Spectrally pure signals are an indispensable requirement when the Signal Generator (SG) is to be used as part of a test bed. However, even sophisticated equipment may not comply with the needs imposed by certain applications. This work approaches the problem by using Digital Pre-Distortion (DPD) based on a polynomial memory-less model obtained for the SG. Using the SG in arbitrary mode (ARB) an input signal is computer-generated and reproduced by the SG. Measurement accuracy is ensured using coherence sampling and grid matching to the Signal Analyzer (SA). Finally, careful time alignment is used to compare the transmitted and received three-tone signals to obtain the polynomials coefficients. Results show that the accuracy of the model and the effectiveness of pre-distortion may vary depending on the amplitude of the three-tone signal. However, using polynomials of 5th and 9th degrees up to 15dB reduction of the 3rd order Inter-Modulation products can be obtained, and spurious powers may be lowered down to 70dBc.

In order to achieve results that are reliable when using the finite element method one has to use an acceptable element mesh with respect to the shape and size of the elements. As a help to produce an acceptable mesh there are quality criteria that must be fulfilled in most pre-processors. One objective with this thesis is to perform a sensitivity study that can be used as a basis for a Mesh guideline for chassis parts which is requested from engineers at Volvo 3P. The software used in the sensitivity study is ANSA as pre-processor, Nastran as solver and Metapost as post-processor. In the first part of the sensitivity study three different models are used for studying quality criteria such as aspect ratio, skewness, mid point alignment, mid point deviation and element size. Solid elements of second order, which are used in the three models, can be generated in two ways, which constitutes another part of the sensitivity study. They may either be generated from the beginning or can be converted from first order elements. This means geometrically that if second order elements where generated from the beginning the element mesh would follow the shape of the component in a better way compared to the other method. Recently a pre- and post-processing program called SimLab was introduced on the market. Since SimLab supports geometry import from several CAD-systems without loss of feature information, the automatic element mesh generation is supposed to be better as the mesh generator has access to more information concerning the geometry. An evaluation of SimLab is the second major objective of the thesis. More specifically, the evaluation concerns the possibility of using the software at Volvo 3P. Results show a surprising insensitivity regarding the criteria and that the method of generating second order elements from the beginning is to be preferred. SimLab is a new program with big potential and the conclusion is that it is possible to use it at Volvo 3P.

The paradigm of separate source-channel coding is inspired by Shannon's separation result, which implies the asymptotic optimality of designing source and channel coding independently from each other. The result exploits the fact that channel error probabilities can be made arbitrarily small, as long as the block length of the channel code can be made arbitrarily large. However, this is not possible in practice, where the block length is either fixed or restricted to a range of finite values. As a result, the optimality of source and channel coding separation becomes unknown, leading researchers to consider joint source-channel coding (JSCC) to further improve the performance of practical systems that must operate in the finite block length regime. With this motivation, this thesis investigates the application of JSCC principles for multimedia communications over point-to-point, broadcast, and relay channels. All analyses are conducted from the perspective of end-to-end distortion (EED) for results that are applicable to channel codes with finite block lengths in pursuing insights into practical design. The thesis first revisits the fundamental open problem of the separation of source and channel coding in the finite block length regime. Derived formulations and numerical analyses for a source-channel coding system reveal many scenarios where the EED reduction is positive when pairing the channel-optimized source quantizer (COSQ) with an optimal channel code, hence establishing the invalidity of the separation theorem in the finite block length regime. With this, further improvements to JSCC systems are considered by augmenting error detection codes with the COSQ. Closed-form EED expressions for such system are derived, from which necessary optimality conditions are identified and used in proposed algorithms for system design. Results for both the point-to-point and broadcast channels demonstrate significant reductions to the EED without sacrificing bandwidth when considering a tradeoff between quantization and error detection coding rates. Lastly, the JSCC system is considered under relay channels, for which a computable measure of the EED is derived for any relay channel conditions with nonzero channel error probabilities. To emphasize the importance of analyzing JSCC systems under finite block lengths, the large sub-optimality in performance is demonstrated when solving the power allocation configuration problem according to capacity-based formulations that disregard channel errors, as opposed to those based on the EED. Although this thesis only considers one JSCC setup of many, it is concluded that consideration of JSCC systems from a non-asymptotic perspective not only is more meaningful, but also reveals more relevant insight into practical system design. This thesis accomplishes such by maintaining the EED as a measure of system performance in each of the considered point-to-point, broadcast, and relay cases.

