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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

The design of a 94 GHz high resolution coherent radar

Celliers, Abraham Francois 29 September 2023 (has links) (PDF)
This thesis describes the design and performance of a 94 GHz short pulse, low duty cycle, high resolution coherent injection locked radar system for sensor applications, with the specific use as an early warning radar ,against high voltage transmission lines. The recent development of solid-state components for frequencies around 94 GHz has made it possible to design coherent millimetre-wave radar systems. Key components of such systems are high power pulsed silicon Impact oscillators, CW Impact oscillators, second harmonic Gunn oscillators, filters, circulators, isolators, couplers, and antennas. Elementary system specifications are derived for the delivery vehicle and the millimetre-wave sensor. Each of the separate components of the system were designed, built, and tested. Measurements were taken with the sensor and are presented. Specific attention is given to the measurement of intra-pulse phase ripple, additive noise, injection locking and coherency. The above-mentioned parameters are critical in the design of a coherent sensor and special care should be given to the various components in the design stage. The sensor is not built into a carrier system yet but was built up as a laboratory model and measurements were taken from the laboratory to various objects and distances outside the laboratory. There is only one article in literature [1] which described a 66 GHz collision warning sensor for helicopters. The system is a noncoherent pulsed radar with the following specifications:
2

HARDWARE AND SOFTWARE FOR A COMPUTER CONTROLLED LIDAR SYSTEM.

BRUHNS, THOMAS VICTOR. January 1985 (has links)
The hardware and software for a computer controlled optical radar, or lidar, system are described. The system builds on a previously installed pulsed ruby backscatter lidar, capable of acquiring data at controlled azimuth and elevation angles through the atmosphere. The described system replaces hardwired logic with computer control. Two coupled computers are used to allow a degree of real time control while data are processed. One of these computers reads and controls mount elevation angle, reads the laser energy monitor, and senses firing of the laser. The other computer serves as a user interface, and receives the lidar return data from a digitizer and memory, and the angle and energy information from the other computer. The second computer also outputs data to a disc drive. The software provided with the system is described, and the feasibility of additional software for both control and data processing is explored. Particular attention is given to data integrity and instrument and computer operation in the presence of the high energy pulses used to drive the laser. A previously described laser energy monitor has been improved to isolate it from laser transients. Mount elevation angles are monitored with an absolute angle readout. As a troubleshooting aid, a simulator with an output that approximates the lidar receiver output was developed. Its output is digitally generated and provides a known repetitive signal. Operating procedures are described for standard data acquisition, and troubleshooting is outlined. The system can be used by a relatively inexperienced operator; English sentences are displayed on the system console CRT terminal to lead the operator through data acquisition once the system hardware is turned on. A brief synopsis of data acquired on the system is given. Those data are used as the basis of other referenced papers. It constitutes soundings for over one hundred days. One high point has been operation of the system in conjunction with a balloon borne atmospheric particulate sampling package. The system has also been used occasionally as the transmitter of a lidar system with physically separated receiver and transmitter.
3

The receiving system of a dual dye LIDAR to study molecular and aerosol densities at the base of the stratosphere

Davidson, John Dexter, 1949- January 1989 (has links)
The operating principles and design of an optical receiver for a Light Detection and Ranging (LIDAR) remote sensing instrument are addressed. The performance and limitations of a biaxial monostatic LIDAR system utilizing this design are investigated. The complete optical and structural design of the receiver, including specifications of components are outlined. The thermal stabilization of the detector assembly and the integration of control electronics are described. A detailed discussion of alignment procedures and possible improvements are made. A sample observation is presented with suggestions for fully automating the system.
4

