Complex sentence: The duration of the measurement pulse and the data sampling interval create a resolution limitation for OTDRs: the shorter the pulse duration and the shorter the data sampling interval, the better the instrument resolution, but the shorter the measurement range.
Split into simpler sentences: The duration of the measurement pulse and the data sampling interval create a resolution limitation for OTDRs. The shorter the pulse duration and the shorter the data sampling interval, the better the instrument resolution, but the shorter the measurement range.