Dissertations / Theses on the topic 'Digital technique'
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1
Azirar, Abdennour. "Transmitter linearisation using the LINC technique and digital correction." Thesis, University of Surrey, 2005. http://epubs.surrey.ac.uk/843164/.
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Wireless high-speed digital communications systems are becoming increasingly commonplace for both commercial and military applications. One of the most effective techniques for combating multipath interference is the multicarrier OFDM (Orthogonal Frequency Division Multiplexing) scheme. However, the high PAPR (Peak-to-Average Power Ratio) of OFDM signals constitutes a problem when non-linear amplifiers are used. In this thesis the PAPR problem is introduced and the LINC (Linear Amplification with Nonlinear Components) technique is considered as a possible solution to counteract the PA (Power Amplifier) nonlinearity distortion. The proposed LINC technique can be implemented using DSP (Digital Signal Processing) techniques, has the potential of high IMD (Inter-modulation Distortion) suppression and it is unconditionally stable, which is a key advantage in broadband applications. It's well known that the unwanted imperfections like the I/Q (In-phase/Quadrature) imbalances present in the analogue IQ modulators in a direct conversion OFDM system contribute to a loss of orthogonality and create ICI (Inter-carrier Interference). These impairments can also severely reduce the efficiency of the LINC technique itself. This thesis investigates a digital compensation mechanism to reduce the IQ imbalance errors in the direct conversion OFDM LINC transmitter. The LINC technique is considered in the first part of this thesis as a possible linearisation technique to counteract the non-linear distortion caused by both the mixer and power amplifier in a single-carrier QPSK (Quaternary Phase Shift Keying) transmitter. Prototype systems for single-carrier QPSK transmitter and multi-carrier OFDM transmitter have been constructed to demonstrate the proposed method's capability.
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Addlesee, Michael Dennis. "Aspects of image compression using the subband technique." Thesis, University of Cambridge, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.385880.
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javeed, khalid. "DIGITAL GAIN ERROR CORRECTION TECHNIQUE FOR 8-BIT PIPELINE ADC." Thesis, Linköping University, Electronic Devices, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-59248.
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An analog-to-digital converter (ADC) is a link between the analog and digital domains and plays a vital role in modern mixed signal processing systems. There are several architectures, for example flash ADCs, pipeline ADCs, sigma delta ADCs,successive approximation (SAR) ADCs and time interleaved ADCs. Among the various architectures, the pipeline ADC offers a favorable trade-off between speed,power consumption, resolution, and design effort. The commonly used applications of pipeline ADCs include high quality video systems, radio base stations,Ethernet, cable modems and high performance digital communication systems.Unfortunately, static errors like comparators offset errors, capacitors mismatch errors and gain errors degrade the performance of the pipeline ADC. Hence, there is need for accuracy enhancement techniques. The conventional way to overcome these mentioned errors is to calibrate the pipeline ADC after fabrication, the so-called post fabrication calibration techniques. But environmental changes like temperature and device aging necessitates the recalibration after regular intervals of time, resulting in a loss of time and money. A lot of effort can be saved if the digital outputs of the pipeline ADC can be used for the estimation and correctionof these errors, further classified as foreground and background techniques. In this thesis work, an algorithm is proposed that can estimate 10% inter stage gain errors in pipeline ADC without any need for a special calibration signal. The efficiency of the proposed algorithm is investigated on an 8-bit pipeline ADC architecture.The first seven stages are implemented using the 1.5-bit/stage architecture whilethe last stage is a one-bit flash ADC. The ADC and error correction algorithms simulated in Matlab and the signal to noise and distortion ratio (SNDR) is calculated to evaluate its efficiency.
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Karlsson, Johanna, and Per Samuelsson. "Choosing a technique for digital signatures from the customers' perspective." Thesis, Blekinge Tekniska Högskola, Institutionen för programvaruteknik och datavetenskap, 2001. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-1392.
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One way to secure identity over the Internet and other channels is to use digital signatures. Since this area is often used in contact with banks, we have during our work co-operated with Nordea IT. In order for customers to use a digital signature whenever they wish to, a way of making them mobile is required. In our thesis we give an overall understanding of digital signatures and how they can be used. Our main goal is trying to find out what technique customers want to use for carrying their digital signature and if information positively affects customers? will to use the new service. We have found theories about the customers from literature, articles and Nordea IT. The most important theories state the importance of listening to customers and the importance of creating a trust between bank and customer. The main method used for the investigation is a questionnaire. This questionnaire is used to find out public opinions regarding the use of digital signatures. As seen from the result of our investigation most theories about the customers are confirmed. The answers from the questionnaire showed that it is important that the technique fulfils the customers? desire. Every other person could consider using digital signatures, if the number of uncertain can be convinced. From those who are negative or uncertain, one fifth are affected by information from the bank. The importance of information about security and bank policies is thus also confirmed. Both the choices of technique and the information positively affects customers? will to use digital signatures.
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Yuping, Lu. "Intelligent technique based digital differential protection for generator-transformer unit." Thesis, City University London, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.410150.
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Hu, Yiqun. "Digital Spatial Domain Multiplexing technique for optical fibre sensor arrays." Thesis, University of Southampton, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.245041.
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Murata, Hidekazu. "NONLINEAR CO-CHANNEL INTERFERENCE CANCELLATION TECHNIQUE FOR DIGITAL MOBILE COMMUNICATIONS." Kyoto University, 2000. http://hdl.handle.net/2433/181010.
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Radhakrishnan, Ram Harshvardhan. "Accelerated Successive Approximation Technique for Analog to Digital Converter Design." OpenSIUC, 2015. https://opensiuc.lib.siu.edu/theses/1630.
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This thesis work presents a novel technique to reduce the number of conversion cycles for Successive Approximation register (SAR) Analog to Digital Converters (ADC), thereby potentially improving the conversion speed as well as reducing its power consumption. Conventional SAR ADCs employ the binary search algorithm and they update only one bound, either the upper or lower bound, of the search space during one conversion cycle. The proposed method, referred to as the Accelerated-SAR or A-SAR, is capable of updating both the lower and upper bounds in a single conversion cycle. Even in cases that it can update only one bound, it does more aggressively. The proposed technique is implemented in a 10-bit SAR ADC circuit with 0.5V power supply and rail-to-rail input range. To cope with the ultra-low voltage design challenge, Time-to-Digital conversion techniques are used in the implementation. Important design issues are also discussed for the charge scaling array and Voltage Controlled Delay Lines (VCDL), which are important building blocks in the ADC implementation.
