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Questions tagged [signal-processing]

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0
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2answers
60 views

Multiple frequencies [closed]

could someone please inform me how it is possible to send multiple frequencies down one wire? I’m referring specifically to a communication protocol known as HART. It seems they send a 4-20mA signal ...
2
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3answers
75 views

Can a sound wave begin with rarefaction?

Some digital recording samples (audio files) of recorded acoustic sounds present sound waves which begin with rarefaction. Is this an actual phenomena that can occur or is it a result of sound ...
3
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1answer
142 views

Applying Kramers-Kronig relation to a simple damped oscillator

I just discovered the Kramers-Kronig relation and am trying to apply it to a simple damped oscillator of the form subjected to an impulse at $t=0$, which is a causal system: $$m\ddot x + c\dot x + k ...
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0answers
29 views

Mathematical Resolution of Overlapping Signals

I would like to take the opinion of physicists (my area is chemistry). During instrumental analysis, the output is a instrument response vs. time. Each peak corresponds to a molecule which is ...
0
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1answer
67 views

Proving a theorem about the average value of a function over a specific region

Let's say transient phenomenon in a function. A transient phenomenon is defined as: "A transient event is a short-lived burst of energy in a system caused by a sudden change of state." So, for ...
0
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1answer
18 views

What does the phase discriminator portion of the Costas Receiver do mathematically?

What does the phase discriminator portion of the Costas Receiver do mathematically? The output of the $I$-channel is $ \frac{1}{2}A_C \cos \phi \, m(t) $. Which means for small deviation of phase $ \...
0
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1answer
42 views

What exactly is the output impedance in this circuit, and why must it be low?

I'm currently considering this circuit: Which is really just two RL filters added together. A single RL-filter looks like this: I want to be able to multiply the transfer functions of the left and ...
1
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0answers
37 views

Fourier Coefficients

Suppose i've a two voice samples v1 and v2. Comparatively voice v1 is louder than the v2. If both the voice is spoken by the same person.(Spoken normally as he speaks) Is it good to state the ...
0
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1answer
23 views

Calculation of speed from accelerometer data

I am trying to use my accelerometer on my mobile device fitness band to find the speed of walking and running. I conducted my experiment of walking and running on treadmill where I asked a person to ...
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0answers
42 views

Dispersion of light

I've been taking digital signal processing course. It's pretty interesting for me. One thought came to my mind while I've been practicing numerical problem on Fourier transform. So my question is ...
1
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0answers
127 views

Fraunhofer diffraction problem in Python: How to interpret discrete Fourier transform (DFT) spectrum?

I have a periodic phase grating consisting of lenslets along the x-direction, invariant in y. I want to use python to calculate the far-field (Fraunhofer) diffraction pattern that one gets when ...
0
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2answers
134 views

What is a “Fourier transform limited pulse”?

I have some doubts about the definiton of a Fourier transform limited pulse. For example if I consider a generic pulse: $$E(z,t)=\frac{1}{\sqrt{2\pi}}\int_{-\infty}^{+\infty}A(\omega)e^{i(-\beta(\...
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0answers
60 views

Are Huygens wavelets just a geometric method for understanding how a wave moves forward or are they an actual thing?

Wavelets are emitted from every point on a wave towards all directions is what I read on a book but on another book I read Wavelets are emitted towards the same direction of the wave. And They create ...
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0answers
16 views

Sawtooth synthesis using random harmonic phase

I was experimenting with Octave and NumPy/SciPy by synthesizing (reverse) sawtooth waves and decided to find out what a sawtooth comprised of harmonics with arbitrary phases would sound like. Note ...
1
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1answer
75 views

Fourier transform of power

In the notes I am reading they use the following. Let $U$ be the voltage (depends on time) and $I$ the current in a circuit with some resistor with resistance $R$. Then the power is given by: $$P(t)=...
1
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1answer
83 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?
0
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2answers
32 views

Why doesn't central obscuration put a big dot in the middle of a PSF for a centrally obscured optic?

