EFTF - IFCS 2009 European Frequency and Time Forum Interational Frequency Control Symposium
TUTORIALS
| Track 1 | Track 2 | Track 3 | |
|---|---|---|---|
| 8:45-10:45 | Phase and Amplitude Modulation Noise Metrology | Physical-chemical foundations of piezo-acoustic sensing mechanisms | Clock Performance Characterization for timekeeping and navigation systems |
| 10:45-11:00 | coffee | coffee | coffee |
| 11:00-13:00 | Advanced Laboratory Methods | Piezo-electric sensors as electronic/electrical devices | Algorithms for TAI |
| 13:00-13:45 | lunch | lunch | lunch |
| 13:45-15:45 | Vibration-Induced Phase Noise in Signal Generation Hardware | Introduction to Atomic Frequency Standards | Precise GNSS time and frequency transfer |
| 15:45-16:00 | coffee | coffee | coffee |
| 16:00-18:00 | Optical Frequency Combs: Introduction, Sources and Applications | MEMS for Frequency Control | Optimal FIR Filtering of Clock Models |
Track 1
Period 1 : Phase and Amplitude Modulation Noise Metrology
- Abstract
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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 Nelson is an electrical engineer at the Time and Frequency Division of the National Institute of Standards and Technology. He received his BSEE from the University of Colorado in Boulder in 1990. After co-founding SpectraDynamics, he joined the staff at the NIST. He has worked on the synthesis and control electronics, as well as software for both the NIST-7 and F1 primary frequency standards. He is presently involved in research and development of ultra-stable synthesizers, low phase noise electronics, and phase noise metrology. Current areas of research include optical oscillators, high-speed pulsed phase noise measurements and phase noise metrology in the 100 GHz range. He has published over 35 papers and teaches classes, tutorials, and workshops at NIST, the IEEE Frequency Control Symposium, and several sponsoring agencies on the practical aspects of high-resolution phase noise metrology.
Period 2 : Advanced Laboratory Methods
- Abstract
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Random phase fluctuations, referred to as phase noise and closely related to frequency stability, affect precision and accuracy of timing. Therefore phase noise impacts on numerous fields and applications, like metrology, physics, digital electronics, radars, telecommunications, optics, microwave photonics, gravitation measurements, particle accelerators, etc.
This tutorial is the continuation of the tutorial given on phase noise by C. Nelson, which introduces the language and goes through the basics. Here, we focus on advanced measurement methods. The main ideas are detailed underneath.Correlation and averaging. Let's measure the noise c of a device or an oscillator with two separate instruments, each of which adds its background noise a and b. Denoting with
x=a+candy=b+cthe readout of the two instruments, the average correlation between x and y converges to c. It is therefore possible to measure a noise process c lower than the instrument background a and b. The noise rejection can be validated on the ground of simple mathematical properties. Amplitude noise, crosstalk and other experimental problems limit the rejection of the background noise.
Bridge (interferometer). After suppressing the carrier by sum of an equal and opposite reference signal, the noise sidebands of the device under test are amplified and converted to dc by synchronous detection. This method exhibits the lowest background noise, both in the white and flicker region. World record low background noise is achieved by correlating the output of two instruments of this type.
Optical-fiber delay line. A delay line converts a frequency into a phase, hence comparing the phase of a signal to the phase of its delayed copy gives the frequency fluctuation. The advantage of the delay line versus the resonant discriminator is that the delay line works at any frequency in a wide range. Hence, this method is suitable to the measurement of the new-generation opto-electronic microwave oscillators, which exhibit high spectral purity, but are difficult to tune to a round frequency. Once again, correlation improves the sensitivity.
Amplitude noise. Though amplitude noise is relevant in some applications, mainly in frequency multiplication and optics, very little documentation is available in the literature. We go through the power detector and the correlation method to achieve high sensitivity.A documentation project is in progress. Check for updates on the arxiv.org web site and on the author's home page http://rubiola.org.
Period 3 : Vibration-Induced Phase Noise in Signal Generation Hardware
This two-part, two-hour Tutorial will focus on vibration-induced phase noise in oscillator and non-oscillator components. Part I will cover the analysis aspects of the subject. Part II will deal with measurement methods and troubleshooting techniques. At the conclusion of the Tutorial, attendees should be able to :
- Identify the sources of vibration-induced phase noise in components and circuit assemblies.
- Translate between the different methods of specifying vibration sensitivity and allowable levels of vibration in components and electronic assemblies.
- Sub-allocate phase noise and vibration sensitivity requirements to subassemblies to guide design decisions.
