Definition of a frequency counter: A frequency counter is a digital circuit that measures and displays the frequency of an input signal by counting cycles over a known time base. Evaluate this definition for correctness.

Introduction / Context:
Frequency counters are ubiquitous test instruments in labs and embedded systems. They rely on precise time bases to translate counts of periodic events into a frequency value that can be displayed numerically.

Given Data / Assumptions:

• The input signal is periodic with a frequency in the counter’s operating range.
• A stable reference oscillator defines the measurement gate time.
• Input conditioning circuitry shapes the signal to logic levels so edges can be counted reliably.

Concept / Approach:
By counting the number of input cycles N within a gate interval T_gate, the instrument computes f ≈ N / T_gate. Alternatively, some counters measure the period and invert it, which improves resolution at low frequencies (reciprocal counting). Both approaches fulfill the stated definition.

Step-by-Step Solution:

Verification / Alternative check:
Datasheets for bench frequency counters and MCU-based counters outline exactly this method, sometimes adding averaging, prescalers, or reciprocal techniques for improved resolution.

Why Other Options Are Wrong:

Common Pitfalls:
Measuring noisy or non-periodic signals; inadequate input conditioning causing false counts; relying on short gate times that magnify quantization error.

Final Answer:
Correct