the U.S. accreditation

body for management systems and is located in Milwaukee, WI.ACLASS is located in Arlington, VA.

With the acquisition of ACLASS, ANAB adds to its existing

programs accreditation of laboratories to ISO/IEC 17025,

inspection bodies to ISO/IEC 17020, and reference material

producers using ISO Guide 34. ANAB accredits certification

bodies (CBs) for ISO 9001 quality management systems (QMS)

and ISO 14001 environmental management systems (EMS), as

well as numerous industry-specific requirements.

ACLASS is internationally recognized by ILAC, APLAC, and

IAAC through the signing of multilateral recognition arrange-

ments. These arrangements facilitate the acceptance of test and

calibration data between ACLASS-accredited laboratories and

the international community.

ANAB cooperates with other accreditation bodies around the

world to provide value to its accredited CBs and their clients,

ensuring that accredited certificates are recognized nationally

and internationally. The global conformity assessment system

ensures confidence and reduces risk for customers engaging in

trade worldwide.

Under terms of the acquisition, the two ACLASS principals

and current staff and experts will be employed by ANAB and

current ACLASS assessors are expected to provide ongoing

service to existing and new clients. There will be no change to

the ILAC recognition process.

For more information about ANAB, visit: www.anab.org. For

more information about ACLASS accreditation, visit:

www.aclasscorp.com.



SPECIAL REPORTS

1. Introduction

The purpose of this paper is to highlight some challenges that

metrologists and developers will be experiencing as new tech-nologies are exploited and new systems are developed with mil-

itary and Global War on Terrorism (GWOT) related

applications. The intent is not to present an all-inclusive list of

these challenges, but rather to highlight a few examples that the

author considers to be particularly challenging or representative

of important applications within the DoD for which metrology

support is either deficient or nonexistent.

2. Aging Workforce and Metrology Training

It is no secret that a significant portion of the experienced

metrology and calibration workforce in the U.S. has either

recently retired, or will be eligible for retirement in the next few

years. This is especially true for the senior technicians, senior

metrologists, and managers in the metrology community, since

they earned their titles after accumulating years of on-the-bench

technical or managerial experience in the laboratory. The senior

staff represents years of corporate knowledge that is very diffi-

cult to replace. The 2005 NCSLI Benchmarking Survey [1] indi-

Electromagnetic Metrology Challengesin the U.S. Department of Defenseand the Global War on TerrorismLarry W. Tarr

Abstract: The Global War on Terrorism and the events that continue to unfold around the world are creating inter-esting and innovative new developments in practically every area of technology. Many of the new developments are in

systems and components operating in the RF microwave and millimeter-wave portions of the electromagnetic spectrum.

The need to provide traceable metrology and calibration support for modern communications, radar, and smart

weapons systems operating at frequencies from a few kilohertz to 100 GHz and beyond presents challenges that con-

tinue to arise as new systems and technologies are developed. This paper will discuss some examples of the support

challenges facing the U.S. Department of Defense metrology community, and attempt to identify areas in which defi-

ciencies currently exist or are expected to develop.

Larry W. Tarr

U.S. Army Primary Standards Laboratory

AMSAM-TMD-S, Building 5435

Redstone Arsenal, AL 35898-5000 USA

Email: [email protected]



SPECIAL REPORTS

cated that at least 60 percent of the participating laboratories

used in-house resources to train their staff. As the highly-trained

and experienced metrologists and technicians retire in increas-

ing numbers, this valuable resource for on-the-job, in-house

training and expertise will be increasingly hard to find.

Traditionally, the largest source of trained calibration techni-

cians for many laboratories, including the Department of

Defense (DoD) service laboratories, has been retired Army,Navy and Air Force personnel who were trained in the military

and served as technicians; electronics repairmen; radar opera-

tors and repairmen; test, measurement and diagnostic equip-

ment (TMDE) specialists; or a host of other related occupational

specialties. Since most of the military calibration training has

either been terminated or severely reduced, the pool of retired

military calibrators available for rehire into the civilian work-

force has diminished significantly in recent years. Experienced

calibrators with a broad knowledge of instrumentation, meas-

urement standards and good measurement practices are becom-

ing increasingly difficult to find. There are a few colleges that

offer specialized training in metrology and calibration skills. A

recent listing on the NCSLI education website included at least13 institutions that offered degree or certificate programs in

metrology or a measurement technology area. Also, a growing

number of companies offer training in uncertainty analysis, sta-

tistical process control, accreditation topics, or specialty classes

in specific measurement parameters. However, training in RF,

microwave and millimeter-wave (MMW) metrology and calibra-

tion techniques is particularly lacking. Personnel with broad

knowledge and experience in these areas are especially difficult

to find. This indeed presents a major challenge to metrology lab-

oratory managers trying to build or sustain a technical staff with

expertise in RF, microwave and MMW measurements.