- Evaluate the vibration sensitivity and vibration-induced phase noise of oscillator and non-oscillator components and signal generation circuit assemblies and be aware of techniques for reducing the vibration sensitivity.
- Become familiar with measurement methods and troubleshooting techniques.
The Tutorial outline is given below.
- Part I : Vibration-Induced Phase Noise Analysis
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- Introduction (objectives, topics, introduction)
- Section 1 : Review of Static Phase Noise Metrology and Performance
- Noise Terminology
- Relationships
- Section 2 : Vibration-Induced Phase Noise
- Vibration Terminology
- Fundamentals
- Measures of Vibration Sensitivity
- Section 3 : Typical Vibration Sensitivity Values and Improvement Techniques
- Oscillators (technologies, cancellation)
- Non-oscillator components (filters, transmission lines, etc.)
- Part II : Vibration Induced Phase Noise Testing
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- Introduction
- Section 1 : Phase Noise Measurement
- Methods by type of UUT (Oscillators, Non-Oscillator Components, Multifunction Assemblies)
- Data distortion issues
- Troubleshooting techniques (real time measurement, changing bandwidths, etc.)
- Section 2 : Vibration Testing
- Typical setup (shakers, accelerometers, analysis)
- Baseline calibration
- Troubleshooting techniques (Acoustics, EMI, Grounding, engraving tool)
- About the authors
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Joe Donovan is an advisory engineer in the Mechanical Systems Group at Northrop Grumman Electronic Systems in Baltimore, Maryland. He is currently focusing on vibration control for electronic equipment. He has particular interest in issues of performance degradation in electronics and optics subjected to vibration. He oversaw development and operation for 9 years of a small vibration laboratory dedicated to enhancing the understanding of the causes of phase noise under vibration. He co-teaches two internal courses, both on the topic of analysis and testing of electronic equipment subjected to vibration. Joe received his BSME in 1990 and MSME in 1991 at Virginia Polytechnic Institute and State University. His thesis work was in the area of modal analysis of structures. Subsequently, he worked in the fields of active and passive vibration control before joining Northrop Grumman in 1995. He has published a total of five papers with the Society of Automotive Engineers, the American Institute of Aeronautics and Astronautics, and the IEEE.
Mike Driscoll joined the Westinghouse Defense Center (now part of Northrop Grumman Electronic Systems) in Baltimore in 1965. He has worked primarily on the design and development of low noise signal generation hardware for use in high performance radar systems. Mike was a Senior Consulting Engineer at Northrop Grumman until retiring in February, 2008 and is currently under contract as a consultant at Northrop Grumman. His responsibilities include the design and development of high stability oscillators as well as characterization and reduction of phase noise in RF signal processing components and circuits. He has been a member of the IEEE Frequency Control Symposium Technical Program Committee since 1987. He is an Associate Editor of the IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control (UFFC) and was the Conference Chair for the 2005 and 2006 IEEE International Frequency Control Symposia. In 1997, he was the recipient of the IEEE UFFC Society CADY award, cited for Contributions to Low Noise Signal Generator Design. In 2006, he was a recipient of the Northrop Grumman Lifetime Achievement Award. He has published and presented over 60 papers in IEEE Journals and at IEEE Conferences. He has presented several IEEE Tutorials and Northrop Grumman Instructional Courses and holds numerous U.S. Patents dealing with the subject of Low Noise Signal Generation.
Period 4 : Optical Frequency Combs: Introduction, Sources and Applications
- Abstract
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This tutorial will review the topic of optical frequency combs, with an emphasis placed on practical details related to the operation of optical frequency combs for various applications. The tutorial will begin with a brief historical perspective, including discussion of key developments in the late 1990’s that ushered in the era of femtosecond laser frequency combs. From there, we will cover the construction, major components, and operation principles of several of the most common types of optical frequency combs. Finally, we will highlight important applications of these frequency combs to research areas such as frequency metrology, optical clocks, precision spectroscopy, optical/microwave synthesis, timing synchronization/ distribution, and attosecond science.
Track 2
Period 1 : Physical-chemical foundations of piezo-acoustic sensing mechanisms
- Abstract
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Piezoelectric resonators are in use as mass-sensing devices for almost half a century. More recently it was recognized that shifts in frequency and bandwidth can come about by a diverse variety of interactions with the sample. The classical "load" consists of a thin film, which shifts the resonance frequency due to its inertia. Other types of loading include semi-infinite viscoelastic media, rough objects contacting the crystal via isolated asperities, mechanically nonlinear contacts, and dielectric films. These interactions are now rather well understood and will be presented in a unified framework.