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Wolin, Martin Michael. "Digital high school photography curriculum." CSUSB ScholarWorks, 2003. https://scholarworks.lib.csusb.edu/etd-project/2414.
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The purpose of this thesis is to create a high school digital photography curriculum that is relevant to real world application and would enable high school students to enter the work force with marketable skills or go on to post secondary education with advanced knowledge in the field of digital imaging.
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Tourabaly, Jamil A. "A jittered-sampling correction technique for ADCs." Connect to thesis, 2008. http://portal.ecu.edu.au/adt-public/adt-ECU2008.0009.html.
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Hetzel, Simon Andrew. "Power efficient linear transmitters and the LINC technique." Thesis, University of Bristol, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.261286.
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Rodriguez, Gutierrez Sergio. "FPGA based digital electromagnetic sensing technique for detection of pit corrosion." Thesis, University of Manchester, 2017. https://www.research.manchester.ac.uk/portal/en/theses/fpga-based-digital-electromagnetic-sensingtechnique-for-detection-of-pit-corrosion(7e9abd26-7658-42da-b4a3-04a1a1f302a4).html.
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This thesis describes the development of an eddy current instrument and its application in detecting early-stage pitting corrosion. Eddy current testing has previously been used in Non-Destructive Testing (NDT) applications detecting large defects, like cracks. However, the challenge of detecting corrosion pits of less than 1mm³ remains unaddressed. This research involved the design of a Field Programmable Gate Array (FPGA)-based eddy current instrument, and the design and modelling of a novel differential electromagnetic sensor. The FPGA provided accurate synchronisation among the major electronic components. The firmware developed as part of this research allowed for exact interfacing to A/D and D/A converters, performed a real-time demodulation and signal generation, the instrument also supported a multi-frequency eddy current application. The firmware showed promising end-results in terms of sensitivity and stability in relation to pitting corrosion detection. In summary, this instrument offered significant improvement in sensitivity; the size of corrosion detected is improved more than 10 per cent compared to the previously reported, which enabled the detection of pits smaller than 1 mm³. For the sensor probe, a novel differential sensor was proposed to minimise the background signal for plate scanning and improve the sensitivity. The designed probe has an advantageous feature: the sensor response can be analysed using a closed form analytical solution.
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Kim, Ji Woo. "A GENERALIZED ARCHITECTURE FOR THE FREQUENCY-SELECTIVE DIGITAL PREDISTORTION LINEARIZATION TECHNIQUE." The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1339690468.
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Alani, Alaa Fadhil. "A steady-state response test generation technique for mixed-signal integrated circuits." Thesis, Brunel University, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.316941.
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Erdogdu, Gozde. "Linearization Of Rf Power Amplifiers By Using Memory Polynomial Digital Predistortion Technique." Master's thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12614420/index.pdf.
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In modern wireless communication systems, new modulation types are introduced in order to support more users by considering spectral efficiency. These new signals are ensitive to nonlinearity when they have high peak to average ratio. The main part in the system that causes nonlinearity is the power amplifier. For power amplifiers, between linearity and efficiency, there is a trade-off. However, by using predistortion techniques, both linearity and efficiency
can be obtained. In this thesis, various predistortion methods are explained and memory polynomial digital predistortion is studied because of its great advantages. The results are obtained by simulations through MATLAB and experiments. An open loop test bench is built up with real amplifier. During experimental procedure, as input two tone signal, 8psk modulated signal and pi/2 bpsk modulated signal are used. Predistortion with memory and memoryless predistortion performances are compared and superiority of the predistortion with memory is shown. Predistortion performance with respect to memory depth and polynomial order is also studied. Moreover, predistortion model range is investigated through evaluation of performance by applying predistorter function estimated at a specific bandwidth and power to
other signals having different bandwidth and power. Besides these works, the details of predistortion algorithm and the problems that can be countered in practice are explained.
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Cicalo, James. "An embedded calibration technique for high-resolution flash time-to-digital converters." Thesis, University of British Columbia, 2007. http://hdl.handle.net/2429/31637.
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As CMOS technology continues to advance, device dimensions will continue to decrease, thus enabling the creation of circuits which operate at increasingly greater frequencies. However, this Increase In operating frequency has resulted in a reduced tolerance for circuit timing uncertainties. Therefore, techniques capable of measuring the timing characteristics of multi-GHz signals are needed to help address the growing number of timing problems found in modem CMOS circuits. For cost and accuracy reasons, embedded time interval measurement techniques which offer picosecond measurement accuracies and millisecond test-times are required to overcome these challenges. The "sampling offset" based flash time-to-digital converter (SOTDC) is an embedded time interval measurement technique that has recently garnered much attention due to its attractive properties. These properties include sub-millisecond test times of multi-GHz signals, in addition to the potential for measurement accuracies in the order of picoseconds. However, the accuracy of an SOTDC is strongly dependent upon the capabilities of its calibration technique, and present SOTDC calibration techniques suffer from some very serious limitations. In fact, these limitations are so severe that present calibration techniques are impractical under realistic production test conditions. This thesis presents the design and analysis of a novel embedded SOTDC calibration technique. The proposed calibration technique offers the potential for both sub-picosecond calibration accuracies and sub-100 millisecond calibration times. However, the main contribution of this work concerns the suitability of the proposed technique with a realistic production test environment. The capabilities of the proposed calibration technique have been proven using both mathematical analysis and behavioural modelling simulations.Applied Science, Faculty of
Electrical and Computer Engineering, Department of
Graduate
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Mekky, Waleed Nicholson P. S. "Fracture toughness of the nickel-alumina laminates by digital image-correlation technique." *McMaster only, 2005.
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Wu, Chih-Ya, and 吳至雅. "Digital Multi-spectral Imaging Technique." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/98067392828286924143.
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碩士國立交通大學
光電工程研究所
104
In this study, we focus on improving the multi-spectral imaging system which has been successfully developed. Firstly, in order to improve the stability of the system, we apply a new technique called weighted principal component analysis (wPCA). Implementation of this method provides the ability in selection of extracted principal eigenvectors. The result shows the reconstructed spectra based on wPCA are significantly improved in comparison to those obtained from the standard PCA. Then, we propose a new experimental framework to simulate an open environment. We establish a mathematical model by giving a calibration target and controllable ambient light. The experimental result shows that the average colorimetric errors and the RMS errors are decreased by 66.54% and 47.45%. Lastly, we utilize the multi-spectral imaging technique to detect bruises on apples and also build a system that can differentiate between good apples and bad apples. The identification rate is up to 87%.
