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Search Publications by: Dylan Williams (Fed)

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Displaying 301 - 325 of 583

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
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