An RF duty cycle counts how much of the total cycle time is spent actively pulsing, so a higher duty fraction means more RF energy delivered per cycle. The two RF windows run 0 to 2 s and 6 to 8 s, giving 4 s of active time out of a 10 s cycle for a duty fraction of 2/5 exactly for the stated toy schedule ledger; real instruments have trigger latency, clock jitter, RF settling, thermal limits, and calibration tolerances.
An ideal RF control line is checked as on and off windows. Exact arithmetic here means exact results for the stated model inputs; measured inputs still carry uncertainty and significant-figure limits.
highlighted = computed this step
Control windows have endpoints
The first RF window runs from 0 s to 2 s. The second runs from 6 s to 8 s.
ttotal=10s
Duty fraction is active time over total time
The active time is 4 s out of 10 s, so the duty fraction is 2/5. This is a control schedule, not a spin-rotation model.