• Introduction.• Modes.• Cordless / Wireless.• History.• Applications Of Wireless Technology:- Mobile Telephones.- Wireless Data Communications.- Wireless Energy Transfer.
• Wireless telecommunications is the transfer of information between two or more points that are not physically connected. Distances can be short, such as a few meters for television remote control, or as far as thousands or even millions of kilometers for deep-space radio communications. It encompasses various types of fixed, mobile, and portable two-way radios, cellular telephones, personal digital assistants (PDAs), and wireless networking. Other examples of wireless technology include GPS units, Garage door openers or garage doors, wireless computer mice, keyboards and Headset (audio), headphones, radio receivers, satellite television, broadcast television and cordless telephones.
• Wireless communications can be via:• radio frequency communication,• microwave communication, for example long-range line- of-sight via highly directional antennas, or short-range communication,• infrared (IR) short-range communication, for example from consumer IR devices such as remote controls or via Infrared Data Association (IrDA).• Applications may involve point-to-point communication, point-to-multipoint communication, broadcasting, cellular networks and other wireless networks.
The term "wireless" should not be confusedwith the term "cordless", which is generallyused to refer to powered electrical or electronicdevices that are able to operate froma portable power source (e.g. a batterypack) without any cable or cord to limit themobility of the cordless device througha connection to the mains power supply.Some cordless devices, such as cordlesstelephones, are also wireless in the sensethat information is transferred from thecordless telephone to the telephones baseunit via some type of wireless communicationsink. This has caused some disparity in the usageof the term "cordless", for example in Digital EnhancedCordless Telecommunications.
# PhotophoneBell and Tainters photophone, of 1880.The worlds first wireless telephoneconversation occurred in 1880, when Alexander Graham Bell andCharles Sumner Tainter invented and patented the photophone, atelephone that conducted audio conversations wirelessly overmodulated light beams (which are narrow projections ofelectromagnetic waves). In that distant era when utilities did notyet exist to provide electricity, and lasers had not even beenconceived of in science fiction, there were no practicalapplications for their invention, which was highly limited by theavailability of both sunlight and good weather. Similar to freespace optical communication, the photophone also required aclear line of sight between its transmitter and its receiver. It wouldbe several decades before the photophones principles found theirfirst practical applications in military communications and later infiber-optic communications.
# Early wireless work• David E. Hughes transmitted radio signals over a few hundred yards by means of a clockwork keyed transmitter in 1879. As this was before Maxwells work was understood, Hughes contemporaries dismissed his achievement as mere "Induction". In 1885, Thomas Edison used a vibrator magnet for induction transmission. In 1888, Edison deployed a system of signaling on the Lehigh Valley Railroad. In 1891, Edison obtained the wireless patent for this method using inductance (U.S. Patent 465,971).• In the history of wireless technology, the demonstration of the theory of electromagnetic waves by Heinrich Hertz in 1888 was important. The theory of electromagnetic waves was predicted from the research of James Clerk Maxwell and Michael Faraday. Hertz demonstrated that electromagnetic waves could be transmitted and caused to travel through space at straight lines and that they were able to be received by an experimental apparatus. The experiments were not followed up by Hertz. Jagadish Chandra Bose around this time developed an early wireless detection device and helped increase the knowledge of millimeter length electromagnetic waves. Practical applications of wireless radio communication and radio remote control technology were implemented by later inventors, such as Nikola Tesla.
# Radio• Marconi did transmit the first radio signal across the Atlantic.• The term "wireless" came into public use to refer to a radio receiver or transceiver (a dual purpose receiver and transmitter device), establishing its usage in the field of wireless telegraphy early on; now the term is used to describe modern wireless connections such as in cellular networks and wireless broadband Internet. It is also used in a general sense to refer to any type of operation that is implemented without the use of wires, such as "wireless remote control" or "wireless energy transfer", regardless of the specific technology (e.g. radio, infrared, ultrasonic) used. Guglielmo Marconi and Karl Ferdinand Braun were awarded the 1909 Nobel Prize for Physics for their contribution to wireless telegraphy.
One of the best-known examples of wireless technologyis the mobile phone, also known as a cellular phone, withmore than 4.6 billion mobile cellular subscriptionsworldwide as of the end of 2010. These wireless phonesuse radio waves to enable their users to make phone callsfrom many locations worldwide. They can be used withinrange of the mobile telephone site used to house theequipment required to transmit and receive the radiosignals from these instruments.
Wireless data communications are an essentialcomponent of mobile computing. The various availabletechnologies differin local availability, coverage range and performance, and in somecircumstances, users must be able to employ multiple connection typesand switch between them. To simplify the experience for the user,connection manager software can be used, or a mobile VPN deployed tohandle the multiple connections as a secure, single virtual network.Supporting technologies include:Wi-Fi is a wireless local area network that enables portable computingdevices to connect easily to the Internet. Standardized as IEEE 802.11a,b,g,n, Wi-Fi approaches speeds of some types of wired Ethernet. Wi-Fihas become the de facto standard for access in private homes, withinoffices, and at public hotspots. Some businesses charge customers amonthly fee for service, while others have begun offering it for free in aneffort to increase the sales of their goods.Cellular data service offers coverage within a range of 10-15 miles fromthe nearest cell site. Speeds have increased as technologies haveevolved, from earlier technologies such as GSM, CDMA and GPRS, to 3Gnetworks such as W-CDMA, EDGE or CDMA2000.Mobile Satellite Communications may be used where other wirelessconnections are unavailable, such as in largely rural areas or remotelocations. Satellite communications are especially important fortransportation, aviation, maritime and military use.
Wireless energy transfer is a processwhereby electrical energy is transmitted from apower source to an electrical load that doesnot have a built-in power source, without theuse of interconnecting wires.
I hope you Liked itDone by: Esraa Ashraf Labib Second Grade. Dr. Dina Abo Zaid.