Fourier series animation using phasor addition9

Posted by Steve Eddins,

I just saw a great animation illustrating the Fourier series decomposition of a square wave. Check it out. The video includes two different animations, so be sure to watch it all the way through to see the second one. ... read more >>

Sinusoids and FFT frequency bins12

Posted by Steve Eddins,

Note: I really didn't expect to be writing about the FFT two weeks in a row. But ready or not, here we go!... read more >>

FFT Stories

Posted by Steve Eddins,

My last meeting of the day ended just a little while ago, and I was starting to think seriously about figuring out a blog post for this week. What to write about? That's when I happened to see that Cleve posted just yesterday about the FFT. Ah ha! I'll write about that, too (in honor of National Blog About the FFT Week).... read more >>

Fourier transforms, vertical lines, and horizontal lines13

Posted by Steve Eddins,

A reader asked in a blog comment recently why a vertical line (or edge) shows up in the Fourier transform of an image as a horizontal line. I thought I would try to explain this using the simplest example I could think of. ... read more >>

Complex surprises from fft7

Posted by Steve Eddins,

One of the discrete-time Fourier transform properties that many people learn is that if a sequence is conjugate symmetric, , then the Fourier transform is real. ... read more >>

Plotting the DTFT using the output of fft6

Posted by Steve Eddins,

In my Fourier transform series I've been trying to address some of the common points of confusion surrounding this topic. For today's espisode I want to look at how to use the fft function to produce discrete-time Fourier transform (DTFT) magnitude plots in the... read more >>

Negative frequencies10

Posted by Steve Eddins,

I recently asked for your advice about how to continue my Fourier transform series. I appreciate all the enthusiastic and helpful responses. I'd like to continue focusing on some basic points that confuse folks who don't have an extensive signal processing background: ... read more >>

Fourier transforms – where to go from here26

Posted by Steve Eddins,

Last fall I started posting occasionally about Fourier transforms. This topic causes much confusion, which is particularly unfortunate given how many people are interested in it. ... read more >>

No units in the DTFT4

Posted by Steve Eddins,

OysterEngineer (I love that name!) asked some interesting questions in response to my last Fourier transform post, which concerned the relationship between the discrete-time Fourier transform (DTFT) and the discrete Fourier transform (DFT). ... read more >>

The DFT and the DTFT8

Posted by Steve Eddins,

It's finally time to start looking at the relationship between the discrete Fourier transform (DFT) and the discrete-time Fourier transform (DTFT). Let's look at a simple rectangular pulse, for . The DTFT of is: ... read more >>

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