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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.
51

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.
52

PTP EX: HIGH-RATE FRONT-END TELEMETRY AND COMMAND PROCESSING SYSTEM

Ozkan, Siragan 10 1900 (has links)
International Telemetering Conference Proceedings / October 25-28, 1999 / Riviera Hotel and Convention Center, Las Vegas, Nevada / This paper describes the PTP EX, a 160 Mbps Telemetry and Command front-end system, which takes advantage of the state-of-the-art in networking and software technology, and the rapid development in PC components and FPGA design. Applications for the PTP EX include High-rate Remote Sensing Ground Stations, Satellite/Payload Integration and Testing, High-rate Bit Error Rate Test (BERT) System and High-rate Digital Recorder/Playback System. The PTP EX Interface Board, the MONARCH-EX PCI High Speed Frame Synchronizer/Telemetry Simulator with Reed-Solomon Encoder/Decoder, is designed with the following key capabilities: · 160 Mbps serial input for CCSDS Frame Processing (Frame Synchronization, Derandomization, CRC, Reed-Solomon decoding, time stamping, quality annotation, filtering, routing, and stripping); · 160 Mbps disk logging of Reed-Solomon corrected CCSDS frames with simultaneous real-time processing of spacecraft engineering data and ancillary payload data; · Onboard CCSDS Telemetry Simulation with 160 Mbps serial output (Sync Pattern, background pattern, ID counter, time stamp, CRC, Reed-Solomon encoding, Randomization, and Convolutional encoding); · Bit Error Rate Testing up to 160 Mbps (Pseudo-random transmitter and receiver with bit error counter). The innovative architecture of the MONARCH-EX allows for simultaneous logging of a high-rate data stream and real-time telemetry processing. The MONARCH-EX is also designed with the latest in field-programmable gate array (FPGA) technology. FPGAs allow the board to be reprogrammed quickly and easily to perform different functions. Thus, the same hardware can be used for both Telemetry processing and simulation, and BERT applications. The PTP EX also takes advantage of the latest advances in off-the-shelf PC computing and technology, including Windows NT, Pentium II, PCI, Gigabit Ethernet, and RAID subsystems. Avtec Systems, Inc. is leveraging the PTP EX to take advantage of the continuous improvement in high-end PC server components.
53

Combining a Reed-Solomon Block Code with a Blind Equalizer: Synchronization and Bit Error Rate Performance

Skrzypczak, Alexandre, Blanc, Grégory, Le Bournault, Tangi 10 1900 (has links)
ITC/USA 2015 Conference Proceedings / The Fifty-First Annual International Telemetering Conference and Technical Exhibition / October 26-29, 2015 / Bally's Hotel & Convention Center, Las Vegas, NV / The performance of telemetry systems may be strongly affected by diverse sources of perturbations. Among them, multipath channels and transmission noise are the most critical. While the effects due to the multipath channels can be attenuated thanks to equalization, the effects of the noise are limited if forward error correction is used. This paper first proves that the combination of blind equalization and forward error correction can strongly improve bit error rates. The other objective of the paper is to show that reasonably powerful codes like Reed-Solomon codes are sufficient to enable quasi-error free transmissions in a large majority of propagation channel scenarios.
54

A Systolic Array Based Reed-Solomon Decoder Realised Using Programmable Logic Devices

Biju, S., Narayana, T. V., Anguswamy, P., Singh, U. S. 11 1900 (has links)
International Telemetering Conference Proceedings / October 30-November 02, 1995 / Riviera Hotel, Las Vegas, Nevada / This paper describes the development of a Reed-Solomon (RS) Encoder-Decoder which implements the RS segment of the telemetry channel coding scheme recommended by the Consultative Committee on Space Data Systems (CCSDS)[1]. The Euclidean algorithm has been chosen for the decoder implementation, the hardware realization taking a systolic array approach. The fully pipelined decoder runs on a single clock and the operating speed is limited only by the Galois Field (GF) multiplier's delay. The circuit has been synthesised from VHDL descriptions and the hardware is being realised using programmable logic chips. This circuit was simulated for functional operation and found to perform correction of error patterns exactly as predicted by theory.
55

The Concept of Development in Ulawa in Solomon Islands and its Implications for National Development Policy and Planning

