Welch's method for smooth spectral decomposition

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[estebanlopez]

FANTASTIC video. I have been struggling with understanding the concept of Welch's method through textbooks and papers, but this conceptual introduction without any math makes all of it make sense now. Thank you!

[chansonjoy]

Have finished watching "New ANT2". I finally understood DFT after graduated from school many many years. This serial of videos are the best in youtub to explain fundamental DSP for people like me without tones of mathematics background (CE major here). I can tell the author put a lots of though on how to explain clearly without involving intimidating math. Many engineers (including me) hardly need to deal with continuous analog signals. DFT is only thing we need and we don't care about all the calculus in the FT. Saddly most DSP tutorial videos out there are heavily calculus mangling which shut my brain off instantly. Such good serial videos I don't understand why so few views. thanks Mike.

[ananthakrishnank]

I find this paradoxical. 2:24 We apply Fourier transform to figure out the frequencies.

Don't we use the fact that any periodic signal can be decomposed into its set of frequencies that make it, for Fourier transform?

So if frequencies f1, f2, f3 etc, are found to be present in the full FFT method, doesn't that mean that sin(2*pi*f1*t), sin(2pi*f2*t), etc are present every time? What am I missing?

This means that all the frequency components with their own amplitude were present at all instances of time, which is obviously wrong.

[Biomechan]

You are a hero! Finally a to the point informative vid without the electrical engineering madness!

[noahdrisort]

best presentation about hann window and stfft I have ever reached

[DexM]

Thanks! A question though: at 7:15, the tapering reduces the average amplitude of the signal, so I'm assuming it also reduces the amplitude of the corresponding Fourier coefficients, right? Is that compensated for in Welch's method? Are the coefficients scaled back to match what we would have without tapering?

[Brono]

Will this method ignore frequencies that are too long for the smaller window?

[mo_lan]

love the way you simplified the whole thing, i just wish you did matlab coding as well

[JsoProductionChannel]

5:56 This is done by multiplying the signal segment with the hamming window?

[tkguha]

Very clearly described, good presentation also.

[AngeloYeo]

Wow ... such a great lecture! Thank you for sharing with us ... I have a question. If Welch's method is fundamentally applying FFT with short time window and averaging over time, then would I get the same result when I apply STFT and average it over the time dimension?

[jasonyong]

I am currently enrolled to this course, but I cannot seem to find this video. Where would I be able to find this?

[jamesb]

Thank you for the series of videos. Could you elaborate what kinds of non-stationarities the Welch method is robust to? or provide some reference to it? Thanks!

[alfredoalarconyanez]

Love your videos, thank you very much !

[shahnillarizvi]

worth watching!!
As u mentioned that welch's method reduced spectral precision so can we use to plot spectral density ?? or fft is better?
I have a time series and want to find the period of that.

[nahalesotoudeh]

this was really nice and clear! thanks!

[PfropfNo]

If the snippets are 200ms, can I discover frequencies with a period of more than 200ms in the welch's method? Because as i understood, all low frequencies are tampered out. Is this what is meant with "reduces spectral precision"?

[terezamikesova]

Thank you for your videos. My task is to distinguish
between EEG in relax condition and EEG in mental arithmetic task. For each condition I have separate signals. Do you think that Welch's method is suitable for my problem, when the features would be band power, relative band power and so on?

[aha]

hi how are you?

good video thx good explained

[shahnillarizvi]

one more thing is that if the length of the segment is equal to total samples in pwelch then pwelch will become fft??