recontrsuction of a discrete time signalusing an ideal D-to-C converter to find
ID: 2248568 • Letter: R
Question
recontrsuction of a discrete time signalusing an ideal D-to-C converter to find the original or equivalent continuous time signal requires the summation of scaled and time shifted pulses. for reconstruction of a discrete time signal using an ideal D-to-C converter check each true statement and leave unchecked each false statement.
1. perfect reconstruction requires interpolation by summing scaled and shifted ideal sinc pulses which are infinite length and therefore non-causal
2.practical reconstruction uses a realizable low pass filter or equivalently, it uses the low pass filter impusle response as the pulse to sum.
3.sampling slower improves the interpolation for each of the non-ideal interpolation methods
4.linear interpolation (triangular pulse) provides better reconstruction than zero-order hold interpolation (square pulse)
5.the reconstruction process in a practical system is a cascade of an anti-aliasing filter followed by an ADC.
Explanation / Answer
2,3 AND 5 STATEMENT IS CORRECT.
generally message signals are low frequency signal hence for reconstuction we are using LPF. but LPF are not ideal that is not having sharp cutoff frequency it having transition band also instead of sharp cutoff frquency hence to avoid aliasing effect we are using anti-aliasing filter.to avoid aliasing the samplig frequency must be greater than or equal of twice the frequency of message signal.
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