Rohorua, Frederick Isom January 2007 (has links)
'Social development' and 'economic development' are complex concepts, concepts that may be interpreted very differently in different contexts and at different times. Not only may the processes involved be different in different contexts, so too may be the criteria by which success is judged. It is argued here that successive Solomon Islands governments have striven for social and economic development without taking full account of the real nature of Solomon Islands society. What is needed is national development policy, planning and implementation that arise out of, and take fully into account, the historical, geographic and cultural context of Solomon Islands. On the whole, the socio-economic structure of Solomon Islands society is currently underpinned by a tri-partite hierarchy in which, for the majority of Solomon Islanders, kastom (traditional beliefs and practices) and church (the beliefs and practices endorsed by the church) take precedence over the state as legitimate forms of authority. This inevitably poses problems for state-led development. If socio-economic development activities are to be successful in achieving a better quality of life for all Solomon Islanders, including those who live in rural areas, they must take full account of the role of kastom and church in the lives of the people. This must include an understanding of the differing concepts of development of people in different areas of the country such as those of Ulawa islanders that are discussed here. The thesis begins with an introduction to the research (Chapter 1) in which the theoretical framework is located broadly within the postmodern paradigm. In Chapter 2 the essentially qualitative and interpretive nature of the methodology is outlined and explained. Chapter 3 provides a critical review of international development literature in which it is argued that official definitions and descriptions of development are based on production and deficit models. The need to accommodate an indigenous and organic concept of development, one that takes account of the diversity of human experience, is stressed. Chapter 4 provides an outline of Solomon Islands society. Here, the historical narrative is complemented by three metaphors - 'island', wantok and betelnut - which serve to reinforce and explain the nature of Solomon Islands society and the ways in which that society has been shaped by historical processes. Chapter 5 is devoted to a discussion of modern development activity in Solomon Islands, the main focus being on the period immediately preceding and following independence. Chapter 6 explores, with particular reference to Ulawa Island, indigenous concepts of development and the impact of national development activities on rural-dwelling islanders. It also engages the issue of state reform, proposing a model based on a two tier system, with central government in its current form dealing directly with the people at constituency rather than provincial level. Finally, Chapter 7 summarizes the main conclusions reached. It is noted that the failure of both pre- and post-independence governments to take full account of the nature of Solomon Islands society has been a major factor in the lack of effective development in the islands.
56

Effective School Leadership: An exploration of the issues inhibiting the effectiveness of school leadership in Solomon Islands' secondary schools

Malasa, Donald Papaku January 2007 (has links)
This study investigates issues impeding effective school leadership in Solomon Islands' secondary schools. In particular, it examines principals' perceptions of those issues that impede their effective leadership of their schools. There is an international literature focusing on this area that has contributed to the study. However, many of the research findings in western contexts are invalid in the context of a developing nation such as the Solomon Islands. Thus contextual specificity was an important underlying factor in the study. The research data was gathered using qualitative methods. Specifically, interviews with five principals were conducted using semi-structured interviews and was analysed using a thematic analysis approach. The research fieldwork was carried out in the Solomon Islands in August 2006. A sample of five participants was used. They were selected from five schools representing Community High Schools (CHS) and senior Provincial Secondary Schools (PSS) in two provinces and the Honiara City Council. The key findings of the study identify a range of factors that inhibit effective school leadership. These included a lack of initial training and support for on-going professional learning, unfavourable conditions of service, poor quality of teachers' professional practice, poor school facilities and infrastructure, poor administrative infrastructure, lack of appropriate and adequate financial resources, lack of support personnel, policy and systemic issues, social and cultural issues, and issues pertaining to school-community partnerships. Based on the findings identified in the study, recommendations were made on how to improve effective leadership of the schools throughout the Solomon Islands. Of particular importance is the establishment of professional development programmes for both newly appointed and servicing principals. Such programmes should enhance the leadership capacity of the principals in the schools and create a more conducive learning environment.
57

The religious attitudes of students in Adventist high schools in the Solomon Islands and Vanuatu

Hay, Anthony L., n/a January 1991 (has links)
This study investigates those factors which influence the development and formation of religious attitudes in students. While there is an increasing body of knowledge and indepth research evolving regarding this field of study there is little done in the Third World and it is the first done on students at Betikama, Kukudu and Aore Adventist High Schools. It is an "ex post facto" study and examines the effects of a number of variables-- school, age, gender, level of schooling, religion, parent's religion, religious practices, parent's schooling, country of citizenship, student future plans, number of years at school, the type of school, school life and school climate-- on the religious attitudes of students attending selected high schools. The significance of the study lies in attempting to identify those factors which assist in the development of propitious religious attitudes in students. The modus operandi of the schools in the study is to encourage students to adopt a world view and lifestyle that is consistent with the tenets and practises of Christianity as espoused by Seventh-day Adventistism. It is the purpose of this study to contribute to the identification of factors which would assist in the achieving of this objective. Those variables which were most significant in the formation of attitudes toward religion were related to the School Climate and School Life as perceived by the students. Other findings related to variables investigating Student Background, Personal Characteristics, Student Religious Practices, and Family Background. These results apparently found some variables to be significant while others appeared not to be as significant. The research seems to suggest that educators and administrators must be aware of the influence of various school experiences on the development of religious attitudes in students. If they want to succeed in their objectives, then school programmes, school curriculum, extra-curricula activities, teaching methods and teacher example should promote student worth, through such aspects as fair treatment, consistency, seeing students as individuals and nuturing caring environments. Further research may include identification of factors which seem to override the importance of gender and age on the religious attitudes of the students in the study. It may also be worthwhile to identify those facets of school life and climate which are most conducive to the development of positive attitudes toward religion.
58

