Saturday 24 March 2012

Basic Parameters of Communication System

Following are the most basic parameters of the communication system. We are going discuss all these one by one in detail.

a)   Bandwidth
b)   Transmit Power
c)   Signal to Noise Ratio

a)  Bandwidth

       Bandwidth is defined as " the range of frequencies required to represent original signal in time domain". This is the simplest definition of bandwidth.

As being engineer we'll use more technical definition of bandwidth which is :-

       " A ring of frequencies that falls in the amplitude of first and last by 3dB and 70% of energy left".

Some important points relating bandwidth are:-
i)   Rate of Transmission of data is directly proportional to bandwidth i.e wider the bandwidth ,
      more    data  will flow .

ii)  With wider bandwidth, there are less collisions and errors are minimum.

iii)  The bandwidth is chosen after detailed analysis which is enough for data to be transmitted. 
       This precaution is taken to avoid addition of noise since with the wider bandwidth thermal noise 
       increases. Hence thermal noise is directly proportional to bandwidth.


b)  Transmit Power

                 As the name suggests that it is the power required for transmission. Transmission power plays an important role due to its duality. 
        
               The increase in transmission power reduces the noise. Secondly information is transmitted more accurately and precisely.
      
      Usually binary (0,1) level transmission is done just to save transmission power. For example if we are going to transmit 4 bits of information withing 2 levels, 2 bits will be transmitted in one pulse width hence bandwidth will be two pulses.

         Suppose we transmit this in 4 levels , one pulse having one bit then transmit power will increase very fast which makes it more expensive system. Just to save transmission power and simplicity we use binary level at the expense of bandwidth.


c)  Signal to Noise Ratio :

     The performance of the system is defined by signal power to noise power ratio.
      Let So is the signal output power and Nois the noise output power then 
          

                                               is known as signal to noise ratio. 

       The greater the signal power less the noise power affects and systems performance is better
        and vice versa.


4 comments:

  1. You are writing great and technical. But very little information is given.

    May Allah strengthen you to complete dis , Ameen !

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    1. Thanks for Appreciation . M not finding time these days as working on my Final Year Project. I'll update all data soon.

      Freedom n Education for all is my Aim.

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