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31 
Design and Implementation of a Practical Aircraft Position and Reporting Identification Beacon (PRIB)Lee Yan, Yuen On 11 July 2003 (has links)
A transponder is a device that is used for tracking aircraft by mean of a secondary radar system, but it can be turned off deliberately, and it is an expensive item for small aircraft. These weaknesses have fatal consequences, as was shown with the terrorist attack on September 11 th , 2001, where four commercial aircraft under the control of international terrorists were used as missiles against the United Stated of America, killing thousands of people. These factors have shown a need for the development of an efficient aircraft tracking system, which does not rely on transponders. To this end a new tracking aircraft system is proposed, which will be referred to as the Positioning and Reporting Identification Beacon (PRIB) system. Due to size, mass, power, and financial constraints, the design must be small, light, power efficient, and costeffective. The PRIB will acquire the aircraft's position from a dedicated GPS receiver and then transmit this information to a base station at a different location using a radio link.
This thesis presents the design of a PRIB unit in light of the system constraints. In addition to the hardware design, the software needed by the unit to control and communicate with the ground stations is presented. The performance of the PRIB is analyzed and ways in which a PRIB could be manufactured using commercial offtheshelf parts is discussed. / Master of Science

32 
Design of a receiver system for use in radio astronomyVan Vuuren, Lukas Martin 03 1900 (has links)
Thesis (MEng)Stellenbosch University, 2015. / ENGLISH ABSTRACT:
Please refer to full text for abstract.

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Optical and Thermal Analysis of a Heteroconical Tubular Cavity Solar ReceiverMaharaj, Neelesh 25 October 2022 (has links) (PDF)
The principal objective of this study is to develop, investigate and optimise the Heteroconical Tubular Cavity receiver for a parabolic trough reflector. This study presents a threestage development process which allowed for the development, investigation and optimisation of the Heteroconical receiver. The first stage of development focused on the investigation into the optical performance of the Heteroconical receiver for different geometric configurations. The effect of cavity geometry on the heat flux distribution on the receiver absorbers as well as on the optical performance of the Heteroconical cavity was investigated. The cavity geometry was varied by varying the cone angle and cavity aperture width of the receiver. This investigation led to identification of optical characteristics of the Heteroconical receiver as well as an optically optimised geometric configuration for the cavity shape of the receiver. The second stage of development focused on the thermal and thermodynamic performance of the Heteroconical receiver for different geometric configurations. This stage of development allowed for the investigation into the effect of cavity shape and concentration ratio on the thermal performance of the Heteroconical receiver. The identification of certain thermal characteristics of the receiver further optimised the shape of the receiver cavity for thermal performance during the second stage of development. The third stage of development and optimisation focused on the absorber tubes of the Heteroconical receiver. This enabled further investigation into the effect of tube diameter on the total performance of the Heteroconical receiver and led to an optimal inner tube diameter for the receiver under given operating conditions. In this work, the thermodynamic performance, conjugate heat transfer and fluid flow of the Heteroconical receiver were analysed by solving the computational governing Equations set out in this work known as the ReynoldsAveraged NavierStokes (RANS) Equations as well as the energy Equation by utilising the commercially available CFD code, ANSYS FLUENT®. The optical model of the receiver which modelled the optical performance and produced the nonuniform actual heat flux distribution on the absorbers of the receiver was numerically modelled by solving the rendering Equation using the MonteCarlo ray tracing method. SolTrace  a raytracing software package developed by the National Renewable Energy Laboratory (NREL), commonly used to analyse CSP systems, was utilised for modelling the optical response and performance of the Heteroconical receiver. These actual nonuniform heat flux distributions were applied in the CFD code by making use of userdefined functions for the thermal model and analysis of the Heteroconical receiver. The numerical model was applied to a simple parabolic trough receiver and reflector and validated against experimental data available in the literature, and good agreement was achieved. It was found that the Heteroconical receiver was able to significantly reduce the amount of reradiation losses as well as improve the uniformity of the heat flux distribution on the absorbers. The receiver was found to produce thermal efficiencies of up to 71% and optical efficiencies of up to 80% for practically sized receivers. The optimal receiver was compared to a widely used parabolic trough receiver, a vacuum tube receiver. It was found that the optimal Heteroconical receiver performed, on average, 4% more efficiently than the vacuum tube receiver across the temperature range of 50210℃. In summary, it was found that the larger a Heteroconical receiver is the higher its optical efficiency, but the lower its thermal efficiency. Hence, careful consideration needs to be taken when determining cone angle and concentration ratio of the receiver. It was found that absorber tube diameter does not have a significant effect on the performance of the receiver, but its position within the cavity does have a vital role in the performance of the receiver. The Heteroconical receiver was found to successfully reduce energy losses and was found to be a successfully high performance solar thermal tubular cavity receiver.

