Wireless communication by fjzhangweiyun

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									A presentation by D.Shekhar
                  2nd b-tech
             CONTENTS

INTRODUCTION
ELECTROMAGNETIC SPECTRUM
MODES
WIRELESS NETWORKS AND SERVICES
APPLICATIONS
           Wireless communication

 Wireless telecommunication, is the transfer of
  information between two or more points that are
  physically not connected.
 Distances can be short, as a few meters as in
  television remote control; or long ranging from
  thousands to millions of kilometers for deep-space
  radio communications.
 Some examples of wireless technology are cordless
  telephones, satellite television broadcasting any
  many more.
        History of wireless communication

 The world's first wireless telephone conversation occurred 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.
 In the history of wireless technology, the demonstration of the theory
  of electromagnetic waves by Heinrich Hertz in 1888 was important.
 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.
 Guglielmo Marconi and Karl Ferdinand Braun were awarded the
  1909 Nobel Prize for Physics for their contribution to wireless
  telegraphy.
              Electromagnetic spectrum

 The electromagnetic spectrum is the range of all possible
  frequencies of electromagnetic radiation. Gamma radiation.
              MODES



Wireless communication is possible via,
  radio frequency communication,
     microwave communication,
       infrared communication
               Radio communication

    The major parts for a radio communication are
1.   Transmitter
2.   Resonant antenna
3.   Receiving antenna
4.   Detector sub-system
 The production of radio frequency alternating electrical energy at a
  transmitting station. Alternating currents are set up in the transmitting
  circuit, of suitable frequency and of great intensity (orhigh voltage).
  This insures a high rate of variation of the
  interlinked electrostatic and electromagnetic fields and a great
  magnitude of these variations.
 The radiation of this energy into space. The transmitting circuit is given a
  shape suitable for producing fields extending to great distances and
  generally in the direction of the receiving circuits more than in other
  directions.
 The absorption of a portion of this electromagnetic energy at the receiving
  stations and its transformation into some form of energy capable of affecting
  some one of the human senses. The receiving circuit is given such a shape
  and position as to link it with as large a proportion of the field of the
  transmitting circuit as possible.
               Microwave transmission

 Microwave transmission refers to the technology
  of transmitting information or power by the use of radio
  waves whose wavelengths are conveniently measured in small numbers
  of centimeters; these are called microwaves. This part of the radio
  spectrum ranges across frequencies of roughly 1.0 gigahertz(GHz) to
  30 GHz.
 Microwaves are widely used for point-to-point communications
  because their small wavelength allows conveniently-
  sized antennas to direct them in narrow beams, which can be
  pointed directly at the receiving antenna. This allows nearby
  microwave equipment to use the same frequencies without
  interfering with each other, as lower frequency radio waves do
Properties
 Suitable over line-of-sight transmission links without obstacles
 Provides large useful bandwidth when compared to lower frequencies (HF, VHF, UHF)
 Affected by the refractive index (temperature, pressure and humidity) of the atmosphere, rain (see rain
   fade), snow and hail, sand storms, clouds, mist and fog, strongly depending on the frequency.
Uses
 [Wireless]] transmission of information
 One-way (e.g. television broadcasting) and two-way telecommunication using communication satellite
 Terrestrial microwave radio broadcasting relay links in telecommunications networks including e.g.
   backbone or backhaul carriers in cellular networks linking BTS-BSC and BSC-MSC.
 A parabolic antenna for Erdfunkstelle Raisting, based in Raisting, Bavaria, Germany.
 Military microwave set in Switzerland
 Wireless transmission of power
 Proposed systems e.g. for connecting solar power collecting satellites to terrestrial power grids
             Infrared communication

 Infrared (IR) light is electromagnetic radiation with
  a wavelength longer than that of visible light, measured
  from the nominal edge of visible red light at
  0.74 micrometers, and extending conventionally to
  300 micrometers.
 IR data transmission is also employed in short-range
  communication among computer peripherals and personal
  digital assistants. These devices usually conform to
  standards published by IrDA,(the Infrared Data
  Association).
Remote control using infrared


                MAIN COMPONENTS:
                1. Buttons
                2.Integrated circuit
                3.Button contacts
                4.Light-emitting diode
                (LED)
               Remote control using IR

 Pushing a button on a remote control sets in motion a series of
  events that causes the controlled device to carry out a command.
  The process works something like this:
 You push the "volume up" button on your remote control,
  causing it to touch the contact beneath it and complete the
  "volume up" circuit on the circuit board. The integrated circuit
  detects this.
 The integrated circuit sends the binary "volume up" command
  to the LED at the front of the remote.
 The LED sends out a series of light pulses that corresponds to
  the binary "volume up" command.
Services provided by wireless
technology
 Infrared ultrasonic remote control devices.
 Cordless computer peripherals.
 Satellite television broad cast.
 Global positioning system.
 Telemetric control and traffic control systems.
Wireless networking
 Wireless network refers to any kind of computer network
  that is not connected by any kind.
 Some types of wireless connections are wireless-
  PAN,LAN,WAN,MAN and mobile devices networks.
 Uses:
    used mostly for cellular communication, inter continental
  network systems.
Applications of wireless technology
 Security systems
 Mobile telephones
 Wireless data communications
 Broadcasting
 Sensor networks.
shekhar

								
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