The tutorial will cover the following topics
- Basics of acoustic resonators
- Oscillator circuits, ring-down, and impedance analysis
- Equivalent circuits and acoustic waves
- Unified description of small loads
- Stratified layers
- Particulate adsorbates
- Electrical and dielectric loads
- Contact mechanics experiments
- Nonlinearities
Period 2 : Piezo-electric sensors as electronic/electrical devices
- Abstract
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This tutorial will cover devices based on piezoelectric crystals and used for physical and chemical sensor applications. Various acoustic wave devices used as temperature, mass, pressure, torque, acceleration sensors, for material characterization, and as chemical agents detectors will be presented and described. The course will focus on two types of piezoelectric sensors that have reached some level of maturity - available as commercial products or under development. They are the thickness shear mode (TSM) resonators and surface acoustic wave (SAW) devices (both Rayleigh SAW and shear horizontal-SAW). Chemically sensitive and selective absorptive coatings used for chemical sensors will also be described. Sensor device principles and modeling including second order effects, design parameters, operating characteristics, and key sensing parameters will be covered. Various measurement schemes used with the piezoelectric sensors will be described.
Fabien Josse received the License in Maths and Physics, the M.S. and Ph.D. degrees in electrical engineering in 1976, 1979 and 1982, respectively. He has been with Marquette University, Milwaukee, WI, since 1982 and is currently professor in the Department of Electrical and Computer Engineering, and the Department of Biomedical Engineering, as well as the Director of Graduates Studies. He is also an adjunct professor in the Department of Electrical and Computer Engineering, Laboratory for Surface Science and Technology (LASST), University of Maine, and has been a visiting professor at the University of Heidelberg, Germany, since 1990, and a visiting professor at Laboratoire IMS, University of Bordeaux, France, and the Physical Electronics Laboratory (PEL) at the Swiss Federal Institute of Technology (ETH), Zurich, Switzerland since 2002. His current research interests include solid state and acoustic wave device sensors (bio-chemical sensors), micro-electro-mechanical systems (MEMS) devices (microcantilevers for sensor applications), investigation of novel sensor platforms, and smart sensor systems. Dr. Josse is a senior member of IEEE and a member of Eta Kappa Nu, Sigma Xi, and associate editor of the IEEE Sensors Journal since 2002.
Period 3 : Introduction to Atomic Frequency Standards
- Abstract
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The fundamental precision of atomic timekeeping is unequaled in any other measurement methodology. Atomic frequency standards provide the ultimate source of accuracy and stability for all modern communications, navigation, and time-keeping systems. State-of-the-art atomic clocks test the frontiers of theoretical and experimental information theory, atomic physics, and cosmology. Practical implementations of atomic clocks range from commodity rubidium oscillators, smaller than a sandwich and accurate to parts in 1011, to one-of-a-kind laboratory-scale optical clocks, manned by teams of scientists and achieving accuracies now measured in parts in 1017.
This tutorial will provide an introduction to atomic frequency standard technology, with particular emphasis on the general scaling rules, atomic physics and engineering challenges common to all implementations in the field.
The tutorial will focus on mature technologies: rubidium oscillators, cesium beam frequency standards, and hydrogen masers. Time permitting we will also introduce emerging technologies, the application of laser sources to atomic interrogation, coherent population trapping and chip-scale atomic clocks, cold atom clocks and fountains, and optical clocks. - About the presenter
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Robert Lutwak is a senior scientist at Symmetricom’s Technology Realization Center. He provides support for the development of products based on mature atomic clock technologies, as well as engineering the transition of emerging technologies from the laboratory to robust implementation. Recently, Dr. Lutwak has led projects to develop next generation atomic clock technology for deployment onboard the GPS-NAVSTAR satellite constellation as well as the development of chip-scale atomic clocks, 100X smaller and lower power than existing technologies. Dr. Lutwak is a Senior Member of the IEEE and has served on the Frequency Control Symposium Technical Program Committee since 2001.
Period 4 : MEMS for Frequency Control
- Abstract
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Due to their need for high frequency selectivity and low noise frequency manipulation, portable wireless communication transceivers continue to rely on high-Q, off-chip resonator technologies that must interface with transistor electronics at the board-level, thus contributing to the substantial percentage (often more than 50%) of portable transceiver area taken up by board-level, passive components. Recent advances in IC-compatible micro-electromechanical system (MEMS) technologies that make possible micro-scale, mechanical circuits capable of low-loss switching, filtering, mixing, and frequency generation, now suggest methods for board-less integration of wireless transceiver components. In fact, given the existence already of technologies that merge micromechanics with transistor circuits onto single silicon chips, single-chip transceivers may eventually become possible, perhaps using alternative architectures that maximize (rather than minimize) the use of passive, low-loss, micromechanical circuits to enhance robustness and reduce power consumption for portable applications. In particular, given that vibrating micromechanical resonator technologies have already achieved on-chip Q’s in excess of 10,000 at 1 GHz at room temperature—something previously not possible—even RF channel-selection becomes plausible, where channels are selected right at RF and inteferers removed before they reach any demodulation circuits.
