The Importance of Satellite Communication and ICT

Published by Mr Ghaz
June 28, 2009, Category: Information

The function of an earth satellite station is to transmit and receive information frequency through microwave signals of a certain frequency. It has a large parabolic disc aerial. A communication satellite will amplify these microwave signals, convert them to another frequency and transmit them to other earth satellite stations. As the world becomes more sophisticated more modern communication methods and devices are introduced to the market.

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An artificial satellite is a spacecraft placed in orbit around the Earth or other planets. The electrical power required by satellite is provided by panels of solar cells and small nuclear reactors.

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Satellites

Satellites are kept in the correct position by small rocket motors called thrusters. They orbit with their disc aerials pointing to Earth. When the thrusters run out of fuel, the satellite eventually drifts out of position and becomes unusable. Satellites are equipped with radio transmitters, radio receivers and electronic circuits for storing data.

Communication satellite provide services such as relaying telephone conversations, transmitting television broadcasts around the world, sending computer data between relay stations on different continents and facsimile transmission. Information is transmitted using microwaves.

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Microwave signals

Microwave signals are used in satellite communication because they can travel far without being scattered by particles in the atmosphere and have very high frequencies in the atmosphere and have very high frequencies. They are also not reflected by the ionosphere. A satellite communication system consists of two systems: a) earth satellite stations b) communication satellites that occupy a special orbit called geostationary orbit.

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Geostationary Communication Satellites

The characteristics of a communication satellite are a) it orbits the Earth once every 24 hours b) it remains in the same spot above the Earth’s surface. It appears to be stationary in the sky. Hence transmitters and receivers on Earth do not need to move and track the satellite c) it orbits above the equatorial axis d) it orbits in the same direction and velocity as the earth and spins once in its axis. The world communication network uses at least three geostationary communication satellites.

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The Advantages of Satellites Communication

The advantages of using satellites for communication are as follows: a) the microwaves of used to carry information are not affected by the change of weather or hilly Earth surfaces b) only a small amount of energy is lost when the microwaves pass through the atmosphere c) more information can be transmitted compared to using metal cables d) the transmission covers a wide area, even in remote areas that have no communication lines e) live telecasts of some events can be broadcast simultaneously to various parts of the world.

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Other than communication, satellite are also used to: a) forecast weather conditions b) study and take photographs of structure on the surface of the Earth c) determine the position of objects such as ships, planes or vehicles on land d) carry out researches on celestial objects. Weather satellites photograph the Earth regularly in visible and infrared light. They provide data to weather stations on the Earth, thus enabling the forecast of weather conditions around the world.

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Navigation Satellites

Remote sensing satellite use high powered cameras to study the structure of the Earth’s surface as well as the chemical and air composition of the Earth’s surface. Navigation satellites provide time, position and velocity data for ships and planes. They also aid navigation by locating ice and mapping ocean currents. Scientific satellites enable scientists to make observations that are impossible to make from the Earth. X-ray and ultraviolet detectors are used to detect X-ray sources and gamma rays emitted by celestial objects.

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The Importance of Using ICT for the Benefit of Mankind

Old-fashioned communications involved the use of smoke, reflected lights, carrier pigeons, the post and the telegraph. The weaknesses in old fashioned communications are: a) it takes a long time to reach b) the amount of information that can be communicated is limited c) it is suitable for short distance communication only d) there is no guarantee of the safety of the message sent.

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Modern day communications is carried out through telecommunications. Information is transmitted over long distances by electric signals, radio waves or light. The most commons forms of telecommunications are by the telephone, radio, television and computer. Information may be sent in the form of analogue signals but nowadays most of the telecommunication signals used are digital.

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Telegraph: a) the first telegraph was invented by George Lesage in 1774 b) A telegraph transmits signals by cable or radio waves c) the information is sent along a signal wire as pulses of electric current d) Each letter of the alphabet or digit is represented by a different code of pulses e) in 1837, an American inventor, Samuel Morse, revised a standardized telegraph code known as the Morse code that eventually made possible the development of the electric telegraph throughout the world f) the Morse code uses dots and dashes to represent alphabets and numbers g) The weakness of the telegraph is that it cannot send symbols or pictures h) The telegraph lasted until the 1950s when international telephone links were established.