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Chen, Chih-Hsiang, and 陳智翔. "Innovative Digital Beam Scanning Technique." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/9jz646.
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Huang, Wei-Jen, and 黃威仁. "Digital Error-Averaging Technique for Pipelined Analog-to-Digital Converter." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/ym9x8n.
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碩士國立臺灣大學
電子工程學研究所
92
The pipeline architecture is more suitable for some applications with the requirement of high resolution than the flash analog-to-digital converter (ADC) architectures, due to its small size and low power consumption. However, the accuracy of a pipelined ADC architecture is susceptible to circuits imperfections, such as offset voltages, gain errors, non-linearity of operational trans-conductance amplifier (OTA) and capacitors mismatch and so on. The effect of circuit impairment is associated with each stage of a pipelined ADC architecture. The disadvantage of non-linearity still remains limited on component mismatch. To date, some techniques have been proposed for improving the INL. These techniques used some extra analog circuits or calibration circuits for the implementation of a pipelined ADC. In this thesis, we present a new digital error-averaging technique to reduce the mismatch effect due to the employed components. In this research, a 12-bit 50MS/s pipelined ADC with a digital error-averaging technique has been designed and implemented with standard 0.35-µm double-poly four-metal CMOS process. This technique used two pass commutating feedback-capacitors at one sample input signal, and used digital circuits to average the twice data for improving the integral non-linearity of pipelined ADC.
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Hsieh, Hsin-Hung, and 謝欣宏. "Study of Digital Copyright Protection based on Digital Watermarking Technique." Thesis, 1999. http://ndltd.ncl.edu.tw/handle/66710346968305194153.
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碩士中正理工學院
電機工程研究所
87
The main purpose of this thesis is to design a comprehensive applied system which includes processes of hiding, retrieving and recognizing watermarks in order to solve problems concerning the original copyright attribute and to protect authors’ legal right. The three most important issues of this research lie in considerations that the visual quality of the watermark-processed image should be consistent with the original one, the watermark should not be easy to find or to be removed by attackers, and the watermark should be strong enough to work against any kind of image-processing attacks. Moreover, the proposed algorithm should be working well when any arbitrary gray level and meaningful image segments (such as fingerprint, logo, image, etc.) are adopted as watermark. The technique developed here is distinctly different from the pseudo-random sequence technique, which is used by most of researchers in this filed and usually generates watermarks without visual meanings. The most significant feature of the proposed method is that it combines the concept of spread spectrum and Toral Automorphisms developed by Voyatzis. Moreover, Toral Automorphisms is improved in this study to reduce its execution time. And watermarks which apply this algorithm will not easy to be detected. Finally, this improved method also provides effective results for the recognition of watermarks.
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Lee, Hweiyu, and 黎慧玉. "Digital Error-Averaging Technique for Pipelined Analog to Digital Converter." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/63809762864166895224.
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碩士國立臺灣大學
電機工程學研究所
90
Digital Error-Averaging Technique for Pipelined Analog to Digital Converter by Hweiyu Lee, M.S. Advisor: Shen-Iuan Liu Electrical Engineering of National Taiwan University E-MAIL: hweiyu@jwit.edu.tw Abstract The pipeline architecture is more suitable for some applications with the requirement of high resolution than the flash ADC architectures, due to its small size and low power consumption. However, the accuracy of a pipeline ADC architecture is susceptible to circuits imperfections, such as offset voltages, gain errors, non-linearity of ot-amplifier (OTA) and capacitors mismatch and so on. The effect of circuit impairment is associated with each stage of a pipeline ADC architecture. The disadvantage of non-linearity still remains limited on component mismatch. To date, some techniques have been proposed for improving the INL. These techniques used some extra analog circuits or calibration circuits for the implementation of a pipeline ADC. In this thesis, we present a new digital error-averaging technique to reduce the mismatch effect due to the employed components. A set of digital error-averaging technique is applied to perform in pipelined analog to digital converter (ADC). This technique used two pass commutating feedback-capacitors at one sample input signal, and used digital circuits to average the twice data for improving the integral non-linearity of pipeline ADC. This design techniques is incorporated in an experimental chip fabricated in a 0.5μm, double-poly, two metal CMOS process. At 10 bits 5-M sample/s, while achieving a maximum differential non-linearity (DNL) of±0.35 least-significant bits(LSB), and integral non-linearity (INL) of±0.55 LSB.
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Chung, Kuo-Chen, and 鐘國禎. "Robust Digital Watermarking Technique of MP3." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/4v3t5b.
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碩士國立成功大學
電機工程學系
89
Nowadays the multimedia technology in distributed environments becomes realistic and the multimedia copyright protection issue becomes more and more important. Various digital watermarking techniques have been proposed in recent years to protect the copyright of multimedia data, and they also have been used on digital audio signals. But, the safety and robustness issues of watermarking techniques are challenged in applying these techniques to MPEG Audio bit streams, especially the MPEG-1 Audio Layer 3 (MP3) encoder. In this paper, we propose a watermark embedding method for MP3 files. The watermarking technique will embed the watermark of copyright information directly into the bit streams of MP3. In this way, we can avoid the distortion of copyright information in the decoding/encoding process. Our experimental results show that the robustness of our watermarking technique, that embeds the watermark into the compressed domain bitstream, is better than the other techniques, which embed the watermark into the uncompressed domain signal. We can not only keep the completeness of the embedded copyright information but also can provide the ownership authentication and secret information protection for different users’ requirements.
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Chen, Chun-Chi, and 陳俊齊. "Digital Watermarks Using Fractal Coding Technique." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/80748589955986435563.
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碩士國立高雄應用科技大學
電子與資訊工程研究所碩士班
95
In 21st century, personal computer and high rapid broadband network have become the necessaries in office and house where documents, business transaction, multimedia animation, photos and artwork are processed by computer. Besides that, it is possible to send those digital copies around the world by broadband network. On the other hand, this oncoming technique brings information community some disadvantage, too. As long as the digital copies were not protected by some ways, people can easily duplicate and spread them around the world which causes the problem of rampant illegal copies. Consequently, watermarking is recommended to protect digital copies and make sure the digital copies holders legal. In this thesis, odd/even region algorithm first comes forward, and then integrating it with LSR algorithm made by J. Puate and F. Jordan, and Isometric algorithm made by C. H. Li and S. S. Wang, is proposed. After that, this thesis brings up a new fractal compression method which can embed watermark with satisfactory image quality and be tolerant with JPEG compression.
