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1
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1answer
111 views

calculate period from peak in frequency of signal

I have been looking at this figure, which I've extracted from some lecture notes, for some time now: It shows the cross spectra of two time series. My notes state that the peak in the spectra ...
2
votes
1answer
195 views

Significance of higher harmonics

I am analyzing a noise signal and have identified the fundamental frequency of a tone and it's higher harmonics. Say for example given the signal below, The fundamental frequency has a sound ...
1
vote
1answer
34 views

Acoustical Design considerations for Active Noise Cancellation Project for Air vent [closed]

I am working on ''Active noise cancellation for air vent'' project. I am using NI myRIO1900, Audio Technica ATR 3350 omni directional microphones and Tevion Loudspeakers. I have done the programming ...
1
vote
1answer
33 views

Karhunen-Loeve transform of a repeating process

This question is inspired by measurements of an unsteady flow. I have some doubts about interpretation of principal component transform using Karhunen-Loeve theorem. I have (centered $\equiv$ zero ...
0
votes
0answers
17 views

Eigenvalues for correlation matrix which have the form of an harmonic function

I am trying to understand the written in the picture below. I took the matrix $C_{2 \times 2}$ which is: $$C=\left[ \begin{array}{} a& ace^{-\frac{|\phi_1-\phi_2|}{2}}\\ ...
1
vote
0answers
40 views

Making eye diagrams for binary signals [closed]

This should be relatively simple, but I'm just not understanding it. For a binary signaling of rate $\frac{1}{T}$, sketch the eye diagram when the following pulse shape ($p(t)$) is applied and the ...
3
votes
0answers
68 views

Remove measured distribution from another distribution [closed]

Take a particle beam as an ensemble of many particles. Assume two independent random variables $X_\beta$ and $\delta$ that add up to the horizontal position $X$ of a particle: $$ X = X_\beta + D_x ...
0
votes
3answers
105 views

About quantization of EM energy for amplitude-modulated wave

Consider an electromagnetic monochromatic plane wave at frequency $f$ and E-field amplitude $E_0$ in vacuum. From the quantum electrodynamics point of view, we could say that the energy that EM wave ...
0
votes
1answer
17 views

How does this RSSI vs Distance equation work?

I came across this equation in a research paper, and can't seem to make sense of it. Let me give an argument for why it doesn't make sense, and perhaps someone can tell me where my flaw is? $$ ...
0
votes
2answers
76 views

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 ...
0
votes
0answers
23 views

Time domain representation of a waveform from an accelerating source (doppler effect)

Consider the scenario where a stationary observer observes a source moving in 3 dimensions, emitting a signal $s(t)$. I would assume only the distance between the source and the observer, $x(t)$, has ...
0
votes
1answer
160 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 ...
0
votes
1answer
34 views

Would optical signal processing still suffer from slew rate?

In electronics, analog signal processing/computation suffers from parasitic capacitance which leads to slew rate—which is the maximum change of voltage allowed, so handling super-high frequency ...
0
votes
2answers
41 views

Calculate energy of a signal

I have trouble with calculating the Energy of the following simple signal $x(t) = e^\left(j\left(t+\pi/2\right)\right)$ Shouldn't it have $A=1=|x(t)|$, So ...
12
votes
3answers
324 views

What does a blackbody sound like?

Update: According to this wikipedia article, blackbody radiation is just thermal noise (Johnson–Nyquist noise); if that's what I'm looking for, what does it sound like? If a blackbody has a ...
0
votes
1answer
60 views

How can one change the virtual position of a sound source with a fixed array of speakers?

I have a question about signal processing: How to make a person, sitting between array of two loudspeakers (one from the left and one from his right), hear the sound that came from both loudspeakers, ...
0
votes
0answers
22 views

How does impulse lose energy in rotation?

I have this kind of empirical signal in Electronics where the signal is 1D current measurement (AD current coming from dynamic processes) such that the wire rotates in a big volume of water/mud: ...
1
vote
0answers
39 views

Discrete Fourier transform for periodic signal?

From the Signal and System textbook, by Oppenheim, I learned that the discrete-time Fourier transform can be written as $$ x[n]=\frac{1}{2\pi}\int_{2\pi}X(e^{j\omega})e^{j\omega n}d\omega $$ $$ ...
0
votes
1answer
44 views

Whether there is any relationship between the frequency of an input signal and the frequency of it's fourier transform?

