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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.
11

A parallel model for the heterogeneous computation of radio astronomy signal correlation

Harris, Christopher John January 2009 (has links)
The computational requirements of scientific research are constantly growing. In the field of radio astronomy, observations have evolved from using single telescopes, to interferometer arrays of many telescopes, and there are currently arrays of massive scale under development. These interferometers use signal and image processing to produce data that is useful to radio astronomy, and the amount of processing required scales quadratically with the scale of the array. Traditional computational approaches are unable to meet this demand in the near future. This thesis explores the use of heterogeneous parallel processing to meet the computational demands of radio astronomy. In heterogeneous computing, multiple hardware architectures are used for processing. In this work, the Graphics Processing Unit (GPU) is used as a co-processor along with the Central Processing Unit (CPU) for the computation of signal processing algorithms. Specifically, the suitability of the GPU to accelerate the correlator algorithms used in radio astronomy is investigated. This work first implemented a FX correlator on the GPU, with a performance increase of one to two orders of magnitude over a serial CPU approach. The FX correlator algorithm combines pairs of telescope signals in the Fourier domain. Given N telescope signals from the interferometer array, N2 conjugate multiplications must be calculated in the algorithm. For extremely large arrays (N >> 30), this is a huge computational requirement. Testing will show that the GPU correlator produces results equivalent to that of a software correlator implemented on the CPU. However, the algorithm itself is adapted in order to take advantage of the processing power of the GPU. Research examined how correlator parameters, in particular the number of telescope signals and the Fast Fourier Transform (FFT) length, affected the results.
12

Block Transmissions On Orthogonal Carriers

Yazici, Ayhan 01 September 2005 (has links) (PDF)
Orthogonal Frequency Division Multiplexing (OFDM) and Single Carrier Block Transmissions (SCBT) are located at the two opposite edges of block transmission concept. In this thesis a system which lies between OFDM and SCBT is proposed. The new system, namely Block Transmissions on Orthogonal Carriers (BTOC), can be considered as a hybrid form of OFDM and SCBT. BTOC system is investigated under the redundant filterbank precoders and equalizers framework. Peak to average power ratio (PAPR) of BTOC is formulated and compared with the PAPRs of OFDM and SCBT. Effect of frequency offset for BTOC is investigated and comparison between OFDM, SCBT, and BTOC is presented. Simulation results of Zero Padded OFDM (ZP-OFDM), SCBT, and BTOC are included.
13

Design of auxiliary communication for audio between computers and DSPs : Programming and optimization of computational resources / Design av ljudkommuniktion mellan dator och signalprocessor : Programmering och optimering av beräkningsresurser

Oscar, Eriksson Janze January 2023 (has links)
This thesis report is about designing a prototype and establishing audio communication between a computer and Digital Signal Processor (DSP) using two preamp circuits using both auxiliary and USB connection. The paper gives the reader an overview on how audio is transmitted from a computer, through the system and to the desired output. The reader should also get a better understanding of how an AD-converter samples the incoming signal to the Discrete plane and how an AUX or phone connector works. This information can be used for designing preamp circuits to communicate between a computer and the DSP. The DSP circuit uses an STM32 processor to control the incoming and outgoing signals with the use of ADC and DAC conversion. The DSP also uses microphones to capture surrounding sound. An addition is to make a prototype on how to use these microphones to  send the signal upstream to the computer. The microphone is then benchmarked with the use of Matlab, calculating Total Harmonic Distortion. Management and optimization of code structure and resources is done in the source files of the project. Using imperative C programing, large functions are broken down into smaller functions to ease readability and control flow. The result is a prototype circuit that can communicate audio signals with both audio jack and USB between computers input and output to the DSP. Using CubeMX in conjunction with CubeIDE to add additional ADC channels to be able to incorporate an automatic source control when the audio jack or USB is connected. / Denna avhandling handlar om att designa en prototyp och etablera ljudkommunikation mellan en dator och en digital signalprocessor (DSP) med hjälp av två förstärkarkretsar genom både aux- och USB-anslutning. Rapporten ger läsaren en översikt över hur ljud skickas från en dator, genom systemet och till önskad utgång. Läsaren bör också få en bättre förståelse för hur en AD-omvandlare fungerar för att sampla den inkommande signalen till tidsdiskreta planet och hur en AUX- eller telekabel fungerar. Målet är att använda denna information för att skapa förstärkare som kan kommunicera mellan en dator och DSP:en. DSP-kretsen använder en STM32-processor för att hantera de inkommande och utgående signalerna med användning av ADC- och DAC-omvandling. DSP:en använder också mikrofoner för att fånga omgivande ljud. Ett tillägg är att skapa en prototyp för hur man kan använda en av mikrofonerna för att skicka signalen till datorn. Mikrofonen jämförs sedan med hjälp av Matlab genom att beräkna total harmonisk distorsion. Hantering och optimering av kodstruktur och resurser görs i projektets källkodsfiler. Genom att använda imperativ C-programmering bryts stora funktioner ned i mindre funktioner för att underlätta läsbarheten och styrningen av flödet. Resultatet är en prototypkrets som kan kommunicera ljudsignaler med både ljuduttag och USB mellan datorns in- och utgång och DSP:en. Genom att använda CubeMX tillsammans med CubeIDE läggs ytterligare ADC-kanaler för att möjliggöra automatisk källkontroll när ljuduttaget eller USB-anslutningen är ansluten.

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