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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

Best Source Selection on Encrypted Data

Guadiana, Juan M. 10 1900 (has links)
ITC/USA 2006 Conference Proceedings / The Forty-Second Annual International Telemetering Conference and Technical Exhibition / October 23-26, 2006 / Town and Country Resort & Convention Center, San Diego, California / The size of the range at White Sands means multiple acquisition sites are needed to properly cover a typical vehicle trajectory. As vehicle complexity increase, the need for robust acquisition grows. Multiple acquisition sites are needed to provide as complete coverage as practical. Space Diversity combining would provide a single composite source for all the displays and recording, but this is not practical due to the large distances between acquisition sites. Instead a composite is made from the various sites by correlation on non-encrypted (or decrypted) data. The previous best source selector, a frame synch histogrammer, could produce encrypted and decrypted composites. Some of our customers have missed the encrypted composites, hence the subject is revisited to encourage development. This paper reviews post decryption correlation and then focuses on correlating on encrypted data. The encryption serves to eliminate the ambiguities that are inherent in decrypted (nonencrypted) signals. So, it may be possible to accomplish this with a small correlator. The expected performance would be similar to that of correlated composites on decrypted or unencrypted data. The typical configuration would be considerably smaller as well since only two decrypters would be needed. One decrypter alone would be insufficient and could not resolve the case where only one site has data and the remaining sites have noise. When there is no correlation the correct site cannot be resolved. Testing these compositing methods is also discussed, as a good test method also provides insight on how the compositor should work.
2

Methods for ultra-broadband correlator development focusing on high-speed digital sampling techniques

Coates, Adam Ross January 2013 (has links)
In radio astronomy, a key limiting factor to observations made is the available bandwidth of the system. This thesis looks at two different approaches to building ultra-broadband correlators for use in radio astronomy. The first was a 2-20GHz double-sideband complex analogue correlator that was constructed before the work of this thesis. Characterisation tests are performed and a basic calibration is attempted. Both these sets of experiments show good results, with the basic calibration successfully being able to compensate for gain difference between the lags over a reduced bandwidth range used in the testing. The second approach was the investigation into different techniques for high-speed digital sampling, capable of providing equivalent bandwidths to the analogue system. The use of FPGA high-speed serial interfaces as direct 1-bit 3.125 GS/s samplers was investigated. Single-frequency sampling showed that a signal-to-noise ratio close to the theoretical maximum across the band was achieved (≈ 0.8 effective bits). Techniques were also identified to use multiple transceivers to generate a single interleaved stream at higher effective sampling rate. Two different methods were also explored for producing greater-than 1-bit sampling. A hysteresis approach was shown not to produce the desired results and a reference based sampler in the end was adopted. Finally, the interleaving and multi-bit techniques were combined to generate a single 1.5-bit 6.25 GS/s sampler. This was seen to have reduced signal-to-noise compared to the expected values. This was believed to be caused by the poor method of RF signal injection causing cross-talk between the channels and large amounts of loss. As a comparison to the direct sampling method, an external 1-bit high-speed Hittite comparator was also examined. The single-frequency experiment was repeated with a slightly higher signal-to-noise ratio found compared to the direct sampling method. This was again believed to be due to the RF environments used. From the sampling setups a four-input, six-baseline lag correlator was constructed using the direct sampling method. The entire correlator, as well as the sampling transceivers, was incorporated into a single Xilinx Virtex 5 FPGA. This was shown to have the expected response to single-frequency, broadband and noise signals. The thesis concludes with a characterisation of the RF devices used throughout the testing procedures. Several new devices were developed through the course of the experiments with the designs being documented. All the necessary components to construct IF chains for both the analogue and digital correlators described are present. This leads to simulations being made of complete IF chains, with the expected responses shown.
3

The Realization of a Digital Correlation Detector of Telemetry Frame-Synchronization-Pattern Using a Neural Network

Jun, Zhang, Yi, Qiu, Yan, Du, Qishan, Zhang 10 1900 (has links)
International Telemetering Conference Proceedings / October 28-31, 1996 / Town and Country Hotel and Convention Center, San Diego, California / In this paper, a method for digital correlation detector that takes advantage of the frame-synchronization-pattern feature of coincidence rate and adopts a multiple-bit detection window is proposed. Based on this method, a new digital correlation detector with a neural network is designed. It can recognizes frame-synchronization-pattern with error bits and slippage bits correctly, which has been approved practically according to the experimental results.
4

THE OPTICAL ALIGNMENT OF A PHASE KEY IN RANDOM PHASE ENCODED VOLUME HOLOGRAPHIC STORAGE SYSTEM BY USING A HOLOGRAPHIC CORRELATOR

Kao, Hung-Jei 26 June 2006 (has links)
Phase key, which uses optical encoding techniques for system security, plays an important role in optical storage, optical communication, and optical display. It employs a random phase generator with a volume hologram for optical encoding. The advantages of using phase keys for optical communication is: (1) it is hard to be duplicated and (2) it requires sensitively alignment to decode the desired signal. Thus, it ensures security of the optical system. However, the adjunctive challenge of using a phase key is the difficulty of alignment by users. In this paper, we propose a method for optical alignment of the phase key in a random phase encoded volume holographic storage system. In this method, a holographic correlator is applied to help the optical alignment of the phase key. It has been shown that the desired signal from the random phase encoded volume holographic storage system can be retrieved easily with high security.
5

