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CorDECT

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Abstract

This report describes a new wireless local loop system for rapid expansion of telecom services developed under a joint project involving Indian scientists form Indian Institute Of Technology, Chennai, Midas technology and Analog Devices Inc., USA. The new system, called corDECT, is based on microcellular architecture and uses a modest bandwidth of 20MHz to provide voice, fax, and data communication in low as well as very high subscriber density environments. The high capacity at a modest bandwidth is made possible without prior frequency planning through a completely decentralized channel allocation procedure called dynamic channel selection. This technology provides cost-effective simultaneous high quality voice and data connectivity, a voice communication using 32Kbps ADPCM and Internet connectivity at 35\70 Kbps. This report discusses the relevance of corDECT in the context of current trends towards wireless systems, contrasts the microcellular architecture of corDECT with existing wireless systems based on macrocellular architectures, and outlines its market potential.

Introduction

A new wireless local loop system to eliminate the physical connections between telephone exchanges and subscribers has just hit the market after a two-year long joint research effort by Indian and US engineers. The new system, called corDECT, is said to offer significant cost-savings, rapid installation, and improved reliability over traditional connections based on copper cables. It is based on a microcellular architecture that is said to offer cost and operational advantages over wireless/mobile telephone systems based on macrocellular architectures. The corDECT system is based on the European Digital Enhanced Cordless Telecommunications standard that uses a modest bandwidth of 20MHz in the 1880-1900 MHz range and does not require prior frequency planning necessary in conventional mobile cellular systems. The corDECT technology uses relatively low-cost, easy-to-install subsystems and can serve relatively high subscriber density environments –several thousands of subscribers per square kilometer. Four Indian companies have bought the technology for domestic manufacture. Its developers believe there is a large market potential in the Asia-Pacific region and in other developing countries. This report will describe the CorDECT wireless local loop system and its subsystems and compare the microcellular architecture of corDECT with macrocellular architectures employed in many wireless telephone systems.

CorDECT Seminar PPT


DECT Interface Unit (DIU)

        The DIU is heart of the CorDECT system It serves as an interface between the PSTN and CBS.The DIU is connected to the CBS by three cables that carry data in ISDN format and device and derive the power to CBS. Each DIU can be connected to a maximum of 20 CBS. Each DIU is connected to PSTN through standard E1 lines. Each CBS can be located up to four kilometers from a DIU.

Network Layer Protocol

The DECT network protocol is defined for the control plane (C plane) only. It provides the means to request, allocate, manage, and deallocate key resources in the central system and the portable. The capabilities of the DECT system in terms of its flexibility to support a wide range of applications and interface to diverse networks is determined by the characteristics of the network protocol were drawn from the ISDN user-network protocol at layer 3 (ITU-T Recommendation Q.931) and to some extend from the GSM layer 3 protocol. Since, however, the DECT architecture and requirements differ considerably from ISDN and GSM, DECT network layer protocol is essentially modu8lar and it is intended to support a number of protocol functions. Some of the protocols, which the network layer supports, are given below.

The main functions of the DIU are
  •         Enabling cell formatting.
  •          Billing.
  •          Administration and monitoring of the network.
  •          Interfacing between PSTN and CBS, and delivering signals without the use of wires to the subscriber.
  •          Providing power to the base station.

Management Entity (MGE)

        The management entity (MGE) is responsible for a number of functions in DECT that involve only one side of the communication link and as such do not appear in an OSI layer. These include such functions as radio resource control (choice of free channels, assessment of channel quality), mobility management (registration of DECT portables), and error handling (call termination at radio link interruption).

 Radio Aspects Of CorDect

In Europe the 1880-1900 MHz band has been set-aside for DECT. To utilize the available 20 MHz band in an efficient and flexible manner for supporting voice and data applications, the DECT standard provides for space, frequency, and time distribution, Space dispersion in DECT is supported through the frequency reuse feature based on the cellular concept. To provide frequency distribution, the available spectrum is segmented into 10 carrier frequencies (frequency channels) from 1881.792MHz with separation of 1.728MHz [i.e. by deploying frequency division multiple accesses (FDMA)]. Time distribution is achieved by using time division multiple accesses (TDMA), where by each frequency channel supports 12 duplex time slots or 32 Kb/s channels.

