Computer Networking 

      COMPUTER NETWORKIN G

COMMUNICATION

.A process in which one computers transfers data instruction , and information to another computers .

.The system by which information is transmitted at one place and receive at another distant place  is called communication .The setup used from communication is know as communication system .

.Every  communication system has three elements , a transmitter , channel and receiver .

ELEMENTS OF COMMUNICATION SYSTEM

1.  TRANSMITTER

Transmitter is an extremely important equipment which convert the information signal into suitable form for transmission through the channel . The important components of transmitter channel are Microphone audio amplifier , oscillator and modulator .

2.   COMMUNICATION CHANNEL OR MEDIUM

The channel is a physical medium that connect a transmitter to a receiver .The message signal , transmitted by transmitter reaches the receiver through a channel .The channel may be in the form of wires or cables  connecting  the transmitter are receiver may be wireless .

3.  RECEIVER

. It is a setup which first receive the transmitted signal form the communication channel and them converts back to their orginal form .

. This process is called Modulation or Detection .

. This Orginal Signal is amplified by amplifier and them transmitted to the sound speaker which converts the signals into information of sound wave .

  BASIC MODES OF COMMUNICATION

A.POINT TO POINT COMMUNICATION MODE

Communication takes place between single transmitter and single receiver Telephone and cell phone are example of point to point communication system .

B. BOARDCAST COMMUNICATION MODE

There are large number of receivers corresponding to single transmitter .

Radio, Television are example of Boardcast communication system .

                       Guided Media

In this type of media , signal  energy is enclosed and guided within a solid medium . The guided media is used either for point to point link or a shared link with various connection .In guided media , interference is generated  by emission in the adjacent cables . Proper shielding of guided media is required to reduce the interference issue .

                      Unguided Media

      In the unguided media , the signal energy propagates through a wireless medium . The wireless media is used for radio board casting  in all directions Microwave links are chosen for long distance board casting  transmission unguided media . Interference is also a problem in unguided media overlapping frequency bands from competing singles can alter or elimate  a signal .

         Transmission Impairment in Data Communication

In communication system , analog signals travel through transmission media , Which tends to deteriorate the quality of analog signal , which means that the signal at the beginning of the medium is not the same as the signal at the end  of the medium . The imperfection causes signal impairment . Below are the causes of the impairment .

Causes of impairment are

. Attenuation

.Distortion

.Noise