Metrology Matters

World Metrology Day snuck up on some of us a couple weeks ago — my thanks to my colleagues Rod Unverrich and Daniel Bogdanoff for reminding me of it. What is metrology? It covers a pretty wide space, but a succinct definition is: "the science of measurement." Pragmatically, a central aim of metrology is having agreed-upon standards for various units of measurement, along with traceability of any given measurement back to the standard definition for that particular unit. This ensures that when a measurement is made, it is consistent with the agreed-upon definition for what is meant by, say, a kilogram, or a nanosecond, or a milliamp.

Traceability is achieved by calibrating the measurement equipment to a known reference or working standard, which itself has been calibrated through one or more steps all the way back to the foundational SI units. (Much of this process will change in the future now that all 7 of the SI base units have been redefined using fundamental constants of nature, though it will take a while. More on that topic is available here.) Uncertainty windows and uncertainty analysis are integral to the overall approach as well.

As in other fields, calibrations are a big deal in electronic measurement, because in one way or another the measurement instrument — a network analyzer for example — is being used by customers to inform business decisions regarding the performance and quality of the circuits, products, or systems being tested. You don't want to make those decisions based on an uncalibrated instrument. This is why Keysight and other reputable providers invest in such thorough calibration services, both in our own factories and in the capabilities we make available to customers after the initial sale.

The measurement of time has long been interesting to me, perhaps because I began my career as a test engineer working on nanosecond-level measurements for oscilloscopes and logic analyzers. I was always proud of the fact that Hewlett-Packard had made pioneering contributions in practical cesium-beam clocks, some of which were so accurate they were certified as primary standards. Among other things, those clocks helped enable GPS and the synchronization of time around the world.

In 2005 my wife and I went to London on vacation and one day we visited the Royal Observatory in Greenwich. It was so great to see one of the HP clocks on display, with a description of how it had contributed to the mission of the observatory. It gave me a feeling of connection to the long line of scientific and technological developments that had occurred there, going back to the time of Isaac Newton.

At Greenwich you can stand on the line marking the Prime Meridian and learn about the relationship between timekeeping and the determination of position, especially the first reliable determinations of longitude. A wonderful book on this subject is Longitude, by Dava Sobel. Here's an overview:

It is a great story that also became a PBS program and I really admired the way the author brought it to life. Little did I know that a few years later, I would have the honor of meeting her and introducing her as a keynote speaker at the 2013 Agilent Technical Conference. Wow! That was really special and is something I will never forget.

As indicated in the top diagram, National Metrology Institutes such as NIST in the U.S. play key roles in metrology. Beyond the atomic clocks, HP and then Agilent and Keysight have had continued interactions with these organizations on various measurement-related topics. I'm a member of NIST's Visiting Committee on Advanced Technology (VCAT), and it has given me an even deeper appreciation for everything the NIST teams are doing, both directly and through many partnerships and collaborations. Here's a note the Director posted on medical measurements for example, including efforts related the COVID-19 pandemic. It's a pretty impressive set of contributions, and I know other NMIs around the world are also doing their parts.

As a closing thought, a more expansive definition that's out there for metrology is as follows: "the science of measurement, embracing both experimental and theoretical determinations at any level of uncertainty in any field of science and technology." This one appeals to me because it suggests that more people, especially engineers, may be "doing metrology" than might be appreciated. We definitely see this among our customers, as they invent and adopt new technologies and determine the best way to make the specific measurements most relevant to their applications. In fact that's another reason why Keysight is committed to full solutions and deep collaborations with customers — we each have a role to play in furthering the appropriate metrology, sometimes more generally and sometimes very focused and specific.

I've only scratched the surface of metrology and the many ways it impacts our lives. Whether you celebrated on May 20th or not ??, know that metrology will continue to advance through the efforts of a wide array of people around the world, one of whom may be you!