Radio Specifications of CorDECT

Access method           :       TDMA
Spectrum allocation    :       1880-1900MHz
Carrier spacing           :       1728 KHz
Number of carriers      :       10
Channels/Carrier         :       12
Modulation                 :       GFSK
Transmission rate       :       1152Kb/s
Frame duration          :       10ms
Speech coding            :       32Kb/s ADPCM
Peak output power     :       250mW

Conclusion

The corDECT wireless local loop system offers relatively low cost and rapid installation of telecom services in areas with even high subscriber density environments. This microcellular system relies on a modest bandwidth of 20MHz for the entire country. Two or three DECT wireless local loop systems and DECT based local area networks could coexist in the same area without interfering with one another -- all operating on the same 20MHz bandwidth.  The high capacity is achieved not by using low bit-rate compression techniques but with toll quality ADPCM or PCM voice coding. The microcellular system can provide ADPCM (32kbps) or PCM (64kbps) and even ISDN (128kbps) services to users. Its developers describe it as a "future proof" system.



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Animatronics

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 Abstract

        Animatronics is a cross between animation and electronics. Basically, an animatronic is a mechanized puppet. It may be preprogrammed or remotely controlled. An abbreviated term originally coined by Walt Disney as "Audio-Animatronics" (used to describe his mechanized characters), can actually be seen in various forms as far back as Leonardo-Da-Vinci's Automata Lion, (theoretically built to present lillies to the King of France during one of his Visits), and has now developed as a career which may require combined talent in Mechanical Engineering, Sculpting / Casting, Control Technologies, Electrical / Electronic, Airbrushing, Radio-Control. Long before digital effects appeared, animatronics were making cinematic history. The scare generated by the Great White coming out of the water in "Jaws" and  the tender otherworldliness of "E.T." were its outcomes. The Jurassic Park series combined digital effects with animatronics. It is possible for us to build our own animatronics by making use of ready-made animatronic kits provided by companies such as Mister Computers.

What Is Animatronics

        Animatronics is a combination of animation and electronics. What exactly is an animatronic? Basically, an animatronic is a mechanized puppet. It may be preprogrammed or remotely controlled. The animatronic may only perform a limited range of movements or it may be incredibly versatile. The scare created by  the Great White coming out of the water in "Jaws" and the tender otherworldliness of "E.T." are cinematic effects that will not be easily forgotten. Later animatronics was used together with digital effects. Through the precision, ingenuity and dedication of their creators, animatronics creatures often seem as real to us as their flesh-and-blood counterparts.




 Introduction

        The first use of Audio-Animatronics was for Walt Disney's Enchanted Tiki Room in Disneyland, which opened in June, 1963. The Tiki birds were operated using digital controls; that is, something that is either on or off. Tones were recorded onto tape, which on playback would cause a metal reed to vibrate. The vibrating reed would close a circuit and thus operate a relay. The relay sent a pulse of energy (electricity) to the figure's mechanism which would cause a pneumatic valve to operate, which resulted in the action, like the opening of a bird's beak. Each action (e.g., opening of the mouth) had a neutral position, otherwise known as the "natural resting position" (e.g., in the case of the Tiki bird it would be for the mouth to be closed). When there was no pulse of energy forthcoming, the action would be in, or return to, the natural resting position.

Jurassic Park

        Long before digital effects appeared, animatronics were making cinematic history. But it was in Jurassic park that the best possible combination of animatronics and digital effects were used together. Spinosaurus was  a new dinosaur animatronic created for "Jurassic Park III" by Stan Winston Studio (SWS). SWS worked with Universal Studios and the film's production team to develop the Spinosaurus design. Below lies the discussion of the amazing process that creates and controls a huge animatronic like this dinosaur!



1.   Jurassic Machines
2.   Dinosaur Evolution
3.   In the Beginning
4.   Creature Creation
5.   Putting it together
6.   Making it Move
                              7. Monster Mash

Electronic

         Another group develops the electronic control systems needed to operate the animatronic. Typically starting from scratch and creating their own custom circuit boards, these engineers are essentially building giant remote-controlled toys. Almost all of the movement of the Spinosaurus will be manipulated by specialized remote-control systems known as telemetry devices.

