Applied DSP No. 4: Sampling and Aliasing

Applied Digital Signal Processing at Drexel University: In this video, I discuss the unintended consequences of sampling, aliasing.
== Errata ==
Starting around 12:30, the amount of audio aliasing is much greater than indicated in the animation, due to a bug in my resampling code. I'm currently investigating and hope to post a link to a corrected video soon. My thanks to ytubeleo for the catch!
==
I'm teaching the course again this Fall (September 2022), so I really will be posting more in this series in the coming weeks. Now would be a great time to subscribe to my channel, @Youngmoo Kim , for updates. Please leave feedback in the comments and let me know if there are DSP topics you'd like to see in future videos!

[@IW2MXP]

I lov the animated graphics of your videos and the way of explaining DSP deals. Great lessons. Thank you, Kim. Go ahead and Jump!

[@hahahahahasjovt]

This is honestly the best explained series I have yet to see on youtube. Good job!

[@andrielmontenegro2027]

Is there another series that the Guy gets even close to this one? Because he just stopped to post :(

[@youngmoo-kim]

@@andrielmontenegro2027 Sorry, I got sidetracked with other projects. Just posted a new video today… I’m teaching the class again the Fall term, so there will be more videos coming soon!

[@andrielmontenegro2027]

@@youngmoo-kim you have made my Day, tks, looking forward to it

[@siddhanthramani5084]

Yes! Hidden gem. I hope more people will get to see it. The graphics are good and minimalist. The explanation crisp. And the simulations are spot on for understanding. @@youngmoo-kim Please do make more videos when you have the time on fundamental concepts. I do not know how the youtube algorithm works. But maybe you can try advertising it to students in universities, etc. I would also be happy to help in any way possible.

[@dakotahrivers6640]

dude that aliasing visualization at 11:55 blew me away. It all made sense in that instant. It's the low end being reintroduced from the high end of the spectrum due to the negative frequency components. That taught me what 2 courses in signals/systems classes at university couldnt

[@nepomukullmann3013]

I have recently taken a uni class on this and I must commend the way you explain! Also one of if not the best intro on all of youtube haha amazing

[@justinwong3280]

Great series! Really helpful and easy to understand for a beginner.

[@OdoSendaidokai]

Great explanation! Thank you!

[@velvetsound]

This is incredible. Please make more!

[@austin_ma]

These are so high quality

[@RooftopDuvet]

Really well paced and animated. Well done, and thanks!

[@BroAlex2077]

Awesome series! Thank you for your work.

[@StephanBuchin]

Great work and excellent videos, clear and concise. Thx ☺

[@ytubeleo]

At 12:15, I think the sampling rate numbers must be a bit out of sync with what we are hearing because there is obvious aliasing even when it says 44.1 kHz, and the aliasing is already bad at 40 kHz. If CD audio has no frequencies above 20 kHz (which it shouldn't by standard), then there shouldn't be any aliasing at all if we sample it at 40 kHz. And even at 36 kHz, a 20 kHz sine wave should reflect off the 18 kHz Nyquist limit and become 16 kHz, which is extremely high frequency and almost inaudible for most adults. Yet the aliasing sounds far lower in frequency. Or maybe something is going wrong when you convert it back into 44.1 kHz (or 48 kHz) for KZbin. What is going on here?

[@youngmoo-kim]

Thanks for the catch! Yes, there's definitely an issue, and more aliasing than indicated in the animations. I believe there's a bug in my resampling code, which is approximately doubling the amount of aliasing at the same point in time. I'll keep looking into this and post a link to a corrected version soon.

[@rogerfederer1622]

please keep going. this stuff is gold.

[@zookaroo2132]

SUBSCRIBED !!!

[@antoniodiaz3896]

Muchas gracias 🙏!!!

[@yabool2001]

Listen at 00:10:25 "These higher frequency sinusoid do exist they come into existence as soon as we sample.". Super!

[@elijahjflowers]

This was so hard to find!

[@spoingus20]

amaziinnggg

[@svetoslavasenov5609]

Thank you! Where can I find #5 of the series? It is missing from your channel.

[@youngmoo-kim]

It’s been long overdue, but I just posted it today. Sorry for the delay!

[@abhijithas9976]

If sampling frequency increase after nyquist frequency then also aliasing occurs right ? Is higher frequency component toke the place of lower frequency component or not ???? Is nyquist frequency is sampling frequency/2 Then sampling frequency= 2* highest frequency component of the signal or >=2 * highest frequency component of the signal

[@mirosaide8786]

How can one knows the highest frequency component without doing an FFT?

[@JGRStudios]

thanks where is part 5?

[@youngmoo-kim]

Just posted it 😀 Apologies for the very long delay in getting it out. I’m teaching the class again this Fall, so there will be more videos coming soon!

[@JGRStudios]

@@youngmoo-kim thanks a lot