An Assessment of the National Institute of Standards and Technology Physical Measurement Laboratory Fiscal Year 2015 (2016) / Chapter Skim
Currently Skimming:
9 Time and Frequency Division
9 Time and Frequency Division
Pages 48-55
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 48... ...
The latter standard was the first United States standard to employ cold atoms in a cesium fountain, while NIST-F2 now places the microwave interaction region in a cryogenic environment, dramatically reducing the frequency uncertainties resulting from the blackbody radiation of the standard housing. The TFD accomplishment of developing the cryogenic, cesium fountain clock as the national standard of the United States has improved national and international timekeeping.
|
From page 49... ...
One area of particular accomplishment focuses on generation of microwave signals with ultralow phase noise and timing jitter through photodetection of optical frequency combs. In this so-called optical frequency division process, the already low optical phase noise associated with individual comb lines that are referenced to ultrastable resonators and atomic frequency references is divided down by the ratio of the optical to microwave frequency.
|
From page 50... ...
This device, which operates near room temperature, achieved performance equivalent to that of SQUID, which requires cooling to below 1 K TFD scientists partnered with medical researchers to demonstrate sensing of weak biomagnetic fields, enabling, for example, precision measurements of fetal heart activity without the need to implant electrodes.
|
From page 51... ...
This excellence is further confirmed by the numerous awards TFD staff members have received, including a 2012 Nobel prize in physics. Additionally, TFD staff members have received multiple external awards, such as the Benjamin Franklin Medal from the Franklin Institute, the Rank Foundation Prize, the IEEE Sensor Technical Achievement Award for chip-scale devices, the IEEE Rabi Awards for time-scale establishment and oscillator development, and the National Conference of Standards Laboratories International (NCSLI)
|
From page 52... ...
As one example, research of optical frequency combs can draw on cold atom and ion frequency standards programs and use these highly stabilized frequency references for stabilization of the comb. Optical frequency comb research can also access maser signals associated with the U.S.
|
From page 53... ...
The research that NIST conducts currently in the field of optical frequency standards will result in the next generation of primary national standards. Eventually this will significantly improve the performance of the UTC time scale.
|
From page 54... ...
The TFD SIM time-scale efforts disseminate high-quality time throughout the western hemisphere and also influence the global UTC scale. At a lower level of precision, NIST, under TFD leadership, continues to broadcast precise timing information from high frequency and low frequency radio stations in Colorado and Hawaii to the continental United States and Pacific waters.
|
From page 55... ...
GPS common view techniques for time transfer, along with those enabled through communication satellites, have been in operation for many years. The TFD is now investigating more precise time transfer that could be enabled through use of a hydrogen maser on the International Space Station (ISS)
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.