Nyquist frequency — best practical description for setting a sampling rate Which statement best reflects the role of the Nyquist concept when deciding a sampling frequency for an analog signal?

Introduction / Context:
Strictly, Nyquist frequency is defined as half the sampling rate (fs/2). In practice, to avoid aliasing, engineers ensure the sampling rate exceeds twice the highest frequency component present in the analog signal. Thus, identifying the signal’s highest frequency component is central to choosing fs.

Given Data / Assumptions:

• Sampling theorem: fs >= 2 * f_max (with real-world margin).
• Anti-alias filter limits input spectrum to f_max.
• We use the signal’s content to set a required fs.

Concept / Approach:
Because Nyquist frequency = fs/2, it must be greater than or equal to f_max to sample without aliasing. Identifying the highest frequency component of the signal (f_max) therefore informs the Nyquist condition for selecting fs.

Step-by-Step Solution:
Determine f_max of the analog signal.Apply condition → fs/2 >= f_max (practically fs ≥ 2.2–2.5 * f_max or more).Conclude → the relevant descriptor is “the highest frequency component of the analog signal.”

Verification / Alternative check:
Check that anti-alias filters roll off content above f_max; then choose fs accordingly to exceed twice f_max.

Why Other Options Are Wrong:

• Resonance, second harmonic, or “lower frequency limit” do not define Nyquist relations for sampling.

Common Pitfalls:
Equating “Nyquist frequency” with “signal frequency”; Nyquist is tied to sampling rate, but system design revolves around f_max.

Final Answer:
The highest frequency component of a given analog signal