Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 34 for “"Direct-digital"”.
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Direct digital control of D.C. machines
… thesis set out to improve on previous methods of digital control of a three phase fully controlled thyristor bridge, using phase control of the thyristors, and to use this bridge for the purpose of controlling the speed of a separately excited D. C. machine, under the supervision of a small …
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Direct Digital Control of Inertial Guidance Sensors
… control systems for inertial sensors using digital controllers. Specific attention is given to the case where a two-degree-of-freedom gyro is used as an attitude sensor in a strapdown inertial measurement system. Because of the similarity of the dynamical behaviour of gyros and …
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Direct digital control of a synchronous machine
… thesis is to investigate the possibilities of direct digital control of a thyristor converter and to determine the major parameters affecting the operation of a variable speed synchronous machine drive.
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Direct digital control of a D.C. machine
… and stabilized on the analogue computor. A new digital computor program was written incorporating those characteristics which were found necessary in the simulation to make the system stable. The modified form of compensation was found to give a satisfactory performance for both step and ramp …
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Phase truncation effects in direct digital frequency synthesis
Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1985.
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Radio frequency direct-digital QPSK modulators in CMOS technology
In this thesis, novel direct-digital Quadrature Phase Shift Keying (QPSK) modulators are proposed in low-cost Complimentary Metal Oxide Semiconductor (CMOS) technology for radio frequency (RF) wireless applications. Direct-digital architectures have attracted much attention recently as they …
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Asynchronous direct digital synthesis modulator implemented on a FPGA
Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1997.
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A Variable Gain Direct Digital Readout System for Capacitive Inertial Sensors
… between the feedforward gain stage and feedback digital to analog (DAC) stage. Interfaced with a commercial accelerometer with sensitivity of 4.5 fF/g, the circuit achieves 40.6 dB SNDR in the x-direction and 42.5 dB SNDR in the y-direction due to limitations of the available testing equipment. …
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Tutorial on direct digital synthesizer structure improvements and static timing analysis
The direct digital frequency synthesizer (DDS) has been widely used in digital communication systems due to its high frequency resolution, fast frequency conversion, and continuous phase change. With the development of microelectronics technology, field-programmable gate array (FPGA) devices have …
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Phase noise and spur reduction in an array of direct digital synthesizers
… signals is to combine the outputs of multiple direct digital synthesizers (DDSs) arranged in a parallel configuration. In such an approach, if all noise is uncorrelated across channels, the noise will decrease relative to the combined signal power, resulting in a reduction of sideband noise and …
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Broadband Terahertz Signal Generation and Radiation Based on Direct Digital-to-Impulse Radiating Arrays in Silicon
… In this dissertation, an on-chip laser-free direct digital-to-impulse (D2I) architecture is introduced that is capable of radiating a THz pulse by creating and exciting a broadband radiating resonator consisting of an on-chip antenna and a broadband matching network. This novel method …
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Tutorial on designing and implementing a direct digital synthesizer (DDS) on a field programmable gate array (FPGA)
… One such a frequency synthesizer is a direct digital synthesizer (DDS). This thesis work utilizes a design that aims to combine digital circuit design and electronic communication knowledge, and apply them in a practical environment. It does so by providing a tutorial on designing and …
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Tutorial on designing and simulating a truncation spurs-free direct digital synthesizer (DDS) on a field-programmable gate array (FPGA)
Direct digital synthesis is a technique for using digital data processing blocks as a means to generate a frequency and phase tunable output signal referenced to a fixed-frequency precision clock source. Many telecommunication applications require such a high-speed switching, fine- tuning and …
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Direct digital control of thyristor networks : an investigation into the on-line control of thyristor networks by means of a small digital computer
… is an investigation into the applications of a digital computer to the on-line control of thyristor networks. This will involve producing hardware and software to determine firing sequences, firing delays, etc., and to execute the firing instructions. These are to be determined by the computer …
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FPGA-based digital phase-locked loop analysis and implementation
The thesis presents a digital PLL project that will be used as an ECE 463 lab module and serve as a platform for future communication research projects. Field Programmable Gate Array (FPGA) technology is used for all digital signal processing tasks. A Direct Digital Synthesizer (DDS) is used to …
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Reasonable computing for architectural fabrication
The use of digital fabrication tools in the architecture industry serve a particular group of individuals whose familiarity of the tools are by trade skill. Machines lack the understanding of people in its ability to objectify common knowledge. This thesis describes the Adeon system, a software …
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A Comparison of five radiographic systems to D-speed film in the detection of artificial bone lesions
The purpose of this study was to compare three direct digital sensors (Kodak 6100, Schick CDR, and Dexis PerfectSize), a phosphor plate system (OpTime), and F-speed film to standard D-speed film in the detection of artificial bone lesions prepared in mandible bone sections. Multiple artificial bone …
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A Radiographic Analysis of Variance in Lower Incisor Enamel Thickness
… thickness of mandibular incisors. At least two direct digital periapical radiographs were made for each of the 80 subjects. Radiographs were scaled to control for magnification errors using dental study models and computer software. Mesiodistal incisor width and mesial and distal enamel …
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Delta-Sigma digital-RF modulation for high data rate transmitters
… wireless transmitter utilizing [Delta]-[Sigma] direct digital modulation of an RF carrier is presented. The transmitter architecture replaces high dynamic range analog circuits with high speed digital circuits and a passive LC bandpass filter, saving power and area compared to conventional IQ …
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Design of a Bandgap-Less Temperature Sensor for Achieving High Untrimmed Accuracy
… sensors offer benefits of low cost and direct digital outputs over conventional sensors. However, they are limited in their absolute accuracy due to the non-ideal behaviour of the devices used to design them. Therefore, these sensors require either calibration or gain, offset and …
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