The Future of Metrology

About this article

This article by John Herniman, Vice President for Quality of Agilent Technologies' Electronic Measurements Group was originally published in the copyrighted document NCSLI Newsletter, 45th Anniversary Special Commemorative Edition (July 2006). It is reproduced with the permission of NCSL International, Boulder, CO, USA.

Preserving the Truth in Times of Continuous Change

We all operate amidst the turmoil and challenges driven by industrial globalization, technology evolution, and regulatory expansion. Fortunately, we can feel pride and stability in being affiliated with calibration laboratories that have unwaveringly addressed “metrology,” the art and science of identifying, measuring, maintaining, and reporting the truth.

Market-driving forces that disrupt processes, redistribute staffing, alter geographical deployment, change hardware and software architectures, and mandate compliance to complex standards have direct effects on the business condition of a worldwide OEM supplier of measurement technology. These forces also significantly impact the hardware, software, and intellectual property (IP) an OEM must provide to customers so that they too can successfully contend with the same forces in the context of their own business environments.

The geographic diversification of manufacturing and R&D for many companies has created a challenge in maintaining quality and consistency. “New products designed in one country may be prototyped in another and manufactured in yet another or even on another continent,” said Pat Byrne, president of Agilent Technologies’ Electronic Measurements Group. “The push to take advantage of the rich diversity of talent across the globe has increased our dependence upon robust measurement tools and techniques to ensure that the performance inherent in designs from the country of origin are maintained across the world at the end of the production line.”

As financial operating margins have thinned, companies involved in research or manufacturing are relying upon metrology to “remove all doubt” as they make decisions on product performance, reliability and predictability. Calibration labs, whether internal parts of a company or external service providers, serve a critical need in reducing the risk of product and process failure and thereby in assuring the financial health of the companies they serve.

Product reliability and accuracy must meet market expectations for a company to maintain the loyalty of its customers. In addition, and process reliability must meet internal expectations for a company to maintain its profitability and the loyalty of its stockholders. It is with this knowledge that metrologists and calibration laboratory personnel can strive to maintain the robust tools and techniques needed to characterize the ever-broadening set of truths to be addressed. The tools and techniques must be portable, delivering consistent results worldwide.

If technology would stand still, metrology could ultimately prevail over all the problems that contribute to the risk of measurement error. Yet, the evolution of technology continues to accelerate, introducing both new challenges and new solutions to the world of measurement. Over the last few years, the most noticeable change has been in the blurring of the lines between the analog and digital worlds. As the size, cost and power consumption of digital components has dropped, the speed of those same components has increased even more dramatically. Measurement hardware that once could be realized only in analog form can now be implemented digitally with processing bandwidths that fully address major sets of measurement requirements.

Some measurement errors such as logarithmic amplifier accuracy in spectrum analyzer IF sections – errors that metrology once had to address – have been eliminated since that function is now performed by Pentium-class processors. Still, the perfect digital measuring instrument – a single super-fast ADC with enough linearity and resolution to cover any application – is yet to be achieved. Instead, combined analog/digital solutions are often still required to measure and characterize some phenomena. The use of digital technology has enabled manufacturers to squeeze ever greater performance out of hardware components. These are characterized during design and manufacture, and compensation for their behavior (even drift) is included in normal instrument operation. As a result, customers can now buy more measurement capability for their money because some hardware is now replaced with software algorithms, increasing performance and reliability while simultaneously driving down manufacturing costs.

The move to software-intensive architectures introduced challenges of its own, of course. Just as you can no longer adjust the mixture in the carburetor of your automobile (most have long since gone to microprocessor-controlled fuel injection), you no longer find “screwdriver tweaks” in your measurement instruments. The specified performance of the instruments depends on providing real-time compensation for component drift or aging. Adjusting the actual performance (if verified as inadequate) requires complex closed-loop iterative calculations to characterize the components and change the measurement loop calculations. The robust measurements used to verify the overall performance of today’s instrument must be able to feed back the results into an automated routine that uses them to make the necessary algorithmic adjustments. What once could be adjusted in a calibration lab with perhaps a scope and a screwdriver must now be done under automated control using external lab standards. On the plus side, though, no amount of manual tweaking could approach the instrument performance made possible by today’s microprocessor-controlled architectures.

The increased performance of today’s instruments manifests itself in other changes in the typical calibration lab. OEMs gain a competitive advantage by squeezing more performance out of hardware and thereby tightening the instrument specifications. As the specs tighten and the feature sets increase – due in large part to digital signal processing – the process of completing a “performance verification” often entails an increasing number of tests and test points. Manual calibration procedures that formerly were reasonable have grown to be untenable for many modern instruments. In particular, “general purpose” instruments have extremely broad sets of functionality, all of which must be verified in the absence of specific advance knowledge of how the product will be used. Automatic calibration routines are virtually mandated if the performance verification is to be completed with high confidence in reasonable time.

This is especially important for mission-critical instruments, which cannot be removed from service for extended periods without adversely impacting costs, schedules or both. Should something drift out of alignment, the automated routines can be used to provide the necessary data for adjustment, and the instrument can be returned to duty with minimal delay. For those reasons, every instrument introduced by Agilent must have calibration procedures that can be supported in our Service Centers at the time of introduction, with full traceability to SI units. In addition, we are making the required engineering investments to make those procedures available to equipment owners who prefer not to (or simply cannot) take advantage of our support services. Robust, automatic routines for both calibration and adjustment are critical tools for calibration labs that support modern instrumentation for equipment owners interested in minimizing turnaround time and overall support costs.

Perhaps the largest visible change in recent years has been the surge toward Web-based business. Web technology plays a critical role in providing global transportability of tools, manufacturer's intellectual property, and information. Current software tools can be downloaded from secure web sites, licenses for the use of IP can be purchased and delivered online, and data reports can be transmitted electronically and formatted to fit specific customer needs if they are to be printed.