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Telephone: a) the telephone was invented by Alexander Graham Bell in 1876 b) the telephone transmits speech in the form of electrical signals c) the mouthpiece of the telephone has a tiny carbon microphone which will change sound waves into electrical signals d) the earpiece of the telephone has a tiny loudspeaker which changes electrical signals to the sound of the caller’s speech e) Conversation through telephone is transmitted through i) metal telephone lines ii) fiber optics iii) ultra high frequency radio waves to transmission disc or receiver disc on a telephone tower iv) microwaves to the satellite f) Metal telephone lines are slowly being replaced by fiber optics because fiber optics: can carry more telephone calls, have less interference during transmission and are cheaper to produce.

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Facsimile Transmission or Fax: a) facsimile transmission or fax is a system of sending information on paper through telephone lines b) A facsimile or fax machine transmits a copy of the document itself c) it can therefore transmit pictures d)the documents is scanned and the image is converted into electrical signals e) when the signals arrive at the telephone receiver of the fax machine, the signals are separated from the carrier wave or decoded and fed into the printer f) the printer prints out a copy of the original documents.

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Radio: a) the first person to develop practical radio equipment was Guglielmo Marconi b) information in the form of sound is transmitted from the transmitter to the receiver and it cannot transmit pictures c) radios transmit information with long waves, medium waves, short waves or very high frequency radio waves.

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Television: a) the television is a system used to broadcast moving pictures and sound by radio waves b) video signals from a TV camera and sound signals from a microphone are modulated with carrier waves before they are transmitted c) these are picked up the receiver’s TV aerial, demodulated and amplified to work the picture tube and loudspeaker of the TV set

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Computer: Computers are used to store and process data b) nowadays, a personal computer is used in communication through the Internet c) The Internet surfer needs to connect a modem to the computer d) the modem changes the information in the form of digital code to electrical signals before transmitting it through telephones lines e) the modem on the receiver computer will change the electrical signals back to digital code and display the information on the screen.

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Modern Communication Methods and Devices

As the world becomes more sophisticated more modern communication methods and devices are introduced to the market. Since the 1960s, satellites are used microwaves to relay information around the world. Most present day communication devices depend on satellites to transmit or receive information. Fiber optics was developed in the 1960s. They are capable of carrying many different types of communication via the same cable. The information is transmitted through a beam of light reflected along the insides of the cable.

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Digital Telephone

With the introduction of the digital telephone, analogue signals were replaced by digital signals in the form of electrical pulses. The pulses produce a series of digits in binary code. The series of digits represent any form of information including speech, music, pictures and printed text. Digital signals are less likely to be distorted compared to analogue signals.

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GPRS, MMS, WAP and VoIP

Present day hand phones are equipped with features that have more functions. Other than a camera and color display, digital music player and down-loadable ring-tones, more advanced hand phones are equipped with features such as GPRS, MMS, WAP and VoIP: a) GPRS or Global Positioning Remote Sensing enables us to locate the position of an object through the hand phone b) MMS or Multimedia Message Service enables us to use the hand phone to send pictures. We can see the receiver while talking using the headphone c) WAP or Wireless Application Protocol enables us to surf the Internet through the hand phone.

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LCDs or Plasma Television

CRT televisions are slowly being replaced by flat panel LCDs or plasma televisions. A more flat screen will reduce the distortion of images. Teletext services through televisions provide current information on share prices and commodities, the money exchange rate and others.

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Personal Digital Assistant (PDA) and Personal Computers

A PDA or Personal Digital Assistant is able to perform instant messaging between computers.

Modern day personal computers are able to perform more functions through the Internet: a) VoIP or Voice over Internet Protocol enables voice calls to be transmitted through the Internet b) we can communicate with people through the ICQ or MSN program c) on-line transactions can be carried out d) e-mails can also be used to send documents e) information can be obtained through web sites.