National Institute of Standards and Technology - NIST

Keeping Time: NIST-F2 Atomic Clock

The U.S. Department of Commerce's National Institute of Standards and Technology (NIST) has officially launched a new atomic clock, called NIST-F2, to serve as a new U.S. civilian time and frequency standard, along with the current NIST-F1 standard.

NIST-F2 would neither gain nor lose one second in about 300 million years, making it about three times as accurate as NIST-F1, which has served as the standard since 1999. Both clocks use a "fountain" of cesium atoms to determine the exact length of a second.

NIST scientists recently reported the first official performance data for NIST-F2,* which has been under development for a decade, to the International Bureau of Weights and Measures (BIPM), located near Paris, France. That agency collates data from atomic clocks around the world to produce Coordinated Universal Time (UTC), the international standard of time. According to BIPM data, NIST-F2 is now the world's most accurate time standard.**

NIST-F2 is the latest in a series of cesium-based atomic clocks developed by NIST since the 1950s. In its role as the U.S. measurement authority, NIST strives to advance atomic timekeeping, which is part of the basic infrastructure of modern society. Many everyday technologies, such as cellular telephones, Global Positioning System (GPS) satellite receivers, and the electric power grid, rely on the high accuracy of atomic clocks. Historically, improved timekeeping has consistently led to technology improvements and innovation.

"If we've learned anything in the last 60 years of building atomic clocks, we've learned that every time we build a better clock, somebody comes up with a use for it that you couldn't have foreseen," says NIST physicist Steven Jefferts, lead designer of NIST-F2.

For now, NIST plans to simultaneously operate both NIST-F1 and NIST-F2. Long-term comparisons of the two clocks will help NIST scientists continue to improve both clocks as they serve as U.S. standards for civilian time. The U.S. Naval Observatory maintains military time standards.

Both NIST-F1 and NIST-F2 measure the frequency of a particular transition in the cesium atom—which is 9,192,631,770 vibrations per second, and is used to define the second, the international (SI) unit of time. The key operational difference is that F1 operates near room temperature (about 27 ºC or 80 ºF) whereas the atoms in F2 are shielded within a much colder environment (at minus 193 ºC, or minus 316 ºF). This cooling dramatically lowers the background radiation and thus reduces some of the very small measurement errors that must be corrected in NIST-F1.

Primary standards such as NIST-F1 and NIST-F2 are operated for periods of a few weeks several times each year to calibrate NIST timescales, collections of stable commercial clocks such as hydrogen masers used to keep time and establish the official time of day. NIST clocks also contribute to UTC. Technically, both F1 and F2 are frequency standards, meaning they are used to measure the size of the SI second and calibrate the "ticks" of other clocks. (Time and frequency are inversely related.)

NIST provides a broad range of timing and synchronization measurement services to meet a wide variety of customer needs. NIST official time is used to time-stamp hundreds of billions of dollars in U.S. financial transactions each working day, for example. NIST time is also disseminated to industry and the public through the Internet Time Service, which as of early 2014 received about 8 billion automated requests per day to synchronize clocks in computers and network devices; and NIST radio broadcasts, which update an estimated 50 million watches and other clocks daily.

At the request of the Italian standards organization, NIST fabricated many duplicate components for a second version of NIST-F2, known as IT-CsF2 to be operated by Istituto Nazionale di Ricerca Metrologica (INRIM), NIST's counterpart in Turin, Italy. Two co-authors from Italy contributed to the new report on NIST-F2.

The cesium clock era officially dates back to 1967, when the second was defined based on vibrations of the cesium atom. Cesium clocks have improved substantially since that time and are likely to improve a bit more. But clocks that operate at microwave frequencies such as those based on cesium or other atoms are likely approaching their ultimate performance limits because of the relatively low frequencies of microwaves. In the future, better performance will likely be achieved with clocks based on atoms that switch energy levels at much higher frequencies in or near the visible part of the electromagnetic spectrum. These optical atomic clocks divide time into smaller units and could lead to time standards more than 100 times more accurate than today's cesium standards. Higher frequency is one of a variety of factors that enables improved precision and accuracy.

