Linked Questions

10
votes
5answers
587 views

A DFT “periodic inputs” question

Why do people say that the fast Fourier transform (FFT) “views”, or “interprets”, or “assumes” its input sequence is periodic? I ask this question because the activities of viewing, interpreting, and ...
4
votes
4answers
284 views

the $L^2$-norm of a signal is also applied as its energy!

I am a newcomer in signal processing. I saw that the $L^2$-norm of a signal is also applied as its energy! How is this concept illustrated for those ones who are working in pure math.
4
votes
8answers
297 views

How Do I Measure the Time Duration of a Finite Length Discrete Sequence?

Assume I have a five-sample time-domain sequence (none of the five samples are zero valued) and the time period between each pair of samples is one second. Measured in seconds, what is the time ...
5
votes
2answers
1k views

Synchrosqueezing Wavelet Transform explanation?

How does Synchrosqueezing Wavelet Transform work, intuitively? What does the "synchrosqueezed" part do, and how is it different from simply the (continuous) Wavelet Transform?
1
vote
5answers
353 views

Positive and negative frequencies in DFT due to frequency folding, or due to negatively indexed frequencies?

When I look for the cause of the mirroring of frequencies in DFT output, I get two types of explanations: The first one which says the frequencies are mirrored because of the complex exponential ...
4
votes
3answers
571 views

FFT of a AM modulated signal

I am generating an AM modulated sinusoidal wave. The carrier frequency is set at $1000 \ \rm Hz$; the modulation frequency is set to $40 \ \rm Hz$ and $100 \%$ of the amplitude is modulated. I ...
2
votes
2answers
279 views

DFT of pure sinusoidal wave

I'm writing a program in which you can synthesize waves by adding to a sound's Fourier transform, and then inverse the transform to get the modified sound. In order to do this, I need to know what to ...
2
votes
3answers
287 views

Does chirp have constant magnitude frequency response?

Pg. 223 claims so, yet my results via DFT differ: Is the textbook wrong? My attempted explanations: (code) DFT vs DTFT: "frequency response" is computed via latter. Still, DFT should ...
4
votes
1answer
145 views

Why DFT is used for approximating CTFT when you can approximate CTFT-integral itself?

I was using MATLAB for approximating FTs. Why DFT is used if we can approximate the transform-integration using summation.
1
vote
3answers
278 views

Does Zero Padding Distort the Spectrum of a Signal?

It's said to "sample the DTFT", revealing what "DFT fails to see". And I fail to see how this sampling isn't distortion. The "spectrum" aims to provide the sinusoidal ...
0
votes
4answers
160 views

what is the relationship between a spectrogram and the uncertainty principle heisenberg? [closed]

what is the relationship between these two things Perhaps more resolution in a spectrogram is equivalent to knowing more the position of the electron and less resolution is knowing the velocity of the ...
0
votes
3answers
93 views

Do symmetric discrete signals have zero phase?

I generated a Hanning window having an even symmetry: where for even-sampled case we either take "left" and "right" to include or exclude the center sample. I was surprised to ...
0
votes
1answer
56 views

Discrete Fourier style transform with non-sinusoidal/arbitrary waveform components

A discrete Fourier transform will produce frequency samples sufficient to recreate the original time sampled signal from sinusoidal waveforms. That works great as long as the original signal is ...
1
vote
1answer
114 views

How does modulation frequency appear in the modulation spectra?

I'm trying to familiarise myself with the concept of modulation spectra that I met in this work. My main question appears in the title: how does the modulation frequency appear in the modulation ...
-2
votes
1answer
306 views

What can be meant by “bandlimited”?

This question was a source of disagreement on whether "amplitude aliasing" can occur for a signal bandlimited to below half the sampling frequency. The question was closed before the ...

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