Optical Fiber

Opical Fiber

An optical fiber is a flexible, transparent fiber made of very pure glass (silica) not much wider than a human hair that acts as a waveguide, or "light pipe", to transmit light between the two ends of the fiber.The field of applied science and engineering concerned with the design and application of optical fibers is known as fiber optics. Optical fibers are widely used in fiber-optic communications, which permits transmission over longer distances and at higher bandwidths (data rates) than other forms of communication. Fibers are used instead of metal wires because signals travel along them with less loss and are also immune to electromagnetic interference. Fibers are also used for illumination, and are wrapped in bundles so they can be used to carry images, thus allowing viewing in tight spaces. Specially designed fibers are used for a variety of other applications, including sensors and fiber lasers.

Optical fiber typically consists of a transparent core surrounded by a transparent cladding material with a lower index of refraction. Light is kept in the core by total internal reflection. This causes the fiber to act as a waveguide. Fibers that support many propagation paths or transverse modes are called multi-mode fibers (MMF), while those that only support a single mode are called single-mode fibers (SMF). Multi-mode fibers generally have a larger core diameter, and are used for short-distance communication links and for applications where high power must be transmitted. Single-mode fibers are used for most communication links longer than 1,050 meters (3,440 ft).

Joining lengths of optical fiber is more complex than joining electrical wire or cable. The ends of the fibers must be carefully cleaved, and then spliced together either mechanically or by fusing them together with heat. Special optical fiber connectors for removable connections are also available.

Communication Devices

iPad Apple

The iPad (pronounced eye-pad) is a line of tablet computers designed, developed and marketed by Apple Inc. primarily as a platform for audio-visual media including books, periodicals, movies, music, games, and web content. Its size and weight falls between those of contemporary smartphones and laptop computers. The iPad runs the same operating system as the iPod Touch and iPhone—and can run its own applications as well as iPhone applications. Without modification, the iPad will only run programs approved by Apple and distributed via the Apple App Store (with the exception of programs that run inside the iPad's web browser).

Like iPhone and iPod Touch, the iPad is controlled by a multitouch display—a departure from most previous tablet computers, which used a pressure-triggered stylus—as well as a virtual onscreen keyboard in lieu of a physical keyboard. The iPad uses a wireless local area network("Wi-Fi") connection to access local area networks and the Internet. Some models also have a 3G wireless network interface which can connect to HSPA or EV-DO data networks and on to the Internet. The device is managed and synced by iTunes running on a personal computer via USB cable.

Apple released the first iPad in April 2010, and sold 3 million of the devices in 80 days.During 2010, Apple sold 14.8 million iPads worldwide,representing 75 percent of tablet PC sales at the end of 2010.

WiFi

Wi-Fi is a mechanism for wirelessly connecting electronic devices. A device enabled with Wi-Fi, such as a personal computer, video game console, smartphone, or digital audio player, can connect to the Internet via a wireless network access point. An access point (or hotspot) has a range of about 20 meters (65 ft) indoors and a greater range outdoors. Multiple overlapping access points can cover large areas.

"Wi-Fi" is a trademark of the Wi-Fi Alliance and the brand name for products using the IEEE 802.11family of standards. Wi-Fi is used by over 700 million people. There are over four million hotspots (places with Wi-Fi Internet connectivity) around the world, and about 800 million new Wi-Fi devices are sold every year.Wi-Fi products that complete Wi-Fi Alliance interoperability certification testing successfully may use the "Wi-Fi CERTIFIED" designation and trademark.

Modem

A modem (modulator-demodulator) is a device that modulates an analog carrier signal to encode digital information, and also demodulates such a carrier signal to decode the transmitted information. The goal is to produce a signal that can be transmitted easily and decoded to reproduce the original digital data. Modems can be used over any means of transmitting analog signals, from light emitting diodes to radio. The most familiar example is a voice band modem that turns the digital data of a personal computer into modulated electrical signals in the voice frequency range of a telephone channel. These signals can be transmitted over telephone lines and demodulated by another modem at the receiver side to recover the digital data.

Modems are generally classified by the amount of data they can send in a given unit of time, usually expressed in bits per second (bit/s, or bps). Modems can alternatively be classified by their symbol rate, measured in baud. The baud unit denotes symbols per second, or the number of times per second the modem sends a new signal. For example, the ITU V.21 standard used audio frequency-shift keying, that is to say, tones of different frequencies, with two possible frequencies corresponding to two distinct symbols (or one bit per symbol), to carry 300 bits per second using 300 baud. By contrast, the original ITU V.22 standard, which was able to transmit and receive four distinct symbols (two bits per symbol), handled 1,200 bit/s by sending 600 symbols per second (600 baud) using phase shift keying.

Internet Communication Technology

Facebook is a social networking service and website launched in February 2004, operated and privately owned by Facebook, Inc.As of July 2011, Facebook has more than 800 million active users.Users may create a personal profile, add other users as friends, and exchange messages, including automatic notifications when they update their profile.