3. Funding Constraints

Since the tragic events of 2001, the Global War on Terrorism

has generated many programs designed to develop new tech-

nologies, systems and methodologies for dealing with real or

perceived threats to the U.S. The GWOT has created entirely

new government agencies and offices, with associated funding

requirements that in most cases have been supported by Con-

gress. In addition, since 2003 Operation Enduring Freedom

(OEF) and Operation Iraqi Freedom (OIF) have required huge

amounts of military funding that in some cases were obtained at

the expense of military organizations whose mission is sustain-

ment of metrology and calibration operations and TMDE. This

has indeed presented significant challenges to military calibra-tion laboratories trying to provide the high-priority support for

soldiers, sailors and airmen in harms way, and at the same time

continue to meet the demands of their regular customers timely,

quality services. In some cases, military laboratories have been

required to provide only mission-essential services for extended

periods of time. In such instances, all other types of expendi-

tures, such as travel, training, overtime, contracts, procure-

ments, and developmental projects, were either cancelled,

delayed, or severely restricted. This environment presents signif-

icant challenges and impediments to the smooth operation of

military calibration laboratories.

4. Traceability Challenges

By regulation, every measurement performed by the DoD is

traceable through the Services calibration hierarchies to the

National Institute of Standards and Technology (NIST), or to

fundamental physical constants. Traditionally, that traceability

has been maintained by periodically submitting artifact stan-

dards to NIST for calibration, or by various Measurement

Assurance Programs (MAPs), standard reference materials, orspecial measurements. As new technologies were developed, or

the state of the art improved, NIST responded accordingly by

developing new measurement systems, standards or techniques,

or by improving existing measurement systems, standards and

techniques. Generally speaking, NIST had the personnel

resources for responding to new measurement requirements,

although the development and characterization of a completely

new measurement standard typically takes from 5 to 7 years.

Also, if new measurement requirements were broad-based and

contributed significantly to the U.S. economy, NIST provided or

obtained funding to do the work. Conversely, if the military had

measurement requirements unique to the DoD, the military pro-

vided the funding. In either case, NIST generally had theresources necessary to provide measurement traceability when

needed.

In recent years, NIST has lost a significant portion of its elec-

tromagnetic metrology technical staff. These include the much-

decorated, widely-published senior metrologists who played a

significant role in developing and establishing the U.S. metrol-

ogy system in use today. These also include the master machin-

ists, researchers, system developers, engineers, physicists,

technicians, and other personnel directly involved with provid-

ing the NIST calibration services so essential to disseminating

traceable measurements to NIST customers. Unfortunately, due

to funding restrictions, NIST has not been able to sustain orreplace many of their key staff positions. This has resulted in a

serious backlog in NIST calibration services. In some parame-

ters it has forced NIST managers to take a critical look at NIST

processes and to consider alternate methods for providing trace-

able measurements to the metrology community. Some of the

schemes under consideration include off-loading NIST measure-

ment services in areas with minimal workload. Magnetic field

intensity and 30 MHz attenuation are example parameters that

are now supported by the Navy and Army primary standards

laboratories, respectively. Other examples can be found in the

NIST Special Publication 250 series describing NIST measure-

ment services. Providing sufficient funding for NIST to ade-

quately support the metrology community remains a majorchallenge.

5. Technological Challenges:

GWOT and Homeland Security Examples

5.1. MMW and Terahertz Imaging

In this application, new scanning systems are being developed

that can at least partially penetrate clothing and still provide suf-

ficient spatial resolution to reveal concealed weapons, including

those containing nonmetallic materials. (see [2], page 46) These

systems are being considered for deployment to airports and



SPECIAL REPORTS

other points of entry. They are also being tested for possible

application in detecting mines and explosives in tactical scenar-

ios. At present, there are few if any standards for quantifying the

spatial resolution, contrast, clothing penetration, and other sub-

jective aspects of image quality that affect the usefulness of

these scanning systems. Also, there are no quantitative measures

by which to intercompare these systems. The challenge will be

to develop standard objects, obscurants, scenarios, and testsystems to compare measurement results to simulations, and to

compare measurement results from different systems with one

another. The challenge will also be to characterize the perform-

ance of concealed weapon detection systems over a range of

conditions. At present, NIST provides few, if any, measurement

services at the MMW and sub-MMW frequencies at which these

scanners operate. Applicable measurement parameters include

power and noise-equivalent temperature difference.

