All Questions
Tagged with signal-processing waves
59
questions
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10
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Phase Slope Distance Calcuation
After trying to implement IFFT algorithms for phase-based ranging, as outlined in this very interesting and descriptive blog post; I've been getting horrendous results (orders of magnitude inaccurate),...
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2
answers
151
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Weird looking sine wave behavior in an electric circuit
while studying an RLC circuit I noticed some weird like sine waves at low frequencies (1-9 kHertz) on the inductor,
The amplitude behavior did not follow the theoretical model. Instead, suggested the ...
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1
answer
33
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What relationship between the time recording length and the frequency bandwidth?
In model testing for ocean waves, the data recording duration is usually longer the better especially for irregular waves. The recording length shall be long enough to achieve sufficiently small ...
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2
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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
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1
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1
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54
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How to justify sound propagation is a linear time-invariant (LTI) system?
Background
A linear time-invariant (LTI) system (black box) is one described by the system:
\begin{align}
\dot{\xi}(t) & = A\xi(t) + B\omega(t), \; \xi(0) = 0 \label{eq-abc-1}\\
\lambda(t)...
- 151
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27
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Comparison between wave equation theory and transfer function theory
I deal with analysis of acoustic signals in solids. And after some literature research in physics and mathematic, I have a question about the followings two theories:
Wave equation theory: Imagine I ...
1
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2
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47
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Is it possible to, like white noise, excite all audio frequencies equally, but with a more immediate & less random burst? Like a signal discontinuity?
I am trying to generate an audio signal that, like white noise, has "equal intensity at different frequencies, giving it a constant power spectral density", but unlike white noise, can be ...
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21
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FWHM and Beam Width of transmitted beam of ultrasonic (ultrasound) transducer
Im a studying ultrasonic transducer and I got a question about FWHM and Beam Width while solving some problems.
In the lecture, I learned that Beam width is calculated by:
$2\Delta\theta = \frac{3.8\...
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0
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25
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Two-Ray Ground-Reflection Model: Understanding the Difference in Phase Offsets at the Receiver
Currently, I'm trying to understand the Two-Ray Ground-Reflection Model.
During my research, I came across the following simplification expressing the received power as follows (taken from Wikipedia):
...
- 11
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0
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24
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Is the strongest acoustic signal always the closest?
I have a single beam echosounder that I use to measure the distance to an object underwater. It emits an acoustic pulse and listens to the reflections. Using the time of flight and the strongest ...
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22
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12
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8k
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How do computers store sound waves just by sampling the amplitude of a wave and not the frequency?
All of this just doesn’t make sense though.
I mean, doesn’t the amplitude represent the loudness and the frequency the pitch? Aren’t they completely independent from each other?
Is the book just ...
- 390
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2
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1k
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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 ...
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1
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58
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Can multi-instrumental sound be reconstructed from a waveform?
This question came about when I saw someone wearing clothing with a waveform on it. I wondered if it would be possible to reconstruct the original sound from the printed waveform.
I understand that a ...
- 101
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2
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561
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What do I hear when listening to a computer-generated sine wave?
When I use a sine-wave generator (such as this one), I give credit to the software and my hardware that a pure sine wave is produced (as close as is technologically possible) — that is, no harmonics. ...
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2
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47
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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
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2
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85
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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'...
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1
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1k
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Understanding Upper Side Band (USB) and Lower Side Band (LSB) of Modulated signal
I want to know that what is UPPER SIDE BAND and LOWER SIDE BAND in this picture?
I have a confusion that the portion above the x axis is the USB and the portion below the x axis is LSB. I have doubt ...
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1
answer
53
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Wavelength and frequency associated with a wave pulse
What are the definitions of wave length and frequency of a wave pulse?
- 468
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1
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127
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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. ...
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2
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1
answer
171
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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 ...
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1
answer
47
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Signal Generated from Transmitter [closed]
Suppose that we have a transmitter of $150.100\ \mathrm{ MHz}$.
We also have a receiver at a fixed point.
The transmitter constantly generates signals toward the direction of the receiver.
Based only ...
- 115
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1
answer
49
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Infer 3D location (Height, Latitude, Longitude) based on Signal Strength
Sorry if my question is irrelevant.
Let's consider two cases:
$1)$ Suppose that we have an Antenna and a tagged individual that can be pinged from the Antenna. Suppose that the individual is pinged ...
- 115
5
votes
2
answers
808
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Rope as Communication Media [closed]
I'm a computer student that used to play microcontroller and sensor. I'm not sure whether this topic fits on this site.
I'm thinking about using rope as media communication instead of fiber optic. I ...
3
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1
answer
130
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Analog Is Digital (Discrete)?
As I started reading a bit about analog vs digital signals, I keep returning to this thought. This could be something pretty obvious to the pros out there, but is it safe to assume that underneath it ...