Facebook was founded by Mark Zuckerberg with his college roommates and fellow computer science students Eduardo Saverin, Dustin Moskovitz and Chris Hughes.The website's membership was initially limited by the founders to Harvard students, but was expanded to other colleges in the Boston area, the Ivy League, and Stanford University. It gradually added support for students at various other universities before opening to high school students, and, finally, to anyone aged 13 and over. However, based on ConsumersReports.org on May 2011, there are 7.5 million children under 13 with accounts, violating the site's terms.

Blogger is a blog-publishing service that allows private or multi-user blogs with time-stamped entries. It was created by Pyra Labs, which was bought by Google in 2003. Generally, the blogs are hosted by Google at a subdomain of blogspot.com. Up until May 1, 2010 Blogger allowed users to publish blogs on other hosts, via FTP. All such blogs had (or still have) to be moved to Google's own servers, with domains other than blogspot.com allowed via Custom URLs.In July of 2011 a news outlet announced that Google intends to change the name of the service from "Blogger" to "Google Blogs," as part of a larger plan to re-brand or retire all non-Google brands in its portfolio of products and services.


On August 23, 1999, Blogger was launched by Pyra Labs. As one of the earliest dedicated blog-publishing tools, it is credited for helping popularize the format. In February 2003, Pyra Labs was acquired by Google under undisclosed terms. The acquisition allowed premium features (for which Pyra had charged) to become free. In October 2004, Pyra Labs' co-founder, Evan Williams, left Google. In 2004, Google purchased Picasa; it integrated Picasa and its photo sharing utility Hello into Blogger, allowing users to post photos to their blogs.

Skype ( /ˈskaɪp/) is a software application that allows users to make voice and video calls and chat over the Internet. Calls to other users within the Skype service are free, while calls to both traditional landline telephones and mobile phones can be made for a fee using a debit-based user account system. Skype has also become popular for its additional features which include ,instant messaging,file transfer, and video conferencing. Skype has 929 million registered users as of September 2011.The network is operated by Skype Limited, which has its headquarters in Luxembourg. Most of the development team and 44% of the overall employees of Skype are situated in the offices of Tallinn and Tartu, Estonia.


Skype was founded in 2003 by Niklas Zennström from Sweden and Janus Friis from Denmark.The Skype software was developed by Estonians Ahti Heinla, Priit Kasesalu and Jaan Tallinn, who were also behind the peer-to-peer file sharing software Kazaa.In April 2003, Skype.com and Skype.net domain names were registered. In August 2003, the first public beta version was released.

One of the initial names for the project was "Sky peer-to-peer",which was then abbreviated to "Skyper".However, some of the domain names associated with "Skyper" were already taken.Dropping the final "r" left the current title "Skype", for which domain names were available.

Twitter is an online social networking and microblogging service that enables its users to send and read text-based posts of up to 140 characters, informally known as "tweets".Twitter Inc,the company that operates the service and associated website, is based in San Francisco, with additional servers and offices in San Antonio, Boston, and New York City.

Twitter was created in March 2006 by Jack Dorsey and launched that July. Twitter rapidly gained worldwide popularity, with 200 million users as of 2011,generating over 200 million tweets and handling over 1.6 billion search queries per day.It is sometimes described as the SMS of the Internet.

Twitter's origins lie in a "daylong brainstorming session" held by board members of the podcasting company Odeo. Dorsey introduced the idea of an individual using an SMS service to communicate with a small group.The original project code name for the service was twttr, an idea that Williams later ascribed to Noah Glass,inspired by Flickr and the five-character length of American SMS short codes. The developers initially considered "10958" as a short code, but later changed it to "40404" for "ease of use and memorability."Work on the project started on March 21, 2006, when Dorsey published the first Twitter message at 9:50 PM Pacific Standard Time (PST): "just setting up my twttr".

"...we came across the word 'twitter', and it was just perfect. The definition was 'a short burst of inconsequential information,' and 'chirps from birds'. And that's exactly what the product was."--Jack Dorsey

Myspace (stylized as My_____ and previously MySpace)is a social networking service owned by Specific Media LLC and pop star Justin Timberlake.Myspace launched in August 2003 and is headquartered in Beverly Hills, California.In August 2011, Myspace had 33.1 million unique U.S. visitors.

In July 2005, News Corporation acquired Myspace and its parent company Intermix Media for $580 million.From 2005 until early 2008, Myspace was the most visited social networking site in the world, and in June 2006 surpassed Google as the most visited website in the United States.In April 2008, Myspace was overtaken by Facebook in the number of unique worldwide visitors, and was surpassed in the number of unique U.S. visitors in May 2009.Since then, the number of Myspace users has declined steadily in spite of several redesigns.As of October 2011, Myspace was ranked 103rd by total web traffic.

In August 2003, several eUniverse employees with Friendster accounts saw potential in its model and decided to mimic the more popular features of the social networking website. Within 10 days, the first version of Myspace was ready for launch, implemented using ColdFusion.A complete infrastructure of finance, human resources, technical expertise, bandwidth, and server capacity was available for the site. The project was overseen by Brad Greenspan (eUniverse's Founder, Chairman, CEO), who managed Chris DeWolfe (MySpace's starting CEO), Josh Berman, Tom Anderson(MySpace's starting president), and a team of programmers and resources provided by eUniverse.