I'm confused as to how central obscuration effects the PSF. Low pass filters make sense since they are inherently oriented with dealing with spatial frequency, resulting in blur in the spatial domain....
0
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1answer
12 views

What influences the variance of signal transmission speed?

I'm currently thinking about the various sources that influence time when it is synchronized with the NTP protocol. One of them is the physical layer (OSI-model). When sending a bit over a cable, ...
1
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1answer
23 views

How do scintillation detectors work, for gamma ray spectroscopy

So I understand what happens in the crystal with respect to the interactions and how the electrons in PMT are multiplied by hitting dynodes etc. But what I can't really seem to find any information on ...
2
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1answer
82 views

Why non-linear fiber capacity limit decrease for higher signal-noise ratios?

In fiber optics communication, there is the concept of nonlinear Shannon limit (see e.g. this article), implying that the communication capacity of an optical fiber decreases for high SNR. I don’t ...
1
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0answers
55 views

Can the periodicity in k-space of the electronic band structure be understood as a result of aliasing?

Discrete sampling in the case of phonons In the case of phonons in periodic solids, the picture is quite intuitive. The motion of the atoms in the lattice is described as a continuous wave (amplitude ...
3
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1answer
59 views

Mathematical term for the on/off gradient functions in MRI imaging

The slice selection gradients, as well as the phase and frequency, in MRI imaging are traditionally represented by on/off box or rectangular symbols: or My question is what is the mathematical name ...
0
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0answers
68 views

Using lock-in to measure $ f $ instead of $ f' $

What I know about lock-in measurement is the following: you have a device you want to test and instead of giving it a DC input, you would modulate your DC input with some sinusoidal modulation and ...
0
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1answer
22 views

Noise reduction approaches in optical spectral measurement

I am using an optical spectrometer to measure some surfaces in the visible, and since the signal is quite noisy I wondering what would be the best way to reduce the noise. In particular, are there ...
0
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0answers
70 views

Mean velocity in unsteady flow

I'm starting hydraulic experiments, where I'd have to measure velocity in an unsteady flow with a device called Acoustic Doppler Velocimeter (acquisition rate: 100 Hz) . In DSP terms, I'd have a ...
-2
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3answers
96 views

Does a 1 kHz signal have harmonics above or below 1 kHz, and where is its fundamental frequency?

I'm having an argument with a friend ─ he believes a 1 kHz audio signal has its fundamental frequency at 1 kHz with harmonics above that value, while I believe the fundamental frequency will be far ...
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2answers
61 views

How does ultrasound work? How is the signal processed?

Why is ultrasound 2D? Is there a way of making ultrasound 3D without piecing together 2D? How close is ultrasound to sonar?
1
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1answer
42 views

Multilateration of Sound in 3D Space

TL:DR - How can you find the 3D coordinates of a emitter than transmits an impulse signal? STORY: I'm working on something to improve my bird-watching. I've got a camera that can take pictures of ...
0
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1answer
82 views

Superposition of waves whose wavelengths are continuous

I know how to find the resultant waves when finitely or countably many waves are superimposed but how do I find the wave equation when there are infinitely many waves whose wavelength is continuous? ...
1
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0answers
349 views

Blocking Infrared Signals [closed]

I am currently working on a project that involves infrared signals. This project has an infrared receiver, but I would like for it to receive signals from front side only. For example, if the signal ...
0
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1answer
29 views

Can a gaussian pulse be a pure tone?

I was given a signal dataset, and I was told it is a gaussian pulse and a pure tone. I am unsure how this is related as when I read about this two terms, there are differences in them. so can a ...
2
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2answers
56 views

Why we can assert, in general, that physical processes have the behaviour of low-pass filter?

Consequently, why is it not allowed to produce physically some controllers for processes that are described by a transfer function that is an improper function? A simple example is the driven ...
0
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2answers
156 views

Is it fair to say that signal processing is a quantum phenomenon?