Structural

         All of the electronic and mechanical components need something to attach to and control, and the skin must have a frame to maintain its shape. This is done by building a plastic and steel frame. To increase the realism, and because it is the natural way to design it, the frame of the Spinosaurus, as well as most other creatures made by SWS, resembles the actual skeleton of the beast. This skeletal frame is largely comprised of graphite, a synthetic material known for its strength and lightness.

Surface 

        The "skin" of the Spinosaurus is made from foam rubber, which is a very light, spongy rubber that is made by mixing air with liquid latex rubber and then curing (hardening) it. While there are other compounds, such as silicone and urethane, that are stronger and last longer, foam rubber is used because it is much easier to work with. The solution is poured into each mold and allowed to cure. As mentioned earlier, parts of the frame are embedded with the foam rubber at certain points. To further strengthen the skin, a piece of fabric is cut to size and embedded in the foam rubber after it is poured into the mold. Once cured, each piece of skin is pulled from its mold.

What Is An Animatronics Kit?

        Everything you need (except batteries and imagination) is included in our easy-to-use kit. Connect the cable to your PC's serial port, install the software and you're ready to start. No soldering or programming skills required. If you can use Windows you can use this Animatronics Kit . The software allows you to record the movements of hobby servos (up to two billion moves) and play them back exactly as recorded. Make your creation come to life!

Conclusion

        Creating a good animatronics figure that is able to perform constantly without fail requires many special skills and lots of technical know how.  Before assuming the task of creating an animatronic figure, you  should have a strong hold on how these things are constructed and be willing to spend a pretty penny on equipment and materials.


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Tunable Lasers

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Abstract

Tunable lasers as the name suggests are lasers whose wavelengths can be tuned or varied. They play an important part in optical communication networks. Recent improvements in tunable laser technologies are enabling highly flexible and effective utilization of the massive increases in optical network capacity brought by large-scale application of dense wavelength division multiplexing. 

The outlined approach of full-band tunable lasers based on DFB technology meet the existing performance specifications and possess a cost structure that will ultimately displace static- wavelength DFBs, making tunability ubiquitous.

Introduction

Tunable lasers as the name suggests are lasers whose wavelengths can be tuned or varied. They play an important part in optical communication networks. Recent improvements in tunable laser technologies are enabling highly flexible and effective utilization of the massive increases in optical network capacity brought by large-scale application of dense wavelength division multiplexing.

In a wavelength-division multiplexed (WDM) network carrying 128 wavelengths of information, we have 128 different lasers giving out these wavelengths of light. Each laser is designed differently in order to give the exact wavelength needed. Even though the lasers are expensive, in case of a breakdown, we should be able to replace it at a moment's notice so that we don't lose any of the capacity that we have invested so much money in.

Tunable Lasers Enable Next-g Capabilities

Beyond the ability to address today’s problems, tunable lasers will play a central role in allowing service providers to offer entirely new value-added services and generate new revenue streams.  Next-generation services and functionality will initially be implemented in a new generation of optical add-drop modules (OADMs) and optical cross-connects (OXCs) that incorporate tunable lasers.

Tunable Lasers Seminar PPT


Current-generation OADMs, which rely on fixed-wavelength lasers, are limited in their ability to add channels to the network. Changing traffic patterns, customer requirements, and new revenue opportunities require greater flexibility than static OADMs can provide, complicating network operations and planning. Incorporating tunable lasers removes this constraint altogether by allowing any channel to be added by the OADM at any time. With the deployment of tunable line cards at OADM sites, sparing and restoration capabilities become more economical as well. Optical cross-connects (OXCs) represent another opportunity for tunable lasers to improve network system efficiency. Line cards with widely tunable lasers covering the full C band enable physical-layer provisioning and switching in the optical domain, allowing an “any channel to any channel” connection to be made at network nodes. Widely tunable lasers simplify OXC planning, since all wavelength channels are available from any tunable line card. Even if a particular channel is already in use, wide tenability allows a18   flexible, potentially automated determination of wavelength conversion, which further simplifies  system planning by complementing and adding value to electrical-level provisioning, grooming, and switching. While today’s networks are large and complex, future networks are expected to be greatly simplified and more purely optical in nature, with significant reductions in both capital and operating costs. One scenario shows a “mesh” architecture in which nodal points on the network are designed to route signals on the basis of wavelength. In this example, tunable lasers can be deployed to route signals to their destination on the basis of wavelength. Tunable lasers will play a key role in these advanced telecom networks, since this type of architecture is unlikely to be fully realized with current-generation fixed-wavelength or even narrowly-tunable lasers.