Design of a bistatic nearfield array for an expanded volume

Terrell, Stephen John 18 April 2005 (has links)
Achieving acceptable plane wave uniformity throughout an expanded volume is necessary to conduct scattering measurements on a large target in a controlled environment. An expanded volume is large relative to the size of the nearfield array configuration used to produce plane wave uniformity. The optimum set of shading coefficients for a nearfield array may not produce acceptable plane wave uniformity as the volume and frequency domain are expanded for a given array configuration. Choosing the frequency domain as a single frequency for an optimum set of coefficients will produce plane wave uniformity throughout the largest possible volume for a given array configuration. This study determines the acceptability of uniformity results produced by an optimum set of frequency dependent coefficients throughout an expanded volume for two array configurations that comprise a system for measuring bistatic target strength in the nearfield. Minimizing the frequency domain chosen for an optimum set of coefficients will produce plane wave uniformity for the largest possible volume for a given array configuration. This study determines the acceptability of uniformity results produced by an optimum set of frequency dependent coefficients throughout an optimistic volume for two array configurations that comprise a bi-static array.
5

Development and evaluation of automated radar systems for monitoring and characterising echoes from insect targets

Dean, Timothy J., Physical, Environmental & Mathematical Sciences, Australian Defence Force Academy, UNSW January 2007 (has links)
This thesis describes the construction of a mobile Insect Monitoring Radars (IMR) and investigations of: the reliability of IMRs for observing insect migration in inland Australia; possible biases in IMR migration estimates; the relation between an insect???s size and its radar properties; radar discrimination between insect species; the effect of weather on the migrations of Australian plague locusts and of moths; the scale of these migrations; and here IMRs are best located. The principles of entomological radar design, and the main features of insect migration in inland Australia, are reviewed. The main procedures used in the study are: calculation of radar performance and of insect radar cross sections (RCSs); reanalysis of a laboratory RCS dataset; statistical analysis of a fouryear dataset of IMR and weather observations; and a field campaign using both two existing fixed IMRs and the new mobile unit. Statistical techniques used include correlation, multiple regression, discriminant analysis, and principal components analysis. The original results of this work include design details of the mobile IMR, extension of radar performance calculations to IMRs and evaluation of flight speed biases, a holistic approach to IMR design, the relation of insect RCS magnitudes and polarization patterns to morphological variables, an estimate of the accuracy of the retrieved parameters, evaluations of three approaches (oneparameter, theory-based, and a novel two-stage method) to target identification, and verification of inferred target identities using results from nearby light traps. Possible sites for future IMRs are identified. The major conclusions are that: a mobile IMR can be built with a performance equal to that of a fixed IMR but at half the cost; significant biases in the signal processing results arise from insect speed; locusts and moths can be distinguished if all RCS parameters are used; IMRs can be designed to match particular requirements; weather has a significant effect on insect migration, the best single predictor of insect numbers being temperature; moonlight has no effect; the spatial correlation of migration properties falls to 50% at a separation of 300 km; and migrating insects can be carried by the wind for 500 km in a single night
6

Construction Of An Experimental Radar System

Kilicoglu, Nezaket 01 December 2010 (has links) (PDF)
In this thesis, an Experimental Radar System is designed and constructed for use in experimental radar studies such as clutter measurement and target detection, both in the laboratory and outdoor. COTS laboratory equipments are utilized as hardware elements of the radar and MATLAB is used as signal processing and user interface software tool. Vector signal generator (as transmitter), spectrum analyzer with vector signal analysis (as receiver), a high power amplifier, a low noise amplifier, horn antennas and a computer are the hardware units of the system. Various transmit signals are generated and pulse Doppler processing is performed at the receiver side. The system is controlled through the user interface which runs on a PC.
7

Development and evaluation of automated radar systems for monitoring and characterising echoes from insect targets

