Detrending method in frequency analysis

・In Japanese
＜Premise knowledge＞
・Frequency analysis
・Effect of DC component
・least squares method

■What is detrending?

An offset-like element in a signal is called a DC component. How to remove the DC component when performing frequency analysis is explained here. A signal has a trend if the DC component changes with time as shown below. Explain how to remove the trend component. This is called detrending

■How to detrend

The detrending method is to find an approximation of this signal using the least squares method and subtract it from the original signal.



The results of frequency analysis of the above are as follows. Compared to before detrending, the frequency bands contained in the signal have changed. This is the actual frequency of the detrended signal.

■Notes on detrending

It is not necessarily better to remove the trend, and it is necessary to use it properly according to the purpose and application. Because this trend may contain important information and discoveries. It's good if the purpose of detrending is clear, but this trend can be useful when discovering new information from big data.

List of related articles TOP MENU Digital signal processing ・Frequency analysis ・Calculate the Fourier transform ・Detrending method ・Sampling theorem ・DC component ・Bilinear transform ・Floating point number ・Resolution, sampling period ・Fixed point number ・Digital Filter ・Octave analysis