The Distributed Feedback Laser

Among the most common diode lasers used in telecommunications today are distributed feedback (DFB) lasers. They are unique in that they incorporate a diffraction grating directly into the laser chip itself, usually along the length of the active layer (the gain medium).As used in DFB lasers, the rating reflects a single wavelength back into the cavity, forcing a single resonant mode within the laser, and producing a stable, very narrow-bandwidth output.

DFB lasers are tuned by controlling the temperature of the laser diode cavity. Because a large temperature difference is required to tune across only a few nanometers, the tuning range of a single DFB laser cavity is limited to a small range of wavelengths, typically under 5 nm. DFB lasers with wide tuning ranges therefore incorporate multiple laser cavities.

Better Use Of Expensive Network

Bandwidth Tunable lasers provide an advantage over fixed sources even when  service providers employ an alternative “hot-backup” approach to sparing  that  is, maintaining idle channels which are only activated when a backup is required.  In this application, upto 50% of the system bandwidth can be rendered unusable when using fixed wavelength lasers because network carriers must maintain a spare channel for each wavelength used. With tunable lasers, however, only a small  number of line cards are held in reserve slots, since each spare can tune to any  required wavelength. Thus tunable lasers can restore usable system bandwidth to 90% or better.

Moreover, in the event of a channel failure, a tunable backup card can be quickly configured to resume communications, providing nearly seamless restoration in the event of malfunction and allowing SONET protection to be implemented entirely in the optical domain. As a further guarantee of service continuity, tunable lasers therefore present additional opportunities for revenue generation.

Conclusion

Recent advances in tunable laser technology have brought the promise of tunable networks into clear focus. Widespread adoption of tunable lasers will not only eliminate logistical and inventory problems and the associated costs that result from fixed-wavelength line cards but will also enable novel network architectures with dynamic functionality such as dynamic add-drop, thus enabling new value-added services and creating new sources of top-line revenue for system providers.

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Google Glass

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Abstract

Project Glass is a research and development program by Google to develop an augmented reality Head-Mounted Display (HMD). The intended purpose of Project Glass products would be the hands-free displaying of information currently available to most smartphone users, and allowing for interaction with the Internet via natural language voice commands. These glasses will have the combined features of virtual reality and augmented reality. Google glasses are basically wearable computers that will use the same Android software that powers Android smartphones and tablets.

Introduction

Virtual reality is often used to describe a wide variety of applications commonly associated with immersive, highly visual, 3D environments. The development of CAD software, graphics hardware acceleration, head mounted displays, database gloves, and miniaturization.

Wearable Computing

Wearable computers, also known as body-borne computers are miniature electronic devices that are worn by the bearer under, with or on top of clothing. This class of wearable technology has been developed for general or special purpose information technologies and media development. Wearable computers are especially useful for applications that require more complex computational support than just hardware coded logics.

Google Glass

Eye Tap Technology

An EyeTap is a device that is worn in front of the eye that acts as a camera to record the scene available to the eye as well as a display to superimpose a computer-generated imagery on the original scene available to the eye. This structure allows the user's eye to operate as both a monitor and a camera as the EyeTap intakes the world around it and augments the image the user sees allowing it to overlay computer-generated data over top of the normal world the user would perceive. The EyeTap is a hard technology to categorize under the three main headers for wearable computing for while it is in theory a constancy technology in nature it also has the ability to augment and mediate the reality the user perceives.

Future Scope

Google Glass is as futuristic a gadget seen in recent times. It’s limited in scope right now, but the future, Google believes, is bright and the device itself is “incredibly compelling”.


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Bittorrent

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What Is Bittorrent?

