Removing linear trend |

If linear trend appears in the signal (i.e. the whole signal raises or falls monotonously), it can
affect the calculation of low frequency components in the FFT. With the help of *Signal
tools/Remove linear trend *option, you can transform the origin signal to a new signal without
linear trend. That signal can be used for further analysis. Linear trend will be removed by
subtracting signal’s linear least squares approximation from the
original signal.

If you want this operation to be performed before each FFT calculation, you can set it in __Spectral
analysis defaults __.