Closed Captioning for the Hearing Impaired: How it Originated

• In the early 1970's, NBS developed a time distribution system that placed a hidden time code on an unused part of the television signal. A decoder in the television set recovered and displayed the time. While the system was not implemented, this technology provided the basis for closed captioning.
• In 1971, NBS and ABC-TV began experimentally transmitting captions. A demonstration was held for the National Conference on Television for the Hearing Impaired, showing an episode of Mod Squad that had been captioned by a NBS employee, Sandra Howe.
• In the following years, the Public Broadcasting System, working with NBS, took up the project and developed convenient encoding equipment and improvements to the captioning format.

• In 1980, ABC, NBC, and PBS began transmitting closed captions on selected programs, and decoders went on sale to the public. This coincided with the establishment of the National Captioning Institute which is still responsible for much of today's captioning.

• In September 1980, NBS, ABC, and PBS received Emmys from the Academy of Television Arts and Sciences for this development. The NBS staff (Dick Davis, Jim Jespersen, and George Kamas) responsible for the work were later invited to the White House to meet with President Carter and receive his congratulations.

• In 1990, President Bush signed a bill requiring that all television sets 13 inches or larger sold in the U.S. after July 1, 1993 have the capability for displaying closed captions.

• Closed captions on a television set appear as white on a black background. They can be on the top or bottom of the screen depending on the nature of the picture. In a typical captioned program, captions do not appear when printed text is on the screen or when there is no speech. All television sets are configured so that captions can be switched on or off. The standard format now being used allows for captioning in two languages, but single language captioning predominates today.

NIST and the National Cybersecurity Center of Excellence (NCCoE) have been using Cooperative Research and Development Agreements (CRADAs) for joint cybersecurity efforts. The NCCoE’s mission is to advance cybersecurity by accelerating the adoption of secure technologies through collaborations with innovators to provide real-world, standards-based cybersecurity capabilities that address business needs. Within the NCCoE business communities have been broken into sectors. This project will discuss the collaborative efforts of one within the healthcare sector, Securing Electronic Health Records on Mobile Devices.

Cybersecurity challenges are brought to the NCCoE by members of the health IT community. Referred to by NIST as a community of interest (COI), this group helps the Center select topics and gives feedback on the results of NIST projects. With the fast-growing area of mobility and the acceptance of electronic health records (EHRs), the community saw a need to secure these systems and the communications between them. The NIST lab at the NCCoE built an environment that simulates the interaction among mobile devices and an EHR system supported by the IT infrastructure of a medical organization using technologies from a consortium of seven vendors and open-source tools.

To start the collaborative effort, the NCCoE issued a call in the Federal Register inviting technology providers with commercial products that matched NIST security characteristics to submit letters of interest describing their products’ capabilities. Companies with relevant products were invited to sign a CRADA with NIST, allowing them to participate in a consortium to build this example solution. NIST aims to describe the process that brings together the collaborators in an open and transparent way. In addition, NIST will examine the lightweight CRADA used and discuss the benefits of its streamlined approach.

CRADA Outcome

The Health IT Mobile Device Use Case research program was a collaboration between the NIST NCCoE and eight industry participants. The collaboration was formalized using a CRADA, a partnering tool that allows federal laboratories to work on research and development projects with U.S. industries, academia, and other organizations. The project worked to design and implement a mobile network build to secure mobile device communication to a backend electronic health record system. The research involved developing interconnections used in mobile devices, networking, secure infrastructure, and backend systems.

Numerous policy issues are involved in industry-collaborative research and development of health information technologies. Intellectual property and other contractual questions require negotiation in any government-industry collaboration. In the case of the NCCoE CRADA, there were major challenges negotiating End User License Agreements (EULAs) and their applicability to the federal government. Another sensitivity involved the legal terms for sharing trade secrets, which included concern about the lack of copyright by the government and the worry of potential Freedom of Information Act (FOIA) disclosure. Additionally, health IT work must comply with human subjects, animal subjects, and Health Insurance Portability and Accountability Act (HIPAA) regulations. Interestingly, there was also discussion about the implications of data encryption of patient information on the Hippocratic Oath.

By using a streamlined CRADA template and requiring the education of both industry and government partners on the process, the consortium reduced the time to execute a CRADA from 9-12 months in 2012-2013 to 2-3 months in 2016. The increased efficiency in the process may be due to the NIST agreement staff increasing the understanding of common objections by industry negotiators and using a template that remains silent on many “difficult” terms.