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
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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
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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)
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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].
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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:
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.
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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
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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
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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-
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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
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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.
2005 Fluke Corporation. All rights reserved. Ad Number 01984.
With the Fluke 9640A RF Reference Source, you can accurately calibratea broad RF measurement workload in half the time of traditional RFcalibration solutions. The 9640A gives you a unique combination oflevel accuracy, dynamic range, and frequency in a single box with:
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.
AM & FM Modulation Sweep frequency Leveled sine
Fluke. Keeping your world up and running.
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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
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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.
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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]
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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
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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.
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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
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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)
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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