The Sampling Theorem states that a bandlimited signal with maximum frequency Fh is completely specified by its samples taken at a rate of at least ...

The Sampling Theorem states that a bandlimited signal with maximum frequency Fh is completely specified by its samples taken at a rate of at least ...

• A. Fh
• B. Fh/2
• C. 2Fh
• D. 4Fh

Answer: (C)

The key idea is the Nyquist rate: to capture all information in a bandlimited signal without aliasing, you must sample at least twice the highest frequency present. When you sample, the spectrum repeats every Fs in frequency. To avoid overlap of the original spectrum with its copies, the sampling frequency must be at least 2Fh. If you sample at Fh or slower, the copies overlap and different frequencies become indistinguishable, causing aliasing. Sampling at 4Fh is also valid but unnecessary for perfect reconstruction; 2Fh is the smallest rate that guarantees it.