5.2. RFID Technologies

The U.S. Government has mandated the adoption of radio fre-

quency identification (RFID) systems for identifying and track-

ing government assets. (see [2], page 47) However, lack ofmetrology support is delaying the implementation of that direc-

tive. The impact is huge, impacting security and inventory

control at government sites, security at U.S. ports and ports of

entry, and operations of many high-volume retailers. For

example, the U.S. expects to issue at least 14 million passports

with RFID E-passports per year at a cost of at least $1.4

billion. The U.S. Government also plans to issue at least 4

million badges with RFIDs to government workers and contrac-

tors. Before these are deployed, standardized test parameters

need to be established to test readers for interoperability and

security, such as shielding against eavesdropping and the sus-

ceptibility of RFID tags to remote activation. The challenge tometrologists will be to provide suitable calibration of load mod-

ulation (i.e., the signal returned from the RFID chip) and the

RFID readers electromagnetic fields to ensure consistent, reli-

able and secure operations of these devices.

5.3. Ultrafast Electronic Communications

Many of the new and emerging systems utilized by the DoD and

in the GWOT require synchronized ultrafast electronic commu-

nications. (see [2], page 195) Many of these systems utilize

technologies that require ultra-low noise measurements. These

systems include surveillance systems, ultra-high-speed comput-

ing, advanced communications, novel imaging systems, and new

defense ranging and positioning systems. The challenge tometrologists is that the required ultra-low noise performance

can only be achieved and verified by substantially improving the

state-of-the-art in noise measurement, up to 10,000 times more

sensitive than is currently available anywhere in the world. The

frequencies of interest span 5 orders of magnitude, from the

upper microwave region (1010 Hz) to the optical region (1015

Hz). Ultralow-noise measurements are required to determine if

performance specifications are being met to ensure proper oper-

ation of these systems. Researchers are developing new ways of

measuring ultralow noise in systems based on the technology of

femtosecond laser frequency combs.1 These combs can gener-

ate extremely precise signals from the microwave to the optical

range with very good control. In fact, the potential for these

combs to make microwave noise measurements nearly 10,000

times more sensitive than the current state-of-the-art in elec-

tronic measurements has been demonstrated recently. However,

much more research and development is needed to transform

this promising technology to reality.

6. Technological Challenges: Military Examples

6.1 Signal Proliferation

According to Richard Russell, the Chief of the Office of Science

and Technology Policy in the Executive Office of the President,

At some point very soon, were going to have a tremendous

spectrum crunch. [3] The problem is caused in part by the pro-

liferation of electromagnetic signals used by the military, and by

the fact that the military does not have a single authoritative

source to track the use of radio frequencies. The problem is par-

ticularly acute in Operation Enduring Freedom and Operation

Iraqi Freedom in the Middle East. Frequency assignments canbe made dynamically as new technology comes online. As a

result, conflicts can develop between wideband wireless com-

munications, radios, radars, and hostile devices such as Impro-

vised Explosive Devices (IEDs). The DoD is spending millions

of dollars to develop IED jammers of various types, which

further complicates the issue. The challenge for metrologists

and especially systems developers is to be cognizant of potential

interference and the implications to personnel, operations and

systems, and to develop new frequency allocation standards for

managing electromagnetic signals in military scenarios and

crowded urban environments.

6.2 Emerging Sub-MMW Systems

The development of satellite communications, radar, and

defense remote sensing systems in the frequency range from 110

to at least 500 GHz is currently inhibited by the lack of antenna

parameter metrology support. (see [2], page 48) Antenna

parameters (e.g., gain, pattern, and polarization) are critical to

optimizing, diagnosing, maintaining, and verifying the perform-

ance of these systems. It is estimated that reducing overall gain

uncertainty from approximately 2.8 dB to at least 2.2 dB would

improve weather forecasting and tracking, and result in an

implied benefit gain of $700 million per year to the U.S.

economy. Long term goals of further reducing radiometer uncer-

tainty to the 1 dB level would result in an estimated benefitcloser to $1 billion in 2003 dollars. The challenge to metrolo-

gists will be to develop and bring on-line a planar near-field

scanning system at NIST to characterize emerging sub-MMW

antennas with uncertainties approaching 1 dB.

