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Search Publications by: Dylan Williams (Fed)

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Displaying 151 - 175 of 294

Terminology for High-Speed Sampling-Oscilloscope Calibration

December 1, 2006
Author(s)
Dylan Williams, Tracy S. Clement, Paul D. Hale, Andrew Dienstfrey
We discuss procedures for calibrating high-speed sampling oscilloscopes at the National Institute of Standards and Technology, and the terminology associated with those calibrations. The discussion clarifies not only the calibration procedures, but how to

Shielding And Attenuation Properties of Large Buildings and Structures

September 4, 2006
Author(s)
Christopher L. Holloway, Galen H. Koepke, Dennis G. Camell, Kate Remley, S. A. Schima, Dylan Williams
For various applications, there is a growing need to understand the shielding and/or attenuation properties of large buildings and structures. In this paper, we present experimental data for the coupling of electromagnetic fields into various types of

Minimum-Phase Calibration of Sampling Oscilloscopes

August 15, 2006
Author(s)
Andrew M. Dienstfrey, Paul D. Hale, Darryl A. Keenan, Tracy S. Clement, Dylan F. Williams
We describe an algorithm for determining the minimum phase of a linear time-invariant response function from its magnitude. The procedure is based on Kramers Kronig relations in combination with auxiliary direct measurements of the desired phase response

Calibration of Sampling Oscilloscopes With High-Speed Photodiodes

August 1, 2006
Author(s)
Tracy S. Clement, Paul D. Hale, Dylan Williams, C. M. Wang, Andrew Dienstfrey, Darryl A. Keenan
We calibrate the magnitude and phase response of equivalent-time sampling oscilloscopes to 110 GHz. We use a photodiode that has been calibrated with our electrooptic sampling system as a reference input pulse source to the sampling oscilloscope. We

Minimum-phase calibration of sampling oscilloscopes

August 1, 2006
Author(s)
Andrew Dienstfrey, Paul D. Hale, Darryl A. Keenan, Tracy S. Clement, Dylan Williams
We describe an algorithm for determining the minimum phase of a linear, time-invariant response function from its magnitude. The procedure is based on Kramers-Kronig relations in combination with auxiliary direct measurements of the desired phase response

Radio Communications for Emergency Responders in Large Public Buildings: Comparing Analog and Digital Modulation

March 7, 2006
Author(s)
Catherine A. Remley, Marc Rutschlin, Dylan F. Williams, Robert T. Johnk, Galen H. Koepke, Christopher L. Holloway, Mike G. Worrell, Andy MacFarlane
To assess in-building radio coverage, in 2004 the City of Phoenix Fire Department carried out extensive testing of their radio systems. They deployed firefighters in standard configurations in a variety of buildings, and rated on a scale of 1 to 5 the

Sampling-Oscilloscope Measurement of a Microwave Mixer With Single-Digit Phase Accuracy

March 1, 2006
Author(s)
Dylan F. Williams, Hassen Khenissi, Fabien Ndagijimana, Catherine A. Remley, Joel Dunsmore, Paul D. Hale, Jack Wang, Tracy S. Clement
We describe a straightforward method of separately characterizing up-conversion and down-conversion in microwave mixers with a sampling oscilloscope. The method mismatch-corrects the results, determines both magnitude and phase, and uses a novel time-base

Covariance-Based Uncertainty Analysis of the NIST Electrooptic Sampling System

January 1, 2006
Author(s)
Dylan F. Williams, Arkadiusz C. Lewandowski, Tracy S. Clement, C. M. Wang, Paul D. Hale, Juanita M. Morgan, Darryl A. Keenan, Andrew Dienstfrey
We develop a covariance matrix describing the uncertainty of mismatch-corrected measurements performed on the National Institute of Standards and Technology's electro-optic sampling system. This description offers a general way of describing the

Propagation and Detection of Radio Signals Before, During, and After the Implosion of a Large Sports Stadium (Veterans’ Stadium in Philadelphia)

October 1, 2005
Author(s)
Christopher L. Holloway, Galen H. Koepke, Dennis G. Camell, Catherine A. Remley, Dylan F. Williams, Susan A. Schima, Seturnino Canales
In this report, we investigate radio communications problems faced by emergency responders (firefighters and police) in disaster situation such as collapsed buildings. A fundamental challenge to communications into and out of large buildings is the strong

Propagation and Detection of Radio Signals Before, During, and After the Implosion of a 13-Story Apartment Building

