Question

Prior to sampling, the type of filter used to attenuate high frequency components of the signal that lie outside the band of interest is

• A. Lowpass aliasing
• B. Highpass aliasing
• C. Lowpass anti-aliasing
• D. Highpass anti-aliasing

Hint:

Before sampling: \[ f_s \ge 2f_m \] and a low-pass anti-aliasing filter is used to remove unwanted high-frequency components.

Answer 1

The Correct Option is C

Concept: Aliasing occurs when frequencies above the Nyquist frequency overlap into the desired spectrum after sampling. To prevent this, a filter is used before sampling.

Step 1: Identify the required filter.
The filter must remove frequencies above the signal bandwidth. Hence it should be a low-pass filter.

Step 2: State its purpose.
Since it prevents aliasing, \[ \boxed{\text{Anti-aliasing Filter}} \] is the correct name.

Step 3: Final Answer.
\[ \boxed{\text{Low-pass Anti-aliasing Filter}} \] Hence, \[ \boxed{\text{Correct Option (C)}} \]