Questions tagged [signal-processing]
The subfield of electrical engineering that focusses on analysing, modifying, and synthesizing signals such as sound, images, and scientific measurements.
383
questions
0
votes
1
answer
398
views
Removing $1/f$ noise with lock-in-amplifiers
On the Wikipedia page for 1/f noise (at the bottom of the page) it suggests the noise can be reduced if the signal of interest is at DC. DC signals suffer from significant 1/f noise, so one method of ...
- 1,816
3
votes
1
answer
230
views
How fast, based on the laws of physics can the Internet be? [closed]
Assuming the actual physics, optics, signal processing and similar, how fast can we increase the 'speed' of the Internet?
I know the limit would be $$v \le c,$$ but are there some other limits:
...
- 4,747
2
votes
1
answer
171
views
Fourier transform of an exponentially decaying waveform
Consider an atom oscillating at a certain frequency. The amplitude of the oscillation decreases over time such that the waveform can be modeled by an exponential function, but the frequency remains ...
- 23
0
votes
2
answers
278
views
Drawing digital signal from analog signal
I was doing a question related to analogue to digital conversion. Here's the question,
Draw the digital signal corresponding to the analogue signal given below. Assume that the system has a bit rate ...
0
votes
1
answer
48
views
Physical validity of taking limits inside an integrand
Consider an integral expression for the spectrum, $$I(\omega)=\int_{-\infty}^{\infty}G(\omega,t)dt\tag{1}$$
with
$$G(\omega,t)=g(\omega,t)e^{t/\tau}.$$
Here $t$ is time, $\omega$ is frequency and $\...
- 155
1
vote
1
answer
47
views
Signal Generated from Transmitter [closed]
Suppose that we have a transmitter of $150.100\ \mathrm{ MHz}$.
We also have a receiver at a fixed point.
The transmitter constantly generates signals toward the direction of the receiver.
Based only ...
- 115
2
votes
1
answer
83
views
Which one is more precise: Phase locked loop or log the waveform then do sliding FFT?
I have an experimental confusion. I am using an interferometer to monitor the movement of a translation stage by monitoring the intensity of the coaxis interference pattern of the He-Ne laser.
...
- 357
0
votes
1
answer
49
views
Infer 3D location (Height, Latitude, Longitude) based on Signal Strength
Sorry if my question is irrelevant.
Let's consider two cases:
$1)$ Suppose that we have an Antenna and a tagged individual that can be pinged from the Antenna. Suppose that the individual is pinged ...
- 115
0
votes
1
answer
127
views
Capacitor microphones for recording studios
This question is formulated exclusively for high school students precisely to interest them in a more concrete way.
Condenser microphones are characterized by a capsule that functions exactly like an ...
- 2,547
0
votes
0
answers
37
views
Is it possible to use a distributed camera array to fake an interferometric sensor without phase data?
Astronomical interferometry is a technique which uses multiple small telescopes to mimic one giant telescope. It requires the phase of the light to be captured for it to work. It is widely used in ...
8
votes
1
answer
98
views
Once LIGO confirms a gravitational wave signal, can data from less sensitive detectors give more insight?
Only detectors above a certain sensitivity can measure with a high enough signal to noise ratio (SNR) to successfully pick out gravitational waves using matched filtering.
However, once we have ...
1
vote
1
answer
43
views
What is the relation between the frequency vector and the Nyquist frequency?
When trying to comprehend the concept of Nyquist frequency in FFT, I came across the following definition for half of the frequency range:
$$f = -f_{n}/2:df:f_{n}/2-1;$$
where $f$ represents the ...
- 753
2
votes
1
answer
381
views
Why can't you filter out the sound of running water using noise-cancelling software?
The book "Clint Emerson - 100 deadly skills", a fun illustrated book of spy techniques claims the following:
Deadly skill No 054, Civilian BLUF:
While noise-canceling software can override ...
- 143
1
vote
1
answer
77
views
Would increase the size of an antenna theoretically improve the ability to capture signals, if we allow changing the shape?
I have an argument with my friend about drone radio systems.
My assumption is this: the bigger the receiver the better reception is possible to achieve. The logic behind this is geometry: transmitter ...
- 111
5
votes
2
answers
808
views
Rope as Communication Media [closed]
I'm a computer student that used to play microcontroller and sensor. I'm not sure whether this topic fits on this site.
I'm thinking about using rope as media communication instead of fiber optic. I ...
3
votes
1
answer
130
views
Analog Is Digital (Discrete)?
As I started reading a bit about analog vs digital signals, I keep returning to this thought. This could be something pretty obvious to the pros out there, but is it safe to assume that underneath it ...
- 131
5
votes
2
answers
963
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 ...
- 3,407
5
votes
1
answer
289
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, ...
- 501
0
votes
0
answers
126
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 ...
- 753
1
vote
1
answer
166
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 ...
- 113
1
vote
1
answer
96
views
Can we decompose sound like white light is decomposed (dispersed) in different colors?
When we send white light through a prism, the light is decomposed in the colors that constitute it due to the different velocities which different frequencies. Is there a way to decompose "white ...
0
votes
1
answer
43
views
Why does CW imaging not provide the same data as Pulsed imaging?
"Unlike pulsed THz imaging, the CW imaging (...) only yields intensity data and does not provide any depth, frequency-domain or time-domain information (...)." [1]
Why does a pulsed signal ...
- 753
1
vote
0
answers
35
views
Can a signal calculate its time period?
I wanted to know if a radio wave has some kind of data for example a kind of packet information (if its a thing) and it gets transmitted and gets received by a receiver, then can it calculate the time ...
- 21
0
votes
1
answer
36
views
Apparent superluminal signals, is it as simple a variation on the following?
I know that astronomers observe jets that apparently move faster than light but really don't. I think I can simulate something that looks superluminal using just a bunch of x-mas lights and i am ...
- 2,238
1
vote
1
answer
46
views
Computing correlation between two time series: confusion regarding nonlinear relationship and nonlinear data
I am trying to understand if correlation can be computed between two time series generated from two different initial conditions for chaotic dynamical systems. In general, correlation is applicable ...
- 235
1
vote
0
answers
244
views
Fourier transform of sound wave
I am a high school student doing a project in Fourier transform. I was planning to learn Fourier transform and manually apply the calculations to a section of a song and see what I get. However, I ...
- 11
1
vote
1
answer
29
views
Is it possible to reveal a slight chronological change in frequency of Voyager 1 and 2 signals due to Hubble flow effect?
Is it possible to reveal a slight change in frequency of Voyager 1 and 2 signals due to Hubble flow effect? As both are about 1 light-day from Earth and as it is unbelievebly small distance compared ...
- 1,815
0
votes
2
answers
682
views
Can unjammable radio communication be achieved by transmitting an error-correcting code of high-energy pulses in a secret, unpredictable pattern?
Signal jamming seems like an annoyingly simple way to sabotage a lot of interesting ideas. It has historically been used to block reception of propaganda broadcasts, and also to ruin military ...
- 75
-2
votes
1
answer
84
views
Breaking apart a sin wave but phase doesn't seem to match up sometimes
I am trying to create a known signal with a known wavelength, amplitude, and phase. I then want to break this signal apart into all of its frequencies, find amplitudes, phases, and wavelengths for ...
- 105
2
votes
1
answer
586
views
Interpreting a normalized Power Spectral Density (PSD)
I am using software to produce power spectral density (PSD) plots of time-series (voltage versus time). Unfortunately, the units of the produced plots are alien to me. I'm used to reading and ...
- 799