Tutorial session

An overview of how traceability to the International System (SI) units is established in time and frequency metrology. This tutorial discusses the definition of traceability, and briefly examines calibration methods, uncertainty analysis, and legal and technical measurement requirements. It describes how broadcast reference signals from satellite and ground-based signals can be used to satisfy traceability requirements, and discusses the remote time and frequency calibration services offered by NIST. David A. Howe is leader of the Time and Frequency Metrology Group of the National Institute of Standards and Technology and the Physics Laboratory's Time and Frequency Division. His expertise includes spectral estimation using digital processing techniques, spectral purity and noise analysis, digital servo design, automated accuracy evaluation of primary cesium standards, atomic beam analysis, reduction of oscillator acceleration sensitivity for special applications, statistical theory, and clock-ensemble algorithms. Mr. Howe has physics and math B.A. degrees from the University of Colorado, is a member of Sigma Pi Sigma and Phi Beta Kappa academic societies, and is an IEEE Senior Member. From 1970-1973, he was with the NIST (then NBS) Dissemination Research Section where he coordinated the first TV time experiments, from which evolved closed captioning, as well as lunar-ranging and spacecraft time-synchronization experiments. He joined the Atomic Standards Section from 1973-1984 doing advanced research on cesium and hydrogen maser standards and ruggedized, compact rubidium and ammonia standards. He returned to the Dissemination Research Section in 1984 to lead and implement several global high-accuracy satellite-based time-synchronization experiments with other national laboratories. For this contribution, he was awarded the Commerce Department's highest commendation, the Gold Medal, in 1990 for advancements in time calibrations among standards laboratories who participate in the maintenance of UTC. From 1994-1999, he worked as a statistical analyst for the Time Scale Section which maintains UTC(NIST) from an ensemble of laboratory atomic frequency standards. Mr. Howe is the developer of the Total and TheoH variances used in high-accuracy estimation of long-term frequency stability. He has over 100 publications and two patents in subjects related to precise frequency standards, timing, and synchronization. 1 J. Kitching, S. Knappe, and L. Hollberg, "Performance of small-scale frequency references," Proceedings of the IEEE International Frequency Control Symposium, New Orleans, LA, 2002. 2 Collected preprints at: http://www.symmttm.com/info_center_white_papers.asp#acd SURFACE ACOUSTIC WAVE ID-TAGS AND WIRELESS PASSIVE RESONANT SENSORS L. M. Reindl, Institute of Microsystems Technology (IMTEK), University of Freiburg, Germany In the recent years unwired SAW sensors and identification tags have come under notice with a growing number of publications and applications. In this presentation the operating principles of wireless passive, mostly SAW based identification marks and sensors are shown. The whole radio based sensor system consists of a read-out unit, comparable to an RADAR device, and a passive transponder, consisting of a surface acoustic wave (SAW) device wired to an antenna. The surface acoustic wave stores the read-out signal for a predefined period of time to suppress all environmental echo interferences. Physical or chemical effects may influence the propagation characteristics of the surface acoustic wave. Two fundamental devices allow storing and modulating of surface acoustic waves: the resonator, and the uniform or chirped delay line. In this presentation, the transponder setup using a reflective delay line, resonator, or impedance sensor is discussed in detail, as well as the setup of the read out unit using a pulse or FMCW radar. Special emphasis is set on the achievable accuracy and on the sensitivity range. Several applications of such sensor systems and their state-of-the-art performance is presented by way of examples which include identification marks and wireless measurements of temperature, pressure, torque, acceleration, tire-road friction, magnetic field, and water content of soil. A discussion of other resonant structures which also could be used in a passive transponder system will close the presentation. Leonhard Reindl received his Diploma in Physics from Technical University of Munich, Germany, in 1985 and his Dr. sc.techn. from the University of Technology Vienna, Austria, in 1997. In April 1985 Dr. Reindl joined the surface acoustic wave group of the Siemens Corporate Technology Division, Munich, Germany. At Siemens Dr. Reindl contributed to the development of SAW convolvers, dispersive, tapped, and reflective delay lines. His primary interest was in the development and application of SAW ID-tag and wireless passive SAW sensor systems. In April 1999 Dr. Reindl joined the