1 Editors Note: Detailed information on the calibration of optical fre-quency combs is included in the paper published in this issue ofMeasure: Jack Stone, Liang Lu, and Patrick Egan, NIST, CalibratingLaser Vacuum Wavelength with a GPS-based Optical FrequencyComb, pp. 2838.



SPECIAL REPORTS

6.3 Ultrawideband Microwave Power Standards

With the adoption of standard 2.4 mm and smaller coaxial con-

nector geometries, several manufacturers have been marketing

or developing wideband power sensors with bandwidths of

50 GHz and higher. Providing accurate, traceable calibrations

of these devices is difficult, often involving several thermistor

mount working standards, characterized precision adapters, and

possibly combinations of waveguide and coaxial connections.There have been attempts at developing precision power stan-

dards suitable for use as NIST-calibrated transfer standards. For

example, a NIST project funded by the military in the late 1990s

resulted in a limited number of power standards utilizing thin-

film technology and useable at frequencies from 10 MHz to

50 GHz, with 2.4 mm coaxial connectors. However, the produc-

tion yield of these sensors was extremely low, and no more

funding has been identified to pursue a follow-on project to

build more. The metrology challenge is to develop an improved

ultrawideband coaxial power standard, possibly calibrated

directly in a NIST-characterized microcalorimeter, at frequen-

cies from a few megahertz to at least 50 GHz.

6.4 Advanced Microwave and MMW Seekers

and Other Devices

Work continues in military and corporate R&D laboratories to

develop advanced seekers and other devices exploiting various

portions of the microwave and MMW spectrum. Applications

include smart munitions, target recognition and designation

systems, secure communications, ultra-high speed data trans-

mission, video distribution, MMW radios, portable radar

systems, and a multitude of other sensing, detection, and

imaging applications. The steady migration to higher frequen-

cies, coupled with the wide variety of application areas, presents

many interesting measurement and standards-related chal-lenges. Some examples include requirements for full-band trace-

ability and measurement capabilities for power, thermal noise,

phase noise, and antenna characterization at frequencies of

110 GHz and higher New or improved standards and measure-

ment techniques may also be required for on-chip testing of

MMICs, measurements of scattering parameters and materials

properties of devices, and measurements of high continuous and

pulsed power at microwave and MMW frequencies. The chal-

lenge to metrologists is to keep up with the development and

potential deployment of these devices, and to ensure that suit-

able measurement standards and metrology support are in place

when required.

6.5 Synthetic Instrumentation

An increasing trend in RF and microwave metrology is the use

of instrumentation that define their functionality and capabili-

ties through software. Although such virtual instruments have

been around at least 20 years, their capabilities are advancing

rapidly and the DoD, as the largest single purchaser of test

equipment in the world, is beginning to exploit this technology.

Maintaining the militarys huge inventory of test equipment has

proved to be a significant and expensive challenge. One solution

was articulated by the DoD Office of Technology Transition [4]:

Recent commercial technology allows for the development of

synthetic instruments that can be configured in real time to

perform various test functions. A single synthetic instrument

can replace numerous single-function instruments, thereby

reducing the logistics footprint and solving obsolescence prob-

lems. The DoD recently formed the Synthetic Instrument

Working Group to address the issue and develop standards for

interoperability of synthetic instruments. With significant DoDinvolvement, synthetic instrumentation will likely become the

wave of the future. Synthetic instrumentation already presents

challenges to the calibration community. Understanding the full

range of capabilities of these systems can be daunting. There can

be a steep learning curve associated with developing the expert-

ise to configure, operate and maintain these systems. In addi-

tion, questions arise about what needs to be calibrated and/or

verified in synthetic instruments, and what happens to the cal-

ibration when the instrument is reconfigured. All of these issues

represent significant challenges to metrologists as instrumenta-

tion continues to evolve from traditional rack-and-stack to more

versatile but complicated synthetic instruments.

6.6 MMW Scanning of the Surface Finish of Aircraft Skins

Work continues on a novel quantitative technique to measure

the macroscopic RMS surface roughness of surfaces made from

conductive and composite materials. By measuring the complex

amplitude variations in the speckle pattern of MMW signals

scattered from rough surfaces, the nature of the roughness can

be quantified directly. [5] This technique has been demonstrated

at 60 GHz and has potential broad applications in measuring

wear and corrosion of various surfaces, such as the interior sur-

faces of pipelines, vessels and aircraft skins. The challenge to

metrologists is to quantify the correlation between observed

reflected MMW speckle patterns and the actual RMS surfaceroughness.