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Chen, Bo-Kai, and 陳博凱. "Digital Image Hiding Using Halftone Image Technique." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/16960347846270720892.
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碩士淡江大學
電機工程學系碩士在職專班
99
Data hiding technique is an important vector of network information communication and plays a role in security. This technique embeds secret information called a mark into host image to provide different purposes such as copyright protection, proof, and so on. Reversible data hiding technique provides not only secret data but also images being definitely in the decoding stage. This is highly desired in quality-sensitive imagery where even the minimal distortion introduced by embedding data is unacceptable since the reversibility helps to mark right decision during image analysis. In recent years, researchers have developed some different reversible image hiding theories and methods based on image histogram modification and pixels difference. But high capacity of digital images is low and the loss of host information happens in traditional reversible image hiding method. This study proposes a novel image hiding method based on histogram hiding and halftoning technique. This method uses reversible data hiding to embed error diffusion halftone image into original image for image secrecy. In image extract process, we use reversible data hiding to extract the halftone information, and hidden image is achieved from LUT inverse halftone. Experimental result shows that the performance of our method can hide high capacity of digital images, the stego-image is almost the same as the cover-image, and it can be reversible.
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Cheng, Ming-Chu, and 鄭明竹. "Digital Watermarking Technique Using Error Correcting Codes." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/55142185393235419884.
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碩士長榮大學
經營管理研究所
94
The development of computer techniques and communication networks make electronic document exchange, digital document exchange, E-commerce, video on demand, and digital library service popular. The digital data can be easily reproduced without any loss, Such that copyright protection becomes an imperative requirement to prevent piracy. To prevent data piracy and plagiarism, digital watermarking has been proposed. It has developed very quickly for the past few years. A digital watermarking is a set of information which is embedded in the data robustly and imperceptibly, and it could be applied on copyright protection and authentication. In this thesis, two integrated watermarking techniques were proposed. In order to increase the robustness of the watermark. The original image's coefficients of middle frequency will be obtained through the DCT process that will be used to the information hiding. At the same time, the ECC would be embedded in. This paper used Hamming Code. The Reed-Solomon Code is usually used for protecting the transmition information. When images to incur the different attacks, the system still can extract the waterwork with the best discernment by combining two technologies.
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Hsu, Sheng-Che, and 徐聖哲. "Digital Image Stabilization Technique and its Applications." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/44411849323717927167.
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博士國立交通大學
電控工程研究所
98
In this dissertation, a digital image stabilization (DIS) technique and its applications are proposed as a way to remove the unwanted shaking phenomena in the image sequences captured by hand-held, in-car or fixed-type surveillance camcorders, without being affected by moving objects in the image sequence or by the intentional panning motion of the camera. DIS contains two major parts: (1) How to estimate an efficient, precise, and reliable global motion vector. (2) How to use the existing GMV to compensate for a smooth motion trajectory within the window shifting allowance boundary. For motion estimation (ME), an inverse triangular method is proposed to look for the local motion vector (LMV). An optimization of the representative points is proposed to reduce computation complexity, and a refined motion vector is proposed to apply to any ill-conditions of the GMV estimation. Skyline detection for in-car applications and background based peer to peer evaluation are proposed to enforce the reliability of the GMV estimation as well. For motion compensation (MC), a plot of the motion trajectory and a smoothness index evaluation are proposed to quantitatively verify the analysis that shows the improvement of the MC. An inner feedback-loop integrator has been applied to the MC to improve image stabilization during the camera’s panning motion. Finally, Fuzzy inference digital image stabilization (FIDIS) is proposed to adaptively determine better motion compensation methods through the use of two different MCs. Experimental results show that the proposed methods of this dissertation adapt to different conditions of image sequencing, such as a lack of features, repeated patterns, large moving objects and large low-contrast areas in the image and that they can also estimate the GMV precisely as well. The degradation of image stabilization during the panning motion is solved by adding an inner feedback-loop integrator. The proposed FIDIS also shows effective improvements in different conditions of image sequence through the evaluations of the smoothness index and the motion trajectory.
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Chen, Bang-Zhao, and 陳邦釗. "A Digital Diagnosis Technique for Pipelined ADC." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/97865180758398450856.
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碩士國立臺灣大學
電子工程學研究所
91
In this thesis, we will discuss how to use the digital output codes of pipelined analog-to-digital converter (ADC) to find out the non-ideal properties of each analog building-block. A ramp signal is used as input test stimulus in this method. First, our discussion will start with the introduction of architecture and function of a general pipelined ADC. And then, we will discuss the non-ideal effects of the analog building blocks in each stage on the digital outputs. Base on these fault effects, the diagnosis methodology can be derived. What we have to emphasize here is that we only observe the digital output instead of measuring the analog signal in the core of converter to avoid modifying of the design. In other words, we only observe the digital output of each stage. Some simulation results and test procedure will also be presented.
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黃恆傑. "Digital Watermarking Based on Spread Spectrum Technique." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/56744541101570382497.
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碩士國立中興大學
電機工程學系
90
The advances of computers and communication networks make digital content service such as digital document exchange, E-commerce, video on demand, and digital library very popular. Since digital data can be easily reproduced without any loss, copyright protection becomes an imperative requirement to prevent piracy. Digital watermarking has been proposed as one of the techniques to prevent data piracy and plagiarism. Digital watermarking is a novel and emerging technology. It has developed very quickly for the past few years. A digital watermark is a set of information that is robustly and imperceptibly embedded in the data to be protected. Applications include copyright protection, and authentication. In the thesis, we developed two watermarking techniques using spread-spectrum technique. We interpreted the watermarking technology based on communication theory. The watermark was the signal to be transmitted. The frequency domain of the original image was the transmission channel. The attacks were regarded as channel noise. There were two methods to implement the spread-spectrum system: direct- sequence spread- spectrum (DSSS) and frequency-hopping spread-spectrum (FHSS). Based on these tow methods, we develop FHSS Watermarking and DSSS Watermarking. JPEG compression is the most widely used image because compression technique of its high compression ratio and reasonable image quality. Here, we develop the watermark embedding method especially for JPEG encoding process since block Discrete Cosine Transform (DCT) was used for JPEG. In our approach, a block DCT-based algorithm was used to embed the image watermarking. In order to survive the JPEG compression, the watermark must be embedded in the bands that can with stand the JPEG quantization. Experiments showed that FHSS Watermarking is more resistant to the attack of JPEG compression. The PhotoImpact 5 digital image processing software was used for other attacks. We found that FHSS Watermarking is more robust than DSSS Watermarking in geometric distortions. But in other signal processing modifications, DSSS Watermarking is more robust than FHSS Watermarking. Therefore, we developed a new method that combined with FHSS Watermarking and DSSS Watermarking, we call the new method “combined SS Watermarking”. The experimental results prove that combined SS Watermarking has both the advantages of FHSS Watermarking and DSSS Watermarking. Therefore, combined SS Watermarking is more robust and can with stand many different attacks.
