All Questions
21
questions
0
votes
2
answers
84
views
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
- 11
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 ...
- 390
0
votes
2
answers
47
views
How to convert from a wave-reading?
I have a series of wave-readings which show wave amplitudes pr. time unit for different events. So on the $x $-axis we have seconds, and on the $y$-axis, wave height.
If I want to convert this to a ...
- 143
1
vote
2
answers
85
views
Signal Processing – Discrete Fourier Transform and Incomplete Fourier Series
I'm working on a paper where I'm collecting sound pressure data from a chord's wave and trying to create a frequency spectrum to find the individual frequencies that make up the chord.
However, I can'...
- 13
1
vote
1
answer
53
views
Wavelength and frequency associated with a wave pulse
What are the definitions of wave length and frequency of a wave pulse?
- 468
0
votes
1
answer
127
views
What would happen when two wave functions intersect in a Fourier series representation of periodic signals? [closed]
I saw a piece of code on github which transforms the planetary movement into the fourier wave function.
These circles are given by the x and y ordinates: x=cos(ωt) y=sin(ωt), which are periodic. ...
- 109
2
votes
1
answer
171
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 ...
- 23
5
votes
2
answers
963
views
What, mathematically, is the power spectrum of a signal?
Given a signal $f(t)$ defined on $t\in(-\infty,\infty),$ what is the precise definition of the power spectrum of $f$, i.e., what is the mathematical operation that takes $f$ to the output of an ideal ...
- 3,407
1
vote
3
answers
157
views
How does a spectrum analyzer works. Example with particular case: eyes [closed]
[edit]: I reformulated my question to first talk about general spectrum analyzer and then ask about how vision works (which is a particular case of spectrum analyzer as I explain below).
Let's assume ...
- 1,450
0
votes
4
answers
481
views
Why exponential terms like $\exp (i\omega t)$ make no contribution when averaged over a long time?
In the physics of waves, I often see expressions like
$$A\exp(i\omega t) + f(t)$$
where $A$ is a constant, $w$ is the angular frequency and $f(t)$ is an arbitrary function that depends on time.
It ...
- 4,235
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). ...
- 101
0
votes
1
answer
103
views
How to solve this problem involving the "longest interval"?
The problem is shown as follows:
If one wants to make a digital record of sound such that no audible information is lost, what is the longest interval, $\Delta t$, between samples that could be ...
1
vote
1
answer
317
views
Why do people study plane wave in wave physics?
I have recently been studying a structure for high sound absorption. There are a lot of literature on similar design, where all of them are using the plane wave as an input to the structure. I have ...
- 171
0
votes
1
answer
182
views
Superposition of waves whose wavelengths are continuous
I know how to find the resultant waves when finitely or countably many waves are superimposed but how do I find the wave equation when there are infinitely many waves whose wavelength is continuous? ...
user183683
20
votes
6
answers
19k
views
Why are cosine and sine functions used when representing a signal or a wave? [closed]
Actually, in the mathematics sine and cosine functions are defined based on right angled triangles. But how will the representation of a wave or signal say based on these trigonometric functions (we ...
- 339