Digital Auto-Correlator: Design and Construction

Masuko, Akira 05 1900 (has links)
This thesis describes a portable special-purpose digital instrument which uses digital-computer processes to provide decimal readouts of the autocorrelation function (and hence the mean square value too) of a fluctuating voltage, and also of the measuring time involved. The mathematical concepts set out in a paper by R. Kitai and F. Diest¹ are extended to provide the basic equations for the measurement of correlation function. The design and construction processes using integrated circuits are described in detail. The time difference between two samples can be varied at will from 10 μseconds downwards, with no lower limit. The measurement commences on a start signal and runs for a programmed time. Readouts are available immediately after the end of the measuring time. The upper frequency limit is several KHz. There are no low-frequency limits. Some familiar signals were measured and the results confirm that the system works satisfactorily. / Thesis / Master of Engineering (ME)
6

HIGH SPEED, WIDE BANDWIDTH SIGNAL DETECTION AND FREQUENCY ESTIMATION

Caprio, James R., Nystrom, Lennart 10 1900 (has links)
International Telemetering Conference Proceedings / October 13-16, 1986 / Riviera Hotel, Las Vegas, Nevada / A digital frequency discriminator (DFD) of the delay-correlator type is described. The device is shown to have an instantaneous frequency measurement capability on very short pulses. The theoretical performance of the DFD in a noisy background is derived and shown to compare favorably with measured results.
7

Desenvolvimento de comunicação de dados sem fio para problemas de detecção de vazamentos em tubulações enterradas / Development of wireless data communication for leak detection problems in buried pipelines

Costa, Alison França Queiroz da 21 December 2018 (has links)
Submitted by Alison França Queiroz da Costa (alisonfqc@gmail.com) on 2019-01-23T16:24:02Z No. of bitstreams: 1 dissertacao_Alison_Franca.pdf: 3877983 bytes, checksum: 3ca6152176a6c8ec61d124d98c1623ee (MD5) / Approved for entry into archive by Cristina Alexandra de Godoy null (cristina@adm.feis.unesp.br) on 2019-01-28T12:25:06Z (GMT) No. of bitstreams: 1 costa_afq_me_ilha.pdf: 4321708 bytes, checksum: 13ff971f8fa75010bf9d693777aac778 (MD5) / Made available in DSpace on 2019-01-28T12:25:06Z (GMT). No. of bitstreams: 1 costa_afq_me_ilha.pdf: 4321708 bytes, checksum: 13ff971f8fa75010bf9d693777aac778 (MD5) Previous issue date: 2018-12-21 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Este trabalho desenvolveu um protótipo de um correlacionador de sinais aplicados a vazamento em tubulações de água aterrada. Para tal foi analisado o SoC Zynq, utilizando a placa Minized juntamente com um conversor analógico-digital, Pmod AD1, um módulo GPS, Pmod GPS, um clock em tempo real, Pmod RTCC e um modulo acelerômetro Pmod NAV. Nesta análise foram utilizados modelos criados no software Xilinx Vivado, baseados em Intellectual Property blocks, e o software Xilinx SDK. A partir dos modelos desenvolvidos foram realizados testes com o propósito de validar o sincronismo entre as placas. Inicialmente testou-se um modelo simples apenas utilizando a placa e o módulo Pmod AD1, sendo o teste realizado para verificar a resolução do relógio da placa Minized. Em seguida foi feito o experimento com a placa Minized e o Pmod RTCC visando o sincronismo entre as placas. Os testes de sincronismo foram finalizados utilizando-se o conjunto Minized, Pmod RTCC e Pmod GPS, que obteve bons resultados. Para a finalização da análise da correlação de sinais verificou-se a utilização do Pmod NAV para a aquisição de dados com testes em bancada, apresentando resultados experimentais satisfatórios. / This work developed a prototype of a signal correlator applied to leakage in buried water pipes. The Zynq SoC was analyzed using the Minized board together with an analog-to-digital converter, Pmod AD1, a module GPS, Pmod GPS, a real-time clock, Pmod RTCC and a Pmod NAV accelerometer module. For this analysis we used models created in the Xilinx Vivado software, based on Intellectual Property blocks, and the Xilinx SDK software. From the developed models tests were carried out in order to validate the synchronism between the boards. Initially, a simple model was tested using only the board and the module Pmod AD1, and the test was performed to verify the resolution of the Minized board's clock. Then the experiment was performed using the Minized board and the Pmod RTCC aiming the synchronism between the boards. In order to finalize the synchronization tests, we used the Minized set, Pmod RTCC and Pmod GPS, which presented good results. For the conclusion of the analysis of the correlation of signals, the use of the Pmod NAV for the data acquisition was verified and then benchmarked, presenting satisfactory experimental results. / FAPESP: 2016/24974-2 / CAPES: Código de Financiamento 001
8