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Huang, Chia-Ching, and 黃嘉慶. "New Technique for Digital Backlight Image Compensation." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/70317825474830727431.
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碩士中華大學
資訊工程學系碩士班
89
Image compensation and segmentation techniques plays an mportant role in the field of image processing and computer vision. There have been many literatures reported good gray image segmentation technique. However, color image segmentation still not achieves satisfactory performance. We proposed two-stage processing technique to compensate the backlight images. The first stage is image segmentation. We transferred the color space to gray space by feature weighting [7], then used fuzzy c-means algorithm to segment the image into subject image and background image. The second stage is image backlight compensation. In this step, we adopted fuzzy logic technique [14] to decide the brightness compensation value, then used local histogram equalization to enhance the contrast of image. Finally, we combine the subject image which have been compensated with the original background image, and obtained the resulting image with better contrast.
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Chen, Ming-Jr, and 陳明志. "Cyclic ADC using Digital Error Correction technique." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/63067949959155050512.
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碩士國立清華大學
產業研發碩士積體電路設計專班
95
Recently, the display panel of portable devices is normally equipped with resistor array for hand writing signal input. In newly development, photo sensitive array has been successfully embedded in the panel and the image capture by through panel has been viable. In this research, we investigate an ADC that has simple structure and could be easily implemented with multiple input array signals in different light intensity environment. With the explosive growth of wireless communication systems and portable consumer electronics, the demand for low-power low-voltage integrated circuits (ICs) is indispensable. Many of the applications nowadays utilize the digital signal processing to resolve the transmitted information. Therefore, between the received analog signal and the DSP system, an analog-to-digital interface is required. Being apart of the system, the A/D interface also needs to adhere to the low-power low-voltage constraint. In this paper, we use cyclic type ADC for subject frame which consists of sample-and-hold, 1.5bit/stage sub-ADC, 2bit Flash ADC, and Multiplying Digital-to-Analog Converter. It used Digital Error Correction Technique to avoid non-ideal circuit defects. For example: opamp gain error and comparator offset etc. This structure besides reduces non-ideal circuit defects, but also control the times of circle number to achieve the purpose of the different resolution. Although the conversion rate was slower, it could achieve low power, the small area and low cost demand. The circuit proposed above is design in a TSMC 0.35um process and verified by HSPICE program.
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Lin, Yi-tai, and 林義泰. "The Parameters of Digital Sphygmomanometer Processing Technique." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/51790906785235947178.
Full textAbstract:
碩士朝陽科技大學
資訊工程系碩士班
100
In Taiwan, people die in Blood vessel disease have higher ratio, the age distribution of death occurs mainly between 65-84 years, but, due to the living environment factors and abnormal rhythms of life, leading to death Age of hypertensive disease have downward trend. In this study , we made a device of measurement of blood pressure, differences with the traditional sphygmomanometer is the pressure sensor and flow meter sensor are all digital sensors, and use the digital filter to replace the traditional analog filter, , then the dynamic ratio of systolic and diastolic to replace the traditional theory of systolic and diastolic ratio, finally, we use estimate the systolic, diastolic and mean blood pressure to comparison with the stethoscope actual systolic, diastolic and mean blood pressure, relevance were 0.84,0.90,0.88.
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Hu, Dong-Ting, and 胡東廷. "180mV Digital Designs Using Subthreshold Circuit Technique." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/34983199581176845430.
Full textAbstract:
碩士朝陽科技大學
資訊與通訊系碩士班
101
Recently, ultra low voltage and low power designs such as mobile systems, sensor networks and biomedical systems has increased the importance of designing digital logic circuits. In this work, novel low power XNOR and full adder designs for ultra low voltage applications are presented. By using subthreshold circuit techniques, the proposed designs not only eliminate voltage drop and cascaded problems but also provides better various performances. Simulation and measurement results show that, when compared with conventional TGA design, as much as saving 24% energy can be achieved by the proposed designs based on TSMC 1P6M 0.18μm CMOS technology.
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Thondapu, Vignu Charan Kumar Babu. "Digital control of alternator using Delta Sigma technique." 2005. http://proquest.umi.com/pqdweb?did=994238941&sid=7&Fmt=2&clientId=39334&RQT=309&VName=PQD.
Full textAbstract:
Thesis (M.S.)--State University of New York at Buffalo, 2005.Title from PDF title page (viewed on May 11, 2006) Available through UMI ProQuest Digital Dissertations. Thesis adviser: Hopkins, Douglas C. Includes bibliographical references.
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Tsao, Chih-Hung, and 曹志鴻. "Application of secret sharing technique on digital signature." Thesis, 1997. http://ndltd.ncl.edu.tw/handle/80425143331189607650.
Full textAbstract:
碩士國立臺灣大學
電機工程學系
85
Owing to the rapid progress of electronic data processing, handwritten signatures will soon be replaced with digital signatures. A digital signature,like a handwritten signature, is used to verify the sender of a particularmessage. However, when the message is on behalf of an organization, a valid message may require the approval of several people. A common example of thispolicy is a large bank transaction, which requires signatures from two people.Such a policy could be implemented by having a separate digital signatures forevery required signer, but this solution increases the efforts to verify themessage linearly with the number of signers. An alternative method is a threshold signature scheme. In a t-out-of-nthreshold signature scheme there is one public key for the group while the private key is shared among the n members of the group. Any t members can cooperate to create a digital signature without revealing their shares of theprivate key. Fewer than t members cannot create a valid signature. In this thesis, we propose a method to share a product among all groupmembers. And we embedded our sharing product method, named send-receive protocol,into a signature scheme based on both factoring and discrete logarithmsproblems to establish a threshold signature scheme. Finally, we discuss thesecurity and efficiency of our proposed scheme.
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Hsieh, Chih-Ping, and 謝志彬. "The Study of Denoising Technique for Digital Images." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/99364049216120536850.
