Это видео недоступно.
Сожалеем об этом.
Where is Frequency in the output of the FFT?
HTML-код
- Опубликовано: 15 авг 2024
- The output of the FFT can be quite confusing. All you are presented with is a list of complex numbers that, at first glance, don't tell you anything about the frequencies present in your signal. In this video, we find out how to find the frequency information in the output of the FFT.
eBook: How the Fourier Series Works
www.amazon.com...
0:00 - Introduction
0:37 - Ident
0:42 - The different types of Fourier Transform
1:18 - Building signals out of sinusoids
2:05 - Properties of a sinusoid
2:22 - The Magnitude graph
2:49 - Which frequencies does the FFT test?
4:42 - Equation for calculating the frequency
4:56 - An example
5:31 - This video's challenge
5:58 - End Screen
Please support the making of these videos:
www.patreon.com/MarkNewman (monthly)
paypal.me/MarkHNewmam (one-time)
Mark you are an absolute blessing especially for all those interested in this field . Your teaching style is superb. Just wanted to say thank you and please continue with these amazing video lessons
You are most welcome. I'm just putting the finishing touchest to the next video in the series "How to calculate the magnitude and phase" which will be out this week.
@@MarkNewmanEducation superb thanks Mark. Also just received your book it's incredibly well structured and easy to follow. Looking forward to the next video ..
The new video is out today: ruclips.net/video/rUtz-471LkQ/видео.html
I've learned the fourier transform years ago but I love these videos because they help the concepts really sink in. If you ever covered how to interpret the results of the fourier transform in two dimensions I would be grateful because I haven't found any videos that explain it very well.
This video deserves many more views. Thank you so much for all the work you put in!! The production value is super high.
You're very kind. I love making these videos. They are a labour of love. Please share with anyone you think would find it helpful.
@@MarkNewmanEducation It shows that they are a labour of love. I shall!!! :)
Thank you for the recording! I am fighting to understand FFT and your video is awesome!
you are really one of the best in this world . Just wanted to say thank you.
This knowledge is not necessary for the work I do, but I love learning how such analysis is done! Excellent presentation and instruction, sir!
Thank you. I am always on the lookout for new subjects to make videos about, so if there is anything I can help you out with, please suggest it in a comment.
You are very professional. Thank you very much 🥰 for your great video. Much of efforts done within just 7 minutes.
Mazel tov! Your videos are amazingly helpful! 😃💯💥👍🥳
What a charming video! I'm struggling to understand how the DFT is useful for studying the frequencies of a signal, and this video helped me a lot!
Amazing. Really glad I was able to help you. I think there is too much assumed knowledge about the FFT. It is an amazing tool, but it is often not well explained, so people get confused easily.
I am Christian and I bless you Mark. Be Strong !!! about the current juncture in Israel.
You are an international treasure. Keep up the amazing work!
Thanks, Brad. You're very kind. More videos are on the way. I'm working on the scripts for the next three as we speak.
thanks! i bought both your fft books
You're welcome. I hope the help you.
Please explain about fractional Fourier transform(FRFT), since the first notion that initiate the birth of the concept of the FRFT itself, about the time-frequency plane rotation which is one of the most complicated stuff to understand, also the applications and how far FRFT can be applicable as we can reach
Thank you for your suggestion. I have added it to the list.
I can answer you question: how to calculate the phase?
because each the value is a complex number, which is a vector, the angle of x-axis is the phase.
Absolutely Correct!! A full explanation is coming in the next video which I'm working on as we speak.
Thanks a lot
Awesome
Thank you very much Mark
You are very welcome
Thanx! 😊
Great video thanks.
Why we ignore the complex numbers during the calculation frequency ? we integrated the index number of complex numbers but I didn't understand clearly that ignoring the complex numbers value ? I will be glad if someone reply this question. Apart from this question, illustrations perfect for understand. Thank you for your great effort.
It's not that we ignore the complex number, it's just that the actual calculation of the FFT only tells you its magnitude and phase. It is the position of the item in the list that tells you its frequency. Think of the FFT result being on the y-axis and the position of the result in the list being on the x-axis.
@@MarkNewmanEducation Thank you for quick reply :) So can we summarize like that ;
We place the k index numbers on the x-axis. Starting from 0 to the length of the fft, for example 512. Here we find the frequency value of each k-index and place these values on the y-axis. Finally, when we combine these lines, it becomes the line of our frequency values. Did I get it right?
I tuoi video sono fatti benissimo, se posso fare una domanda, cosa sono i frequency bins?
您好，非常感谢您的辛苦付出，请问你的书籍有中文版吗？
Thank you very very much!
I learned Fourier Transfrom Now!
Wish you will make more better videos:-)
More to come!
Mark could you please help, I follow what you are saying in the video, but for applications of the FFT, typically the algorithm does not ask for the Fs of the signal when I implement it in MATLAB or Python. At most it allows for me to specify the size if I want to pad it up to a different length, but it doesn’t need the Fs. I know how to scale the axis when it gives me an output, but how does it know what frequencies to test in the signal if I don’t feed it the sample rate?
👍👍👍👍👍👍👍👍
One book sold :)
Amazing, thanks. I hope it will be helpful to you.
Sir when will your book on Fourier series available on Amazon in India
The Kindle version is available in India:
www.amazon.in/dp/B0B1BY5H6T
The paperback version is not available locally in India as Amazon doesn't appear to have a "print on demand" service there, but the paperback can be purchased from any of the following Amazon stores.
Amazon.com/dp/B0B19XLDTZ
Amazon.co.uk/dp/B0B19XLDTZ
Amazon.de/dp/B0B19XLDTZ
Amazon.fr/dp/B0B19XLDTZ
Amazon.es/dp/B0B19XLDTZ
Amazon.it/dp/B0B19XLDTZ
Amazon.nl/dp/B0B19XLDTZ
Amazon.pl/dp/B0B19XLDTZ
Amazon.se/dp/B0B19XLDTZ
Amazon.ca/dp/B0B19XLDTZ
Amazon.com.au/dp/B0B19XLDTZ
Thank you.
Can you explain how Matlab choose R?
When I apply fft(data) I don't tell matlab what is my sampling rate
MATLAB doesn't choose R as far as I know. All MATLAB is giving you is the sample index k. It is a while since I used MATLAB, but as far as I remember, it just gives you the list of complex numbers in the output. You have to convert the sample index, k, to frequency according to the rate at which you sampled the signal. MATLAB doesn't know.
@@MarkNewmanEducation Thanks for replying. It actually makes sense if I sample data at sample rate fs, Matlab would calculate the fft but when I'll plot it I could plot it for every other fs. If the new fs is higher than the real sample rate I will not earn new information because the data already sampled. But if I choose lower fs to plot fft, it would look like I sampled at lower rate. I guess.