Nyquist criterion states the minimum sampling frequency Fs must be at least twice the bandwidth of the signal. Which option reflects that requirement?

Nyquist criterion states the minimum sampling frequency Fs must be at least twice the bandwidth of the signal. Which option reflects that requirement?

• A. A Fs must be at least twice the bandwidth
• B. B Fs must be equal to the bandwidth
• C. C Fs must be less than the bandwidth
• D. D Fs must be four times the bandwidth

Answer: (A)

To avoid aliasing when sampling, the rate must be at least twice the highest frequency present in the signal (twice the bandwidth for a bandlimited signal). This minimum, known as the Nyquist rate, ensures the spectral replicas created by sampling don’t overlap, so the original signal can be reconstructed from its samples. Therefore, the statement that Fs must be at least twice the bandwidth captures this minimum requirement. If you used Fs equal to the bandwidth, or less, aliasing would occur; a rate of four times the bandwidth would work but is not the minimum needed.