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Khayyam: progress and prospects of coupling a spatial heterodyne spectrometer (SHS) to a Cassegrain telescope for optical interferometryHosseini, Sona, Harris, Walter 04 August 2016 (has links)
In the temporal study of faint, extended sources at high resolving power, Spatial Heterodyne Spectrometer (SHS) can offer significant advantages about conventional dispersive grating spectrometers. We describe here a four-year continuous progress in Mt. Hamilton, Lick Observatory, toward development of a prototype reflective Spacial Heterodyne Spectrometer, Khayyam, instrument-telescope configuration to combine all of the capabilities necessary to obtain high resolving power visible band spectra of diffuse targets from small aperture on-axis telescopes where significant observing time can be obtained. We will discuss the design considerations going into this new system, installation, testing of the interferometer-telescope combination, the technical challenges and procedures moving forward.
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Sensor Fusion for Automotive ApplicationsLundquist, Christian January 2011 (has links)
Mapping stationary objects and tracking moving targets are essential for many autonomous functions in vehicles. In order to compute the map and track estimates, sensor measurements from radar, laser and camera are used together with the standard proprioceptive sensors present in a car. By fusing information from different types of sensors, the accuracy and robustness of the estimates can be increased. Different types of maps are discussed and compared in the thesis. In particular, road maps make use of the fact that roads are highly structured, which allows relatively simple and powerful models to be employed. It is shown how the information of the lane markings, obtained by a front looking camera, can be fused with inertial measurement of the vehicle motion and radar measurements of vehicles ahead to compute a more accurate and robust road geometry estimate. Further, it is shown how radar measurements of stationary targets can be used to estimate the road edges, modeled as polynomials and tracked as extended targets. Recent advances in the field of multiple target tracking lead to the use of finite set statistics (FISST) in a set theoretic approach, where the targets and the measurements are treated as random finite sets (RFS). The first order moment of a RFS is called probability hypothesis density (PHD), and it is propagated in time with a PHD filter. In this thesis, the PHD filter is applied to radar data for constructing a parsimonious representation of the map of the stationary objects around the vehicle. Two original contributions, which exploit the inherent structure in the map, are proposed. A data clustering algorithm is suggested to structure the description of the prior and considerably improving the update in the PHD filter. Improvements in the merging step further simplify the map representation. When it comes to tracking moving targets, the focus of this thesis is on extended targets, i.e., targets which potentially may give rise to more than one measurement per time step. An implementation of the PHD filter, which was proposed to handle data obtained from extended targets, is presented. An approximation is proposed in order to limit the number of hypotheses. Further, a framework to track the size and shape of a target is introduced. The method is based on measurement generating points on the surface of the target, which are modeled by an RFS. Finally, an efficient and novel Bayesian method is proposed for approximating the tire radii of a vehicle based on particle filters and the marginalization concept. This is done under the assumption that a change in the tire radius is caused by a change in tire pressure, thus obtaining an indirect tire pressure monitoring system. The approaches presented in this thesis have all been evaluated on real data from both freeways and rural roads in Sweden. / SEFS -- IVSS / VR - ETT
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Signal processing techniques for modern radar systemsElhoshy, Mostafa Kamal Kamel 07 August 2019 (has links)
This dissertation considers radar detection and tracking of weak fluctuating targets
using dynamic programming (DP) based track-before-detect (TBD). TBD combines target
detection and tracking by integrating data over consecutive scans before making a decision
on the presence of a target. A novel algorithm is proposed which employs order statistics in
dynamic programming based TBD (OS-DP-TBD) to detect weak fluctuating targets. The
well-known Swerling type 0, 1 and 3 targets are considered with non-Gaussian distributed
clutter and complex Gaussian noise. The clutter is modeled using the Weibull, K and
G0 distributions. The proposed algorithm is shown to provide better performance than
well-known techniques in the literature. In addition, a novel expanding window multiframe
(EW-TBD) technique is presented to improve the detection performance with reasonable
computational complexity compared to batch processing. It is shown that EW-TBD has
lower complexity than existing multiframe processing techniques. Simulation results are
presented which confirm the superiority of the proposed expanding window technique in
detecting targets even when they are not present in every scan in the window. Further, the
throughput of the proposed technique is higher than with batch processing. Depending
on the range and azimuth resolution of the radar system, the target may appear as a point
in some radar systems and there will be target energy spillover in other systems. This
dissertation considers both extended targets with different energy spillover levels and point
targets. Simulation results are presented which confirm the superiority of the proposed
algorithm in both cases. / Graduate
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