Institute of Electrical Information Technology, Clausthal University of Technology, where he became professor of communications and microwave techniques. In May 2003 he accepted a full professor position as the chair for Electrical Instrumentation at the Institute for Microsystem Technology (IMTEK) at the University of Freiburg, Germany. Dr. Reindl is member of the IEEE, of the TPC of the IEEE Frequency Control Symposium, and of the German biannual Symposium Sensoren und Messsysteme. He has been elected member of the AdCom of the IEEE UFFC society in 2005 to 2007. He holds more than 30 patents on SAW devices and wireless passive sensors and has authored or co-authored more than 100 papers in this field. CHIP-SCALE ATOMIC MAGNETOMETERS Svenja Knappe, Time and Frequency Division, NIST Boulder High-resolution laser spectroscopy enables the precise measurements of many physical quantities such as time, magnetic field, rotation, acceleration, temperature, and pressure. Despite their good performance, atomic sensors have been excluded form many everyday applications due to their large size and weight, high power consumption, or expensive price. Combining laser and atomic physics with Micro-Electromechanical Systems (MEMS) could benefit such applications. Enhanced precision or accuracy of atomic stabilization could be combined with wafer-level fabrication processes to reduce size, cost, and power consumption. Rapid advancements in the field of atomic magnetometry have made these sensors competitive with superconducting quantum-interference devices (SQUIDs). The operating principles of atomic magnetometers depend largely on the requirements of the specific application. This tutorial will give an introduction into atomic magnetometry. Different excitation schemes, transitions, and modes of operation will be discussed. Magnetic sensitivity, bandwidth, and operating range are important factors in the choice of the sensor. Fabrication of chip-scale atomic magnetometers will be outlined. Applications can range from geophysical surveys to medical imaging. Issues involving the miniaturization of such sensors specific to the applications will be illustrated. Finally, other chip-scale atomic sensors will be introduced briefly. Svenja Knappe received her diploma in physics from the University of Bonn, Germany in 1998. The topic of her diploma thesis was the investigation of single cesium atoms in a magneto-optical trap. She obtained her PhD from the University of Bonn in 2001, with a thesis on "Dark resonance magnetometers and atomic clocks". Since 2001, she has been pursuing research in the Time and Frequency Division at NIST, Boulder. Her research interests include precision laser spectroscopy, atomic clocks and atomic magnetometers, laser cooling, alkali vapor cell technology, applications of semiconductor lasers to problems in atomic physics and frequency control, miniaturization of atomic spectroscopy, and chip-scale atomic devices. MICROWAVE FREQUENCY SYNTHESIZERS: ARCHITECTURES AND NEW DEVELOPMENTS Alexander Chenakin, Phase Matrix, Inc. This tutorial presents an overview of today’s microwave frequency synthesizer technologies. It begins with basic requirements and specifications followed by a detailed survey of various synthesizer techniques, which are compared in terms of performance, circuit complexity, and cost impact. Included are direct analog, direct digital and indirect synthesizer architectures along with their main characteristics and performance trade-offs. The latest frequency synthesizer developments, new market demands, design challenges, and various solutions are discussed. Dr. Alexander Chenakin is the Director of the Frequency Synthesis Group at Phase Matrix, Inc., www.phasematrix.com. He earned his degree from Kiev Polytechnic Institute and has worked in a variety of technical and managerial positions around the world. He also founded Critical Design Company, LLC, focusing on the research and development of low phase noise microwave oscillators and frequency synthesizers. In 2005 Dr. Chenakin joined Phase Matrix, Inc. where he leads the development of advanced frequency synthesizer products for test & measurement applications. Dr. Chenakin can be reached by phone at 408-954-6409 or by e-mail at achenakin@phasematrix.com. PHASE AND AMPLITUDE MODULATION NOISE METROLOGY Craig Nelson, NIST Noise is everywhere. Its ubiquitous nature interferes with or masks desired signals and fundamentally limits all electronic measurements. Noise in the presence of a carrier is experienced as amplitude and phase modulation noise. Modulation noise will be covered from its theory, to its origins and consequences. The effects of signal manipulation such as amplification, frequency translation and multiplication on spectral purity are examined. Practical techniques for measuring AM and PM noise, from the simple to complex will be discussed. Calibration of measurements and common problems and pitfall will also be covered. Craig Nelso