Dean, Timothy J., Physical, Environmental & Mathematical Sciences, Australian Defence Force Academy, UNSW January 2007 (has links)
This thesis describes the construction of a mobile Insect Monitoring Radars (IMR) and investigations of: the reliability of IMRs for observing insect migration in inland Australia; possible biases in IMR migration estimates; the relation between an insect???s size and its radar properties; radar discrimination between insect species; the effect of weather on the migrations of Australian plague locusts and of moths; the scale of these migrations; and here IMRs are best located. The principles of entomological radar design, and the main features of insect migration in inland Australia, are reviewed. The main procedures used in the study are: calculation of radar performance and of insect radar cross sections (RCSs); reanalysis of a laboratory RCS dataset; statistical analysis of a fouryear dataset of IMR and weather observations; and a field campaign using both two existing fixed IMRs and the new mobile unit. Statistical techniques used include correlation, multiple regression, discriminant analysis, and principal components analysis. The original results of this work include design details of the mobile IMR, extension of radar performance calculations to IMRs and evaluation of flight speed biases, a holistic approach to IMR design, the relation of insect RCS magnitudes and polarization patterns to morphological variables, an estimate of the accuracy of the retrieved parameters, evaluations of three approaches (oneparameter, theory-based, and a novel two-stage method) to target identification, and verification of inferred target identities using results from nearby light traps. Possible sites for future IMRs are identified. The major conclusions are that: a mobile IMR can be built with a performance equal to that of a fixed IMR but at half the cost; significant biases in the signal processing results arise from insect speed; locusts and moths can be distinguished if all RCS parameters are used; IMRs can be designed to match particular requirements; weather has a significant effect on insect migration, the best single predictor of insect numbers being temperature; moonlight has no effect; the spatial correlation of migration properties falls to 50% at a separation of 300 km; and migrating insects can be carried by the wind for 500 km in a single night
8

Bladder Monitoring Using Ultra-Wideband Radar and Vivaldi Antenna

Jonsson, Erica, Kovács, Attila January 2023 (has links)
Millions worldwide cannot tell when their bladder is nearing total capacity. The catheter, a tube to empty the bladder, is a vital part of life for many people. A catheter is, however, not a comfortable option, and it is the most common cause of infection in people staying in hospitals. This thesis aims to make the process more comfortable and non-invasive. The proposed idea is to use a UWB radar system with Vivaldi antennas to monitor the bladder state. Research shows that UWB radars can see a difference between a full and an empty phantom bladder. However, current research that explores the usage of UWB radar systems to monitor the bladder state does not consider regulations other than the ones set by FCC. They also only perform experiments on a phantom bladder. This thesis investigates the practical viability of using a UWB radar system designed per the restricted regulations set by Post- och Telestyrelsen. The thesis includes the design, simulations,manufacturing, and testing of the antennas as well as the radar system. The goal was to test the system in both simulations, with a phantom model and with a human body as a target, to advance the current state of research and determine its practicality forreal-life applications. The simulations showed a significant difference in reflections between full and empty bladders. The measurements from the experiments showed a slight difference in amplitude as well, although not as great as predicted due to a longer pulse. The Vivaldi antennas performed as expected according to both theory and simulations and they should work as desired in further experiments that use a UWB radar to monitor the bladder state per the PTS regulations. This thesis is solely based on an original idea and has not been influenced or derived from any external company.
9

Genetic algorithm design and testing of a random element 3-D 2.4 GHZ phased array transmit antenna constructed of commercial RF microchips

Esswein, Lance C. 06 1900 (has links)
Approved for public release, distribution is unlimited / The United States Navy requires radical and innovative ways to model and design multifunction phased array radars. This thesis puts forth the concept that Genetic Algorithms, computer simulations that mirror the natural selection process to develop creative solutions to complex problems, would be extremely well suited in this application. The capability of a Genetic Algorithm to predict adequately the behavior of an array antenna with randomly located elements was verified with expected results through the design, construction, development and evaluation of a test-bed array. The test-bed array was constructed of commercially available components, including a unique and innovative application of a quadrature modulator microchip used in commercial communications applications. Corroboration of predicted beam patterns from both Genetic Algorithm and Method of Moments calculations was achieved in anechoic chamber measurements conducted with the test-bed array. Both H-plane and E-plane data runs were made with several phase steered beams. In all cases the measured data agreed with that predicted from both modeling programs. Although time limited experiments to beam forming and steering with phase shifting, the test-bed array is fully capable of beam forming and steering though both phase shifting and amplitude tapering. / Outstanding Thesis / Lieutenant Commander, United States Navy

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