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Description of  Data Communication & Computer Network

Definition of termsi) NetworkA colection of independent entities that are arranged in such a manner to exchange data,information or resources e.g Road networks, telephone networks.ii) Computer networksA collection of computers linked together using transmission media for the purpose of communication and resource sharingiii) Transmission Mediais a physical and non-physical link between two or more computers and in which a signal can be made to flow from source to destinationiv) Resource SharingIs the sharing of the resources that are attached to the network for access by users eg file, printers , data, application programs etcv) Data CommunicationA process of transmitting data signal from one point to anothe through the networkvi) TelecommunicationThe communication i.e. transferring of data and information over significant distances is known as telecommunication.Image result for computer networkingAdvantages of computer network are: Data and software of computer can be shared with other computer on the network. Only the authorized user of a network can use the facilities of the network. Computers on the network can communicate with each other.The disadvantages of computer network are: Data and information may be stolen by computer hackers if the security of network is not reliable. If any computer in a network gets affected by computer virus, there is high chance of spreading computer viruses on the other computer. Computers on the network have to depend on the server computer for resources. This sharing of information may leak the privacy of other clients.Explain how computer network reduce expences in an office.- Computer Networks can allow businesses to reduce expenses and improve efficiency by sharing data and common equipment, such as printers, among many different computers. At the same time, the network may be connected through cables, telephone lines, infrared beams etc, which is cheaper and helps to reduce the expenses.TERMS USED IN DATA COMMUNICATIONi) Data siganalIs a voltage signal level in the circuirt which represents the flow of data. This can be either Analog orDigital in natureii) Signal mgnaodulation and DemodulationIs a process of converting data signal to and from a form that is suitable for transmission over atransmition medium.MODEM - Converts digitl signal by superimposing it on an analog carrier signal which is trnsmittedover analog telephone line. A process known as ModulationA modem at the receiving end converts the analog signal into digital form a process calledDemodulation.iii) MultiplexingIs a process of sending multiple data signals over the same medium e.g a wire conductor can carry several data signal either simultenously or at differenet times.DemultiplexingA preocess of seperating the multiplexed signals at the receiving end.Image result for multiplexingiv) bandwidth- Is a maximun amount of data that the trnsmission medium can carry at any one time. e.g a cable having a bandwidth of 100 mbps.v) Basesband- A digiltal signaal that is generated and applied to transmission medium directly without modulation.- It utilises the full capacity of transmission medium hence at any time, only one signal can be sent unless they are multipled.vi) Attenuation/ Signal loss- Is the decrease in magnitute and energy as a signal progressively move along a transmission medium. The signal is not boosted, it will totally be lost along the way and may never reach the destination.- It corrected by placing a signal amplifier ( repeater station) along the medium at appropriate distances in order to receive the wek signal, clean it, amplify it then restart it.