NIELIT 2022 April Scientist B | Section B | Question: 93

Question

A bandlimited signal is sampled at the Nyquist rate. The signal can be recovered by passing the samples through :

• A. an $\text{RC}$ filter
• B. an envelope detector
• C. a $\text{PLL}$
• D. an ideal low-pass filter with the appropriate bandwidth

Answer 1

 

D.  An ideal low-pass filter with the appropriate bandwidth ….

 

A continuous-time signal can be represented in its samples and can be recovered back when sampling frequency fs is greater than or equal to twice the highest frequency component of the message signal …

 

i.e. fs ≥ 2 fm ...

Therefore when we want to convert continuous signals to discrete signals ….

The sampling must be done at the Nyquist rate.

If the low pass filter is not ideal, just sampling at the Nyquist frequency will not work we need to sample above the Nyquist frequency…