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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

Mismatch Calibration of Time-Interleaved Digital-to-Analog Converters

D'souza, Rowena Joan 27 July 2010 (has links)
This thesis presents a stable technique for distribution of data in Time Interleaved Digital-to-Analog Converters (TIDAC) that allows usage of the entire Nyquist bandwidth. The data distribution uses a Thiran all-pass filter to ensure stability and preserve the phase in the bandwidth of interest. Also, an online technique to compensate for the gain error mismatch in different channels and a skew error calibration technique for open loop configuration is proposed. For the over-all sampling rate of FS, i.e. bandwidth of FS/2 (according to Nyquist), this proposed technique allows calibration of skew error for input signal for most of the Nyquist bandwidth where frequency translation is applied to the input signal to provide calibration in the lower half of the Nyquist band. The simulation results for a 2-channel 14-bit current steering binary weighted TIDAC shows a substantial improvement in SNDR after calibration for input signals up to Nyquist frequency.
2

Intrusions and mixing in the Western Equatorial Pacific Ocean

Banks, Helene Theresa January 1996 (has links)
No description available.
3

A modulation/demodulation chip design with error correctable and high error detected ability for Power Line Communication

Guo, Jia-Wei 15 February 2011 (has links)
In the 2010, targets of National Science and Technology Program - Energy¡¥s project plan had mentioned about the development of power line communication (PLC). This shows the importance of PLC. The data transmission occur burst errors easily by the noise interference from the environment. In order to reduce the error rate, we design a modulation/demodulation chip with error correctable and high error detected ability for power line communication in this thesis. The proposed design consists of Cyclic Redundancy Check (CRC), Pulse Width Modulation (PWM), Frequency Shift Keying (FSK), Forward Error Correction (i.e. binary BCH code), and interleaving techniques. The CRC can detect the errors occurred in the digital communication. The probability of finding error is 99.997%. The BCH code is capable of correcting any combination of 3 or fewer errors in block. The function of PWM is to generate the digital pulses that exhibit the changeable pulse width according to the swing of the input voltage. In the telecommunication, FSK is a frequency modulation scheme such that the digital information can be transmitted through the discrete frequency changes of the carrier. Interleaving can make burst errors look like random errors. The design is implemented TSMC 0.18£gm process. The fabricated chip area is 1.16 millimeter square with 3.3V/1.8V supply voltages. The measured data shows that the proposed design is fully functional and consumes 55.5 £gW.
4

INVESTIGATING THE ROLE OF EXAMPLE TYPE IN INTERLEAVED PRACTICE

Todaro, Rachael Danielle 09 May 2019 (has links)
No description available.
5

Coded modulation techniques with bit interleaving and iterative processing for impulsive noise channels

Bui, Trung Quang 22 August 2006
Power line communications (PLC) surfers performance degradation due mainly to impulsive noise interference generated by electrical appliances. This thesis studies coded modulation techniques to improve the spectral efficiency and error performance of PLC. Considered in the first part is the application of bit-interleaved coded modulation with iterative decoding (BICM-ID) in class-A impulsive noise environment. In particular, the optimal soft-output demodulator and its suboptimal version are presented for an additive class-A noise (AWAN) channel so that iterative demodulation and decoding can be performed at the receiver. The effect of signal mapping on the error performance of BICM-ID systems in impulsive noise is then investigated, with both computer simulations and a tight error bound on the asymptotic performance. Extrinsic information transfer (EXIT) chart analysis is performed to illustrate the convergence properties of different mappings. The superior performance of BICMID compared to orthogonal frequency-division multiplexing (OFDM) is also clearly demonstrated.<p>Motivated by the successes of both BICM-ID and OFDM in improving the error performance of communications systems in impulsive noise environment, the second part of this thesis introduces a novel scheme of bit-interleaved coded OFDM with iterative decoding (BI-COFDM-ID) over the class-A impulsive noise channel. Here, an iterative receiver composed of outer and inner iteration loops is first described in detail. Error performance improvements of the proposed iterative receiver with different iteration strategies are presented and discussed. Performance comparisons of BI-COFDM-ID, BICM-ID and iteratively decoded OFDM are made to illustrate the superiority of BI-COFDM-ID. The effect of signal mapping on the error performance of BI-COFDM-ID is also studied.
6

Pulse And Noise shaping D/A converter (PANDA) – Block implementation in 65nm SOI CMOS

Hägglund, Joel January 2009 (has links)
In the European research projects SIAM and 100GET, building blocks for 100Gbit Ethernet optical link have been implemented. Data are sent from a computer, modulated, converted to analog, mixed onto the RF-band, sent through an optical link, down-mixed, converted back to digital, demodulated and sent to a receiving computer. Signal Processing Devices Sweden AB is contributing to this project by their implementation PANDA. This thesis has been to study, as a proof of concept, and implement a prototype of PANDA as the component converting from digital to analog signal, the DAC, in 65nm SOI CMOS technology. The idea of the system is to use the concept of time interleaving, where two or more components interact by performing the same operations on a different set of data, ideally scaling the performance linearly with the amount of components used. This report presents design, implementation and verification at simulation level. It includes interfacing with off-chip components in low voltage specifications, clock generation, filtering and current-steered switches.
7

