Questions tagged [signal-processing]
The subfield of electrical engineering that focusses on analysing, modifying, and synthesizing signals such as sound, images, and scientific measurements.
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Terminology: "3σ detection over the continuum"
I am reading a research paper and they use the expression:
"This is a weak signal, i.e. 3-4σ detection over the continuum".
I saw this sentence in a lot of papers, but I can not find what ...
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Fringe movement analysis to extract displacement
I am using a Michelson interferometer with the interferogram recorded on a CMOS sensor. I have taken a video of the fringes moving when a displacement of 50 $\mu m$ is imposed to one of the mirrors.
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If radio signals attenuate when travelling through space, then what kinds of emissions are we looking for when searching for extraterrestreal life?
My understanding is that radio waves travel forever, like ripples in a pond, but attenuate with distance. They get mixed with other signals and become cosmic noise.
I'm looking at these answers, which ...
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Implement EPR Imaging deconvolution
I have bruker's EPRI data and I want to deconvolute it.
I read some article, that says
$$
f(r) = x(r) \circledast g(r) \\
F(ω) = X(ω) \times G(ω) \\
X(ω) = \frac{F(ω)}{G(ω)}
$$
$f(r)$: imaging spectre,...
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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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Maximum distance between two towers for space wave propogations
Context: Space waves are a form of radio wave propagations, a space wave travels in a straight line from the transmitting tower. The problem here is related to line of sight communication.
In the ...
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Computing a second harmonic resistance out of a wave-like resistance signal
I want to reproduce the results of a paper, in which they measure the Anharmonic Hall Effect (AHE) resistance $R_{AHE}^{2\omega}$. There are several protocols for measuring it experimentally, but I'm ...
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Are there any application in the exp of log of DFT matrix? [closed]
Just a fun thought.
Since the N point DFT matrix $W$ is a complex rotation matrix:
$$W^*W = I$$
$$det(W)=1$$
It may make sense to work on a rotated domain with a projection matrix $W_\phi$:
$$W_\phi=...
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Why square wave-form output is higher than a sin or a triangle wave-form output?
I'm working on a digital audio synthesiser and I'm facing out an issue about the amplitude level.
I'have a sinusoid signal which have a max amplitude of $-1 / +1$ and a square signal which have a max ...
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Does Fourier Series "decodes" the sources of the signal?
I understand the mathematical concept behind Fourier Series that every periodic function can be represented as the sum of sines and cosines. But I can't understand its applications. Lets assume that ...
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Amplitude based "filtering"
Standard filters in electronic circuits are devices that allow a certain range of frequencies to pass through while attenuate other frequencies. I was wondering if something similar could be built ...
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Positive vs. Negative pulse on an electrode
For a particle detector (e.g. ionization chamber, proportional counter,...), what factor determines the polarity of the pulse of the "raw" signals (signals straight from the electrodes ...
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FFT on a signal with a length that is not a multiple of the period of its harmonics
I was very surprised to find an apparent limitation to a FFT on a simple signal.
Let's consider a timeseries made of L=100 points, and simply composed of the sum of two sinus waves: one with a ...
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How to hide radio communications between airplanes? [closed]
I have 2 airplanes and I would like completely hide the communications between them.
There is a possible way that this communications would not be detected by our radio receivers around the world? ...
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Why does a capacitor act as a frequency filter?
What is it about a capacitor which allows it to filter frequencies?
I understand the construction of a high-pass RC filter, and the mathematics behind it, but I'm struggling to find an explanation of ...
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What distribution shape does this broadband signal have if the bandwidth changes?
In the Lumerical tool, I'm simulating a setup using a broadband dipole signal. It is (or should be) centered at $\lambda=$ 922.5 nm and has various bandwidths $\Delta \lambda$ for different ...
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What causes the non-arrival of the signal of my remote (infrared) control device for our TV?
Recently I made this video. It can be seen and heard that the remote control (MTLogic) of our TV doesn't work when I place an object between it and the TV. This is the remote control:
It's obvious ...
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How to determine waveform of thermal (white) noise?
Here, the mean power of thermal noise is given by:
$P = 4kT$ ($T$ = temperature, $k$ = Boltzmann’s constant)
And the voltage in the instrument is, of course, thus given by:
$V^2/R = 4kT$
The thermal ...
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Intuitive explanation of Nyquist rate?
Is there an intuitive way to understand Nyquist rate (i.e., that, in order to prevent loss, an analog signal must be digitized at a rate twice as high as the highest frequency component of the signal)....
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What is the maximum electromagnetic bandwidth achievable between planets? [closed]
As an example, if communication was done using visible light, communication would be limited by the respective atmospheres, dust and obstacles along the line of sight. At the same time, multiple ...
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How does an optical chopper work?
How is an optical chopper eliminating drift? Or in more concrete words: Why is a chopped signal eliminating drift (DC -> AC)?
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Does the “direction” of a signal physically matter?
I am thinking of the typical (sound, electromagnetic or whatever) signal which can be represented in time or frequency domain as a collection of infinite amplitudes for, respectively, each time-point ...
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Frequency of signal means changing or moving?
I saw some where frequncy means how fast a signal is changing and i am confused.
Since frequncy means how much cycle a signal completes in unit of time and we may say how fast a signal is moving but ...
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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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Noise spectral density for waveguide: I don't understand this calculation
In Introduction to Quantum Noise, Measurement and Amplification, on page 64 is computed the power spectral density of noise on a classical waveguide. I am really struggling to understand a step of the ...
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Noise power spectral density and $|X(\omega)|^2$. Why are those quantities associated usually ? Their definitions are different
I consider a generic signal $X(t)$. We could imagine to fix ideas $X(t)=\sqrt{R}I(t)$ ($R$ being a resistor and $I$ current flowing through it)
The energy of this signal is defined as $E=\int_{-\infty}...
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Why don't we have heat circuits?
Common circuits use electricity to transmit power and signals.
I know we transfer heat power using things like HVAC (heating, ventilation, and air conditioning).
I don't know anything that encodes/...
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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)$$
where $A$ is a constant, $w$ is the angular frequency and $f(t)$ is an arbitrary function that depends on time.
It ...
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In square wave modulation: should the low frequency part of the graph not take place in the low amplitude part of the pulse?
I try to get my sound program right, and hoped to find some help here with the understanding of frequency modulation by a square wave.
My modulation looks like this: (please excuse if my formula ...
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Substitution of frequation in Fourier transform of the signal $\hat x(f)$ to $\hat x(\omega)$
In wikipedia of ESD and PSD, there is a pair of equations, one is
$$\hat x(f) = \int_{-\infty}^\infty e^{-2\pi ift}x(t){\rm d}t$$
We know $\omega= 2\pi f$. How can we obtain then the other
$$\hat x(\...
