This article is about dynamic analysis of A/D and D/A converters. This test method is based on applying a (pure) sinewave input signal to the converter and capture the conversion results.
For the dynamic parameter calculations the captured sinewave must converted to the frequency domain, using the (fast) fourier transform. See the first chapter.
In some situations it is not possible to capture an integer number of sinewaves. This will lead to spectral leakage. In these situations Signal windowing can be useful.