Coded modulation techniques with bit interleaving and iterative processing for impulsive noise channels

Bui, Trung Quang 22 August 2006 (has links)
Power line communications (PLC) surfers performance degradation due mainly to impulsive noise interference generated by electrical appliances. This thesis studies coded modulation techniques to improve the spectral efficiency and error performance of PLC. Considered in the first part is the application of bit-interleaved coded modulation with iterative decoding (BICM-ID) in class-A impulsive noise environment. In particular, the optimal soft-output demodulator and its suboptimal version are presented for an additive class-A noise (AWAN) channel so that iterative demodulation and decoding can be performed at the receiver. The effect of signal mapping on the error performance of BICM-ID systems in impulsive noise is then investigated, with both computer simulations and a tight error bound on the asymptotic performance. Extrinsic information transfer (EXIT) chart analysis is performed to illustrate the convergence properties of different mappings. The superior performance of BICMID compared to orthogonal frequency-division multiplexing (OFDM) is also clearly demonstrated.<p>Motivated by the successes of both BICM-ID and OFDM in improving the error performance of communications systems in impulsive noise environment, the second part of this thesis introduces a novel scheme of bit-interleaved coded OFDM with iterative decoding (BI-COFDM-ID) over the class-A impulsive noise channel. Here, an iterative receiver composed of outer and inner iteration loops is first described in detail. Error performance improvements of the proposed iterative receiver with different iteration strategies are presented and discussed. Performance comparisons of BI-COFDM-ID, BICM-ID and iteratively decoded OFDM are made to illustrate the superiority of BI-COFDM-ID. The effect of signal mapping on the error performance of BI-COFDM-ID is also studied.
8

Rumination and time allocation across tasks

Duggan, Geoffrey January 2015 (has links)
Background and Objectives: Rumination may contribute to depression by impairing the most effective allocation of time across activities. An experiment tested the role of rumination in time allocation across tasks. Methods: State rumination was manipulated by cueing an unresolved goal in one condition (32 participants) and cueing a resolved goal in another condition (32 participants). Trait rumination and depressive symptoms were also measured. All participants completed two word generation tasks and allocated a fixed overall time budget between the tasks by interleaving between them. Results: No difference was found in task performance or time allocation following the manipulation of state rumination. Self-reported rumination did not differ between conditions throughout the experimental task. Differences in time allocation behaviour were associated with trait rumination. Limitations: Use of a non-clinical population and tasks that are unrepresentative of everyday problem solving limited the generalisability of the results and may have limited the effect of the state rumination manipulation on task performance. Conclusions: The absence of a difference in self-reported rumination throughout the task suggests that either the word generation task reduced levels of rumination or that the level of rumination induced did not have a large effect on the cognitive processes required to complete the word generation task.
9

Τεχνικές συνελικτικής κωδικοποίησης για κανάλια συσχετισμένου θορύβου / Convolutional encoding techniques for correlated noise channels

Γομάτου, Παναγιώτα 16 June 2011 (has links)
Σκοπός της διπλωματικής είναι η μελέτη ενός τηλεπικοινωνιακού συστήματος αποτελούμενου από συνελικτικό κωδικοποιητή, interleaver, qam διαμορφωτή, κανάλι με παρουσία συσχετισμένου Gaussian θορύβου, soft qam αποδιαμορφωτή, deinterleaver και αποκωδικοποιητή Viterbi. Ιδιαίτερη έμφαση δίνεται στην απόδοση του interleaving/symbol παρουσία συσχετισμένου θορύβου. Μελετάται η απόδοση στο BER, η πολυπλοκότητα, το κόστος υλικού καθώς και χρονική καθυστέρηση του παραπάνω συστήματος σε σχέση με ένα αντίστοιχο σύστημα που υλοποιεί interleaving/bit παρουσία συσχετισμένου θορύβου. / The aim of the thesis is to study a telecommunications system consisting of convolutional encoder, interleaver, qam modulator, channel in the presence of correlated Gaussian noise, soft qam demodulator, deinterleaver, and decoder Viterbi. Particular emphasis is placed on the performance of interleaving/symbol presence of correlated noise. Studied the performance of the BER, the complexity, cost of material and time delay of the above system with respect to a corresponding system that implements interleaving/bit presence of correlated noise.
10

ERROR DETECTION AND CORRECTION -- AN EMPIRICAL METHOD FOR EVALUATING TECHNIQUES

Rymer, J. W. 10 1900 (has links)
International Telemetering Conference Proceedings / October 23-26, 2000 / Town & Country Hotel and Conference Center, San Diego, California / This paper describes a method for evaluating error correction techniques for applicability to the flight testing of aircraft. No statistical or math assumptions about the channel or sources of error are used. An empirical method is shown which allows direct “with and without” comparative evaluation of correction techniques. A method was developed to extract error sequences from actual test data independent of the source of the dropouts. Hardware was built to allow a stored error sequence to be repetitively applied to test data. Results are shown for error sequences extracted from a variety of actual test data. The effectiveness of Reed-Solomon (R-S) encoding and interleaving is shown. Test bed hardware configuration is described. Criteria are suggested for worthwhile correction techniques and suggestions are made for future investigation.

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