Signal extension methods pad the borders of a signal to lessen discontinuity that might exist at the beginning and end of the signal.

Note This topic contains information that applies to the LabVIEW Time Frequency Analysis Tools and the LabVIEW Wavelet Analysis Tools.

The Time Frequency Analysis Tools and Wavelet Analysis Tools provide the following three extension methods:

  • Zero—Uses zeros to pad the borders of a signal.
  • Symmetric—Replicates a signal to pad the borders of that signal. The symmetric extension method left-flips the signal replication at the beginning of the signal and right-flips the signal replication at the end of the signal.
  • Periodic—Replicates a signal to pad the borders of that signal. The periodic extension method adds a signal replication before the signal and another signal replication after the signal.

    • The following figure shows a linear chirp signal and the extended versions of this signal with the zero, symmetric, and periodic padding methods.

    Figure 1. Linear Chirp Signal with Zero, Symmetric, and Periodic Padding

    In the previous figure, the linear chirp signal appears from 100 s to 355 s. Notice the appearance of the extended signal when different extension methods pad the signal before 100 s and after 355 s.