34 
Adaptive Thresholding for Detection of Radar Receiver SignalsBenson, Stephen R. 01 November 2010 (has links)
No description available.

35 
Reduced Complexity Sequential Monte Carlo Algorithms for Blind ReceiversOzgur, Soner 10 April 2006 (has links)
Monte Carlo algorithms can be used to estimate the state of a system given relative observations. In this dissertation, these algorithms are applied to physical layer communications system models to estimate channel state information, to obtain soft information about transmitted symbols or multiple access interference, or to obtain estimates of all of these by joint estimation.
Initially, we develop and analyze a multiple access technique utilizing mutually orthogonal complementary sets (MOCS) of sequences. These codes deliberately introduce interchip interference, which is naturally eliminated during processing at the receiver. However, channel impairments can destroy their orthogonality properties and additional processing becomes necessary.
We utilize Monte Carlo algorithms to perform joint channel and symbol estimation for systems utilizing MOCS sequences as spreading codes. We apply RaoBlackwellization to reduce the required number of particles. However, dense signaling constellations, multiuser environments, and the interchannel interference introduced by the spreading codes all increase the dimensionality of the symbol state space significantly. A full maximum likelihood solution is computationally expensive and generally not practical. However, obtaining the optimum solution is critical, and looking at only a part of the symbol space is generally not a good solution. We have sought algorithms that would guarantee that the correct transmitted symbol is considered, while only sampling a portion of the full symbol space. The performance of the proposed method is comparable to the Maximum Likelihood (ML) algorithm. While the computational complexity of ML increases exponentially with the dimensionality of the problem, the complexity of our approach increases only quadratically.
Markovian structures such as the one imposed by MOCS spreading sequences can be seen in other physical layer structures as well. We have applied this partitioning approach with some modification to blind equalization of frequency selective fading channel and to multipleinput multiple output receivers that track channel changes.
Additionally, we develop a method that obtains a metric for quantifying the convergence rate of Monte Carlo algorithms. Our approach yields an eigenvalue based method that is useful in identifying sources of slow convergence and estimation inaccuracy.

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Parameterizable Channelized Wideband Digital Receiver for High Update RateBuxa, Peter E. 30 July 2007 (has links)
No description available.

37 
A 2.4 GHz receiver in silicononsapphirePeters, Michael January 1900 (has links)
Master of Science / Department of Electrical and Computer Engineering / William Kuhn / From 2004 to 2008, Kansas State University's Electrical and Computer Engineering (ECE) department, along with the NASA Jet Propulsion Laboratory and Peregrine Semiconductor, researched design techniques for producing a lowpower, 400 MHz microtransceiver suitable for future use on Mars scout missions. In 2012, Dr. Kuhn's Digital Radio Hardware Design class, ECE765, adapted the KState circuit designs from this research project to investigate the possibility of producing a 2.4 GHz microtransceiver in Peregrine Semiconductor’s newer 0.25 [mu]m Silicon on Sapphire process.
This report expands upon the work completed in the Digital Radio Hardware Design (ECE765) course. The schematics and layout of the subsections of the receiver portion of the microtransceiver chip, consisting of a transmit/receive switch, lownoise amplifier, mixer, intermediatefrequency amplifiers, and an analogtodigital converter are described. Circuits designed to date require a total of 15 mW to operate. This report is intended as a guide for future students who will take over this project, make modifications, adapt the transmit portion of the microtransceiver from previous work, and finish layout before fabrication of a full 2.4 GHz prototype chip.

38 
THE DESIGN OF C/A CODE GLONASS RECEIVERHui, Liu, Leelung, Cheng, Qishan, Zhang 10 1900 (has links)
International Telemetering Conference Proceedings / October 2730, 1997 / Riviera Hotel and Convention Center, Las Vegas, Nevada / GLONASS is similar to GPS in many aspects such as system configuration, navigation mechanism, signal structure, etc.. There exists the possibility of receiving and processing GLONASS signals with GPS technology. The frequency plan of the GLONASS system is different from that of GPS. This makes the frontend of GLONASS receiver more complicated. The work here manifests our initial effort in GLONASS receiving. A design scheme is proposed of a C/A code GLONASS receiver.

39 
A receiver function study in the Peloponnese, GreeceMorice, Stephen Patrick January 1995 (has links)
No description available.

