In digital and pulse waveform measurements, the time required for a pulse to transition from 10% to 90% of its final amplitude is defined as:

Introduction / Context:
Accurate time-domain characterization of digital signals requires standard definitions so different engineers and instruments report consistent results. One of the most common parameters is rise time, which captures how quickly a signal edge moves toward a new logic level.

Given Data / Assumptions:

• The pulse transitions from a lower steady value to a higher steady value.
• Standard measurement thresholds are 10% and 90% of the final amplitude.
• We are not measuring width, period, or duty cycle, but specifically the edge speed.

Concept / Approach:
Rise time focuses on the central part of the edge where the slope is most meaningful and least affected by noise or saturation. The 10% and 90% thresholds avoid slow tails and baseline jitter that can skew a 0%–100% metric.

Step-by-Step Solution:
Identify the lower level and final upper level of the transition.Compute 10% and 90% of the amplitude step.Measure the elapsed time as the waveform crosses from 10% to 90%.This elapsed time is, by definition, the rise time.

Verification / Alternative check:
Oscilloscopes typically provide automatic rise time measurements using these thresholds. Datasheets for logic families (e.g., CMOS, TTL) specify typical rise times in nanoseconds based on this standard.

Why Other Options Are Wrong:

• Pulse width: duration the signal stays in the active level; unrelated to edge speed.
• Propagation delay: time through a device from input transition to output response.
• Duty cycle: ratio of pulse width to period; again not an edge-speed metric.

Common Pitfalls:

• Using 0%–100% bounds increases sensitivity to noise; industry uses 10%–90% (or 20%–80%).
• Confusing rise time with bandwidth; while related, they are not the same measurement.

Final Answer:
rise time