Tutorial - A very very simple filter

jorge · 13 Feb 2004

Gustavo, this very simple schematic might help you understand how filters work:

[old link]

here is a screen capture of it:

The filter response is done with an FFT component which presents a mirrored image, so think of the highest frequency as being in the middle.

the important part is inside the simpleFilter module:

basically two consecutive samples are being added, as the multiplier for the delayed sample is 1, when you have the maximum frequency: 1,-1,1,-1, it gets completely canceled, it is basicaly a lowpass filter.

when the multiplier is -1 you get the following response:

so with a multiplier of 1 we get a lowpass filter, and for a multiplier of -1 we get a highpass filter