Aspects of List-of-Two Decoding

Eriksson, Jonas January 2006 (has links)
<p>We study the problem of list decoding with focus on the case when we have a list size limited to two. Under this restriction we derive general lower bounds on the maximum possible size of a list-of-2-decodable code. We study the set of correctable error patterns in an attempt to obtain a characterization. For a special family of Reed-Solomon codes - which we identify and name 'class-I codes' - we give a weight-based characterization of the correctable error patterns under list-of-2 decoding. As a tool in this analysis we use the theoretical framework of Sudan's algorithm. The characterization is used in an exact calculation of the probability of transmission error in the symmetric channel when list-of-2 decoding is used. The results from the analysis and complementary simulations for QAM-systems show that a list-of-2 decoding gain of nearly 1 dB can be achieved.</p><p>Further we study Sudan's algorithm for list decoding of Reed-Solomon codes for the special case of the class-I codes. For these codes algorithms are suggested for both the first and second step of Sudan's algorithm. Hardware solutions for both steps based on the derived algorithms are presented.</p>
59

Aspects of List-of-Two Decoding

Eriksson, Jonas January 2006 (has links)
We study the problem of list decoding with focus on the case when we have a list size limited to two. Under this restriction we derive general lower bounds on the maximum possible size of a list-of-2-decodable code. We study the set of correctable error patterns in an attempt to obtain a characterization. For a special family of Reed-Solomon codes - which we identify and name 'class-I codes' - we give a weight-based characterization of the correctable error patterns under list-of-2 decoding. As a tool in this analysis we use the theoretical framework of Sudan's algorithm. The characterization is used in an exact calculation of the probability of transmission error in the symmetric channel when list-of-2 decoding is used. The results from the analysis and complementary simulations for QAM-systems show that a list-of-2 decoding gain of nearly 1 dB can be achieved. Further we study Sudan's algorithm for list decoding of Reed-Solomon codes for the special case of the class-I codes. For these codes algorithms are suggested for both the first and second step of Sudan's algorithm. Hardware solutions for both steps based on the derived algorithms are presented.
60

Advanced channel coding techniques using bit-level soft information

Jiang, Jing 02 June 2009 (has links)
In this dissertation, advanced channel decoding techniques based on bit-level soft information are studied. Two main approaches are proposed: bit-level probabilistic iterative decoding and bit-level algebraic soft-decision (list) decoding (ASD). In the first part of the dissertation, we first study iterative decoding for high density parity check (HDPC) codes. An iterative decoding algorithm, which uses the sum product algorithm (SPA) in conjunction with a binary parity check matrix adapted in each decoding iteration according to the bit-level reliabilities is proposed. In contrast to the common belief that iterative decoding is not suitable for HDPC codes, this bit-level reliability based adaptation procedure is critical to the conver-gence behavior of iterative decoding for HDPC codes and it significantly improves the iterative decoding performance of Reed-Solomon (RS) codes, whose parity check matrices are in general not sparse. We also present another iterative decoding scheme for cyclic codes by randomly shifting the bit-level reliability values in each iteration. The random shift based adaptation can also prevent iterative decoding from getting stuck with a significant complexity reduction compared with the reliability based parity check matrix adaptation and still provides reasonable good performance for short-length cyclic codes. In the second part of the dissertation, we investigate ASD for RS codes using bit-level soft information. In particular, we show that by carefully incorporating bit¬level soft information in the multiplicity assignment and the interpolation step, ASD can significantly outperform conventional hard decision decoding (HDD) for RS codes with a very small amount of complexity, even though the kernel of ASD is operating at the symbol-level. More importantly, the performance of the proposed bit-level ASD can be tightly upper bounded for practical high rate RS codes, which is in general not possible for other popular ASD schemes. Bit-level soft-decision decoding (SDD) serves as an efficient way to exploit the potential gain of many classical codes, and also facilitates the corresponding per-formance analysis. The proposed bit-level SDD schemes are potential and feasible alternatives to conventional symbol-level HDD schemes in many communication sys-tems.

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