The technique also has applications in sensitive surface vibra-

tion measurements of optically rough materials. Since the

signal-to-noise ratio of such vibration measurements increases

as the square root of the amount of reflected light detected, and

since materials whose surfaces appear optically rough and

diffuse in visible light may appear much more reflective at

MMW frequencies, vibration measurements of optically diffuse

surfaces can be greatly improved by utilizing MMW systems

instead of optical interferometers. The challenge to metrologists

is to identify or develop improved high-speed MMW sensors

with sensitivities comparable to existing photon sensors in wide-

spread use in optical interferometry and vibration analysis.

6.7 Complex On-Chip Testing at Microwave

and MMW Frequencies

As military systems become more and more complex, RF Inte-

grated Circuits (RFICs) and Monolithic Microwave Integrated

Circuits (MMICs) are proliferating in applications ranging from

radios and wideband communications, to practically anything

employing electronic circuitry. RFICs are typically based on

CMOS or similar technologies, and their operation until

recently has been limited to a few gigahertz. MMIC devices are



SPECIAL REPORTS

typically based on gallium arsenide or similar technologies,

which have many proven applications at much higher frequen-

cies, including the MMW bands. Testing of these devices is

becoming more and more complex, requiring sophisticated mul-

tiport on-chip probing stations, complex network analyzers and

associated instrumentation, precision miniaturized measure-

ment standards and components, and a highly trained staff to

perform these measurements. Complicating the testing is thecontinuing push toward RFICs and MMICs operating at higher

frequencies, even into the MMW bands. The challenge to

metrologists is to acquire the expertise to accurately character-

ize, operate and maintain these systems, the ability to develop

suitable measurement procedures and test plans, and the expert-

ise to analyze, interpret and report the results obtained.

7. Conclusions

New developments continue to unfold, almost on a daily basis,

in military uses of the RF, microwave and MMW spectrum in

the Global War on Terrorism. Staying abreast of these new and

emerging technologies and applications is a major challenge for

the metrology community. Developing the required metrologyand calibration support solutions can be a daunting task. Even

more fundamental are the issues related to training a new gen-

eration of metrologists and calibrators capable of meeting these

challenges. In this brief paper, we have presented a few exam-

ples of the challenges facing the military metrology community,

and we have attempted to identify areas in which deficiencies

currently exist or are expected to develop.

8. Acknowledgments

The authors would like to thank the reviewers of this paper for

their critique and helpful comments.

9. References[1] Wade Keith, Monica Soltis, Nicholas Tyma, and Craig Gulka,

2005 NCSL International Benchmarking Survey, NCSLI

MEASURE, vol. 1, no. 1, pp. 1823, March 2006.

[2] An Assessment of the United States Measurement System:

Addressing Measurement Barriers to Accelerate Innovation,

NIST Special Publication 1048, Appendix B, Feb. 2007. (Avail-

able at http://usms.nist.gov/usms07/index.html)

[3] D. Perera and G. Grant, Managing Technology Mixed Signals,

Government Executive, pp. 6162, March 1, 2007. (Available at

www.govexec.com/features/0307-01/0307-01admt.htm)

[4] E. Starkloff, Creating a Synthetic Virtual Instrument for Avion-

ics Testing,Defense Tech Briefs,pp. 811, April 2007. (Available

at www.defensetechbriefs.com/content/view/1004/36/)

[5] J.B. Spicer, Microwave Metrology for Nondestructive Evalua-

tion, Materials Science and Engineering Dept., Johns Hopkins

Univ., Sept. 1998 (Available at www.jhu.edu/~opticnde/Doug/

microwav.htm)

JOE D. SIMMONSMEMORIAL SCHOLARSHIP

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to supp ort the stu dy of metr olog y

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Completed applications are due March 1.

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or write to: Simmons Scholarship

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PROMOTING ACADEMIC EXCELLENCE IN METROLOGYASQ Measurement Quality Division NCSL International Measurement Science Conference

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SPECIAL REPORTS

1. Introduction

In 1999, the International Committee for Weights and Measures

(CIPM) drew up an arrangement for the mutual recognition of

national measurement standards and of calibration and measure-

ment certificates issued by National Metrology Institutes (NMIs),

the CIPM Mutual Recognition Arrangement (MRA) (available at

www.bipm.org/en/cipm-mra/), with the objectives of:

Providing international recognition of national measurement

standards maintained by NMIs; Providing confidence in, and knowledge of, the measurement

capabilities of participants for all users, including the regula-

tory and accreditation communities;

Providing the technical basis for acceptance, between coun-

tries, of measurements used to support the trade of goods and

services, as a result of the world wide acceptance of certifi-

cates issued in the framework of the CIPM MRA, and thus

Ultimately reducing non-tariff or technical barriers to trade.

