In this post, we discover how to use a filter’s impulse response to filter a signal. Included in the post are snippets of JavaScript code demonstrating how you can write your own FIR filter.

Filters are practical things. Therefore they need to work in the real world. How can we turn a mathematical equation into something that actually works?

How to use the inverse Fourier Transform to tailor the impulse response of our filter to give us the frequency response we are looking for.

How do FIR filters work? If you’ve ever calculated a running average, then you have a partial answer to this question. We look how a running average is a sort of convolution, and convolution is how FIR filters work.