Questions tagged [signal-processing]

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3answers
147 views

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 maths behind it, but I'm struggling to find an explanation of the ...
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0answers
8 views

Peak Spectral Period

I'm doing a small assignment for my signals subject. I'm stuck trying to understand the meaning of the "spectral peak period", it was mentioned in a video I'm referring to. I do know what ...
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0answers
17 views

Fourier analysis for the study of signals doubt [closed]

I know that Fourier analysis in an experimental way is very important, but can we say that it is the most powerful tool we have to study signals? or what is it that most contributes to the study of ...
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0answers
10 views

How to extract wavelet from signal?

I got signal with different wavelets, the first wavelet is strongest one and I need to extract it from signal. It could start at t >= 0, it is not intersects ...
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0answers
13 views

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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1answer
73 views

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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1answer
41 views

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 ...
2
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1answer
922 views

Bandwidth of a control system

Why is it said that larger bandwidth leads to better command following , better disturbance rejection and speedy response , but the practical bandwidth being limited by external noise?
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0answers
4 views

Autocorrelation Matrix of sub-band

So, I'm dealing with the smart antenna and different DoA algorithms. In order to define narrowband signal directions I have to calculate autocorrelation matrix of this antenna in the frequency domain. ...
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1answer
32 views

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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1answer
479 views

How to estimate the frequency of the sample rate?

I'm studying for my class of physics laboratory and I need help with something: Let's say I need to deduce the constant of elasticity of a spring and I will do it using a dual-range force sensor, ...
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0answers
32 views

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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0answers
13 views

How to calculate resolution given sampling rate/size?

In a research paper documenting the analog to digital conversion process of an experiment’s radio receiver, the following is written: The station consists of 10 channels. Each channel writes 1 ...
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0answers
23 views

Why is the worst case input/output impedance of an $RC$ filter $R$?

I'm going through the Art of Electronics in my spare time, and I ran across a problem I've been scratching my head about for a few days. The book states that in the worst case for any $RC$ filter, the ...
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1answer
45 views

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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3answers
666 views

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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2answers
2k views

What are some good resources for learning photonics?

Including the generation, transmission, modulation, signal processing, amplification, and detection/sensing of light, I am interested in getting a good understanding of photonics. Does anyone have any ...
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1answer
35 views

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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1answer
16 views

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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3answers
115 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 ...
4
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1answer
120 views

Can you get a better signal to noise ratio by connecting multiple microphones in series?

From my very basic understanding of microphones, they generate a tiny bit of electricity as the membrane moves, this is the signal. It would stand to reason then, that if I connect a bunch of ...
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1answer
77 views

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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0answers
46 views

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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1answer
56 views

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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0answers
28 views

Difference in mathematical formula between signal to noise ratio (SNR) and signal to noise and distortion ratio (SINAD)

I am trying to get a grip on mathematical meaning of signal to noise ratio (SNR) and signal to noise and distortion ratio (SINAD). What I found out is that in terms of power: $$SNR=\frac{P_{signal}}{...
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4answers
72 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 ...
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0answers
23 views

How to normalize a deconvolution of a signal?

What I have: A recorded signal, in dimensions voltage (or any kind of intensity) over time A response function of the system, responding to a nearly gaussian input signal What I try to achieve: I ...
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0answers
34 views

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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0answers
36 views

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(\...
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0answers
19 views

A problem with high pass filter circuit

What physically happens when the input frequency is "too high"? At "normal" frequencies the circuit should act as expected and block lower frequencies while getting only higher ones. I found that if ...
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2answers
1k views

Convolutions in Physics

At a high-level Wikipedia states: "A convolution between two functions produces a third expressing how the shape of one is modified by the other." But there are clearly many ways of combining ...
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1answer
39 views

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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0answers
31 views

How to calculate Doppler Shift for multipaths from moving objects?

Let's say we have a radar where the transmitter and receiver are placed together, and form an angle theta with a target object moving with velocity ...
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4answers
104 views

An apparent contradiction in various explanations of frequency bands and data bandwidth

From wikipedia: "A key characteristic of bandwidth is that any band of a given width can carry the same amount of information, regardless of where that band is located in the frequency spectrum. For ...
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1answer
28 views

Does the light pulse broadens in time when passing bandpass filter?