A parameter-free solution is presented for data projector calibration using a single camera and Gray coded structured light patterns. The proposed method assumes that both camera and projector exhibit significant non-linear distortion, and that projection surfaces can be either planar or freeform. The camera is calibrated first through traditional methods, and the calibrated images are then used to detect Gray coded patterns displayed on a surface by the data projector. Projector to camera correspondences are created by decoding the patterns in the camera images to form a 2D correspondence map. Calibrated systems produce geometrically correct, ex- tremely short throw projections, while maintaining or exceeding the projection size of a standard configuration. Qualitative experiments are performed on two baseline images, while quantitative data is recovered from the projected image of a chessboard pattern. A typical throw ratio of 0.5 can be achieved with a pixel distance error below 1. / Thesis (Master, Electrical & Computer Engineering) -- Queen's University, 2010-06-29 09:33:50.311

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No description available.

Broadcasting authorities presently measure intermodulation distortion by applying a three tone simulation of a composite video and sound signal to the transposer and then measuring the relative amplitude of the major in-band intermodulation product (nominally at vision carrier frequency plus 1,57 MHz in the 625 line I/PAL System) on a spectrum analyser. This method is slow and requires a skilful operator to achieve repeatable results. Furthermore it tests the common RF amplification equipment at one luminance level and one chrominance level and therefore does not subject the transposer equipment to operation over its full range. A new sampling measurement technique has been proposed which overcomes all these problems by selectively mixing, while transmitting a colour bar test pattern, the demodulated output video signal of the frequency transposer with a pulse train coinciding with a particular colour. This thesis describes the design of a very stable proportional timing generator and its application to the measurement of intermodulation distortion on frequency transposers. The timing generator, which locks automatically onto the video signal and produces narrow sampling pulses which coincide accurately with a particular section of each line over a 50°C temperature range, is applicable to all PAL and NTSC TV Systems. / Thesis (Ph.D.)-University of Natal, Durban, 1989.

Fingerprints are the most accurate and widely used biometrics for human identification due to their uniqueness, rapid and easy means of acquisition. Contact based techniques of fingerprint acquisition like traditional ink and live scan methods are not user friendly, reduce capture area and cause deformation of fingerprint features. Also, improper skin conditions and worn friction ridges lead to poor quality fingerprints. A non-contact, high resolution, high speed scanning system has been developed to acquire a 3D scan of a finger using structured light illumination technique. The 3D scanner system consists of three cameras and a projector, with each camera producing a 3D scan of the finger. By merging the 3D scans obtained from the three cameras a nail to nail fingerprint scan is obtained. However, the scans from the cameras do not merge perfectly. The main objective of this thesis is to calibrate the system well such that 3D scans obtained from the three cameras merge or align automatically. This error in merging is reduced by compensating for radial distortion present in the projector of the scanner system. The error in merging after radial distortion correction is then measured using the projector coordinates of the scanner system.

A single-phase, buck-boost based, dual-output AC-DC converter is studied in this thesis. The converter has two DC outputs with opposite polarities, which share the same ground with the input power line. The power stage performance, including the input filter, is studied and procedure to select power components is given. The circuit model is analyzed to develop appropriate control. Zerocrossing distortion of the source input current is addressed and a solution is proposed. Experimental results are satisfactory in that a high power factor line current results for steady-state operation.

Power inverters, used to convert DC power to AC, are often used in e.g. solar power applications. However, they tend to be impractically large and expensive; as such, power miniaturization is an active research area. In this thesis, several classes of modern power inverters are evaluated and compared with regards to size, efficiency and output quality in order to identify areas of potential improvement. Methods for estimation of THD, power losses and input ripple are created and verified against a simulation of a five-level neutral-point-clamped inverter with SPWM control. Finally, this design is implemented physically and is found to achieve 94.5% efficiency and 7% THD under low voltage laboratory conditions, while remaining smaller than an average textbook.