                 BitTorrent is a protocol designed for transferring files. It is peer-to-peer in nature, as users connect to each other directly to send and receive portions of the file. However, there is a central server (called a tracker) which coordinates the action of all such peers. The tracker only manages connections, it does not have any knowledge of the contents of the files being distributed, and therefore a large number of users can be supported with relatively limited tracker bandwidth. The key philosophy of BitTorrent is that users should upload (transmit outbound) at the same time they are downloading (receiving inbound.) In this manner, network bandwidth is utilized as efficiently as possible. 

What Bittorrent Does?

                  When a file is made available using HTTP, all upload cost is placed on the hosting machine. With BitTorrent, when multiple people are downloading the same file at the same time, they upload pieces of the file to each other. This redistributes the cost of upload to downloaders, (where it is often not even metered), thus making hosting a file with a potentially unlimited number of downloaders affordable. Researchers have attempted to find practical techniques to do this before. It has not been previously deployed on a large scale because the logistical and robustness problems are quite difficult. Simply figuring out which peers have what parts of the file and where they should be sent is difficult to do without incurring a huge overhead. In addition, real deployments experience very high churn rates. Peers rarely connect for more than a few hours, and frequently for only a few minutes. 

Bittorrent


Pareto Efficiency

                  Well known economic theories show that systems which are pareto efficient, meaning that no two counter parties can make an exchange and both be happier, tend to have all of the above properties. In computer science terms, seeking Pareto efficiency is a local optimization algorithm in which pairs of counter parties see if they can improve their lot together, and such algorithms tend to lead to global optima. Specifically, if two peers are both getting poor reciprocation for some of the upload they are providing, they can often start uploading to each other instead and both get a better download rate than they had before.

Abstract

              Torrent refers to the small metadata file you receive from the web server (the one that ends in .torrent.) Metadata here means that the file contains information about the data you want to download, not the data itself. This is what is sent to your computer when you click on a download link on a website

Conclusion

             Legitimate P2P use is here and has a definite role to play in the future of the Internet. It is without a compromise between the copyright holders and the file sharers, that there will be an ever-escalating arms race of technology versus legal maneuvers. BitTorrent is a nifty program that works in a simple, if counter-intuitive.

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A Plan For No Spam

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 Introduction
 
        Unwanted and irrelevant mass mailings, commonly known as spam are becoming a serious nuisance that if left unchecked may soon be regarded as a Denial of Service Attack against the email infrastructure of the Internet itself.

Best Practices

        The traditional response of the internet to problem uses administrators of deployed protocols is to specify some form of 'Best Practices'. Spam is an attack on the Internet community. The short survey and prosecutions by the FTC and others show that the spam senders are in many cases outright criminals, how then can best practices help? One area in which best practices can provide concrete benefit is in ensuring that the vast majority of Internet users who are acting in good faith do not inadvertently make the problem worse by poorly chosen or poorly coordinated mitigation strategies. 

 
Naive Keyword Inspection  

        Messages are scanned for the presence of words or phrases that occur frequently in spam messages such as HGH or multi-level marketing. This type of filtering is implemented in many common email clients such as Outlook [MSFT].    Keyword Inspection alone is simple to implement but tends to have very high rate of false positives.

Authentication And Authorization

        Practically all spam messages sent today attempt to evade anti-spam measures by use of false header information. None of the spam messages that were examined in the writing of this paper carried a genuine sender address. Most of the massages contained from addresses that were obviously fake. In some cases the addresses were not even valid. Some contained no sender address at all. 

Legislation And Litigation

        The purpose of criminal legislation in a democratic is to deter persons from engaging in prohibited conduct. While it is unlikely that the criminal legislation alone would eliminate spam. Such legislation would certainly create a deterrent for both the spam senders and the advertisers seeking their services. The legislative process is very slow & time consuming. Legislators are reluctant to pass any legislation until they are confident that the implications are fully understood. Legislators will have to be convinced that any new legislation to address the problem of spam will bring benefits that significantly outweigh both the cost of enforcement and the political cost of committing the scarce resource of legislative time to the problem of spam rather than to other pressing problems.

Conclusion

        There are many techniques that address a part of the spam problem. No currently known technique provides a complete solution and it is unlikely that address a part of the problem. No currently known technique provides a complete solution and it is unlikely that any technique will be found in the future that provides a complete and costless solution.


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