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Sunday, July 13, 2008


INTRODUCTION: - The world is becoming smaller by each day, as many modes of communication are available today. In the Internet age of today, communication is very vital in day-to-day life. Electronic communication is the widely used communication system today. Two persons living in any nook and corner of the world can facilitate communication between them by the advanced communication technique i.e. wireless communication. The wireless communication includes satellite communication, cellular mobile, TV broadcasting, radio, computer etc.

The wireless communication system use communication medium as free space. They do not require wire for sending the information from one point to other. There are main five types of wireless communication. Satellite " Communication medium as free space. They do not required wires for sending the message from" Cellular mobile" RADAR" Computer" Broadcast The transmitted signal is in the form of electromagnetic wave. This system needs transmitting antenna at transmitter and receiving antenna at receiver.
a)-SATELLITE COMMUNICATION SYSTEM:- A satellite communication is a microwave repeater. It receives energy beamed up atin by an earth section, amplifies it and return it to the earth. The frequency difference between the up link and down link prevents the difference between the signals. A satellite is positioned at about 36000kms above the earth where it experiences veryLess gravitational pull of the earth.

" The information transmitted through earth station to satellite.1. Thus, the satellite may be thought of large repeaters in space that receives the modulated RF carrier in its up link frequency spectrum." Received signal at satellite amplifies and retransmits them back to the earth in downlink frequency spectrum." The signal at receiving earth station is processed to get original information." UP LINK:-uplink of a satellite is the one in which the earth station is transmitting the signal and the satellite is receiving it." DOWN LINK:-down link of a satellite is the one in which the satellite is transmitting it and earth station is receiving it.
Application of satellite communication:-1. Remote sensing and earth observation.2. Meteorological application.3. Military application.4. Scientific and technological applications.
b)-CELLULAR MOBILE:- Cellular mobile provides the standard telephone operation. The service area divides into many smaller areas known as cell, so the name cellular. The handset is movable so the name mobile.

This system consist of 5 major sections:-1. Transmitter: - transmit the original information through antenna to the receiver.2. Receiver: -the receiver is dual conversion superhectrodyne. The transmitted signal is demodulated here and is sent to the cell site so that MTSO can monitor the received signal from the cell and make decision about switching to another cell.3. Frequency synthesizer: - the frequency synthesizer section develops the entire signal used by transmitter and receiver. This sets the transmit and receive channel frequency.4. Logic unit: - the logic unit contains the master control circuitry for cellular mobile. It is made up of a microprocessor with both RAM and ROM puts additional circuitry used for interpreting signals from the MTSO/cell site and generating control signal foe the transmitter and receiver.5. Control unit: - the control unit contains the handset with speaker and microphone. The control unify operated by a separate microprocessor that drives the LCD display and other indicators. It also implements all manual control functions.

A basic cellular communication system consists of three parts.1. A mobile unit2. A cell site3. A mobile telephone switching office (MTSO)

A mobile unit: - a mobile telephone unit contains a control unit, transmitter, receiver and an antenna system.A cell site: - the cell site provides interface between the MTSO and the mobiles units. It has a control unit, radio, cabinets, antennas, a paper plant, and data terminals.MTSO: - the switching office, the control coordinating element for all cell sites, contains the cellular processor and cellular switch. It interfaces with telephone company zone offices, control cell processing and handless billing activities. The MTSO is the heart of the cellular mobile system.

The transition of binary data between computers is called Data communication. Computers are used telephone system as medium. Modems make the computers and telephone network compatible. Data communication also takes place over terrestrial microwave relay links and satellites.

d) RADAR: - RADAR means radio detection and ranging. This is a special form of communications that make use of reflected microwave signals for detecting ships, planes and missiles and also for determining ther range, direction and speed.
Application of RADAR: - 1. Military.2. Civilian's aircraft.3. Marine services.
e) BROADCAST: -One common transmitter but lots of receivers then system known as broadcasting. Commercial stations broadcast music, news entertainment, information and educational programs. For example. TV broadcasting. FM broadcasting. AM broadcasting.

Hence, we have studied the working and the different types of wireless communication in brief.

REFERENCE:- 1. Electronic communication system- George Kennedy

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