AN-3:Â An Adaptive Filtering Plug-In using the FFT
by Will Pirkle
This App Note is a continuation of AN-2 where the same side-chained FFT processing is used to analyze the input signal. In addition to showing the spectrum on the LED Meters, it also analyzes the FFT to find the highest amplitude frequency component. This is then used to set the center frequency of a notch filter to adaptively remove this component. The FFT is in a feed-forward side-chain. The reader is asked to explore the same look-ahead technique from Chapter 13 of my book to improve the tracking of the notch filter. With this App Note and Project as a basis, you can come up with a variety of side-chained FFT adaptive filters.