Full textAbstract:
碩士國立中正大學
資訊工程研究所
89
In this thesis, we propose three digital image noise reduction methods. The first method is an adaptive median filter, which is based on the standard median filter. In this method, a threshold and the standard median is used to detect noise and change the original pixel value to a newer that is closer to or the same as the standard median. We also incorporate the center weighted median filter in this method. In the second method, we shall propose a new noise detection method that is based on the human visual effect and is used to reduce the impulse noise of images. The detection function is used to classify each pixel into the group of either corrupted pixels or uncorrupted pixels. After this classification, we shall also propose a filter scheme based on the standard median filter to process the corrupted pixels. And the last method that we proposed in this thesis is a fast and efficient noise reduction method. The main idea of this method is to reduce the running time of the standard median filter. The major difference between this method and the standard median filter is the preprocessing work before filtering. We use a simple noise detection scheme to decide which pixel should be processed with the standard median filter and our noise detection scheme is based on image hiding technology.
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amdy and 蘇勝中. "Complementary Digital Watermarking Technique Based on Wavelet Transformation." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/03543501649717108783.
Full textAbstract:
碩士國立中興大學
電機工程學系
91
Abstract Digital image watermark is a technique which takes advantage of the inability of human’s eyes to differentiate the subtle change of images. It is a special information embedded and hidden in the original image. Even if the image data is encrypted and decrypted, compressed, unintentional or any other kind of attack, the embedded digital image watermark can still be detected. In this thesis,we propose a complementary watermark technique which uses the skill of wavelet transformation to protect image data. Two complementary watermarks are hidden in the high and low frequencies respectively in the transformed frequency domain. Using this technique , there will be at least one watermark can survive under attack .Besides, in the process of retriever the watermark, the original image isn’t needed. Thus,save a lot of memory. The simulation results show that distortion of the original image caused by the insertion of watermark can be minimized. we also examine the outcome of watermark detection under JPEG compression, blurring, sharpening, noise and cutting based on the average image processing skills of Photoshop. The results show that our method can survive from most of the attack.
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KUONG, TAM IO, and 譚耀光. "Color Filter Array Interpolation Method and Digital Image Watermark Technique for Digital Still Cameras." Thesis, 2000. http://ndltd.ncl.edu.tw/handle/18904262571141547270.
Full textAbstract:
碩士國立臺灣大學
電信工程學研究所
88
Digital still cameras have been widely used as image input device nowadays. Before a color image is generated, a lot of color image processes must be performed. Among these color image processes, the Color Filter Array (CFA) interpolation maybe the most important image process in digital still cameras. In this dissertation, we study the CFA interpolation problem, and we also develop an effective CFA interpolation algorithm. Recently, the idea of trustworthy digital camera is proposed. Digital cameras with automatic watermark function will be a new trend in the near future. We investigate the digital watermarking problem, and we also propose a robust image watermark method in this dissertation. This dissertation includes six chapters. In chapter 1, we give a brief introduction of the CFA interpolation problem and the importance of digital watermarking. A detailed study of the conventional CFA interpolation algorithms is presented in chapter 2. The proposed CFA interpolation method is introduced in chapter 3. Experiment results and detailed discussion will also provided. In chapter 4, the problem of digital watermarking will be studied. Watermark techniques are classified into three main categories based on different applications. These three categories are: visible watermark, invisible robust watermark, and invisible fragile watermark. In chapter 5, an invisible robust watermark technique is developed based on the idea of quantization. We proved that the proposed watermark method is extremely robust to common image processing. Our method is shown to provide very good results both in terms of invisibility and robustness. In chapter 6, we will conclude our researches and the future works will also be discussed.
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Huang, Wei-Rong, and 黃偉榮. "Design of Digital Predistortion Technique for Nonlinear Power Amplifier." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/suey4s.
Full textAbstract:
碩士國立雲林科技大學
電機工程系
105
The power amplifier is a main nonlinear component in the wireless communication, so it is necessary to develop the linearization technology of power amplifier (PA).The nonlinear element introduce the problems such as spectral regrowth, signal distortion, and constellation offset. There are several predistortion technologies, i.e., look-up table method, polynomial method, and so on.This research investigates the applicability of adaptive filtering architectures for digital predistortion techniques in nonlinear amplifiers. The adaptive method is required for a power amplifier because of variations in the power amplifier due to changes over time and temperature, or when the input signal power changes. In this thesis, the predistortion compensator is constructed using memory polynomial structure with indirect learning algorithms. The Saleh’s PA model is considered to describe the AM/AM and AM/PM conversion. By using the power amplifier input and output signals, the adaptive post-inverse filter is learning to train the filter weights. Several adaptive learning methods are investigated, i.e., (1) complex least means squares algorithm (CLMS), (2) complex normalized least means squares algorithm (CNLMS), (3) complex recursive least squares algorithm (CRLS), and (4) complex kernel least means squares (CKLMS) algorithm, are adopted to achieve better performance in terms of convergence rate and quality of solution. The proposed techniques are verified using the QPSK, 16-QAM, 64-QAM, and DSSS modulation signal generation, respectively. The power spectral density plot, mean square error (MSE) and constellation plot are simulated by using Matlab/Simulink tool to verify the compensation performances.
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Fang, Bing-Nan, and 方炳楠. "Low Power Pipelined ADCs Design Using Digital Calibration Technique." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/abzury.
