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0
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2answers
49 views

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

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 ...
1
vote
0answers
9 views

Low Pass Filtered Noise Power Spectra, Showing Low Power @ Lowest Frequencies [migrated]

White noise is being passed through a voltage follower, then filtered through a simple first order low pass RC circuit (C=0.5 micro Farad, varying resistance between 2k-10k, ohm depending on RC value ...
2
votes
1answer
108 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 ...
4
votes
1answer
115 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
92 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 ...
0
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0answers
41 views

On the application of chaos in signal processing [migrated]

Paper: A novel channel equalizer for chaotic digital communication system (DOI, RS link). I am having problem in understanding their claim which is that a nonlinear system, considered here to be a ...
1
vote
2answers
98 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
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0answers
21 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
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0answers
25 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 ...
0
votes
0answers
8 views

How does impulse lose energy in rotation, forward and striking earth?

I have this kind of empirical signal in Electronics. where the electronics simulate events signal in rotation signal going forward and signal hitting the earth. The area of the signal is ...
3
votes
2answers
185 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
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0answers
46 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
40 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
107 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
0answers
31 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 ...
1
vote
5answers
229 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
31 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
65 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
69 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
53 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 ...
4
votes
1answer
673 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
67 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
71 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
47 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
25 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
55 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 ...
1
vote
1answer
110 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
46 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
126 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
114 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
0answers
60 views

Can we use EEG to record signal from spinal cord?

My hype is about the idea that Spinal cord around neck is the place every signal sent to control whole body. So if we can record all signal, we could analyze movement of our body from finger to leg ...
0
votes
1answer
28 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
118 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
75 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
152 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 ...
2
votes
2answers
173 views

Mapping between numbers and symbolic representations

I am not a physicist but applying symbolic dynamics for information coding in signal processing. Is there any mapping between symbols and numbers?
0
votes
0answers
42 views

Standard way to quantify the total difference between power spectra?

I have two signals. I'm interested in quantifying, with a scalar value, the difference in power spectra between them. Is there a standard distance measure for power spectra? If not, what are some ...
0
votes
1answer
76 views

If halving signal strength is only a 3db drop, why can't cell phones be much lower powered?

My phone can receive a signal that's -90dBm. That's roughly one-billionth of a milliwatt. Cutting a signal's strength in half only drops the signal by 3dBm. Apart from slightly higher range, is there ...
0
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0answers
14 views

How does time relate to frequency in terms of averaging to reduce noise?

It seems for the longer time we average, the more frequencies we can incorporate in calculating the V(rms) of the noise. Why is this?
0
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0answers
8 views

Extracting times of hits from a composite detector response

I have a detector that registers a sequence of "hits" over a period of time. Each hit produces a signal that has the approximate form ...
14
votes
3answers
5k views

How Earth communicates with Voyager I?

After taking a basic signals & systems class and learning about the frequency domain, I started wondering: How the heck do scientists still communicate with Voyagers I and II??   Do they ...
0
votes
0answers
30 views

Nyquist plots in electronics

Being purely biologist I'd like to obtain some general background in the application of any forms of Nyquist plots for study of signal transduction. For instance from one of the electronic lecture ...
1
vote
0answers
34 views

Why can't we use the Neyman-Pearson likelihood ratio directly?

If you have a bunch of events and would like to choose a cut to distinguish background and signal, you can take the likelihood ratio $$ \lambda(\vec x) = \frac{f(\vec x| s)}{f(\vec x| b)} $$ and the ...
12
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4answers
480 views

Reconstruction of “wavefunction” phases from $|\psi(x)|$ and $|\tilde \psi(p)|$

Consider a "wavefunction" $\psi(x)$, which has a Fourier transform $\tilde \psi(p)$ Suppose that we know, for each $x$, $|\psi(x)|^2$, and that we know, for each $p$, $|\tilde \psi(p)|^2$. Have we ...
0
votes
0answers
55 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 ...
-1
votes
1answer
94 views

Bandwidth of telephone wire

Internet providers try to sell us the more and faster "fast internet" - 15Mb, 40Mb, 100Mb, and so on. But it's well known that the bandwidth the channel (in the most cases it's the telephone wire) ...
3
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2answers
1k 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. ...
2
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0answers
147 views

Why is Erbium Doped Fiber Amplifier (EDFA) preferred over Erbium Doped Waveguide Amplifier (EDWA)?

Why is Erbium Doped Fiber Amplifier (EDFA) preferred over Erbium Doped Waveguide Amplifier (EDWA)? The question has been asked from an engineering point of view, but obviously I would also be ...
5
votes
1answer
131 views

Why does a wall act as a low-pass filter?

Learning about the fourier transform and its connection to filtering/convolution got me curious about naturally occurring filters. Why/how is it that brick walls naturally act as a low-pass filter ...