Whether there is any relationship between the frequency of an input signal and the frequency of it's fourier transform? For example, suppose I gave a 100Hz signal, whether my FFT frquency will also be ...
3
votes
2answers
2k views

Why is bandwidth, range of frequencies, important when sending wave signals, such as in radio?

So in wired/wireless networking and radio, signals are sent in form of wave. Then the concept of bandwidth comes in, which is the difference between highest frequency and lowest frequency in a signal. ...
1
vote
0answers
41 views

Signal-to-Noise ratio given pixel intensity map [closed]

I have a question regarding calculing the SNR of a signal given the pixel intensities. Say I'm given the pixel intensity values below: $\begin{array}{ |c|c|c| } \hline 3&3&3&3&3 \\ ...
0
votes
2answers
103 views

Why is a sine wave considered the fundamental building block of any signal? Why not some other function? [closed]

It is mathematically possible to express a given signal as a sum of functions other than sines and cosines. With that in mind, why does signal processing always revolve around breaking down the signal ...
4
votes
1answer
307 views

White Noise Generator Through Low Pass Filter - Autocorrelation of normalized data dropping below 0 (showing negative correlation)

I am doing the following experiment: http://physlab.lums.edu.pk/images/a/ab/Correlation.pdf It is basically a white noise generator running through a low pass filter. Sample voltages are taken and ...
1
vote
3answers
130 views

Whether the job of Fourier Transform is just to convert signals from time domain to frequency domain only or more than it?

I am a beginner . We convert a signal in time domain to frequency domain by applying Fourier transform on the signal to obtain frequency and phase spectrum. So,whether the job of Fourier transform ...
1
vote
2answers
110 views

How do phase carries structural information about the function? [closed]

Suppose you are on a railway platform and you hear the sound of train coming towards you. Now, Using Fourier transformation we can convert the time domain function (here take sound as a function) ...
0
votes
0answers
31 views

Deconvoluting Raman spectras from different wavelengths

I am using a laser source that is wider than typical laser source for Raman spectroscopy. This mean that the full width at half maximum (FWHM) of the laser is about 5-10 nm, compared to the normal 1-3 ...
0
votes
0answers
61 views

How power spectral density in time domain can be understood?

I got some data which basically gives me the variation on the time of a PSD measured across specific frequency bands ranges, for instance [10Hz-30Hz]. However I have not found any good explanation ...
3
votes
2answers
234 views

What is the significance of the Fourier coefficients?

Let us take an example, a white ray (which is composed of bunch of frequency components) is passed through a prism, the ray gets split (decomposed) into its elementary vibgyor colours (i.e.different ...
1
vote
0answers
62 views

Can anybody explain about phase shift and phase spectrum terms in case of multidimensional signal?

I know about phase of a 1D signal, but when I move into higher dimensions like 2D or 3D etc, it becomes headache to grasp the concept. What do the terms "phase shift" and "phase spectrum" mean in ...
0
votes
1answer
46 views

How to compute phases of the signals?

Let us take 4 signals which are sinusoidal and periodic. Suppose you are given a phase spectrum or (/and) equation of the (main) signal only and you are said that the given (main) signal is formed of ...
0
votes
1answer
142 views

Have some queries about Fourier transform [closed]

I have some queries about the Fourier transform In most of the cases, the Fourier transform of a signal is symmetric with respect to positive and negative frequency. I think the computational ...
1
vote
5answers
235 views

Normal distribution of x, xdot [closed]

I have some real measurements from a process and I happened to look at the mutual distribution of (x(t), xdot(t)). I found that they seem to follow 2d normal distribution around (mu, 0). See image, ...
1
vote
0answers
36 views

What is the concept of phase congruency?

