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1answer
14 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 ...
1
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0answers
37 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
78 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 ...
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
25 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 ...
4
votes
1answer
132 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 ...
0
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0answers
33 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
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0answers
11 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 ...
1
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0answers
49 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 ...
3
votes
2answers
186 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 ...
0
votes
1answer
115 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
3answers
102 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
0answers
34 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 ...
2
votes
1answer
110 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
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0answers
32 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 ...
0
votes
1answer
67 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 ...
0
votes
1answer
55 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
700 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
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0answers
73 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 ...
0
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0answers
48 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 ...
4
votes
1answer
72 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
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0answers
27 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
57 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
111 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 ...
0
votes
2answers
119 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
29 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
131 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
0answers
44 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
82 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 ...
0
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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
37 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 ...
0
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2answers
157 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 ...
0
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0answers
62 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 ...
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
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0answers
74 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
104 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
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
1answer
1k views

Compression vs Rarefaction in Sound Waves

I am currently looking into solutions for Sound Classification, and I came across Ludvigsen's methodology (if anyone wishes to refer to it). The problem is that a sample graph of amplitudes in one of ...
0
votes
0answers
27 views

A sonar continuously emits x(t), a general but known waveform and is reflected by a target. hypothetical question

A sonar continuously emits x(t), a general but known waveform that is reflected by a target and received by the sonar. Both the sonar and the target move in the 3-dimensional space in a general but ...
5
votes
1answer
133 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 ...
1
vote
0answers
17 views

Spatial Resolution in Magnetocardiography

In the science paper called Development of an optical cardio-magnetometer by George Bison, it is mentioned that spatial resolution of 10-20mm is required for mapping MCG signal(page 52). What does the ...
4
votes
1answer
244 views

Image Reconstruction:Phase vs. Magnitude

Figure 1.(c) shows the Test image reconstructed from MAGNITUDE spectrum only. We can say that the intensity values of LOW frequency pixels are comparatively more than HIGH frequency pixels. $$ ...
3
votes
3answers
234 views

Why don't you always use a high sampling rate?

I was just curious, as I was reading about aliasing. As far as I understand, aliasing comes from the fact, that you use a bad sampling rate, resulting in getting a wrong waveform compared to the one ...
4
votes
4answers
676 views

Continuous Fourier transform vs. Discrete Fourier transform

Continuous Fourier transform vs. Discrete Fourier transform. Can anyone tell me what the difference is physics-wise? I know the mathematical way to do both, but when do you use the other instead of ...
0
votes
1answer
58 views

Is there any way to find difference between two same sounds of different people?

I am trying to understand and find a way to distinguish two same sounds of different people by some physics formula, so could you guys help me? OK I'll try to explain my question in this way that, ...