Dense Wavelength Division Multiplexing (DWDM)

Dense Wavelength Division Multiplexing (DWDM) is a fiber-optic transmission technique. It involves the process of multiplexing many different wavelength signals onto a single fiber. So each fiber have a set of parallel optical channels each using slightly different light wavelengths. It employs light wavelengths to transmit data parallel-by-bit or serial-by-character. DWDM is a very crucial component of optical networks that will allow the transmission of data: voice, video-IP, ATM and SONET/SDH respectively, over the optical layer.

From both technical and economic perspectives, the ability to provide potentially unlimited transmission capacity is the most obvious advantage of DWDM technology. The current investment in fiber plant can not only be preserved, but also optimized by a factor of at least 32. As demands change, more capacity can be added, either by simple equipment upgrades or by increasing the number of lambda’s on the fiber, without expensive upgrades. Bandwidth aside, DWDM’s technical advantages are transparency, scalability and dynamic provisioning.

DIGITALWATERMARKING

The growth of high speed computer networks has explored means of new business, scientific, entertainment, and social opportunities. Digital media offer several distinct advantages over analog media, such as high quality, easy editing, high fidelity copying. The ease by which digital information can be duplicated and distributed has led to the need for effective copyright protection tools. Various software products have been recently introduced in attempt to address these growing concerns. It is done by hiding data within digital audio, images and video files. One way such data hiding is copyright label or digital watermark that completely characterizes the person who applies it and, therefore, marks it as being his intellectual property. Digital Watermarking is the process that embeds data called a watermark into a multimedia object such that watermark can be detected or extracted later to make an assertion about the object. Watermarking is either visible or invisible. Although visible and invisible are visual terms watermarking is not limited to images, it can also be used to protect other types of multimedia object.

Datagram Congestion Control Protocol (DCCP)

Fast-growing Internet applications like streaming media and telephony prefer timeliness to reliability, making TCP a poor fit. Unfortunately, UDP, the natural alternative, lacks con- gestion control. High-bandwidth UDP applications must im- plement congestion control themselves a difficult task or risk rendering congested networks unusable. We set out to ease the safe deployment of these applications by designing a congestion-controlledunreliable transport protocol. The out- come, the Datagram Congestion Control Protocol or DCCP, addstoaUDP-like foundation the minimum mechanisms necessary to support congestion control.We thought those mechanisms would resembleTCPs,but without reliability and,especially,cumulative acknowledgements,we had to reconsider almost every aspect of TCPs design. The resulting protocol sheds light on how congestion control interacts with unreliable transport, how modern network constraints impact protocol design, and how TCPs reliable byte stream semantics intert wine with it so thermechanisms,including congestion control.

DNA AND DNA COMPUTING IN SECURITY

As modern encryption algorithms are broken, the world of information security looks in new directions to protect the data it transmits. The concept of using DNA computing in the fields of cryptography and steganography has been identified as a possible technology that may bring forward a new hope for unbreakable algorithms. Is the fledgling field of DNA computing the next cornerstone in the world of information security or is our time better spent following other paths for our data encryption algorithms of the future? This paper will outline some of the basics of DNA and DNA computing and its use in the areas of cryptography, steganography and authentication. Research has been performed in both cryptographic and steganographic situations with respect to DNA computing but researchers are still looking at much more theory than practicality. The constraints of its high tech lab requirements and computational limitations combined with the labour intensive extrapolation means, illustrate that the field of DNA computing is far from any kind of efficient use in todays security world. DNA authentication on the other hand has exhibited great promise with real world examples already surfacing on the marketplace today

Distributed Quota Enforcement for Spam

Spam, by overwhelming inboxes, has made email a less reliable medium than it was just a few years ago. Spam filters are undeniably useful but unfortunately can flag non-spam as spam. To restore email\'s reliability, a recent spam control approach grants quotas of stamps to senders and has the receiver communicate with a well-known quota enforcer to verify that the stamp on the email is fresh and to cancel the stamp to prevent reuse. . The literature has several proposals based on this general idea but no complete system design and implementation that: scales to today\'s email load (which requires the enforcer to be distributed over many hosts and to tolerate faults in them), imposes minimal trust assumptions, resists attack, and upholds today\'s email privacy. DQE\'s enforcer occupies a point in the design spectrum notable for simplicity: mutually untrusting nodes implement a storage abstraction but avoid neighbor maintenance, replica maintenance, and heavyweight cryptography.The DQE`s are based on a managed distributed hash table (DHT) interface, showing that it can be used in conjunction with electronic stamps (for quota allocation) to ensure that any non-negligible reuse of stamps will be detected

DecryptingContent-Scrambling System DeCSS

DeCSS is a computer program capable of decrypting content on a DVD-Video disc encrypted using the Content-Scrambling System (CSS).

Origins and history

DeCSS was devised by three people, two of whom remain anonymous. It was released on the Internet mailing list LiViD in October 1999. The one known author of the trio is Norwegian programmer Jon Lech Johansen, whose home was raided in 2000 by Norwegian police. Still a teenager at the time, he was put on trial in a Norwegian court for violating Norwegian Criminal Code section 145[1], and faced a possible jail sentence of two years and large fines, but was acquitted of all charges in early 2003. However, on March 5, 2003, a Norwegian appeals court ruled that Johansen would have to be retried. The court said that arguments filed by the prosecutor and additional evidence merited another trial. On December 22, 2003, the appeals court agreed with the acquittal, and on January 5, 2004, Norway's Økokrim (Economic Crime Unit) decided not to pursue the case further.

