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Bibliography: p. 297-304. Uses a widely accepted stochastic model of scintillation activity to investigate the effects of scintillations on GPS receivers and systems.

Continuously-operating networks of GPS receivers (CGPS) are not capable of determining the characteristics of crustal deformation at the fine temporal or spatial scales required. Four ???temporal densification schemes??? and two 'spatial densification schemes' to augment the CGPS networks have been developed and tested. The four ???temporal densification schemes??? are based on the high rate Real-Time Kinematic (RTK) GPS technique, GPS multipath effects, Very Long Baseline Interferometry (VLBI) and Satellite Laser Ranging (SLR). The 'serial scheme' based on using GPS as a seismometer has been proposed. Simulated seismic signals have been extracted from the very noisy high rate RTK-GPS results using an adaptive filter based on the least-mean-square algorithm. They are in very good agreement with those of the collocated seismometers. This scheme can improve the CGPS temporal resolution to 0.1 second. The 'retro-active scheme' takes advantage of the fact that the GPS multipath disturbance is repeated between consecutive days. It can therefore provide a means of correcting multipath errors in the observation data themselves. A reduction of the standard deviations of the pseudo-range and carrier phase multipath time series to about one fourth and one half the original values respectively, has been demonstrated. The 'all-GPS parallel scheme' uses the multipath effects as a signal to monitor the antenna environment. Models relating the changes of multipath and antenna environment have been derived. The 'cross-technique parallel scheme' integrates the collocated CGPS, VLBI and SLR results, taking advantage of the decorrelation among their biases and errors. Crustal displacement signature has been extracted as a common-mode signal using data from two stations: Matera in Italy and Wettzell in Germany. Two 'spatial densification schemes' which can verify with each other have been developed and tested. The 'soft' scheme integrates CGPS with radar interferometry (InSAR). The Double Interpolation and Double Prediction (DIDP) approach combines the strengths of the high temporal resolution of CGPS and the high spatial resolution possible with the InSAR technique. This scheme can improve the spatial resolution to about 25m. The 'hard' scheme requires the deployment of single-frequency receivers to in-fill the present CGPS arrays. Alternatively some receivers may be installed at some geophysically strategic sites outside existing CGPS arrays. The former has been tested within Japan's GEONET, while the latter has been tested using a five-station array.

Since its introduction in the early 1980????s, the Global Positioning System (GPS) has become an important tool for high-precision surveying and geodetic applications. Carrier phase measurements are the key to achieving high accuracy positioning results. This research addresses one of the most challenging aspects in the GPS data processing algorithm, especially for precise GPS static positioning, namely the definition of a realistic stochastic model. Major contributions of this research are: (a) A comparison of the two data quality indicators, which are widely used to assist in the definition of the stochastic model for GPS observations, has been carried out. Based on the results obtained from a series of tests, both the satellite elevation angle and the signal-to-noise ratio information do not always reflect the reality. (b) A simplified MINQUE procedure for the estimation of the variance-covariance components of GPS observations has been proposed. The proposed procedure has been shown to produce similar results to those from the standard MINQUE procedure. However, the computational load and time are significantly reduced, and in addition the effect of a changing number of satellites on the computations is effectively dealt with. (c) An iterative stochastic modelling procedure has been developed in which all error features in the GPS observations are taken into account. Experimental results show that by applying the proposed procedure, both the certainty and the accuracy of the positioning results are improved. In addition, the quality of ambiguity resolution can be more realistically evaluated. (d) A segmented stochastic modelling procedure has been developed to effectively deal with long observation period data sets, and to reduce the computational load. This procedure will also take into account the temporal correlations in the GPS measurements. Test results obtained from both simulated and real data sets indicate that the proposed procedure can improve the accuracy of the positioning results to the millimetre level. (e) A novel approach to GPS analysis based on a combination of the wavelet decomposition technique and the simplified MINQUE procedure has been proposed. With this new approach, the certainty of ambiguity resolution and the accuracy of the positioning results are improved.

Thesis (Ph. D.)--University of Rhode Island, 2005. / Typescript. Includes bibliographical references (leaves 273-285).

This thesis describes the hardware design of a positioning system which locates a vehicle relative to a digital map of an underground mine. The mines of interest are potash mines of Saskatchewan, and they are at a depth of approximately 1000 meters and they cover an area larger than 10 kilometers by 10 kilometers. An important application of an in-mine positioning system is tracking a ground penetrating radar system. Ground penetrating radar is used to determine the current condition of the mine ceiling and to evaluate its risk of delamination. A ground penetrating radar system is driven along a mine tunnel and measurements are logged. It is necessary to record position information along with the radar signal and this can be done with the aid of a positioning system. The design and evaluation of the hardware system that supports a positioning system, which can locate a vehicle inside a mine tunnel with reasonable accuracy and cost is described in this thesis. The hardware system includes a dead reckoning system (DRS), which is built using MEMS (Micro Electro Mechanical System) accelerometer and gyroscope sensors and ultrasonic distance sensors, along with a data acquisition system.