This course presents a detailed overview of the micromechanical circuits and associated technologies expected to play key roles in reducing the size and power consumption of future communication transceivers. It begins with a review of transceiver operation, emphasizing the need for low-loss and high-Q in both the transmit and receive paths, and identifying the functional blocks that stand to benefit most from MEMS implementation. Detailed coverage of the operation, design, and fabrication of the micromechanical devices most useful for communication applications then follows, including expositions on high-Q micromechanical resonators, filters, and mixer-filters; low-loss micromechanical switches; and medium-Q micro-machined inductors and tunable capacitors. Receiver architectures are then proposed that best harness the tiny size, zero dc power consumption, and ultra-high-Q (or low-loss) of micromechanical resonator and switch circuits. The course concludes with discussions pondering micro-scale physical phenomena that may eventually limit the scalability, and hence application range, of RF MEMS.
- Biography
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Prof. Clark T.-C. Nguyen received the B. S., M. S., and Ph.D. degrees from the University of California at Berkeley in 1989, 1991, and 1994, respectively, all in Electrical Engineering and Computer Sciences. In 1995, he joined the faculty of the University of Michigan, Ann Arbor, where he was a Professor in the Department of Electrical Engineering and Computer Science up until mid-2006. In 2006, he joined the Department of Electrical Engineering and Computer Sciences at the University of California at Berkeley, where he is presently a Professor and a Co-Director of the Berkeley Sensor & Actuator Center. His research interests focus upon micro electromechanical systems (MEMS) and include integrated micromechanical signal processors and sensors, merged circuit/micro-mechanical technologies, RF communication architectures, and integrated circuit design and technology. In 2001, Prof. Nguyen founded Discera, Inc., the first company aimed at commercializing communication products based upon MEMS technology, with an initial focus on the very vibrating micromechanical resonators pioneered by his research in past years. He served as Vice President and Chief Technology Officer (CTO) of Discera until mid-2002, at which point he joined the Defense Advanced Research Projects Agency (DARPA) on an IPA, where he served for three-and-a-half years as the Program Manager for 10 different MEMS-centric programs in the Microsystems Technology Office of DARPA. He is an IEEE Fellow and is presently serving as a Distinguished Lecturer for the IEEE Solid-State Circuits and Systems Society.
Track 3
Period 1 : Clock Performance Characterization for timekeeping and navigation systems
- Abstract
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A reference time scale versus which all the clocks can be synchronized and estimated;
an algorithm for forming a single time scale from a clock ensemble;
the steering of a time scale or a clock with respect to another one;
a good statistical tool to characterize clock stability, accuracy, and reliability;
an efficient algorithm for predicting the clock behavior,
a rapid algorithm able to identify clock failures or anomalies:
are those the needs of Timing laboratories or of Navigation systems ?In many cases the questions are the same but the answers may be different due to the different aims, requirements, technology availabilities, environment. The tutorial will present the needs of Timing and Navigation, and the different tools that are well suited to satisfy them, giving insight on the most challenging topics that are still under investigation.
Period 2 : Algorithms for TAI
- Abstract
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The time laboratories realize a stable local time scale using individual atomic clocks or a clock ensemble. Clock readings are then combined at the Bureau International des Poids et Mesures (BIPM) through an algorithm designed to raise the stability, accuracy and reliability of the time scale above the level of performance that can be realized by any individual clock in the ensemble.
An efficient algorithm is necessary for the statistical generation of a time scale. ALGOS is algorithm maintained at BIPM, which produces, monthly, the international reference UTC (Coordinated Universal Time).The calculation of UTC using ALGOS is articulated in three different steps :
- The ensemble time scale EAL (Echelle Atomique Libre) is computed as a weighted average of about 350 free running atomic clocks spread worldwide. The weighting procedure is optimized for long-term stability of the scale.
- The frequency of EAL is steered to maintain agreement with the definition of the SI (International System of Units) second, and the resulting time scale is called International Atomic Time (TAI). The steering correction is determined by comparing the EAL frequency with that of primary frequency standards.
- Leap seconds are inserted to maintain agreement with the time derived from the rotation of the Earth. The resulting time scale is UTC.