Full textAbstract:
博士國立交通大學
電子工程學系 電子研究所
101
CMOS process scaling leads to lower supply voltages and small-size devices. With transistors becoming smaller and smaller, chips really become a system with both analog and digital portions inside. Analog-to-digital converters (ADCs) are used to convert real world analog signals into digital representations. The pipelined ADCs are widely used in high speed and medium-to-high resolution applications, due to their optimal tradeoff between conversion speed and resolution. Most of the pipelined ADCs are implemented by switched-capacitor (SC) circuits, comprise opamps, analog switches, and capacitors. The linearity of A/D conversion is mainly determined by high dc gain of opamp and matching of capacitors. Any errors caused by the finite dc gain of opamp or capacitors mismatch, will degrade the output performance of the ADCs. In nanoscale CMOS technologies, the short-channel devices with the lower intrinsic gain and lower supply voltage make the design a high-speed and high-gain opamp becomes quite stringent, and produce a lot of power consumption. In addition to variances of the parameters, these parameters of nanoscale devices will be varied with device placement and the surrounding circuits. This makes some circuits that require a good match to work properly, such as the current mirror design becomes more stringent. As result of device parameters variations and process, supply voltage and temperature (PVT) variations, the circuit must be designed to cover the range of variations, resulting in additional power consumption. In nanoscale CMOS technologies, the performance of analog circuits can be improved by digitally assisted techniques, and will be verified as a very efficient way. So, it can greatly reduce the accuracy requirements of analog circuits. The research objects of this thesis is mainly to develop a robust, high-speed, high performance and low power consumption of ADC. It can overcome the influence of the process, voltage and temperature variations, and can scale down with the evolution of nanoscale technologies. A high speed switching opamp is with very short turn-on time, is developed to reduce power consumption. The digital background calibration is developed to correct the A/D conversion errors caused by the low dc gain of opamps and capacitors mismatches. The digital bias technique monitors the settling behavior of opamp by the acquired calibration data and automatically adjusts bias currents in opamps, such that the settling behavior of opamps can be maintained without excessive current consumption. The digital bias circuits are used to replace the conventional bias circuits, produces the required bias voltages in analog circuits. Both external bias sources and current mirrors are not required, hence the matching requirements can be reduced significantly. The digital bias techniques are insensitive to fluctuations of PVT variations. Therefore, the design margins for each bias current of opamps can be further reduced on a chip by chip, reduction of power dissipation, chip area and a higher yield in mass production can be achieved. However, the digital bias techniques can track the operating frequency to produce appropriately bias voltage, thus the power consumption is proportional to operating frequency. As a result, the ADC which operates in different frequency applications as reconfigurable, is with minimal power consumption. To demonstrate the above techniques, a 10-bit pipelined ADC was designed and fabricated using a 65 nm CMOS technology. Operating at 300~MS/s sampling rate, the ADC consumes 26.6~mW from a 1~V supply and occupies die area of 0.36~${\text{mm}}^2$. It achieves a signal-to-noise-plus-distortion ratio (SNDR) of 55.4 dB and a spurious-free dynamic range (SFDR) of 67.2 dB. According to the proposed techniques, the performance of the ADC could be maintained under various environmental changes.
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Chen, Yu-Wei, and 陳昱維. "Mesh-Based Robust Digital Watermarking Technique Against Geometric Attacks." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/75261036738464883554.
Full textAbstract:
碩士大同大學
資訊工程學系(所)
94
The great challenge of existing watermarking methods is their limited resistance to the extensive geometric attacks. Geometric attacks can be decomposed into two classes: global distortion such as rotations and translations and local distortion such as the StirMark attack. We have found that the weakness of multiple watermark embedding methods that were initially designed to resist geometric attacks is their inability to withstand the combination of geometric attacks. In this thesis, the watermark is used in the gray-scale authentication image, and a robust image watermarking scheme is proposed that can withstand the geometric attacks through using local tri-mesh feature points. Our proposed method can re-synchronize the attacked images and is independent of the embedding and authentication process. The geometric invariant scheme is combined with the complementary modulation embedding strategy to enhance the resistance of geometric attacks. The experimental results verify that the proposed scheme is excellent for geometric attacks.
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Hu, Wehn-Feng, and 胡文峰. "Digital image stabilizer system based on optical flow technique." Thesis, 1999. http://ndltd.ncl.edu.tw/handle/06464515489142095748.
Full textAbstract:
碩士國立交通大學
電機與控制工程系
87
This thesis proposes a digital image sequence stabilization system based on optical flow techniques. The system includes three major modules 1) motion estimation, 2) motion extraction, and 3) motion correction. First, in motion estimation module, we employ the optical flow technique to obtain the local motion vector field. The outputs of optical flow estimation are the velocity vectors corresponding to every pixel in the current image frame. There could be many inaccurate motion estimations in the motion estimation procedure because optical flow techniques are rather noise sensitive. The motion extraction module makes use of a new version of Hough transform, which acquires field motion vector in terms of parameter space of the image field. The motion parameters to be estimated for the current image frame are angular velocity, and horizontal and vertical translational motion relative to the previous frame. Then the motion extraction module plays the role of extracting the most possible motion parameters. The motion estimation module can produce very precise field motion vectors. Finally, the correction module integrates the field motion vectors and performs the de-motion of correcting the residue shake motion, including translation and rotation as well.
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Chang, Chia-Chin, and 張嘉欽. "Self-Correction of Digital Images Using Self-Embedding Technique." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/32154163751287343330.
Full textAbstract:
碩士大葉大學
資訊工程學系碩士班
91
Digital images transferred in the internet maybe be modified by hackers. In this paper, we propose a new self-embedding image watermark to do the error detection and self-recovery of the modified images to improve the image qualities. In the embedding procedure, we use a key-dependent basis transform to transfer an image from the spatial domain into the frequency domain. The basis has arranged so that the number of zero crossing increases with the row number. The similar neighboring-block-direction-codes and the approximation of an original image are extracted and embedded them into the image in the frequency domain. After all, we get an image which is embedded with the recovering data. The embedded image maybe tampered by the attackers. After attack, we need to improve the quality of modified image. In the recovery procedure, we use the secret key to generate the basis which is the same as embedding procedure. Use the key-dependent basis, the approximation and the block-direction-codes can be extracted from the modified image. We can use them to detect error regions of the modified image and use the similar neighboring-block-direction-codes to help us recover the error regions. The experimental results have shown that the proposed self-healing method can detect and recover the error regions and improve the qualities of modified images.
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Lee, Cheng-Hao, and 李正豪. "Apply augmented reality technique to creating digital learning environments." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/73716987896820622117.
Full textAbstract:
碩士國防大學理工學院
資訊科學碩士班
99
As the techniques of creating augmented reality become more advanced, there is an increase in its use to create engaging digital teaching materials or a more efficient e-Learning environment. Recently, most relevant applications are limited to marker-based augmented reality techniques. However, markerless augmented reality techniques are more flexible and not limited by the use of markers, providing a broader range of applications. Visual tracking techniques is a critical core technique of augmented reality, and its use is often affected by the four factors of environmental lighting, image angle recognition, image resolution and image texture recognition. On the other hand, in a “markerless augmented reality e-Learning system”, the complexity and moving speed of the tracked object will also strongly affect tracking recognition. Only with high quality object identification and tracking abilities will the learners recognize objects and move them as they wish when operating the system, making it more applicable for its purpose. The purpose of this thesis is to provide recommendations on the use of augmented reality techniques to create digital learning material and e-Learning environments, and to analyze limiting factors in tracking techniques currently employed in “markerless augmented reality e-Learning systems”. We also recommend to apply object tracking techniques for real-time tracking in which object speed has reduced effects on tracking ability. The methods that this study suggests will be able to raise the practicality and popularization of markerless augmented reality systems on a technical basis. On the basis of application, the methods will also allow people to understand the relevant issues in the creation of augmented reality digital learning materials and e-Learning environments. For example, when applied to the military equipment maintenance in the army of Taiwan, such digital learning schemes can effectively reduce personnel training time and costs, helping to improve maintenance quality and hence the performance of military equipments. When applied to training schemes of military tactics, the contents can be made dynamic to increase learners’ motivation and interest.
