Design of the circularly polarized ceramic antenna, suitable for GPS system, on an asymmetric ground plane is presented in this thesis. Firstly, to obtain two isolated ground planes, we insert an L slit on an asymmetric ground plane, making the antenna with a symmetric ground plane. Then, we isolate the excited surface current between the two ground planes by using a quarter-wavelength mini-coaxial cable. The surface current can distribute uniformly on the ground plane when the proposed antenna is in operation, which makes possible a good circularly polarized radiation pattern in the operation band.

Design considerations and experimental results of a dual-band circularly polarized stacked microstrip antenna for GPS operations at 1227 and 1575 MHz are presented. The antenna is achieved by stacking two corner-truncated square microstrip patches. The obtained circular polarization (CP) bandwidths, determined from 3-dB axial ratio, are about 15 MHz (about 1.2%) and 17 MHz (about 1.1%) at 1227 and 1575 MHz, respectively. Good CP radiation patterns and antenna gain have also been observed.

The Chaochou Fault (CCF) is both an important lithologic boundary and a significant topographic feature in the Taiwan orogenic belt. It is the geologic boundary between the Slate Belt to the east, and the Western Foothills to the west. Although the fault is known to be a high angle oblique sinistral thrust fault in places, both its kinematic history and its current role in the development of the orogen are poorly understood. Field fabric data suggest that structural orientations vary along strike, particularly in the middle segment, the suspected location of the intersection of the on-land Eurasian continent-ocean boundary and the Luzon Island Arc. Foliation/solution cleavage is oriented NE-SW and in the northern and southern sections, but ESE-WNW in the middle segment. Slip lineations also reveal a change in fault motion from dip-parallel in the north to a more scattered pattern in the south. This correlates somewhat with recent GPS results, which indicate that the direction of current horizontal surface motion changes along strike from nearly perpendicular to the fault in the northern field area, to oblique and nearly parallel to the fault in the southern field area. The magnitude of vertical surface motion vectors, relative to Lanyu Island, decreases to the south. Surface morphology parameters, including mountain front sinuosity and valley floor width/valley height ratio indicate higher activity and uplift in the north. These observations correlate well with published apatite/zircon fission track data that indicate un-reset ages in the south, and reset ages in the northern segment. Geodetic and geomorphic data indicate that the northern segment of the CCF and Slate Belt are currently undergoing rapid uplift related to oblique arc-continent collision between the Eurasian continent and the Luzon arc. The southern segment is significantly less active perhaps because the orogen is not yet involved in direct arc-continent collision.

This thesis presents a methodology for conducting logistic regression modeling of trip and household information obtained from household travel surveys and vehicle trip information obtained from global positioning systems (GPS) to better understand the trip underreporting that occurs. The methodology presented here builds on previous research by adding additional variables to the logistic regression model that might be significant in contributing to underreporting, specifically, trip purpose. Understanding the trip purpose is crucial in transportation planning because many of the transportation models used today are based on the number of trips in a given area by the purpose of a trip. The methodology used here was applied to two study areas in Texas, Laredo and Tyler-Longview. In these two study areas, household travel survey data and GPS-based vehicle tracking data was collected over a 24-hour period for 254 households and 388 vehicles. From these 254 households, a total of 2,795 trips were made, averaging 11.0 trips per household. By comparing the trips reported in the household travel survey with those recorded by the GPS unit, trips not reported in the household travel survey were identified. Logistic regression was shown to be effective in determining which household- and trip-related variables significantly contributed to the likelihood of a trip being reported. Although different variables were identified as significant in each of the models tested, one variable was found to be significant in all of them - trip purpose. It was also found that the household residence type and the use of household vehicles for commercial purposes did not significantly affect reporting rates in any of the models tested. The results shown here support the need for modeling trips by trip purpose, but also indicate that, from urban area to urban area, there are different factors contributing to the level of underreporting that occurs. An analysis of additional significant variables in each urban area found combinations that yielded trip reporting rates of 0%. Similar to the results of Zmud and Wolf (2003), trip duration and the number of vehicles available were also found to be significant in a full model encompassing both study areas.

