Every day, in our work and in our leisure time, we come in contact with and use a variety of modern communication systems and communication media, the most common being the telephone, radio, television, and the Internet. Through these media we are able to communicate (nearly) instantaneously with people on different continents, transact our daily business, and receive information about various developments and events of note that occur all around the world. Electronic mail and facsimile transmission have made it possible to rapidly communicate written messages across great distances.
ELEMENT OF COMMUNICATION SYSTEM
Information signal is given to the transmitter which then transmits the message over the medium to the receiver. Noise gets added up to the message in the channel. It degrades the transmitted information.
It has a collection of electronic components and circuits which are designed to convert information signal into electronic signals compatible with the medium.
It accepts the transmitted message and converts it back into an understandable form.
It is the medium by which electronic signal is sent from one location to the other. Signals which have to be transmitted are converted into electric and magnetic fields that propagate readily over long distances. Also, the medium attenuates the signal which results in the signal degradation. Finally the amplitude of the signal received will be much lower than original signal. Hence, the amplification of the signal should be done both at the transmitter and the receiver.
It is the unwanted electrical energy which gets added up with the information signal at the channel. E.g.: Noise due to lightening i.e., from the atmosphere, Internal noise due to internal agitation of atoms inside the components. Due to noise message may get completely missed or misinterpreted.
TYPES OF ELECTROMAGNETIC WAVES
For convenience, various types of EM radiations are classified according to their wavelength- or, equivalently, their frequency. The term electromagnetic spectrum is used collectively to describe EM waves of all frequencies. The table below list most of the common names used for EM waves in order of increasing frequency, with approximately frequency and wavelength limit. Radio, microwaves and infrared waves are commonly used for communication.
RADIO WAVE PROPAGATION MODE
Ground Wave Propagation
Follows contour of the earth Can Propagate considerable distances Frequencies up to 2 MHz Example : AM radio
Sky Wave Propagation
Signal reflected from ionized layer of atmosphere. Signal can travel a number of hops, back and forth. Examples SW radio
Transmitting and receiving antennas must be within line of sight example Satellite communication Ground communication
THE HISTORY/EVOLUTION OF COMMUNICATION SYSTEM IN MALAYSIA
The First Telegraph Line
The first telegraph line connecting from the British Resident at Perak house in Kuala Kangsar to the house of Deputy British Resident in Perak at Taiping by the Department of Posts and Telegraph in 1874. This telegraph line measured 42.5 km and travelled across forest at Bukit Berapit, it signalled the beginning of the era of telecommunications in Malaysia. However, during Japanese occupations, the telegraph lines were nearly broken down by the Japanese army. The Telecommunications In Malaysia
* In 1968, the SEACOM cable line was introduced, connecting the Peninsula Malaysia to Sarawak via the South China Sea. * In 1983, the Data Telecommunications System (Datel) was introduced. * In 1985, the ATUR, first wireless telephone system was introduced by Jabatan Telekom Malaysia (JTM). * In 1987, JTM was incorporated as Syarikat Telekom Malaysia Berhad (STMB) or Telekom Malaysia (TM) following the National Corporatization Policy, which was launched in the 1980s. * In 1988, Celcom Malaysia Sdn Bhd was...
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