I am beginner in signal processing. I am studying the importance of phase in signals. I want to know about Phase Congruency, but there is very little information available on internet. So can anybody ...
4
votes
1answer
2k views

Signal-to-noise ratio of the difference between two signals

Something tells me this must be a fairly simple question, but I have somehow been unable to find an answer to it. In short: I need to calculate the difference between two signals, A and B, each one of ...
0
votes
1answer
86 views

Is this a frequency domain plot for audio? [closed]

I have a program "spectrum" that draws an chart for an audio file (a short .wav with an human voice recorded on it). I believe it is a frequency domain chart. The ...
3
votes
1answer
72 views

Optical signal filters

Are there any optical filters which filter the signal's frequency and not based on the wavelength of the light? So what I mean is, if I have a modulated/pulsating light signal riding on a large DC ...
0
votes
1answer
85 views

Energy and power of a signal via Fourier [closed]

It is asked to evaluate the energy and power of the signal $$x(t)=10\cos(100t+30°)-5\sin(220t-50°)$$ Since it is periodic, I need to find $$\int _{-\infty}^\infty |x(t)| dt\quad \text{ and }\quad ...
5
votes
1answer
780 views

Dialing emergency numbers with no network available. How? [closed]

When the network is not available on my phone, it says "emergency calls only". It means that even if I'm in the middle of the desert, with no towers in the vicinity, I can dial the emergency number. ...
0
votes
0answers
114 views

why Angular Frequency is useful in comparison with spatial frequency in video?

what is difference between angular frequency and spatial frequency when we are talking about eye perceiving in a video. In many texts about video (for example Yao Wang's Video Processing and ...
4
votes
1answer
82 views

What is the interpretatation of individual contributions to the Shannon entropy?

If $X=\{ x_1,x_2,\dots,x_n\}$ are assigned probabilities $p(x_i)$, then the entropy is defined as $\sum_{i=1}^n\ p(x_i)\,\cdot\left(-\log p(x_i)\right).$ One may call $I(x_i)=-\log p(x_i)$ the ...
0
votes
0answers
56 views

Measuring typical distance between patches using 2D Fourier Transform

I need to extract information about the typical distance between the black patches in an image like the one I attached here. I tried to perform 2D FFT on it (using OpenCF fdt function in Python), but ...
0
votes
0answers
29 views

What does bispectrum mean?

I am working on a project that uses EEG signals of the brain to identify emotional states. While surveying the literature, I came across several references where "derived features of bispectrum" are ...
1
vote
1answer
117 views

Two superimposed sounds traveling through low- and high-density matter: is separation possible?

Two superimposed sounds (at source: $s(t) = s_1(t) + s_2(t)$; the two sound components overlap completely in time, partially in spectra) travel through low- and high-density matter and are recorded ...
1
vote
0answers
60 views

Why is information transfer usually done through frequency modulation but not amplitude modulation [closed]

For example, if we were to transmit a sequence of code, we could do so by alternating the flash rate of the source, or alternate the strength of the source. Both methods can represent a large amount ...
1
vote
3answers
145 views

What does a constant signal sound like?

Say I was sampling a sound incorrectly and it produced a constant signal as below: What would this signal sound like? In Matlab, it plays nothing. Is this correct?
0
votes
2answers
164 views

Does a rotating DC motor near a TV affects the signals coming in the TV?

In my TV cable the signals were quite noisy so i cut the wire and hanged both the wire parallel to each other. Then the signals became very clear and everything was going alright. Once I was ...
0
votes
1answer
34 views

What should the cross-correlation of two signals look like if their difference is non-significant?

I have some signal data from my lab that I want to present but I want to be able to say whether the signals I have are significantly different or not. I thought I could use cross-correlation. I ...
0
votes
2answers
192 views

Why need for 96kHz, 192kHz audio? [closed]

Human can hear 20-20,000 Hz waves, so by Nyquist theorem it's sufficient to sample audio with 40 kHz. Indeed, 44.1 kHz widely used. But what do we need higher sample rates for? 96 kHz, 192 kHz are ...
1
vote
2answers
89 views

Energy of a signal

"The energy" of a signal $x(t)$ is defined as : $$E_s = \int_{-\infty}^{\infty}|x(t)|^2$$ Why is it called energy if it's not homogeneous to energy ? What does it actually represent ? Parseval's ...
0
votes
2answers
196 views

What does it mean to have two phase coherent signals at different frequencies?

Just as the title states, I don't understand what it means to have two different signals that are phase coherent but are at different frequencies. I am attempting to implement a MSK modulator in ...