Different algorithms can be considered depending on the requirement; for an international reference such as UTC, the requirement is extreme reliability and long-term stability.
Each month the differences between the international time scale UTC and the local time scales UTC(k) for all contributing time laboratories are reported in the official document called Circular T.
The most important algorithms used in ALGOS are three :
- The weighting algorithm optimized to guarantee long term stability to the time scale
- The prediction algorithm used to avoid time and frequency jumps due to different clock ensemble used in consecutive calculation periods
- The steering algorithm used to improve the time scale accuracy.
Period 3 : Precise GNSS time and frequency transfer
- Abstract
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GPS measurements are used since the eighties for the remote clock comparisons needed for TAI. The technique is based on “Common View”, i.e., the simultaneous observation of the same satellite by two ground stations in order to deduce the synchronization error between the ground clocks and the satellite clock; from that one deduces the synchronization error between the two ground clocks. On a GPS signal, two types of measurements can be performed: the pseudorange (code), but also the phase of the carrier wave. Thanks to the shorter wavelength, the noise level on the GPS phase observable is about 100 times smaller than the corresponding noise level on the code observable. For this reason, the carrier phase measurements have been used for a long time for geodetic applications requiring very high precision, and were later introduced in time transfer studies. When analyzed together with a consistent modeling of the measurements similar to GPS data analysis dedicated to precise positioning, the carrier phases provide a very powerful tool for frequency comparisons between remote clocks, with a precision at the 100 ps level at each epoch. However, since the carrier frequency cycles are not time-tagged, they cannot provide any information about the absolute offset between these clocks. The carrier phase measurements can thus only be used for frequency transfer, i.e. for the determination of the evolution of the phase differences between the clocks. The absolute value of the clock offset will have to be determined using the code information. A combined analysis using both carrier phase and code observations is necessary to get both the absolute value of the clock offset and a very precise determination of the frequency transfer, and the precision of the absolute clock offset determination is still limited by the code noise level (some ns). The tutorial will present the way of introducing code and phase measurements in a combined analysis for precise time and frequency transfer, and the results that can be expected using different approaches.
Period 4 : Optimal FIR Filtering of Clock Models
- Abstract
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In recent years, finite impulse response (FIR) filtering has demonstrated important features making the approach attractive for various applications in timekeeping. In this tutorial, we review methods of optimal FIR filtering of discrete-time clock models. The tutorial is organized to have two parts. In the first part, possible methods for optimal filtering of clock state are observed and it is pointed out that FIR filtering is most natural for solving clock problems. In the second part, we give simple engineering presentations for methods of FIR filtering and discussed a number of useful applications associated with filtering out the measurement noise, clock synchronization by the Global Positioning System (GPS) timing one pulse per second (1PPS) signals, prediction of clock errors, holdover problem, ascertaining the initial clock state by FIR smoothing, best linear fitting of clock errors, and some others. The methods of FIR filtering are supplied with the engineering algorithms. For the comparison, the trade-off between the Kalman algorithm and the optimal FIR one is also discussed in almost each of the applications. We show that the most efficient engineering solution for clocks is the l-degree unbiased FIR filter, predictor, or smoother. Neither of these estimators involves noise and the clock initial state to the algorithm. Herewith, in applications to clocks, each of them demonstrates features often superior to the Kalman algorithm, when a number of measurements on the averaging interval is large.
Yuriy S. Shmaliy received the B.S., M.S., and Ph.d. degrees in 1974, 1976 and 1982, respectively, from the Kharkiv Aviation Institute, Ukraine, all in Electrical Engineering. In 1992 he received the Doctor of Technical Sc. degree from the Kharkiv Railroad Institute. In March 1985, he joined the Kharkiv Military University. He serves as Full Professor beginning in 1986. In 1999, he joined the Kharkiv National University of Radio Electronics, and, since November 1999, he has been with the Guanajuato University of Mexico. Dr. Shmaliy has 242 Journal and Conference papers and 80 patents. His books “Continuous-Time Signals” (2006) and “Continuous-Time Systems” (2007) were published by Springer. He was rewarded a title, Honorary Radio Engineer of the USSR, in 1991; was listed in Marquis Who's Who in the World in 1998; and was listed in Outstanding People of the 20th Century, Cambridge, England in 1999. He is a member of several professional Societies and Organizing and Program Committees of Int. Symposia. His current interests include the statistical theory of clocks and optimal filtering of clock models.
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Joël PETETIN
41 bis avenue de l’Observatoire
B.P. 1615
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0033 381 666 930
eftf.ifcs.2009@free.fr
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Conference location
Micropolis Conference Center
April 20th-24th 2009
