# Questions tagged [signal-processing]

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1answer
180 views

### What, mathematically, is the power spectrum of a signal?

Given a signal $f(t)$ defined on $t\in(-\infty,\infty),$ what is the precise definition of the power spectrum of $f$, i.e., what is the mathematical operation that takes $f$ to the output of an ideal ...
0answers
47 views

### Pink noise and averaging

Disclaimer: I am aware this is somehow at the boundary between physics and statistics, but I have the impression that it is more likely that somebody doing/studying physics, rather than statistics, ...
0answers
92 views

### How can the Fourier delta function produce different matrices in single-pixel imaging?

The pattern in the masks used for single-pixel imaging are created applying equation $(1)$, $$P_\phi (x,y) = \frac{1}{2} \left[ 1 +| F^{-1} \{\delta_H (u,v) e^{i\phi}\}|\right], \tag{1}$$ in which the ...
1answer
30 views

### What is the meaning of the absolute of the Fourier transform in this context?

In a course talking about Fourrier transform and Nyquist frequency, there is this sentence that I can't understand: "If a signal has $|F(w)| \geq 0$ only for frequencies till f, than such ...
0answers
11 views

### Does less than half a wavelength antenna spacing help?

In Metamaterial based Holographic Beamforming (https://pivotalcommware.com/wp-content/uploads/2017/12/Holographic-Beamforming-WP-v.6C-FINAL.pdf), the spacing of the elements is much lesser than half ...
0answers
77 views

### How do I calculate the inverse Fourier transform of the delta function? [migrated]

In the context of single-pixel imaging, the following statement is given: "A Fourier basis pattern $P_F (x,y)$ can be obtained by applying an inverse Fourier transform $\delta_F (u, v, \phi)$to ...
0answers
16 views

0answers
31 views

### 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 ...
1answer
31 views

### 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 ...
2answers
161 views

### 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 ...
0answers
22 views

### 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 ...
0answers
30 views

### 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 ...
0answers
31 views

### Octave analysis Versus FFT analysis?

Why is the one-octave method more significant or of great value compared to FFT analysis? Is it because of the sensitivity of the human ears to perceive sound in octaves? is there any other reason?
1answer
88 views

### 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? ...
0answers
14 views

### Analogue to digital signal graph

I star‌ted the digital electronic course on youyube recently and i am new to the signals concept In the pictures below i tried to convert an analogue signal graph to a digital signal graph So first i ...
10answers
4k 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 mathematics behind it, but I'm struggling to find an explanation of ...
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 ...
0answers
16 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 ...
1answer
138 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 ...
0answers
10 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. ...
1answer
34 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 ...
0answers
41 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)....
0answers
14 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 ...