May 1, 2005
Author(s)
Christopher L. Holloway, Galen H. Koepke, Dennis G. Camell, Catherine A. Remley, Dylan F. Williams, Susan A. Schima, Seturnino Canales, Douglas T. Tamura
In this report we investigate communications problems faced by emergency responders (firefighters and police) in disaster situations (i.e., collapsed buildings). A fundamental challenge to communications into large building structures is the strong

Calibrated 200 GHz Waveform Measurement

April 1, 2005
Author(s)
Dylan Williams, Paul D. Hale, Tracy S. Clement
We develop a method for mismatch-correcting temporal waveforms measured with a high-speed electro-optic sampling system. The new calibration characterizes the source in both the time and frequency domains, and accounts for all impedances and multiple

Linearization of Large-Signal Scattering Functions

April 1, 2005
Author(s)
Jan Verspecht, Dylan Williams, Dominique Schreurs, Kate Remley, Michael McKinley
We present an improved smallsignal linearization of large-signal scatteringparameter functions that takes on a convenient form similar to scattering parameters. We develop rules for the evolution of the linearization and large-signal scattering functions

Radio Propagation Measurements During a Building Collapse: Applications for First Responders

March 3, 2005
Author(s)
Christopher L. Holloway, Galen H. Koepke, Dennis G. Camell, Catherine A. Remley, Dylan F. Williams
The National Institute of Standards and Technology is involved in a research project to improve wireless communications for first responders (firefighters and police) in large structures (i.e., large apartment and office buildings, supermarkets, sports

Measurement of Weak Signals Using a Communications Receiver System

March 1, 2005
Author(s)
Marc Rutschlin, Kate Remley, Robert T. Johnk, Dylan Williams, Galen H. Koepke
We describe the calibration of an inexpensive, reliable system for use in weak-signal detection. The calibration procedure described allows the conversion of signals measured with the communications receiver system-which is based on a standard

Scattering-Parameter Models and Representations for Microwave Mixers

January 1, 2005
Author(s)
Dylan F. Williams, Fabien Ndagijimana, Catherine A. Remley, Joel Dunsmore, Sean Hubert
We present straight-forward models and representations for RF and image mixers, and develop simple rules for transforming electrical problems involving mixers and signals at several frequencies into equivalent single-frequency problems. We show how those

Uncertainty of the NIST Electrooptic Sampling System

December 1, 2004
Author(s)
Dylan F. Williams, Paul D. Hale, Tracy S. Clement
We present an uncertainty analysis of measurements performed with NIST's electrooptic sampling system. The system measures the voltage waveform injected by a photodetector on a coplanar waveguide fabricated on an electrooptic LiTaO3 wafer. The frequency

Multiport Investigation of the Coupling of High-Impedance Probes

November 1, 2004
Author(s)
Dylan F. Williams, Pavel Kabos, Uwe Arz
We used an on-wafer measurement technique that combines two- and three-port frequency-domain mismatch corrections in order to characterize the influence of a high-impedance probe on a device under test. The procedure quantifies the probe’s load of the

Simplifying and Interpreting Two-Tone Measurements

November 1, 2004
Author(s)
Kate Remley, Dylan Williams, Dominique Schreurs, John Wood
We develop a mathematical description of the response of systems to second-order memory mechanisms based on a time-varying gain modulation function. We show that intermodulation products arising from interactions at baseband have different phase symmetries

Extended NVNA Bandwidth for Long-Term Memory Measurements

June 11, 2004
Author(s)
Catherine A. Remley, Dominique Schreurs, Dylan F. Williams, John Wood
We present a new technique for measuring the magnitude and phase of intermodulation products outside the measurement bandwidth of our instrumentation. We apply the technique to measurements of long-term memory effects, and realte our measurements to

Vector Mixer Characterization for Image Mixers

January 1, 2004
Author(s)
Joel Dunsmore, Sean Hubert, Dylan Williams
The vector mixer characterization method first introduced by Dunsmore [1] can be used only for mixers where the Local Oscillator (LO) frequency lies between the RF input and output frequencies. Attempts to use the method for mixers with the LO greater than

An Optimal Vector-Network-Analyzer Calibration Algorithm

December 1, 2003
Author(s)
Dylan Williams, Chih-Ming Wang, Uwe Arz
We present an iterative algorithm for calibrating vector network analyzers based on orthogonal distance regression. The algorithm features a robust, yet efficient, search algorithm, a complete error analysis that includes both random and systematic errors