All Questions
Tagged with signal-processing fourier-transform
105
questions
12
votes
8
answers
5k
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Feynman claimed "The ear is not very sensitive to the relative phases of the harmonics." Is that true?
In The Feynman Lectures on Physics, Dr. Richard Feynman claimed that the ear (I assume he meant the human ear) is not sensitive to the relative phases of harmonics.
However, I was asked to test ...
- 348
0
votes
0
answers
46
views
Fourier Transform of periodic Signals
If $f(x)$ is a periodic signal with a period $A$ then the Fourier transform of the signal $F(k)$ is zero, unless $k A$= $2 \pi n$ where $n$ is an integer. How can there Be a Fourier transform of a ...
- 207k
1
vote
1
answer
65
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Is this a good use of the convolution?
I would like to replicate the real response of an instrument to some signal. Here's what I have in mind: I generate some ideal signal. I then add Gaussian noise to it to produce a realistic signal s(t)...
- 591
2
votes
0
answers
44
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How to extract the "matter fluctuation amplitude" from the CMB power spectrum?
How do you convert the value listed in Planck 2018 results. VI. Cosmological parameters, $A_s = 2.101\times10^{-9}$ to the value of the matter fluctuation amplitude $\sigma_8=0.8111$? I tried ...
- 207k
18
votes
5
answers
4k
views
Fourier vs. Laplace transforms
Electronics books often use Laplace to analyze circuits, while in physics we use Fourier, most of the times... if not always: from complex impedances to electromagnetism, quantum mechanics, Green ...
- 591
0
votes
2
answers
84
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I don't understand intuitively why the instantaneous frequency is obtained by calculating the time derivative of the phase
I don't understand intuitively why the instantaneous frequency is obtained by calculating the time derivative of the phase
- 207k
2
votes
1
answer
172
views
Fourier transform of an exponentially decaying waveform
Consider an atom oscillating at a certain frequency. The amplitude of the oscillation decreases over time such that the waveform can be modeled by an exponential function, but the frequency remains ...
- 207k
2
votes
1
answer
123
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Where can I learn Fourier analysis and complex signal processing for quantum mechanics?
I'm requesting resourses to dive deep and get a good grip on complex signals, Fourier analysis and connections to information theory and information encoded by complex signals.
My background: 3rd year ...
- 11
1
vote
2
answers
411
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How can we show that a lens is a low pass filter?
I understand from the derivation in Goodman Chapter 6 that a lens Fourier transforms light from the front focal plane onto the back focal plane, ignoring aperture effects. I've also read that a lens ...
- 11
5
votes
1
answer
4k
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How is energy conserved for discrete Fourier transforms of different bin size?
I have gotten myself into a muddle regarding the discrete Fourier transform (DST) and would appreciate if someone could help me become unstuck.
I noticed that the fft of the following are the same:
...
- 15.6k
0
votes
1
answer
70
views
Doubt on time invariant system
Now I am delaying the output of a system (which takes $x \left( t \right)$ as input and gives $t \cdot x \left( t \right)$ as output) by $T$ then final output is:
Let's denote the output of the ...
- 19.8k
0
votes
2
answers
377
views
Superimposed Waves
This question has been bothering me for a very long time.
Imagine a wire carrying electric current. It carries two alternating current (AC) signals of different frequencies (say $50$ Hz and $60$ Hz). ...
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- 1
0
votes
1
answer
145
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What is the physical meaning of the pressure of an acoustic point source being complex?
Context
From various sources of Acoustics (such as "Acoustics -
An Introduction to Its Physical Principles and Applications" by Allan D. Pierce and "Fundamentals of General Linear ...
- 13.1k
7
votes
2
answers
1k
views
Why does superposing an infinite number of waves of different wavenumbers eliminate periodicity and may sometimes result in a localised wave?
I am studying how wave packets are defined in quantum mechanics, but I am finding it hard to intuitively understand why superposing an infinite number of waves of different wavenumbers $k$ may ...
- 207k
0
votes
1
answer
126
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The solar spectrum on the time domain
This is the solar spectrum by wavelength:
By formula $c=f\lambda$, we can plot the solar spectrum over the frequency domain:
Then we can conduct inverse Fourier transform to transform the plot into ...
- 29.1k