What I don't understand about relationship between laser pulse width in time and frequency, is where these rules apply, namely rules of Bandwidth-limited pulses. Say, I have a femtosecond laser ...
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0answers
29 views

A question on $s$-parameters

I have been playing around on CST to create a rectangular 2-port waveguide with a block of material at the centre and plot s-parameters. I have done this successfully, however I cannot get my head ...
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2answers
46 views

Wireless data transmission more than a bit at a time

I'm not that educated in wireless data transmission, but, the basics of frequency modulation and or amplitude modulation are quite basic. Is there any examples of transferring more than a bit at a ...
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0answers
16 views

Copper or Glass for Low Latency?

I'd like to preface the main content of this post with the following: I understand this question may be equally suited to the Network Engineering Stack Exchange, but I believe the answer relies on a ...
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0answers
40 views

Any method to detect extremely weak electromagnetic wave signal? (10^12Hz, level ~10^(-28) Watt per meter^2 per Hz)

Could you please let me know whether there is any method on the Earth to detect some EXTREMELY weak electromagnetic wave signal, if it is a planar wave, if its exact waveform is completely known (...
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0answers
16 views

Is there a graphical summary of which modulation technique to use in communication systems using Visible Light Communication techniques?

I am currently looking at various papers written (some listed at the bottom) that discuss how laser pulses can be modulated to send encoded messages to a receiver for communication systems. The more I ...
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0answers
21 views

Scattering matrix for a reversed mirror

Suppose I have a mirror which is asymmetric, for example, it is a dielectric coating put onto a glass substrate. Call the air side of the coating the primary side and the glass side of the coating the ...
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1answer
281 views

How can I calculate the sensitivity of a seismometer?

I would like to know how to find the minimum ground motion a seismometer can measure, specifically if a certain seismometer can measure 1 micron/sec velocity. I have a few specs from the datasheet but ...
2
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1answer
50 views

How are sampled signals reconstructed to original?

Recently I've read an article and watched a video by Monty Montgomery, where he's dealing with the so-called "staircases" in sampled signals. He clearly demonstrated that a signal within Nyquist ...
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4answers
1k views

Difference between analog signal and digital signal

There is no perfect generator of a true digital signal in the real world natural phenomenon. Most of the physical signals produced by humans and animals like roaring, speaking, playing, clapping, ...
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3answers
67 views

Can a resonance plot be upside down, i.e., inverted?

Given the following RLC circuit with an AC driving source, $\hskip3in$ I have found an expression for the amplitude to be $$ I(t) = \left(\frac{V_{0}}{R}\right)\frac{(\omega \tau)}{\sqrt{(\omega\...
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1answer
38 views

Power Spectrum Density of real valued time series data

There are real valued time-series data X(t) and corresponding auto-correlation function ACF(t)=$\left<X(0)X(t)\right>$. As written in wikipedia, Power Spectrum Density (PSD) can be calculated ...
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1answer
27 views

RLC Bandpass Filter network

Can anybody tell me what the "s" in this equation is? I am looking for the transfer function of this circuit
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1answer
35 views

Why are an audio signal and its cochlear response modelled as two-dimensional variables?

According to Eguíluz et al, amplification of an incoming audio signal by the human ear can be described by a supercritical Hopf-bifurcation $$\dot x(t) =(\lambda-i\omega_0-|x(t)|^2)x(t)+S(t),$$ ...
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1answer
441 views

Signal distortion due to impedance mismatch

Does impedance mismatch only reduces the power transmission efficiency or it gives rise to signal distortion also? Can anyone please explain this in detail?
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1answer
76 views

Fourier Transform of finite time series

I have some signal $s(t)$ which is real data i.e. finite. The time runs from $-T$ to $+T$. The signal amplitude is large at $t=0$ and small ($\rightarrow 0$) at the $\pm T$ limits. I can do a finite ...

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