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2
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963
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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 ...
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1
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96
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Can we decompose sound like white light is decomposed (dispersed) in different colors?
When we send white light through a prism, the light is decomposed in the colors that constitute it due to the different velocities which different frequencies. Is there a way to decompose "white ...
1
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0
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35
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Can a signal calculate its time period?
I wanted to know if a radio wave has some kind of data for example a kind of packet information (if its a thing) and it gets transmitted and gets received by a receiver, then can it calculate the time ...
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1
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170
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Does phase of a signal (very low frequency, 0-100Hz) change due to pink noise?
One might experience pink noise when dealing with low frequency signals (0-100Hz). Curious to know whether pink noise has an effect on phase of the signal specially in lowest frequencies 0-10Hz.
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3
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157
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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 ...
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4
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481
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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
2
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1
answer
86
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Doppler effect on non-periodic signals
I would like to understand what's happening to a signal emitted from a moving source and arriving to a moving receptor. But, when I am looking on internet about Doppler effect, I can only find ...
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2
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377
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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
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1
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103
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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
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1
answer
317
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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 ...
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3
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313
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Can a sound wave begin with rarefaction?
Some digital recording samples (audio files) of recorded acoustic sounds present sound waves which begin with rarefaction. Is this an actual phenomena that can occur or is it a result of sound ...
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75
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Are Huygens wavelets just a geometric method for understanding how a wave moves forward or are they an actual thing?
Wavelets are emitted from every point on a wave towards all directions is what I read on a book but on another book I read Wavelets are emitted towards the same direction of the wave. And They create ...
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1
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182
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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
3
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1
answer
70
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Sound an amplifier makes when you plug / unplug a cable [closed]
When you plug, unplug or even touch a jack cable of an aplifying system with speakers, one can hear a low-pitch sound that is of roughly always the same frequency, which does not seem to depend on the ...
- 2,469
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2
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735
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Low frequency wave ability to penetrate object
as shown in this em wave spectrum image, the lower the frequency the better a wave ability to penetrate object.
https://c479107.ssl.cf2.rackcdn.com/files/20642/area14mp/pvgrynkw-1361853572.jpg
my ...
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0
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61
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Low frequency waves influence of high frequency waves
If I have a 20 MHz surface wave travelling along a material, and then introduce a 50 or 100 Hz wave source, will there be a noticeable difference to the output?
(Surface acoustic wave type device, ...
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-1
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2
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35
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How can I send a wave towards something and have it respond with a specific value?
Imagine a bat, for example. It uses its echo-location to send waves which get reflected back and thus return information about the surroundings. I want to do the same thing, but instead of just ...
- 1,183
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1
answer
2k
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What is the difference between collimating, waveguiding, attenuating, and polarizing? [closed]
What's the difference between collimating, waveguiding, attenuating, and polarizing? Are they related on any level at all?
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6
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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
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3
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1k
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Does a square (or any non-sinusoidal) wave a definite wavelength?
I'm currently reading/studying the FLP and I have a question regarding waves. In a chapter about QM, Feynman says that any short wave train doesn't have a definite wavelength. I understand this, ...
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2
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106
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Meaning of $v_\mathrm{source}$ in the Doppler effect
The Doppler equation is given by
$$f_{observed} = \frac{c+v_r}{c+v_s} \cdot{ f_{emitted}}$$
Does $v_s$ refer to the velocity of the source, relative to the receiver at the time the wave (now at the ...
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5
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2k
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Existence of monochromatic pulses?
Why there can not be a monochromatic pulse? My physics professor told us that we can't generate a monochromatic light pulse and I was wondering what are the physical limitations causing this.
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2
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519
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Simplification of the sum of sine waves [closed]
I have passed a signal through a filter and gotten the following wave, consisting of a DC component and odd harmonics:
$$1 + 2\sin4000πt + \frac23 \sin12000πt + \frac25 \sin20000πt + \frac27 \...
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1
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59
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Subtracting Audio from a Song with Multiple Forms
This question may start oozing into the realm of copyright infringement, but let's discuss the theory first and foremost.
I have a song with vocal and orchestral accompaniment from a well-known movie ...
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105
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Which information do we get from the phase spectrum about the wave?
Let a wave is represented by an equation
$$y=f(t)=10\sin(\frac{2\pi f_1t}{T} + \pi/6)+5\cos(\frac{2\pi f_2t}{T} +\pi/3)$$.
Here, let us take $f_1=10 ,f_2=5 ,T=100$
Then, from the Fourier transform ...
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3
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7k
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Do electromagnetic waves produce sound?
Preamble:
At 5 AM in the morning, if I sit quietly and listen attentively, I can hear many different noises, on a very high frequency. If I try to isolate the ones that are less noisy, I can clearly ...
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