This thesis describes the hardware design of a positioning system which locates a vehicle relative to a digital map of an underground mine. The mines of interest are potash mines of Saskatchewan, and they are at a depth of approximately 1000 meters and they cover an area larger than 10 kilometers by 10 kilometers. An important application of an in-mine positioning system is tracking a ground penetrating radar system. Ground penetrating radar is used to determine the current condition of the mine ceiling and to evaluate its risk of delamination. A ground penetrating radar system is driven along a mine tunnel and measurements are logged. It is necessary to record position information along with the radar signal and this can be done with the aid of a positioning system. The design and evaluation of the hardware system that supports a positioning system, which can locate a vehicle inside a mine tunnel with reasonable accuracy and cost is described in this thesis. The hardware system includes a dead reckoning system (DRS), which is built using MEMS (Micro Electro Mechanical System) accelerometer and gyroscope sensors and ultrasonic distance sensors, along with a data acquisition system.

In this thesis, we use E-Beam lithography to finish the process of positioning system and 2D photonic crystal. We use the new E-Beam system to define some array patterns. By this test, we obtain the minimum linewidth is 55nm, and the maximum writable range is 250£gm*250£gm. First, we fabricated the 2D photonic crystal microcavity and positioning system on the InGaAs/InAlAs which grown by molecular beam epitaxy (MBE) on InP substrate at 1564nm emission wavelength by E-beam lithography. For the positioning system, we set up a origin point first. And then we design many rectangles whose length is 1£gm, width is 10£gm and gap is 1£gm along X axis and Y axis from the origin point. All of the patterns are regarded as the ruler. Finally, we design a big rectangle whose length is 250£gm and width is 10£gm to adjust the positioning angle above the ruler. The maximum error of the positioning system is 20nm. For the 2D photonic crystal (2D PhC) microcavity, a triangular array of air columns is adopted. The lattice constant and air columns radius are 1150nm and 460nm, respectively. The TE modes photonic band gap of this structure are corresponding to wavelength range in 1535nm~1635nm. We remove signal defect and seven defects in the 2D PhC to form 2D PhC microcavities and the PhC microcavities have many defect modes. The Micro-PL measurement shows when the etching depth was deep enough, the PhC microcavities which have 1-defect and 7-defect appeared defect mode at 1622nm (a/£f=0.74) both. The intensity of 7-defect PhC is 7 times than 1-defect PhC. Both of them cooperate with our simulation and design. And the maximum Q value is about 324 at the defect mode.

Thesis (Ph. D.)--University of Texas at Austin, 2000. / Vita. Includes bibliographical references (leaves 177-187). Available also in a digital version from Dissertation Abstracts.

Continuously-operating networks of GPS receivers (CGPS) are not capable of determining the characteristics of crustal deformation at the fine temporal or spatial scales required. Four ???temporal densification schemes??? and two 'spatial densification schemes' to augment the CGPS networks have been developed and tested. The four ???temporal densification schemes??? are based on the high rate Real-Time Kinematic (RTK) GPS technique, GPS multipath effects, Very Long Baseline Interferometry (VLBI) and Satellite Laser Ranging (SLR). The 'serial scheme' based on using GPS as a seismometer has been proposed. Simulated seismic signals have been extracted from the very noisy high rate RTK-GPS results using an adaptive filter based on the least-mean-square algorithm. They are in very good agreement with those of the collocated seismometers. This scheme can improve the CGPS temporal resolution to 0.1 second. The 'retro-active scheme' takes advantage of the fact that the GPS multipath disturbance is repeated between consecutive days. It can therefore provide a means of correcting multipath errors in the observation data themselves. A reduction of the standard deviations of the pseudo-range and carrier phase multipath time series to about one fourth and one half the original values respectively, has been demonstrated. The 'all-GPS parallel scheme' uses the multipath effects as a signal to monitor the antenna environment. Models relating the changes of multipath and antenna environment have been derived. The 'cross-technique parallel scheme' integrates the collocated CGPS, VLBI and SLR results, taking advantage of the decorrelation among their biases and errors. Crustal displacement signature has been extracted as a common-mode signal using data from two stations: Matera in Italy and Wettzell in Germany. Two 'spatial densification schemes' which can verify with each other have been developed and tested. The 'soft' scheme integrates CGPS with radar interferometry (InSAR). The Double Interpolation and Double Prediction (DIDP) approach combines the strengths of the high temporal resolution of CGPS and the high spatial resolution possible with the InSAR technique. This scheme can improve the spatial resolution to about 25m. The 'hard' scheme requires the deployment of single-frequency receivers to in-fill the present CGPS arrays. Alternatively some receivers may be installed at some geophysically strategic sites outside existing CGPS arrays. The former has been tested within Japan's GEONET, while the latter has been tested using a five-station array.