Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1992. / Vita. Abstract. Includes bibliographical references (leaves 106-108). Also available via the Internet.

Thesis (M.S.)--University of Nevada, Reno, 2008. / "December 2008." Includes bibliographical references (leaves 66-69). Online version available on the World Wide Web.

This work presents a design process for developing a dedicated hybrid thick-film time domain reflectometer. The design process allows for variation of the pulse generator characteristics as well as the output impedance of the unit. The unit is fabricated using standard thick-film hybrid techniques while giving consideration to problems encountered at microwave frequencies. This thesis also presents an overview of time domain reflectometry and its applications. Special emphasis is given to the problem of characterizing material dielectric constants using delay measurements. / Master of Science

Thesis--University of Florida. / Typescript. Vita. Description based on print version record. Bibliography: leaves 87-88.

The effects of time-dependent electron density fluctuations on a synthesized time domain reflectometry response of a one-dimensional cold plasma sheath are considered. Numerical solutions of the Helmholtz wave equation, which describes the electric field of a normally incident plane wave in a specified static electron density profile, are used. Included in this work is a study of the effects of Doppler shifts resulting from moving density fluctuations in the electron density profile of the sheath. / Master of Science

One of the most important steps in the search for life on Mars is to determine if a specific sub-surface location it is "habitable", or that it provides the conditions and requirements to support life as we know it. In this thesis, I present a miniature, thermal-IR radiometer and reflectometer designed to determine temperature, the presence of water ice, and the discrimination of minerals, all necessary for a habitable environment. A dual use detector was selected for the thermal and five reflectance channels. The IR source is provided by five LEDs. These components were embedded in a thermally controlled aluminium block. Integrated electronics provided signal amplification and demodulation. This device will be suitable for drilling applications with less than 25 mm diameter boreholes and with limited available power (<5watts). Thermal testing was within a simulated borehole mounted in a thermal vacuum chamber. The results were compared to a theoretical model of the expected temperature. The maximum temperature error between predicted and measured was 0.21 K (∼0.08%). The total RMS error of all sources were calculated to be <3%. Reflectance testing in all five channels included a variety of minerals and a two point calibration method. The results were compared to the predicted reflectance values for the samples. The results of the reflectance channel testing demonstrated that the measured values matched the predicted values with a 2.5% measured error. The total RMS error was 6.1%. Detection and discrimination of water ice and hydrated minerals included a non-linear mixing model and/or testing. The model predicted that water ice mixed in a pyroxene mineral matrix can be detected and discriminated from 5% to 60% concentration by weight. Testing with a hydrated mineral mixed within a non-hydrated mineral matrix demonstrated that the measured result matched the predicted result from 5-45% concentration by weight.

Thesis (Ph. D.)--Brigham Young University. Dept. of Physics and Astronomy, 2003. / Includes bibliographical references (p. 127-137).

Time Domain Reflectometer (TDR) measures the electrical length of a cable from the applied end to the location of an impedance change. An impedance change causes a portion of the applied signal to reflect back based on the value of its reflection coefficient. The time of flight (TOF) between the applied and reflected wave is computed and multiplied with previously determined signal propagation velocity to determine the location of the impedance change. We intentionally open terminate the output end of the cable which makes the reflection coefficient be maximum (=1) to measure its electrical length. Conventional TDRs designed for testing integrity of long cables use various closed pulse shaped test signals i.e. the half sine wave and the Gaussian pulse, that disperse (change shape) and change velocity while propagation along the cable. Quoting Dr. Leon Brillouin’s comments on electromagnetic energy propagation [10], “in a vacuum, all waves (e.g. frequencies) propagate at the same velocity, hence withoutdistortion, whereas in a dispersive lossy media, except for an infinitely long sinusoidal waveform, distortion will occur due to frequency dependent velocity.” This signal distortion generally degrades the accuracy of the measurement of the signal’s TOF. We discuss here an Enhanced Resolution Time Domain Reflectometer (e-TDR). The enhanced resolution is due to a newly discovered signal called SPEEDY DELIVERY (SD) by Dr. Robert Flake at The University of Texas at Austin (US PATENT 6,441,695 B1 issued in August 27, 2002). This SD signal has a propagation velocity that is a programmable constant and this signal preserves its shape during propagation through dispersive lossy media (DLM). This signal behavior allows us to use ‘e-TDR’ in applications where remotely located signals need to be synchronized or asynchronized precisely. Potential applications include signal based synchronization of devices like sensors connected in a network. Since the cable carrying data from sensors at discrete and remote locations to a collecting center have different electrical lengths, it is necessary to precisely offset the timestamp of the incoming signal from these sensors to allow accurate data fusion. Our prototype is capable of synchronizing signals 1,200 ft (~ 400 m) apart with sub-nanosecond resolution. / text

Thesis (Ph. D.)--University of Washington, 1996. / Vita. Includes bibliographical references (leaves [197]-201).

Thèse(M.Ress.Renouv.)-- Université du Québec à Chicoutimi, 2002. / Document électronique également accessible en format PDF. CaQCU