Passing on two-lane roadways is one of the most difficult movements a driver may perform and guidance on where passing maneuvers are prohibited is given by the location of no-passing zones. Currently the processes for identifying no-passing zone locations can be daunting and many practices require work crews to operate in the roadway creating potentially hazardous situations. Due to these challenges new alternatives need to be developed for the safe, accurate, and efficient location of nopassing zones on two-lane roadways. This thesis addresses the use of Global Positioning System (GPS) coordinates to evaluate sight distance along the vertical profile of roadways to provide an alternative for an automated no-passing zone location system. A system was developed that processes GPS coordinates and converts them into easting and northing values, smoothes inaccurate vertical elevation data, and evaluates roadway profiles for possible sight restrictions which indicate where no-passing zones should be located. The developed automated no-passing zone program shows potential in that it identifies the general location of no-passing zones as compared to existing roadway markings.; however, as concluded by the researcher, further evaluation and refinement is needed before the program can be used effectively in the field for the safe, accurate, and efficient location of no-passing zones.

Many location-based routing protocols have been developed recently, and have been demonstrated to be scalable and efficient for packet routing in mobile ad hoc networks. Using location-based routing requires that a node obtains the node position with which it wants to communicate. This task is generally achieved by a location service. This work presents a novel routing protocol, called Hierarchical Cell-Structured Routing (HCR) Scheme, with a location service. The network area is divided into a number of regular triangular regions, called cells. The nodes forward the packets by some chosen cells, and are classified to be three level hierarchical structures. The hierarchical approach of HCR makes it especially suitable for high network density. Moreover, the traffic loads in HCR are shared by all nodes rather than just by some specific nodes, thus the overhead is reduced at high traffic loads. Simulation results indicate that HCR has better performance than Location-Aid Routing (LAR), in terms of packet delivery ratio, end-to-end delay and overhead in high traffic load.

Zugl.: Giessen, Universiẗat, Univ. Diss., 2009.

Reproduction de : Thèse de doctorat : Signaux, image et acoustique : Toulouse, INPT : 2002. / Texte en anglais. Indroduction, conclusion, table des matières et résumé en français. Titre provenant de l'écran-titre. Bibliogr. 19 réf.

The United States Department of Defense has introduced two new GPS civilian signals on its “Link 2” (L2) and “Link 5” (L5) center frequencies. The first of these new civilian signals to reach full operational capability in the GPS constellation will be the L2 C signal. The L2 C signal boasts new signal structure features aimed at better tracking performance in comparison to the legacy L1 C/A signal. Amongst these are two new chip-by-chip interleaved spreading code sequences, Civilian Moderate (CM) and Civilian Long (CL), and a new, higher resolution navigation message, CNAV. The two new C codes are longer than the legacy C/A code and feature a data less pilot signal (CL) for improved tracking performance in weak signal environments. This work investigates L2 C acquisition and tracking considerations and implements algorithms for acquiring and tracking the signal in a software-defined receiver developed in MATLAB. The Emergent MATLAB L2 C (EMAL2) receiver was developed for the purpose of GPS signal simulator testing. This software-defined receiver differs from legacy receivers containing application specific integrated circuits (ASICs) in that all of EMAL2’s digital signal processing is done in software able to run on a general purpose processor. This approach offers greater flexibility and ease in configuration over ASICs for tracking a number of different types of signal structures in the receiver. The EMAL2 receiver’s design and implementation is described here-in. Initial testing of the EMAL2 receiver was conducted with live-sky signal data captured by antennas and front-ends at the University of Texas Radionavigation Laboratory (UT RNL). The data was processed by the GRID receiver (also at the UT RNL) to provide EMAL2 baseline received signal characteristics. / text

Free2Move AB is developing products for the market within wireless communication and identification, among those active RFID-tags. The company had an idea about providing one of their active RFID tags with a GPS receiver and transmit positions via an existing RFID protocol. Desire from the company was also the possibility to log positions and measure temperature. The finished prototype should also be able to be activated by movement. The company had proposal about components that were to be used in the project. A large part of the work was to understand how these worked and how to combine them to fulfill the requirements established in agreement with supervisor at Free2Move. A PIC microcontroller was used in the design of the prototype and software implemented for communication with GPS, RFID tag and other components. The result was a working prototype where an existing RFID tag was integrated in the same printed circuit board layout as the GPS receiver and other components that were used in the project.