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Wednesday 4 September 2013

IGNOU BCA 4th sem Solved Assignment - Explain the process of sampling used digital communication

Explain the process of sampling used digital communication
Ans
To understand sampling theorem you need to know first what is sampling. Sampling is a process where you convert continuous time signals(analog signals) into discrete time signals(digital system). On paper CT signals are represented by "full lines" where as DT signals are only "points" chosen from the original CT signals. Now it is clear that DT signals are a rough representation of thier respective CT signals. Now the question arises, why do we need sampling? We need it because it is very efficient to use "rough" DT signals in telecommunication instead of "precision" CT signals. Now you may ask, if we're use "rough" DT signals doesn't the information that is to be transmitted and henceforth recieved is also "rough" or inaccurate? That's where the sampling theorem comes in.
The sampling theorem gives you a rule using which you can use DT signals to transmit/recieve the information accurately. ST simply states that the 'sampling frequency' should be greater than or equal to twice the frequency of the CT signal, where sampling frequency is frequency of sampled signals(DT signals) to be obtained by sampling.  It simply means that when you're taking samples(choosing those "points" from "full line") from the CT signal, do it in such a manner that the samples("chosen points") are more closely spaced. And also take higher number of samples(that is choose higher number of points from the CT signal)

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