WIRELESS
Published on Nov 25, 2015
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PRESENTATION OUTLINE
Wireless communication is the transfer of information between two or more points that are not connected with wires.
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HISTORY OF WIRELESS
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PHOTOPHONE
The world's first wireless telephone conversation happened in 1880, when Alexander Graham Bell and Charles Sumner Tainter invented and patented the photophone, a telephone that conducted audio conversations wirelessly over modulated light beams. There were no practical applications for their invention because it was too ahead for the times, however the photophone was highly limited by the climate. The photophone also required a clear line of sight between the two station. It would be several decades before the photophone's principles found their first practical applications in military communications and later in fiber-optic communications.
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EARLY WIRELESS WORK
David E. Hughes transmitted radio signals over a few hundred yards by means of a clockwork keyed transmitter in 1878. In 1885, Thomas Edison used a vibrator magnet for induction transmission. In 1888, Heinrich Hertz demonstrated the existence of electromagnetic waves, the basis of most wireless technology. Hertz demonstrated that electromagnetic waves traveled through space , could be transmitted and received by an experimental device.
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RADIO
In 1895 Marconi was field testing his system but even with improvements he was only able to transmit signals up to 800m, . Marconi raised the height of his antenna and hit upon the idea of grounding his transmitter and receiver. With these improvements the system was capable of transmitting signals up to 3.2 km and over hills. Marconi would go on to win the Nobel Prize in Physics in 1909.
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FREE SPACE OPTICAL COMMUNICATION
Free-space optical communication (FSO) is an optical communication technology that uses light propagating in free space to wirelessly transmit data for telecommunications or computer networking. "Free space" means the light beams travel through the open air or outer space. The technology is useful where physical connections are impractical due to high costs or other considerations. For example free space optical links are used in cities between office buildings which are not wired for networking, where the cost of running cable through the building and under the street would be impossible.
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SONIC
Sonic, especially ultrasonic short range communication involves the transmission and reception of sound (submarine radar).
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ELECTROMAGNETIC INDUCTION
Electromagnetic induction is a short range communication. This has been used in biomedical situations such as pacemakers, as well as for short-range RFid tags.
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GLOBAL POSITIONING SYSTEM
It allows drivers of cars and trucks, captains of boats and ships, and pilots of aircraft to ascertain their location anywhere on earth.
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WIRELESS COMPUTER PERIPHERALS
The wireless mouse is a common example; keyboards and printers can also be linked to a computer via wireless using technology such as Wireless USB or Bluetooth
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SATELLITE TELEVISION
Channels are broadcasted from satellites in geostationary orbit. Typical services use direct broadcast satellite to provide multiple television channels to viewers.
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ELECTROMAGNETIC SPECTRUM
Light, colors, AM and FM radio, and electronic devices make use of the electromagnetic spectrum. The frequencies of the radio spectrum that are available for use for communication are treated as a public resource and are regulated by national organizations. This determines which frequency ranges can be used for what purpose and by whom. In the absence of such control or alternative arrangements such as a privatized electromagnetic spectrum, chaos might result if, for example, airlines didn't have specific frequencies to work under and an amateur radio operator were interfering with the pilot's ability to land an aircraft. Wireless communication spans the spectrum from 9 kHz to 300 GHz.
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APPLICATIONS OF WIRELESS TECHNOLOGY
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MOBILE TELEPHONES
One of the best-known examples of wireless technology is the mobile phone, also known as a cellular phone, with more than 4.6 billion mobile cellular subscriptions worldwide at the end of 2010. These wireless phones use radio waves to enable their users to make phone calls from many locations worldwide.
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WIRELESS DATA COMMUNICATIONS
Wireless data communications are an essential component of mobile computing. The various available technologies differ in local availability, coverage range and performance, and in some circumstances, users must be able to employ multiple connection types and switch between them.
Wi-Fi is a wireless local area network that enables portable computing devices to connect easily to the Internet.
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Standardized as IEEE 802.11 a,b,g,n, Wi-Fi approaches speeds of some types of wired Ethernet. Wi-Fi has become the de facto standard for access in private homes, within offices, and at public hotspots. Some businesses make customers pay a monthly fee for service, while others have begun offering it for free in an effort to increase the sales of their goods.
Cellular data service offers coverage within a range of 10-15 miles from the nearest cell site. Speeds haveincreased as technologies have evolved, from earlier technologies such as GSM, CDMA and GPRS, to 3G networks such as W-CDMA, EDGE or CDMA2000, HSDPA,HSUPA, and the latest 4G.
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Mobile Satellite Communications may be used where other wireless connections are unavailable, such as in largely rural areas or remote locations. Satellite communications are especially important for transports, aviation, maritime and military use.
Wireless Sensor Networks are responsible for sensing noise, interference, and activity in data collection networks. This allows us to detect relevant quantities, monitor and collect data, formulate meaningful user displays, and to perform decision-making functions.
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WIRELESS ENERGY TRANSFER
Wireless energy transfer is a process where electrical energy is transmitted from a power source to an electrical load that haven't a built-in power source, without the use of interconnecting wires. There are two different fundamental methods for wireless energy transfer. They can be transferred using either far-field methods that involve beam power/lasers, radio or microwave transmissions or near-field using induction. Both methods utilize electromagnetism and magnetic fields.
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WIRELESS MEDICAL TECHNLOGY
New technologies such as mobile body area networks (MBAN) allow us to monitor blood pressure, heart rate, oxygen level and body temperature, all with wireless technologies. The MBAN works by sending low powered wireless signals to receivers that feed into nursing stations or monitoring sites. This technology helps with the intentional and unintentional risk of infection or disconnection that arise from wired connections.
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