National Instruments Order Analysis Toolset - page 26

Chapter 2 Order Analysis
© National Instruments Corporation 2-11 LabVIEW Order Analysis Toolset User Manual
Figure 2-7. Padding Schemes
In zero padding, shown in Figure 2-7(a), the first window and the last
window only cover one data block each. The remaining area in the
range of the window is filled with zeros. Thus, extra data samples are
added. After Gabor expansion, the reconstructed data is longer than the
original data.
To avoid the reconstructed data being longer than the original data,
consider the signal as periodic and use wrap padding, shown in
Figure 2-7(b). In wrap padding, when the first few data blocks are
analyzed, data blocks at the end of the data samples are wrapped ahead
to fill the windows. You also can wrap data blocks backward from the
beginning of the data sample to the end.
Zeros 1 2 n–1 n Zeros
n–1 n 1 2 n–1 n 1
(a) Zero Padding
(b) Wrap Padding
Windows
Windows
Data Blocks
Data Blocks