How to Understand Aliasing in Digital Sampling

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Iain Explains Signals, Systems, and Digital Comms

Iain Explains Signals, Systems, and Digital Comms

2 жыл бұрын

Explains Aliasing in digital sampling with a practical example using the wheel of a bicycle.
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Full categorised list of videos with PDF Summary Sheets: iaincollings.com

Пікірлер: 55
@zhou6486
@zhou6486 2 жыл бұрын
Have to say that a new creative, successful explanation style is born. Thanks for creating the video. Cannot wait for more.
@iain_explains
@iain_explains 2 жыл бұрын
Thanks. I'm glad you liked it. Have you seen the other videos I've made in a similar style? "How to Understand Convolution" kzfaq.info/get/bejne/rpl2l8dnu8Wsn58.html and "What is the Fourier Transform used for?" kzfaq.info/get/bejne/jNqShcidqtTRo2w.html
@KF7JO
@KF7JO 2 жыл бұрын
Excellent video! Nyquist sampling theorem says that if you want to figure out how fast the bike tire is moving (frequency) and which direction it's moving, you need to sample it at least twice as fast as it is spinning. Sample slower than that and it'll look like the wheel is spinning backwards, even when it's spinning forward. You won't be able to tell if the wheel is spinning forward at f_nyquist + delta or f_nyquist - delta. This is aliasing where the spectrum "folds back" onto itself about the Nyquist sampling rate. Some designs actually rely on sampling in higher Nyquist regions, though it requires a high pass filter or band pass filter to guarantee that there is no frequency content below that Nyquist region. Otherwise you will get an aliased spectrum.
@iain_explains
@iain_explains 2 жыл бұрын
Thanks. Yes, I've got a couple more videos explaining it in more detail: "Aliasing Ambiguity Explained" kzfaq.info/get/bejne/sLtxnsRl1NjWenU.html and "What is Aliasing?" kzfaq.info/get/bejne/eJmejbh3s9G4d40.html
@gurratell7326
@gurratell7326 Жыл бұрын
And this is why we need motion blur in videos; to reduce aliasing. Though to get rid of the aliasing all together we'd need at least a 720 degrees shutter which unfortunately is physically impossible, and it would also make everything looking a bit to smooth.
@edmundkemper1625
@edmundkemper1625 2 жыл бұрын
Greatly appreciated professor, your initiative to give special importance to intuition when teaching a concept is what impresses me the most!
@iain_explains
@iain_explains 2 жыл бұрын
Thanks for your nice comment. I'm glad you like the intuition. I think it's so important to have different ways of thinking about mathematical equations and operations.
@BearfootBrad
@BearfootBrad 8 ай бұрын
I like the bird yelling in the background towards the end
@TheRedBullHulk
@TheRedBullHulk 11 ай бұрын
That was so helpful, thank you so much!
@iain_explains
@iain_explains 11 ай бұрын
Glad it was helpful!
@datamatters8
@datamatters8 2 жыл бұрын
Another great explanation. Thanks. The star jumps are a wonderful example.
@iain_explains
@iain_explains 2 жыл бұрын
Glad you liked it!
@kates-creates
@kates-creates 4 ай бұрын
this channel is great! thank you for all of your effort
@iain_explains
@iain_explains 4 ай бұрын
Glad you like it! Thanks for your comment.
@PhG1961
@PhG1961 2 жыл бұрын
A remarkable approach on the theory of aliasing ! Very well and comprehensive explained !
@iain_explains
@iain_explains 2 жыл бұрын
Thanks. I'm glad you liked it.
@PhG1961
@PhG1961 2 жыл бұрын
@@iain_explains I always do... ;-)
@sagarraj4521
@sagarraj4521 Жыл бұрын
I don't think there is a better video than this to explain aliasing.... Thanks a lot for the effort n knowledge........
@iain_explains
@iain_explains Жыл бұрын
I'm so glad you liked the video. Thanks for your nice comment.
@DoesntReadReplies
@DoesntReadReplies 9 ай бұрын
Thank you for this. I wish my professor had explained it this way. So much more intuitive than staring at sine waves of different frequencies trying to puzzle out what the heck aliasing is from that.
@iain_explains
@iain_explains 9 ай бұрын
It's great to hear that my video helped you to visualise aliasing. I also wish my own professor had explained it this way - back when I was a student.
@chengshen7833
@chengshen7833 2 жыл бұрын
Very brilliant explanations! Haven't been to Manly since covid
@iain_explains
@iain_explains 2 жыл бұрын
Thanks. I'm glad you liked it. I'm guessing that the lack of hot days this year has also been a factor in Manly visits.
@vtrandal
@vtrandal Жыл бұрын