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GUO, YUAN-JIE, and 郭元傑. "A Wavelet-Based Digital Watermarking Technique for ECG Signals." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/09223596464019777413.
Full textAbstract:
碩士東海大學
應用數學系
101
In nowadays society, we pay much attention to a variety of copyright protection issues and the emphasis on personal information. Digital watermarking technology is the most widely used encryption technology in the field of multi-media and medical information. In this thesis, we redesign a wavelet-based digital watermark to Electrocardiogram (ECG) signals to achieve the purpose of protection of patient rights. Certain hidden data for personnel identification are embedded into specified low-frequency coefficients of its wavelet transform according to different quantization sizes using the quantization approach. In addition, since the proposed watermark scheme is not reversible, we evaluate the impact of watermarking to the PQRST complexes of the ECG signal in which we conclude that the impact is small and the watermarked data can meet the requirement of physiological diagnostics. In order to measure the robustness of our scheme, three attacks including noise, resampling, and low-pass filter are adopted to test the watermarked ECG data. The experimental result verifies that the proposed scheme is slightly robust than DCT- and FFT-implemented quantization watermarking techniques after testing with ECG signals from the MIT-BIH arrhythmia database.
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Wu, Yuan Lun, and 吳沅倫. "Common-path interferometric ellipsometer integrating with digital sampling technique." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/89685145959053537539.
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CHEN, WEI-ZHOU, and 陳偉洲. "Design of Adaptive Digital Predistortion Technique on Kernel Method." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/h556f2.
Full textAbstract:
碩士國立雲林科技大學
電機工程系
107
Nonlinear power amplifiers play an important role in wireless communication systems. The general signal will be distorted after passing through the amplifier, such as spectrum spread, amplitude distortion and constellation offset. The signal is not accurately received, so pre-distortion of the nonlinear power amplifier is a necessary technique. The predistortion compensator is constructed by using the memory polynomial, and the predistortion compensator is trained by the adaptive learning algorithm. In the thesis, a positive definite function called regenerative kernel is used to derive the theory of Reproduction Kernel Hilbert Spaces (RKHS). This theory can nonlinearly map input data to high-dimensional feature spaces. If the adaptive operation is to be performed in the RKHS space, it can be directly expressed as the inner product of the projection vector. Based on this method, various adaptive learning methods are analyzed in the paper. (1) complex kernel least mean squares algorithm (CKLMS), (2) complex kernel normalized least means squares algorithm (CKNLMS), amd (3) complex kernel recursive least squares algorithm (CKRLS). Use Quadrature Amplitude Modulation (QAM) as the input signal. The kernel function uses a Gaussian kernel and a polynomial kernel. The linearization effect is presented in the form of a constellation diagram and a spectrogram, respectively. According to these adaptive learning training algorithms, the difference between good and bad is analyzed, and the best linearization algorithm in the proposed method is compared.
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Hsu, Pai-Hsiang, and 許百享. "Design of High-Performance ADCs with Digital Calibration Technique." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/3m8pm6.
Full textAbstract:
碩士國立交通大學
電機工程學系
107
The analog-to-digital converter(ADC) has already become an essential component in a variety of electronic devices since it is a link between the analog world and the digital interface. In this thesis, two different ADC designs are discussed. Both ICs were fabricated by using 0.18-μm 1P6M TSMC CMOS process. The first one is a linearity-improved 10-bit SAR ADC which adopts the pseudo-random switching scheme. The supply voltage is 1.8V and the input full swing voltage is 1.8Vpp. With a sampling rate of 1MS/s, the measured SNDR, SFDR, and ENOB achieves 58.71dB, 77.89dB, and 9.45 bits,respectively,while consuming a power of 102uW. The circuit occupies an area of 1258.615um×867.745um and the FOM is 145 fJ/conv. step. The second IC is a 14.5-bit SAR-SS ADC with background digital calibration. The calibration circuit is off-chip. The design combines the advantages of SAR and SS ADCs. The first 7.5 and the last 8 bits are implemented by SAR an SS ADCs ,respectively, and there is a one-bit-overlap between the two. The supply voltage is 1.8V. With a sampling rate of 100KS/s and a 1.6Vpp input signal, the measured SNDR, SFDR, and ENOB achieves 69.01dB, 78.50dB, and 11.17 bits ,respectively, while consuming a power of 40uW. The circuit occupies an area of 200um×400um and the FOM is 24.4 fJ/conv. step.
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CHEN, CHIH FENG, and 陳志鋒. "Digital Dynamic Impact Measurement System:Manufacturing Technique and Application Evaluations." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/b4w7m7.
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Malviya, Pankaj. "Digital Forensic Technique for Multiple Compression based JPEG Forgery." Thesis, 2015. http://ethesis.nitrkl.ac.in/6778/1/Digital__Malvia_2015.pdf.
Full textAbstract:
In today's digital world digital multimedia like, images, voice-notes and videos etc., are the major source of information/data exchange. The authenticity of these multimedia is greatly vital in the legitimate business, media world and broadcast industry. However, with enormous multiplication of ease, simple-to-utilize data manipulation tools and softwares lead to the faithfulness of digital images is in question. In our work, we propose a technique to identify digital forgery or tampering in JPEG (Joint Photographic Experts Group) images which are based on multiple compression factor. We are dealing with the JPEG images on the grounds because JPEG is the standard storage format used in almost all present day digital devices like digital camera, camcorder, mobile devices and other image acquisition devices. JPEG compresses a image to the best compression in-order to manage the storage requirement. JPEG is a lossy compression standard. At the point when an assailant or criminal modifies some region/part of a JPEG image by any image processing tools and save it, the modified region of the image is doubly-compressed. In our work, we exploit this multiple compression in JPEG images to distinguish digital forgery or falsification.