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 53 for “"Global Navigation Satellite System (GNSS)"”.
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Design and Simulation of a Planar Crossed-Dipole Global Navigation Satellite System (GNSS) Antenna in the L1 Frequency Band
… the performance of a planar cross-dipole Global Navigation Satellite System (GNSS) receiver antenna to operate in GNSS L1 frequency band with multipath mitigation performance. First, a crossed-half-wavelength dipole antenna was designed to resonate centered at 1.6 GHz, and then various …
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Dense, sonar-based reconstruction of underwater scenes
… accuracies of (i) its pose estimate in some global frame, (ii) the estimates of offsets between mapping sensors and platform, and (iii) the accuracy of the mapping sensor measurements. Typically, surface-based surveying platforms will employ highly accurate positioning sensors-e.g. a …
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SIGNAL ANALYSIS AND RADIOHOLOGRAPHIC METHODS FOR AIRBORNE RADIO OCCULTATIONS
Global Positioning System (GPS) radio occultation (RO) is an atmospheric sounding technique utilizing the change in propagation direction and delay of the GPS signal to measure refractivity, which provides information on temperature and humidity. The GPS-RO technique is now operational on several …
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Development and analysis of a parallelized direct position estimation-based GPS receiver implementation
… one-step Direct Position Estimation (DPE)-based Global Navigation Satellite System (GNSS) receivers can achieve more accurate localization than their two-step counterparts. However, numerical solutions to DPE equations and approximations made for those equations introduce new effects that can …
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GNSS-based relative navigation for LEO nanosatellite laser communications
… in concert with rising interest in small satellite mission concepts. The CubeSat Laser Infrared CrossinK (CLICK) mission has the objective of demonstrating the first Low-Earth orbit (LEO) nanosatellite crosslink. The need for precise and accurate pointing with laser instruments motivates a …
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Vision-Based Aerial Navigation Using Satellite Offline Maps
While Global Navigation Satellite System (GNSS) technology combined with advanced augmentation techniques provides high accuracy, its reliance on signal integrity leaves safety-critical applications vulnerable to spoofing and jamming. To address this, a lightweight vision-based localization module …
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Using Random Sampling Consensus (RANSAC) to Detect Errors in Global Navigation Satellite Systems (GNSS) Signals and Data
A positioning, navigation, and timing (PNT) signal can be used to estimate a user's position at an identified time. A global navigation satellite system (GNSS) uses the PNT signal to provide satellite-based navigation. Advanced receivers can track multiple GNSS constellations simultaneously. In …
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Navigation for UAVs using Signals of Opportunity
… reliance of Unmanned 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 …
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Impact Analysis and Design Development for Air-Dropped Antarctic Seismo-Geodetic Ice Penetrator
… rapid deployment of a broadband seismometer and Global Navigation Satellite System (GNSS) positioning system designed to sense ice shelf resonant forcings caused by ocean gravity waves and atmospheric waves. Additionally, SGIP will track seismic indications of calving and rifting, facilitating …
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Aerodynamic and Thermal Considerations for an Antarctic Ice Penetrator
… kinetic penetrator designed to deliver a Global Navigation Satellite System (GNSS) and geodesy-grade seismometer to the Ross Ice Shelf (RIS) in Antarctica such that the seismometer becomes buried 2 m deep in the ice, ensuring coupling with the ice shelf. This vehicle provides a means to …
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THE USE OF CONDUCTIVE INK IN ANTENNA EDUCATION AND DESIGN
… designs satisfy the requirements of a compact Global Navigation Satellite System (GNSS) antenna while showing a competitive performance within the current market. One best design is shown along with three other structures. These antennas consist of a bowtie cross-dipole over a reflective disc …
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Place recognition for GNSS-denied autonomous multi-robot search and rescue
… of this task is exacerbated in areas without Global Navigation Satellite System (GNSS) coverage, as absolute pose measurements are unavailable. This thesis explores solutions to the place recognition problem for UAVs under a dense forest canopy. The perception and communication challenges in a …
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GNSS-based Spacecraft Formation Flying Simulation and Ionospheric Remote Sensing Applications
The Global Navigation Satellite System (GNSS) is significantly advantageous to absolute and relative navigation for spacecraft formation flying. Ionospheric remote sensing, such as Total Electron Content (TEC) measurements or ionospheric irregularity studies are important potential Low Earth Orbit …
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GNSS Hardware-In-The-Loop Formation and Tracking Control
… research explores the creation of a predictive navigation and control algorithm for formation keeping and tracking, raw measurement data collection, and building a real-time GNSS closed HWIL testbed for simulations of different vehicles. The L1 frequency band of the Global Positioning System …
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Management and Analysis of Localization Information in Uncrewed Aerial Systems
… (UAVs), particularly in environments where Global Navigation Satellite System (GNSS) signals are degraded or unavailable. This thesis investigates how 5G cellular networks - leveraging dense terrestrial infrastructure, precise timing, and recently standardized UAV oriented capabilities - can …
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Incorporation of GNSS multipath to improve autonomous rendezvous, docking and proximity operations in space
… of space stations, repair and refueling of large satellites, and active removal of orbital debris. These operations depend critically on accurate, real-time knowledge of the relative position and velocity between two space vehicles. Unfortunately, Global Navigation Satellite System (GNSS) …
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UAV-based investigations into the hydrology and dynamics of the Greenland Ice Sheet
… the rate of meltwater input into the subglacial system of the Greenland Ice Sheet can force dynamic responses on a range of scales from hourly to interannual. Observations of the ice sheet dynamic response are commonly made either through ground-based Global Navigation Satellite System (GNSS) …
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Remote Sensing of 21st Century Water Stress for Hazard Monitoring in California
… has led to poroelastic compaction of the aquifer system and subsidence of the land surface. Water mass loss also causes elastic deformation of the solid Earth, an opposite and smaller amplitude response than the poroelastic deformation of aquifer systems. These mass changes can disturb the …
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Precise Point Positioning – The evolution of an alternative GNSS positioning solution
… Positioning (PPP) employs readily available Global Navigation Satellite System (GNSS) orbit and clock correction products to perform point positioning using a single GNSS receiver. Over the last 20 years, the New South Wales (NSW) state government has invested in Continuously Operating …
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GNSS Integrity Monitoring with Modelling Temporal Correlated Measurement Noise and an Application to RTK
The reliability of a navigation system is important in support of applications from self-driving cars to smartphones, especially for safety-critical and liability-critical applications which require stringent reliability requirements. In recent years, there is an increasing demand for global …
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