I recently saw a video by 3Blue1Brown, in which he explained that the uncertainty principle isn't a quantum phenomenon, but a result of basic signal properties. The basic premise was: the more precise ...
3
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1answer
46 views

Sound an amplifier makes when you plug / unplug a cable [closed]

When you plug, unplug or even touch a jack cable of an aplifying system with speakers, one can hear a low-pitch sound that is of roughly always the same frequency, which does not seem to depend on the ...
0
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2answers
77 views

Low frequency wave ability to penetrate object

as shown in this em wave spectrum image, the lower the frequency the better a wave ability to penetrate object. https://c479107.ssl.cf2.rackcdn.com/files/20642/area14mp/pvgrynkw-1361853572.jpg my ...
0
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1answer
28 views

what does the “T” really represent in the signal power equation

In the signal power equation $$ P(g(t)) = \lim _{T\to \infty }{\frac{\left(\int_{-\frac{T}{2}}^{\frac{T}{2}}g\left(t \right)^2dt\ \right)}{T}} $$ What does the $T$ really represent ? From my ...
0
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0answers
105 views

High speed data transfer over a fiber optic cable

Can someone please explain how can we transmit very high speed data (e.g. $10~\rm Gbps$) over fiber optics, knowing the fact that the wave that travels through the fiber is an optical wave (in the ...
0
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0answers
34 views

Low frequency waves influence of high frequency waves

If I have a 20 MHz surface wave travelling along a material, and then introduce a 50 or 100 Hz wave source, will there be a noticeable difference to the output? (Surface acoustic wave type device, ...
-1
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2answers
27 views

How can I send a wave towards something and have it respond with a specific value?

Imagine a bat, for example. It uses its echo-location to send waves which get reflected back and thus return information about the surroundings. I want to do the same thing, but instead of just ...
1
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2answers
48 views

Recognizing speech at 1bit quantise depth?

i found on german wikipedia an audio example of 1 bit depth quantising, where the speech still can be recognized. how is it possible if at 1 bit depth we have just two values: "signal" and "no-signal"?...
1
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1answer
159 views

What is the difference between collimating, waveguiding, attenuating, and polarizing? [closed]

What's the difference between collimating, waveguiding, attenuating, and polarizing? Are they related on any level at all?
-1
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0answers
56 views

How do I analyze this frequency spectrum obtained from pouring water into a bottle?

I measured the frequency of sound in the bottle neck while pouring water into a bottle and obtained a frequency spectrum which is in the comment section of the link in Quora. Please tell me how to ...
0
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1answer
25 views

When can raw data can be used to look for phase synchronization between time series?

I'm studying a system formed by multiple rotors non-linearly coupled to each other. If I want to look for phase synchronization, I could just look at the angle for predefined points around the ...
0
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1answer
67 views

Acoustic power spectral density change due to diffraction

Say we have an acoustical point source emitting white noise - i.e., a power spectral density of $$S_x(f) = \frac{N_0}{2}$$ The source is embedded in the plane such that it radiates in half-space - i.e....
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3answers
103 views

Use of negative frequency for the sake of simplifying mathematics?

How can we use the idea of negative frequency for the sake of simplifying mathematics if negative frequency does not exist (to my knowledge) in nature ? For example, when plotting the spectra of a ...
0
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1answer
28 views

reading radar / waves changing after hitting each other

Can you read a radar or any wave when it hits another wave...it changes? So say a radar wave hits another wave changing it miles away, can you get info of that hit happening miles away from the radar ...
0
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1answer
42 views

Understanding feedback =1 and comparing with a system with no feedback

I was studying this system In this V its a Voltage in a circuit and V_c its the voltage in a capacitor, the circuit was not provided, then calculated the step response (well I was told the step ...
0
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1answer
31 views

Can the telephone signals be tapped by an intruder? [closed]

I have a doubt. There are lots of telecommunication signals moving across the world, at the same time. For example, take the case of mobile phone calls. Millions of speech signals are propagating ...
1
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0answers
190 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 ...
18
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6answers
9k views

Why are cosine and sine functions used when representing a signal or a wave? [closed]

Actually, in the mathematics sine and cosine functions are defined based on right angled triangles. But how will the representation of a wave or signal say based on these trigonometric functions (we ...