Such a structure constituted an important step towards

improving the international metrology system and the overall

traceability of measurements to the International System of

Units (SI, available at www.bipm.org/en/si/). As such, theCIPM MRA was welcomed by all sectors of the metrology com-

munity, by commercial and industrial companies, and by regu-

latory and accreditation bodies.

The CIPM MRA is an arrangement signed by metrology insti-

tutes. It can, however, have a positive impact only if quantita-

tive information supporting international recognition is

provided in an open and clear manner. Consequently, the CIPM

MRA created a database, maintained by the Bureau Interna-

tional des Poids et Mesures (BIPM) and known as the BIPM

key comparison database (BIPM KCDB). The KCDB openly

displays, on the internet, data on international comparisons of

A Users Guide to the Information inthe BIPM Key Comparison DatabaseC. Thomas and A.J. Wallard

Abstract: The launch of the Mutual Recognition Arrangement by the International Committee for Weights and Meas-

ures (CIPM MRA) created a process within which calibration and measurement certificates from National Metrology

Institutes (NMIs), which are signatories, could be recognized and accepted worldwide. This process has become of great

interest to regulators and accreditors. More recently, it has attracted the attention of international companies who wish

to take advantage of the mutual recognition offered by these certificates by realizing traceability to the International

System of Units (the SI) through local NMIs. This latter aspect of the use to which the BIPM key comparison database

(KCDB) can be put has recently been made more straightforward as the result of a new search engine installed by the

BIPM. This paper describes the current situation and shows how to access relevant information from the data base.

C. Thomas

A. J. Wallard

Bureau International des Poids et Mesures (BIPM)

Pavillon de Breteuil, F-92312 Svres Cedex

France

Email: cthomas @bipm.org


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SPECIAL REPORTS

They are composed of:

The key comparison reference value,

either deduced through a statistical

analysis of the results or by other

means accepted by the participants;

The degree of equivalence of each

national measurement standard,

expressed quantitatively by two terms:

(1) its deviation from the key compar-

ison reference value and (2) the uncer-

tainty of this deviation, at a 95 % level

of confidence; and

The graph of equivalence, which is a

graphical representation of the set of

degrees of equivalence (the zero-axis

represents the key comparison refer-

ence value).

The next step is the linkage between

two key comparisons of the same family,

and thus the expansion of the results ofthe CIPM key comparison. This linkage

can be established only if there is a

common participation of one or more

members in the CIPM key comparison

and the equivalent RMO key compari-

son. The linkage does not modify the

value and the uncertainty of the CIPM

key comparison reference value, which

remains unique and unaltered for the

whole family. It simply extends the set of

degrees of equivalence and the graph of

equivalence in order to give evidence of

the comparability between institutes thathave only participated in one of the com-

parison exercises. The expanded uncer-

tainty included in their degrees of

equivalence is, however, generally higher

than if they had been compared directly.

An example is given in Fig. 2.

2.2.3 Contents of the KCDB

As of 5 April 2007, 720 comparisons

were registered in the KCDB, among

which there were:

567 key comparisons (78 from theBIPM, 288 from the CCs, and 201

from RMOs), and

153 supplementary comparisons.

On the same date, results were inter-

preted in terms of equivalence for 254

key comparisons, leading to the publica-

tion in the KCDB of the corresponding

Final Reports and of about 800 graphs of

equivalence. 76 Final Reports of supple-

mentary comparisons were also available.

2.2.4 Impact

The interpretation of results in terms ofequivalence requires that complete and

documented uncertainty budgets are

established by all of the participants. The

output of the process is the elaboration

of sets of degrees of equivalence, forming

quantitative and objective information,

which has been reviewed and approved.

No attempt is given in the KCDB to

judge the performance of any one partic-

ipant relative to the others on a scale

from worst to best, but comparability

Figure 1. Organization of CIPM and RMO key comparisons.

NMI participating in CC key comparisons.

NMI participating in CIPM and RMOkey comparisons.

NMI participating in RMO keycomparisons only.

NMI participating in BIPM key compar-isons (series of bilateral comparisons witha unique facility maintained at the BIPM).

NMI participating in bilateral keycomparisons.

International Organization parti

NCSLI Measure 2007 Dec

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