Engineering Seminar Topics and Seminar Topics

Download Full ArticleBLAST

BLAST is a wireless communications technique which uses multi-element antennas at both transmitter and receiver to permit transmission rates far in excess of those possible using conventional approaches.

       In wireless systems, radio waves do not propagate simply from transmit antenna to receive antenna, but bounce and scatter randomly off objects in the environment. This scattering known as multipath, as it results in multiple copies (“images”) of the transmitted sign arriving at the receiver via different scattered paths. In conventional wireless system multipath represents a significant impediment to accurate transmission, because the image arrive at the receiver at slightly different times and can thus interfere destructively, canceling each other out. For this reason, multipath is traditionally viewed as a serious impairment. Using the BLAST approach however, it is possible to exploit multipath, that is, to use the scattering characteristics of the propagation environment to enhance, rather than degrade transmission accuracy by treating the multiplicity of scattering paths as separate parallel sub channels.

INTRODUCTION

                    The explosive growth of both the wireless industry and the Internet is creating a huge market opportunity for wireless data access. Limited internet access, at very low speeds, is already available as an enhancement to some existing cellular systems. However those systems were designed with purpose of providing voice services and at most short messaging, but not fast data transfer. Traditional wireless technologies are not very well suited to meet the demanding requirements of providing very high data rates with the ubiquity, mobility and portability characteristics of cellular systems. Increased use of antenna arrays appears to be the only means of enabling the type of data rates and capacities needed for wireless internet and multimedia services. While the deployment of  base station arrays is becoming universal it is really the simultaneous deployment of base station and terminal arrays that can unleash unprecedented  levels of performance by opening up multiple spatial signaling dimensions .Theoretically, user data rates as high as 2 Mb/sec will be supported in certain environments, although recent studies have shown that approaching those might only be feasible under extremely favorable conditions-in the vicinity of the base station and with no other users competing for band width. Some fundamental barriers related to the nature of radio channel as well as to the limited band width availability at the frequencies of interest stand in the way of high data rates and low cost associated with wide access.

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Download Full ArticleBlu—Ray DVD

               Blu-ray, also known as Blu-ray Disc (BD) is the name of a next-generation optical disc video recording format jointly developed by nine leading consumer electronics companies. The format was developed to enable recording, rewriting and playback of high-definition video (HDTV). Blu-ray makes it possible to record over 2 hours of digital high-definition video (HDTV) or more than 13 hours of standard-definition video (SDTV/VHS picture quality) on a 27GB disc. There are also plans for higher capacity discs that are expected to hold up to 50GB of data.

                The Blu-ray Disc technology can store sound and video while maintaining high quality and also access the stored content in an easy-to-use way. Adoption of the Blu-ray Disc in a variety of applications including PC data storage and high definition video software is being considered.

Introduction

                Tokyo Japan, February 19, 2002: Nine leading companies today announced that they have jointly established the basic specifications for a next generation large capacity optical disc video recording format called “Blu-ray Disc”. The Blu-ray Disc enables the recording, rewriting and play back of up to 27 gigabytes (GB) of data on a single sided single layer 12cm CD/DVD size disc using a 405nm blue-violet laser.

By employing a short wavelength blue violet laser, the Blu-ray Disc successfully minimizes its beam spot size by making the numerical aperture (NA) on a field lens that converges the laser 0.85. In addition, by using a disc structure with a 0.1mm optical transmittance protection layer, the Blu-ray Disc diminishes aberration caused by disc tilt. This also allows for disc better readout and an increased recording density. The Blu-ray Disc’s tracking pitch is reduced to 0.32um, almost half of that of a regular DVD, achieving up to 27 GB high-density recording on a single sided disc.

Because the Blu-ray Disc utilizes global standard “MPEG-2 Transport Stream” compression technology highly compatible with digital broadcasting for video recording, a wide range of content can be recorded. It is possible for the Blu-ray Disc to record digital high definition broadcasting while maintaining high quality and other data simultaneously with video data if they are received together. In addition, the adoption of a unique ID written on a Blu-ray Disc realizes high quality copyright protection functions.

                The Blu-ray Disc is a technology platform that can store sound and video while maintaining high quality and also access the stored content in an easy-to-use way. This will be important in the coming broadband era as content distribution becomes increasingly diversified. The nine companies involved in the announcement will respectively develop products that take full advantage of Blu-ray Disc’s large capacity and high-speed data transfer rate. They are also aiming to further enhance the appeal of the new format through developing a larger capacity, such as over 30GB on a single sided single layer disc and over 50GB on a single sided double layer disc.

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Download Full ArticleDWCS

The basic problems of wireless access are that the available spectrum is too limited and there is great attenuation of energy. These can be solved by frequency reuse and by reducing the maximum distance from the terminal to the nearest base station.

Distributed wireless communication system (DWCS) is a new architecture for a wireless access system with distributed antennas, distributed processors, and distributed controlling. The basic idea is to flatten the tree cellular structure. With distributed antennas, system capacity can be expanded through dense frequency reuse, and transmission power can be greatly decreased. With distributed processors controlling, the system works like software or network radio, so different standards can coexist, and the system capacity can be increased by co processing of signals to and from multiple antennas.