The program was first released on October 6, 1999 when Johansen posted an announcement of DeCSS 1.1b, a closed source Windows-only application for DVD ripping, on the livid-dev mailing list. The source code was leaked before the end of the month. The first release of DeCSS was preceded by a few weeks by a program called DoD DVD Speed Ripper from a group called Drink or Die, which didn't include source code and which apparently did not work with all DVDs. Drink or Die reportedly disassembled the object code of the Xing DVD player to obtain a player key. The group that wrote DeCSS, including Johansen, came to call themselves Masters of Reverse Engineering and may have obtained information from Drink or Die.

The CSS decryption source code used in DeCSS was mailed to Derek Fawcus before DeCSS was released. When the DeCSS source code was leaked, Fawcus noticed that DeCSS included his css-auth code in violation of the GNU GPL. When Johansen was made aware of this, he contacted Fawcus to solve the issue and was granted a license to use the code in DeCSS under non-GPL terms.

On January 22, 2004, the DVD CCA dropped the case against Jon Johansen BJ93GJCCMXAR

Direct sequence code division multiple access (DS-CDMA)

The ordinary CDMA technology has the disadvantage of identifying the users using the appropriate signature of each user. Since many users tend to use the transmission media, there is always a chance for superimposition of signals that can cause interference in network.

The solution for this inconvenience comes in the form of interleaving which separates the users. This special form of CDMA technology offers some of the features of CDMA such as the dynamic channel sharing, mitigation of cross cell reference, asynchronous transmission, ease of cell planning and robustness against fading, apart from the low cost interference cancellation technique available for systems with large number of users in multi path channels. Available with the second and third generation mobile phones, the cost per user of this algorithm is independent of the number of users. Giving a better performance along with the simplicity in usage it can maintain it’s low complexity and high performance even in multi path situations too.

dynode

A dynode is one of a series of electrodes within a photomultiplier tube. Each dynode is more positively charged than its predecessor. Secondary emission occurs at the surface of each dynode. Such an arrangement is able to amplify the tiny current emitted by the photocathode by typically one million.

DLP Projector

DLP Projector is an optical system driven by digital electronics. Its the only display solution that enables movie video projectors, televisions, home theater systems and business video projectors to create an entirely digital connection between a graphic or video source and the screen in front of you. At the heart of every DLP projection system is an optical semiconductor that manipulates light digitally known as the Digital Micromirror Device, or DLP chip which is a rectangular array of up to 2 million hinge-mounted microscopic mirrors( each of these micro mirrors measures less than one-fifth the width of a human hair. When a DLP chip is coordinated with a digital video or graphic signal, a light source, and a projection lens, its mirrors can reflect an all-digital image onto a screen or other surface. It has three key advantages over existing projection technologies. The digital nature of DLP enables digital gray scale and color reproduction and also positions DLP to be the final link in the digital video infrastructure. Because it is based on the reflective DMD, DLP is more efficient than competing transmissive LCD technologies. Finally, DLP has the ability to create seamless, film like images. DLP makes images look better. You\'ve heard the digital revolution, now see it with Digital Light Processing.

Need more information mail me or download this
http://www.infocomm.org/cps/rde/xbcr/infocomm/ProjectorTechnologyExplained.pdf
http://www.xilinx.com/esp/broadcast/collateral/projectors.pdf

Digital T.V

Broadcasters are concerned with many in-band and out-of-band transmission parameters, including data signal quality, clock tolerance, radiated power tolerance, carrier phase noise, adjacent channel emissions, and precision frequency offset requirements. The FCC permits DTV power-level changes and/or transmitting antenna location and height and beam tilt in the context of de minimise interference levels. The Advanced Television System Committee (ATSC) has provided guidelines for broadcasters in the form of suggested compliance specifications, which will be covered in this paper. On December 24, 1996, the FCC adopted the Advanced Television System Committee (ATSC) system (minus video formats) as the new digital television standard for the U.S. Shortly thereafter, on April 3, 1997, the FCC issued its rules for digital operation as well as its first set of channel allocations, loaning each U.S. broadcaster a second 6 MHz channel for digital television transmission. Subsequently, a revised set of allocations was issued in March 1998 with additional rules and changed rules, including a new transmission emission mask and potential increased transmission power provided new de minimise interference criteria are met. Terrestrial digital (DTV) broadcasting is now underway in the major markets in the United States after the Federal Communications Commission (FCC) in several Reports and Orders set the standard on December 24, 1996, and subsequently released rules of operation and broadcaster channel allocations. DTV broadcasters are mainly concerned about the in band and out of band parameters. The in-band parameters describe the signal quality. The important in-band parameters are spectral shape, data pulse shape, data eye pattern, transmitted power specifications etc. The out of band parameters include rigid TV emission mask, NTSC weighted out of band power, DTV un-weighted out of band power, beam tilt techniques etc.