8. IIR Filters - Infinite Impulse Response - Digital Filter Basics

In this video, we'll subject an impulse signal through a first order feedback filter to get an impulse response, and we'll see why this response is called an infinite impulse response and what makes a filter unstable. We'll then briefly talk about the zeros and poles of a filter, and make a simple modification to create a p-z filter. We'll end the discussion with the advantages and disadvantages on an IIR filter.
Find the full playlist here: • An Introduction to Dig...
Content:
0:00 Impulse response
4:42 Poles and zeroes
8:41 p-z filter
9:27 Direct form 1 and 2
10:23 Bi-quads / Advantages
13:02 Disadvantages
Repository:
github.com/Thrifleganger/filt...
References:
Designing Audio Effect Plugins in C++, Will C. Pirkle -
www.willpirkle.com/about/books/
Digital Filters: A Practical guide, David Dorran
dx.doi.org/10.13140/RG.2.2.260...
In this series on Digital Filter Basics, we'll take a slow and cemented dive into the fascinating world of digital filter theory. Many resources present this topic with dense and exhausting mathematics. Although a fair understanding of complex mathematics is required to fully comprehend the science of filter design, understanding the basics of filters and how they fundamentally work is better left to analysis and visualizations, which I try to do in this series. We'll learn about feedforward and feedback filter topologies, impulse and impulse responses and and wide variety of other topics.
If you've got any questions, suggestions or recommendations, type them out here, or send me a message on any of my social channels mentioned below.
A lot of time was spent on creating this series, and I plan to do more. So please consider subscribing if you wish to be notified about more releases in the future. And if you feel generous: / akashmurthy
Check out my music here: farfetchd-official.bandcamp.com/
Check out the audio track in the intro and outro here: / tinderbox
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Website - www.akashmurthy.com/
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[@quanvo9454]

I'm having a Signal Processing final exam in an hour. Thank you very much for the series. It helped me build great intuition regarding the subject.

[@akashmurthy]

That's great, all the best for your exam!

[@baptistelegoff5606]

Finally a comprehensive and visual way to understand these concepts. Thanks !

[@akashmurthy]

Thank you, it's took it's time, but hopefully it'll be useful to beginners.

[@TheMasteringProject]

Long time awaited!

[@akashmurthy]

Long time indeed!

[@user-uk5ep9hm5k]

Very informative video. Thank you very much!

[@jayhu2296]

Another amazing video from Akash senpai 🤩

[@tillgo323]

So good man thank you these videos, should be on the ytube front page

[@itryforwhat]

This one really helps me a lot to understand IIR filter. Very glad if you can make a video about adaptive filter.

[@akashmurthy]

Thanks! Probably not going to do that in this series. This series is mainly about audio and with as little mathematics as possible.

[@HimanshuAtchutha]

great work! I finally understood what an IIR is

[@akashmurthy]

That's awesome!

[@ernestosteron]

You enlightened me!

[@akashmurthy]

Aww, thanks so much for the support!

[@hrushikway]

Thank you so much for such a clear explanation

[@akashmurthy]

You're welcome!

[@guillaume8437]

Hi. Thanks for this neat video. I am not sure that phase is not perceived by human ears... what I read in the past is that phase of an audio wave is synonym of distance. If you change the phase, you may change the 3D effect of the audio. If so, it would be even more perceptible if you have stereo... for example, the exact same wave (I mean, same frequency), but with difference of phase. You may feel your left ear is closer to the emitter than your right ear, or the other way round. Another approach that includes phase is group delay and phase delay. As said earlier, I do not master digital filters but I have way more experience in analog electronics and automation. I don't know much about digital filters as I only studied their theory at school but never have gotten the opportunity to run some practice around them.

[@akashmurthy]

Yea, change in phase of a signal is totally perceptible when summed up with other signals. Difference in phase is how we get filtering in the first place! What I mentioned in the video is that change in phase makes no perceptible difference when listening to a signal in isolation. Listening to a single mono signal in isolation, changing the phase is imperceptible.

[@Alexagrigorieff]

Fun fact: Although it's very well known that an IIR cannot have a constant group delay (linear phase response), you *can* have a constant (very close) group delay by applying an IIR to a *time-limited* signal in forward direction, making sure to keep filtering until the tail decays enough, and then in *backward* direction.

[@akashmurthy]

Yea that is a cool thing you can do, if the use case is non-real time.

[@chandankumarmishra336]

golden content

[@elsharko87]

This is amazing! Thank you! I like and I subscribe

[@akashmurthy]

Thanks for checking it out!