Thank you for making so many wonderful videos. An example I like to use involves an ordinary clock with hour and minute hands. If we look at the clock every 11 hours, then the hour hand will appear to move backward 1 hour. Similarly for the minute hand if we observe it too infrequently it too will appear to move strangely. And many other false or aliased outcomes occur by sampling too infrequently as you have so nicely demonstrated.
@iain_explains
@iain_explains Жыл бұрын
Thanks for sharing that example too!
@ecuasonic_7
@ecuasonic_7 Жыл бұрын
Amazing explanation!
@iain_explains
@iain_explains Жыл бұрын
Glad it was helpful!
@pitocipo2080
@pitocipo2080 2 жыл бұрын
Very clear and very good approach to move the concept to real world. Nice bicycle tough 👍🏻.
@iain_explains
@iain_explains 2 жыл бұрын
Glad you like it!
@ADRIANO-MUSIC
@ADRIANO-MUSIC 18 күн бұрын
Thank you for this artfully made and thought-provoking film. Best Regards 😉
@iain_explains
@iain_explains 17 күн бұрын
I'm so glad you liked it.
@annapatata6258
@annapatata6258 6 ай бұрын
thanks bro you are inspiring
@iain_explains
@iain_explains 5 ай бұрын
I appreciate that!
@mohamedhadjalla
@mohamedhadjalla 2 жыл бұрын
I really want to thank you, i have just understood decimation and interpolation with your videos , Good Luck from Algeria 🇩🇿 ❤️ I wish you make videos about Adaptive filters and Blind Source Separation , Thank you !
@iain_explains
@iain_explains 2 жыл бұрын
I'm glad the video was helpful. And thanks for the suggested topics. I've put them on my "to do" list.
@arjunmenonkandanat6328
@arjunmenonkandanat6328 2 жыл бұрын
Wonderful explanation
@iain_explains
@iain_explains 2 жыл бұрын
Glad you liked it
@stringstoparadise2392
@stringstoparadise2392 Жыл бұрын
you are a magician as i always said professor
@iain_explains
@iain_explains 11 ай бұрын
I'm glad you're continuing to find the videos helpful.
@arizmohammadi5354
@arizmohammadi5354 8 ай бұрын
The True Professor
@iain_explains
@iain_explains 8 ай бұрын
Thanks for your nice comment. I'm glad you like the videos.
@arjunsnair4986
@arjunsnair4986 2 жыл бұрын
Nice explanation sir
@iain_explains
@iain_explains 2 жыл бұрын
Thanks for liking
@antoniodaltoe6158
@antoniodaltoe6158 9 ай бұрын
Professor, the most impressive is your didactic - the easy way you explain difficult terms. Thanks. Obs: rim brakes are better than disk brakes … 😂
@iain_explains
@iain_explains 9 ай бұрын
Glad you like the videos. Maybe I should do a video on the signals produced by disk brakes compared to rim brakes. Disks can certainly be more squeaky, but they definitely stop more quickly! ... my new bike has disk brakes 😁
@neotodsoltani5902
@neotodsoltani5902 Жыл бұрын
Hi, I really liked the environments that you recorded the videos in (next to the sea, etc); can you tell me what country/city is that? it was very beautiful
@iain_explains
@iain_explains 11 ай бұрын
It's Sydney, Australia. I'm glad you liked the views. Perhaps I should try to include them in more of my videos ....
@thiranjajayasundara6040
@thiranjajayasundara6040 5 ай бұрын
Was so easy to understand!
@iain_explains
@iain_explains 5 ай бұрын
I'm glad to hear that.
@user-xz2rb7ze4j
@user-xz2rb7ze4j Жыл бұрын
Hello professor, I really appreciate your special explanation. But, what I am still confused about is the phase reversal. With ALIASING, the wheel looks rotating backward because of its angular freq.. But, the textbook said it is because of the phase reversal and I cannot understand it. Could you please explain the relationship between backward spinning of the wheel and the phase reversal?
@iain_explains
@iain_explains Жыл бұрын
Hopefully this video will help: "What is Aliasing?" kzfaq.info/get/bejne/eJmejbh3s9G4d40.html
@oviya1317
@oviya1317 2 жыл бұрын
Sir why nobody teaches how things happen, how to figure things out as a curious yet not properly guided youngster like me???. And i really want to ask why on the world should we learn aliasing . Just because i took electronics in graduation ? How should i see the physics behind it to use it in daily life
@iain_explains
@iain_explains 2 жыл бұрын
Any continuous time signal (eg. voice signals, music, temperature changes, ...) and any analog image (video, photos, ...) that is stored on a computer or digital camera or memory stick or hard drive ... has been sampled. Basically sampling happens in anything in daily life that is controlled or measured by a digital system / computer.
@RobRoschewsk
@RobRoschewsk 2 жыл бұрын
Do you have a pet pterodactyl ?
@iain_explains
@iain_explains 2 жыл бұрын
🤣 ... Australian birds are very noisy!
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