The beyond 3G ie 4G mobile communications is aimed at much larger capacity and coverage requirements. DWCS is a candidate architecture to fulfill these requirements.

INTRODUCTION

With the rapid progress in telecommunications, more and more services are provided on the basis of broadband communications, such as video services and high-speed Internet. With worldwide fundamental construction of a backbone network based on optical fiber providing almost unlimited communications capability, the limited throughput of the subscriber loop becomes one of the most stringent bottlenecks. Compared to the capacity of the backbone network, which is measured by tens of gigabits per second, the throughput of the subscriber loop is much lower, only up to hundreds of megabits

per second for wired systems (including fixed wireless access). However, for mobile access the throughput is even lower, and depends on the mobility of the terminal. For example, the peak data rate is only 2 Mb/s for 3G systems.

Since there will be more and more need for mobile services, the poor throughput of mobile access not only limits user applications based on interconnection, but also wastes the capability of the backbone network. This case is quite similar to the traffic conditions shown in Fig. a, which is an image of an ultra-wide expressway with a few narrow entrances.

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 Download Full ArticleOrbiting Satellite Carrying Amateur Radio
Amateur Radio Operators (Hams) who share an active interest in building, launching and then communicating with each other through non-commercial Amateur Radio satellites. By any measure, AMSAT’s.Amatuer Radio Satellite Group) track record has been impressive. Since its founding 25 years ago, AMSAT has used predominantly volunteer labor and donated resources to design, construct, and, with the added assistance of international government and commercial agencies, successfully launch, over 30 Amateur Radio satellites into Earth orbit. Today, almost 20 of these satellites are operational. These satellites were generally called as OSCAR (Orbiting Satellite Carrying Amateur Radio).This paper focus on various technical aspects of OSCAR from its history, tracking, accessing up to its technology.

The Space age is barely a half century old .During this time a considerable amount of money is spent on space exploration and the related technologies .The investment has clearly begun pay of-earth satellites are the prime example . For nearly a decade most international telecommunications have been handled by satellite.

Orbiting Satellites Carrying Amateur Radio (OSCAR) series of small satellites was initiated for radio amateurs to experience satellite tracking and participate in radio propagation experiments. The World Administrative Radio Conference (WARC) allocated frequencies for the Amateur Satellite Service Transmitting low-powered signals, initially battery operated and offering short lives, the satellites have become increasingly sophisticated. More recently, they have served school science groups, provided emergency communications for disaster relief, acted as technology demonstrators, and transmitted Earth imagery.

The resourcefulness, ingenuity and skill of the Amateur Radio satellite community in the years have made a fascinating story. Hams have pursued the dream of reliable, predictable, long-distance and long-duration radio communication on different frequencies – from hf to microwaves. Each successive OSCAR has been one more step toward the realization of that dream. This paper covers the basic facts of OSCAR, its tracking, accessing and so on……..

The Space Age, was marked from the launch of Sputnik-I on October 4, 1957. OSCAR-I WAS launched on December 12, 1961.OSCAR –III, the first amateur satellite with a “transponder” was launched on March 9, 1965. In almost 40 years since the launch of first amateur satellite, the related technology has seen great advances, contributing to the exponential growth in the popularity of OSCAR operation.

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Download Full ArticleDigital Watermarking Using Wavelet Transforms

                With the rapid growth of Internet and networks technique, multimedia data transforming and sharing is common to many people. Multimedia data is easily copied and modified, so necessity for copyright protection is increasing. It is the imperceptible marking of multimedia data to “brand” ownership. Digital watermarking has been proposed as technique for copyright protection of multimedia data. Digital watermarking invisibly embeds copyright information into multimedia data. Thus, digital watermarking has been used for copyright protection, finger printing, copy protection and broadcast monitoring. Indeed, a watermarking algorithm requires both invisibility and robustness, which exist in a trade-off relation. Thus good watermarking algorithm must be satisfied the requirements.

                 The process of digital watermarking involves the modification of the original multimedia data to embed a watermark containing key information such as authentication or copyright codes. The embedding method must leave the original data perceptually un-changed, yet should impose modifications which can be detected by using an appropriate extraction algorithm. Common types of signals to watermark are images, music clips and digital video.  The application of digital watermarking to still images is concentrated here. The major technical challenge is to design a highly robust digital watermarking technique, which discourages copyright infringement by making the process of watermarking removal tedious and costly.

1.1 Advantage of frequency domain watermarking

                  In general, the digital watermarking is classified into two classes by depending on the domain of watermarking embedding: the spatial domain watermarking and the frequency domain watermarking. The spatial domain watermarking algorithms usually embed the watermark to the least significant bits (lsbs) of the image pixels. The watermark is embedded on randomly selected pixels using neighbours dependant function. In the detection process, the idea is to verify the surrounding pixels to decide if one has truly been modified. The detection of changes in small details of the image is based on mathematical morphology. Furthermore, it is able to reject small distortion introduced by high quality image compression. However, the technique suffers from the major drawback of spatial domain watermarking: frequency localization of modifications is difficult. Because the marks are on certain particular pixels, it is often impossible to detect frequency alterations applied to the entire image. .

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