Identical tools can be deployed worldwide, identical judgments can be applied in determining pass/fail, and identical techniques can be used to adjust or repair instruments that do not pass with the required margin. Whether operating on two systems, in two buildings, or across two continents, consistency is the key to credibility, and the entire metrology business is founded upon credibility.  Automation in calibration can provide the same benefits automation pays in a manufacturing operation – speed, repeatability, and consistent accuracy.  Calibration results can be more readily used to improve business results.

“But who checks the checker?” is a common question we get. Equipment suppliers strive for the highest possible performance and reliability, but things change; components age, environmental conditions vary, and unintentional abuse may occur. Calibration labs exist to ensure that the equipment in question can be compared to certified standards, and automated tools may ensure that comparison can be consistently performed. But who checks to make sure the tools are correctly applied, or that uncertainty analyses are properly performed, or that the end customer can indeed be confident his service provider has removed all doubt?  In large part, that role has been taken on by certifying and regulatory agencies. 

The advent of international standards like ISO/IEC 17025 or the mandate of compliance with standards such as ANSI/NCSL Z540 have helped to unify terminology and document conditions under which calibrations are made.  Convergence on the ISO Guide for Expression of Measurement Uncertainty (GUM) has had the benefit of stating under which conditions measurement uncertainty calculations are to be performed, and in what manner they are to be performed if they are to be considered “in compliance.”

Accreditation bodies worldwide need our support in maintaining the credibility of our industry. No one wants to bear the burden of bureaucratic oversight, but we cannot afford to devalue in any way our hard-earned accreditations by allowing slipshod enforcement of the underlying standards. Even the most carefully written regulations or standards leave room for interpretation, so it falls to the metrology community to provide some level of self-policing to ensure that robust process control is maintained, and that “softer services” such as uncertainty calculations are developed and used in appropriate fashion.

That, of course, places an additional burden on anyone developing automated calibration routines because uncertainty calculations are complex. They depend heavily on the equipment being used as lab standards and, in many cases, on the internal operating conditions of both the lab standards and the instrument under test. The ultimate is, of course, dynamic measurement uncertainty calculation, which requires point-by-point computation as the calibration process proceeds. While this is made possible by automatic calibration routines, it is computationally intensive and requires careful development – but in the end it provides the highest confidence in pass/fail results. It also provides the highest degree of flexibility when choosing between various lab standards without compromising results.

Equipment suppliers and calibration software providers must work to present their products using industry-accepted standards for communication and computation to allow for the broadest possible set of lab standards and tools. Object-oriented design techniques can be used in both hardware and software to provide standard interfaces and minimize interactions, making it possible to substitute lab standards when needed while still maintaining the highest level of calibration quality. Technology does not stand still, but much can be done to standardize on equipment and techniques that will minimize the expense when a calibration lab must install a new measurement capability. Change is inevitable, but we can control the cost of evolution through careful adherence to software and hardware standards.

Another common question is, “What does the future hold?” Pat Bryne's answer was, “Instruments will continue to get smarter and include an ever-increasing amount of digital signal processing. As that relates to metrology, that’s good, because tasks performed digitally have great repeatability and are not subject to traditional calibration.” However, as product functionality increases – for example digital I/Q modulation – some of the new “money specs” (those that matter most to end customers) can easily become more complex and require more exotic techniques for verification. Fortunately, the verification and adjustment software, along with other pertinent IP, can be easily moved from the equipment supplier to calibration labs in electronic form. Upgrades and repairs, coupled with targeted training, can all be delivered over the Web, making it possible to maintain a state of readiness that has never before been available when such deliveries had to be made via snail mail, printed manual, or classroom chalkboard.

The automated tools used by OEMs to characterize and manufacture new products can be shared with customers – but only if those tools are developed with customer use in mind. Calibration labs can take advantage of automation, capitalize on IP provided by product-focused metrologists, and provide results that help their customers contend with the myriad of market forces.

Pat continued, “New measurement challenges will be found and answered in RF/microwave and optical communications, in genome research, in transportation and utilities, in healthcare, and in other markets striving to use technology to provide improvements in lifestyle, life quality, and life security.” While equipment providers are the source of fundamental measurement capability, calibration labs around the world are the means by which we ensure that technology is consistently and reliably applied. The movement of IP from OEM to calibration labs to customers is becoming as important as the movement of the measurement hardware that has been the mainstay of the Test and Measurement business. Embodied in software tools, training, and techniques, that IP completes a synergistic relationship between OEM suppliers and their customers. It is the only way the full power of OEM metrology can be offered to customers fighting business battles in their own unique environments.

As mentioned earlier, there is an immense satisfaction in being affiliated with an organization whose mission it is to provide and preserve the truth in measurements. As metrologists, test engineers and technology providers, an unwavering commitment to the accuracy, repeatability and correct interpretation of measurements is at the core of our mission. As we strive to continuously improve and to exceed expectations, we always know the target. That is comforting in an otherwise tumultuous world.

Acknowledgement
John Herniman wishes to extend a sincere acknowledgement to Fred Kruger and Gary Whitman for their major contributions to this article.

About the author John Herniman began his career in 1985 at British Telecom Research Laboratories. In 1992, he took a senior engineer position with the Hewlett-Packard Fiber Optics Components Operation in the United Kingdom, formerly BT&D Technologies. He joined HP's Fiber Optics Communication Division in 1997, moving to project manager for the division's R&D and production group. In 2003 he became Agilent’s Wireless Business Unit Quality Manager, and in 2005, V.P. for Quality in the Electronic Measurements Group.