Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 20 for “"satellite signals"”.
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Optimal estimation of ionosphere-induced group delays of global positioning satellite signals during launch, orbit and re-entry
… sources of range error in a Global Positioning Satellite (GPS) signal that has traveled to a receiver near the earth's surface. Among these is the ionospheric group delay. In the past, a single-state, dual-frequency filter has been used to estimate the ionospheric delay for authorized users. …
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Direct position tracking in GPS using vector correlator
… track the code and carrier of individual satellite signals and estimate the position and velocity of the receiver using trilateration. Different from this two-step approach, direct maximum likelihood estimation of position has proved to be beneficial in weak signal and multipath …
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Preliminary processing and evaluation of radar measurements in satellite-path propagation research
… attenuation and depolarization of high frequency satellite signals. Some characteristics of rain can be measured by dual-polarized radar. These characteristics can then be used to predict the effects of the rain on satellite-path propagation. This thesis describes briefly the theory of radar and …
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Design of a satellite beacon receiver for ionospheric remote sensing
In today's world of communication, satellite communication plays an important role. The communication between ground stations and satellites orbiting the earth at high altitudes needs to be increasingly accurate to handle today's data flow requirements. The study of the ionosphere allows engineers …
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Reprocessing interference : an artistic exploration of the visual material generated by interference
… lines, computer networks and, most recently, satellite signals. The development of and access to networked systems has brought about this "utopian promise" (Mitchell 2005: 305), an ideal of instant connectivity that allows a user to be in contact with others through technological devices over …
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A model for predicting indoor signal levels of satellite transmitted signals
… approaches to creating a model for predicting satellite signal levels inside buildings are examined. These models make use of resonant cavity modes and vector ray addition. The cavity mode approach yields inconclusive results because of a problem with uniqueness, there are too many potential …
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Ultrawideband Indoor Location And Tracking System
… a local replacement for GPS systems since satellite signals are not available indoors. UWB systems are particularly suitable for indoor location systems due their inherent capabilities such as low-power, multi-path rejection, and wide bandwidth. In our application, we are using UWB radios …
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Navigation for UAVs using Signals of Opportunity
… Aerial Vehicles (UAVs) on Global Navigation Satellite System (GNSS) for autonomous operation represents a significant vulnerability to their reliable and secure operation due to signal interference, both incidental (e.g. terrain shadowing, ionospheric scintillation) and malicious (e.g. …
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Elevation Effects on GPS Positional Accuracy
… allow the collection of data with four satellites (3D mode), yet field data conditions are often less than ideal. Four satellites may not always be in view because of mountainous topography, heavy forest cover, or other obstructions which block satellite signals from the receiver. This …
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Localizatation estimation usign the technique of multi-sequence positioning
… perceive less obstruction and shielding of satellite signals whereas MSP can be effected by cellular networks in which it limited by the cell size.
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A Localization Solution for an Autonomous Vehicle in an Urban Environment
… and tunnels. Each of these can corrupt GPS satellite signals, or completely obscure them, making it impossible to rely on GPS alone. Dead reckoning is still a useful tool in this environment, but as is always the case, measurement and modeling errors inherent in dead reckoning systems will …
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Exploiting Signals of Opportunity for High-Precision PNT: Optimized Bayesian Estimation Across 5G and LEO Networks
… systems. While traditional global navigation satellite systems (GNSS) degrade severely in deep urban canyons, emerging terrestrial 5G millimeter-wave and non-terrestrial low Earth orbit (LEO) satellite signals of opportunity offer highly promising alternatives. However, the practical …
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Mapping the magnetization density near magnetic atoms in copper: Nuclear magnetic resonance studies of CuMn and CuCr
… of these neighbor shells appear as weak ""satellite"" resonances near the iutense resonance produced by the majority of the copper nuclei which are far from any impurity. We have observed satellites for eight distinct shells in CuMn and six distinct shells in CuCr. These data are the first …
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Development and Testing of A Space-borne GPS Signal Strength Sensor
The Global Positioning System (GPS) satellite signals provide not only traditional radionavigation service but inexpensive and convenient radio beacons for signal propagation studies on ionosphere and atmosphere. This thesis describes the development and testing of a specialized GPS sensor which …
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Integrity and attack-resilience of GPS-based positioning and timing: a Bayesian and measurement fusion approach
… due to tall structures that block and reflect satellite signals. Degraded positioning is not safe for the operation of autonomously driving vehicles. Furthermore, GPS signals are susceptible to external attacks due to their low signal power and unencrypted signal structures. Researchers have …
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The Global Navigation System Scope (GNSScope): a toolbox for the end-to-end modelling simulation and analysis of GNSS
… end-to-end modeling, simulation and analysis of satellite navigation signals and systems, covering the signal acquisition, tracking, and range processing operations that take place in a generic Global Navigation Satellite System (GNSS) receiver, accompanied by a Graphical User Interface (GUI) …
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Improving the robustness of GPS direct position estimation
… and inherent joint optimization across multiple satellite signals make DPE more robust than scalar and vector tracking. In addition, since the parameter of interest is the navigation solution, DPE provides a natural framework for directly incorporating additional navigation information. The …
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A comparison of digital beacon receiver frequency estimators
… and power of the carriers of 20 GHz and 30 GHz satellite signals are compared. Both algorithms operate on a prefiltered sequence generated by lowpass filtering followed by signal decimation for the purpose of sampling rate reduction. The lowpass filtering is accomplished via the overlap-add …
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Writing Coastlines: Locating Narrative Resonance in Transatlantic Communications Networks
… packets, ships, submarine cables, aeroplanes, satellite signals and wireless radio waves have attempted to bridge this distance. These comings and goings have left traces. Generations of transatlantic migrations have engendered networks of communications. As narratives of place and displacement …
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GPS-LiDAR sensor fusion aided by 3D city models for UAVs
… urban areas using only GPS is challenging, since satellite signals might be reflected or blocked by buildings, resulting in multipath errors or non-line-of-sight (NLOS) situations. In such cases, additional on-board sensors are desirable to improve global positioning of the UAV. Light Detection …