40 
Retrospective seismology by sourcereceiver interferometryEntwistle, Elizabeth January 2015 (has links)
Seismology is the study of earthquakes and the Earth’s internal structure using seismic waves. Traditional seismology is constrained by the timing and location of seismic sources, and by the location of seismometers with which energy from the sources are recorded. Improvements in the global seismometer networks have reduced the latter constraint. Furthermore, recent advances into Seismic Interferometry (SI) have enabled detailed information about the Earth’s interior to be obtained using ambient seismic noise, hence even in areas with low natural seismicity. The most common approach to SI is to use the crosscorrelation of ambient noise recordings to construct an estimate of the Green’s function between two seismometer locations. The Green’s function estimate is then analysed or inverted for seismic properties of the Earth. This method of noise interferometry is now a popular approach in earthquake seismology as in some situations it renders active seismic sources (earthquakes or synthesised explosions) obsolete, as subsurface information can be obtained even in times of seismic quiescence. This thesis investigates a different method: SourceReceiver Interferometry (SRI). SRI can be used to construct earthquake seismograms on seismometers that were not necessarily deployed when the earthquakes occurred  a form of ‘retrospective seismology’. This might be useful if, for example, we wish to analyse old earthquakes with newly installed seismometers. The application of SRI involves evaluating two interferometric integrals. The first integral is evaluated using ambient noise interferometry: at least 6 months of noise data is crosscorrelated to estimate the Green’s functions between pairs of seismometers. These interreceiver Green’s functions are then used as the “propagators” for SRI. Their role is to project earthquake signals recorded on a backbone array of seismometers to the location of a target sensor at which a new, novel earthquake seismogram is to be constructed  a form of spatial redatuming. To spatially redatum the earthquake data, the second interferometric integral is evaluated using either processes of correlation (resulting in correlationcorrelation SRI) or convolution (correlationconvolution SRI). The method used depends on the relative location of the target sensors with respect to both the backbone seismometer array and the earthquake epicentre. The SRI process is completed by integrating (summing) over all projected earthquake signals. To regularise the spatial distribution of the projected earthquake data and to invoke this second interferometric integral more precisely, the backbone seismometers are embedded within 2D spatial Voronoi cells. New seismograms for 87 earthquakes were reconstructed on up to eight target sensors, seven of which were deployed when the earthquakes occurred and are used to test the success of the method by comparing with the SRI results with the directlyrecorded seismograms. The seismogram reconstructions on the eighth target sensor are truly novel. The SRI method was developed to operate over two length scales. The first focusses on relatively small length scales in which the interstation distance between the eight target sensors and the backbone array seismometers is between ~ 210 km and 540 km. Both correlationcorrelation SRI and correlationconvolution SRI are used to reconstruct the earthquake seismograms on four of the same target sensors. Applying correlationconvolution SRI is shown to remove spurious signals associated with correlationcorrelation SRI. Second, a significantly larger length scale is considered where a second set of target sensors are located up to 2420 km from a second backbone seismometer array. The correlationcorrelation and correlationconvolution SRI methods are used in parallel to increase the spatial extent of the study. The quality of the SRI seismograms constructed is shown to depend on the quality of three components: 1) the SRI propagators constructed using ambient noise interferometry, 2) the earthquake signals recorded on the backbone seismometer array, and 3) the correlation (or convolution) functions that are summed in the second interferometric integral to construct the final SRI seismogram. The quality of each component is quantified by its signaltonoise ratio and rootmeansquare value, and criteria are proposed to obtain optimal earthquake seismogram reconstructions using SRI. SRI is most successful when the target sensors are located less than 540 km from the backbone array seismometers. Such SRI seismograms are being used to create a catalogue of new, ‘virtual’ earthquake seismograms that are available to complement real earthquake data for use in future earthquake seismology studies. An alternative approach to noise interferometry is also considered: the recordings from just 15 earthquakes are used to perform multidimensional deconvolution (MDD) to estimate the Green’s functions between pairs of seismometers. This is the first time such data has been used to perform MDD, which is valid in attenuating media and is thus theoretically more valid in earthquake seismology settings than correlational interferometry. The Green’s functions estimated using MDD are compared with those same Green’s functions estimated using ambient noise interferometry and the results are comparable on several occasions, despite using far fewer data for MDD. However, the quality of the results of MDD is significantly affected by the illumination of the receiver array from the earthquake sources. A greater density of earthquakes that sufficiently illuminates all backbone array seismometers is required to obtain accurate Green’s functions by MDD.

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