Desenvolvimento de comunicação de dados sem fio para problemas de detecção de vazamentos em tubulações enterradas /

Costa, Alison França Queiroz da January 2018 (has links)
Orientador: Ailton Akira Shinoda / Resumo: Este trabalho desenvolveu um protótipo de um correlacionador de sinais aplicados a vazamento em tubulações de água aterrada. Para tal foi analisado o SoC Zynq, utilizando a placa Minized juntamente com um conversor analógico-digital, Pmod AD1, um módulo GPS, Pmod GPS, um clock em tempo real, Pmod RTCC e um modulo acelerômetro Pmod NAV. Nesta análise foram utilizados modelos criados no software Xilinx Vivado, baseados em Intellectual Property blocks, e o software Xilinx SDK. A partir dos modelos desenvolvidos foram realizados testes com o propósito de validar o sincronismo entre as placas. Inicialmente testou-se um modelo simples apenas utilizando a placa e o módulo Pmod AD1, sendo o teste realizado para verificar a resolução do relógio da placa Minized. Em seguida foi feito o experimento com a placa Minized e o Pmod RTCC visando o sincronismo entre as placas. Os testes de sincronismo foram finalizados utilizando-se o conjunto Minized, Pmod RTCC e Pmod GPS, que obteve bons resultados. Para a finalização da análise da correlação de sinais verificou-se a utilização do Pmod NAV para a aquisição de dados com testes em bancada, apresentando resultados experimentais satisfatórios. / Abstract: This work developed a prototype of a signal correlator applied to leakage in buried water pipes. The Zynq SoC was analyzed using the Minized board together with an analog-to-digital converter, Pmod AD1, a module GPS, Pmod GPS, a real-time clock, Pmod RTCC and a Pmod NAV accelerometer module. For this analysis we used models created in the Xilinx Vivado software, based on Intellectual Property blocks, and the Xilinx SDK software. From the developed models tests were carried out in order to validate the synchronism between the boards. Initially, a simple model was tested using only the board and the module Pmod AD1, and the test was performed to verify the resolution of the Minized board's clock. Then the experiment was performed using the Minized board and the Pmod RTCC aiming the synchronism between the boards. In order to finalize the synchronization tests, we used the Minized set, Pmod RTCC and Pmod GPS, which presented good results. For the conclusion of the analysis of the correlation of signals, the use of the Pmod NAV for the data acquisition was verified and then benchmarked, presenting satisfactory experimental results. / Mestre
9

A Sliding Correlator Channel Sounder for Ultra-Wideband Measurements

Pirkl, Ryan Jesse 29 June 2007 (has links)
This body of work forms a detailed and comprehensive guide for those interested in performing broadband wireless channel measurements. Discussion addresses the theoretical and practical aspects of designing and implementing a sliding correlator channel sounder, as well as how such a system may be used to measure and model the ultra-wideband wireless channel. The specific contributions of this work are as follows: Developed a systematic methodology for designing optimal sliding correlator-based channel sounders. Constructed a UWB channel sounder based upon a 17-bit LFSR that attained 1.66 ns of temporal resolution and 34 dB of dynamic range. Performed an exemplary measurement campaign of the UWB channel from which UWB angular spreads and RMS delay spreads are reported. The design procedure developed in Chapter 3 will allow researchers to build optimal channel sounders for investigating next-generation wireless channels. Chapter 4 s discussion addresses the real-world challenges of constructing a high performance sliding correlator channel sounder. Finally, the measurement campaign discussed in Chapter 5 outlines a procedure for investigating the spatio-temporal characteristics of the wireless channel and provides some of the first examples of UWB angular spread measurements.
10

Design and Implementation of a Real-Time Digital Replica Correlator Using Bit Slice Microprocessor for Processing Sonar Signals

Man, John 09 1900 (has links)
<p> In the past, analog circuits, discrete digital logic circuits or minicomputers have been used to implement the signal processing section of a sonar systems. More recently, microprocessor based logic circuit designs have produced a new breed of system design approach which gives designers the flexibility that has never been available through the use of analog or discrete logic circuits; however, due to the inherent slow speed of the metal-oxide semiconductor (MOS) logic circuits, incorporating microprocessors in the implementation of a sonar signal processor is not feasible. With the advent of bipolar Schottky large scale integrated circuit technology, the speed performance of the microprocessors have been improved considerably, and signal processor designs employing microprocessors are now feasible. </p> <p> The main objective of this work is to design, implement, and test a real-time digital sonar signal processor for processing pulsed CW signals. With design based on the use of the bit slice microprocessor, a signal processor has been constructed that has an 8 bit input, a 16 bit output. The processor is capable of detecting 16 different Doppler shifts. Laboratory generated signals are used in the testing and the experimental results show good agreement with the theory. A possible means of expanding the existing single channel signal processor into a multichannel processor has also been outlined. </p> / Thesis / Master of Engineering (MEngr)

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