The signal-processing tag has no wiki summary.
11
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2answers
3k 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 ...
8
votes
1answer
233 views
Can the Kramers–Kronig relation be used to correct transfer function measurements?
In experimental physics, we often make measurements of linear transfer functions; these are complex-valued functions of frequency. If the underlying system is causal, then the transfer function must ...
6
votes
2answers
574 views
How to distinguish female and male voices via Fourier analysis?
What makes one, without looking, be able to identify the gender of the talker as male or female?
I mean if we Fourier analysed the voice of males and females, how the 2 spectrums are different which ...
6
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3answers
1k views
Why is the bispectrum not commonly used in experimental physics?
Power spectra, coherence spectra, and linear transfer functions are ubiquitous tools of experimental physics. However, our instruments often retain small nonlinear effects which can contaminate ...
5
votes
2answers
154 views
Multiple channels of information in single electromagnetic wave?
I'm trying to understand how can multiple radio stations transmit information just by transmitting using different frequency. The way I understand it all those different frequency waves add up to a ...
5
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3answers
1k views
Can Laplace's equation be solved using Fourier transform instead of Fourier series?
Sorry for the long text, but I am unable to make my question more compact.
Any periodic function can be Fourier expanded. Usually, they say in mathematical physics books, if the function is not ...
4
votes
2answers
149 views
Autocorrelation of sound in liquids vs gas
This is just a curiosity and you need to bear with me as my math skills were always sub-par and so is my English academic language. My specialty is Electronics but I have always been a programmer.
...
4
votes
1answer
143 views
Products of Gaussian stochastic process variables
In the classic experimental physics text "Statistical Theory of Signal Detection" by Carl. W. Helstrom, Chapter II, section 4 concerns Gaussian Stochastic Processes. Such a process is observed at ...
4
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1answer
400 views
How does phase modulation conspire to eliminate power variations?
A purely phase-modulated signal has no power modulation. This is obvious enough if you look at the time series, but I'd like to "see" it in the frequency domain.
In physical terms, if we take a ...
3
votes
3answers
113 views
What information is stored on gramaphones/tape recorders/CDs/DVDs
I'm a Software Developer by profession and my physics knowledge is limited what I had learned at high school level. Please excuse me if the question is trivial.
Question:
From what I know, a sound ...
3
votes
1answer
655 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 ...
3
votes
2answers
183 views
Why is the observed signal the convolution of the true signal with the instrumental function?
Imagine we are observing a star. The light coming from a star enters an optical instrument that will give us some observed data, such as the spectrum of light say.
What we observe is not the true ...
3
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3answers
429 views
Loss of Power at high frequencies
One of my work colleagues told me that a cable he is sending a signal through is losing power at high frequencies. So he recommends the signal should be amplified before being sent. The explanation ...
3
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1answer
95 views
Frequency of a periodic signal with distortions
I would like to evaluate frequency of some unstable periodic signal coming from a detector:
The signal is registered continuously and may or may not be present (i.e. be periodic). The frequency ...
3
votes
1answer
28 views
How to determine frequency components present in distorted signal, with the set of possible components already known?
I am trying to choose the best approach to digitally analyse a signal, which is a mix of an unknown number (but less than 16) fundamental signals at specific frequencies (e.g., sines).
The goal is ...
2
votes
1answer
102 views
How would one generate Brownian light? What would it look like?
When light is an equal mix of all visible frequencies, we call it white light.
By analogy, sound that is a mix of all audible frequencies is called white noise.
For sound, there is an additional ...
2
votes
2answers
312 views
Simulating eye diagrams
I'm trying to figure out how to simulate eye diagrams for communications systems using Python. I'm not sure I have the theory down completely, though. From what I could figure out using some old ...
2
votes
2answers
79 views
Electronic filter
Can you explain, please, step-by-step how Electronic filter does work?
For example, high pass filter. I know It's a trivial things, but I can't get it completely. Don't bring me formula and etc... ...
1
vote
5answers
165 views
Normal distribution of x, xdot
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
1answer
37 views
What creates the differences between the two channels of a stereophonic signal?
Given two identical microphones arranged in an ideal XY pattern, recording a single sound source at equal distance from both capsules, the two signals obtained are equal in amplitude, perfectly in ...
1
vote
2answers
446 views
Noise amplitude increases as sample rate increase
I am testing the material properties of some very low stiffness materials.
I'm using a force probe connected to software, sensing at about a hundredth of a gram of force.
Now, what's interesting is ...
1
vote
1answer
557 views
Amplitude of power spectral density
Why is the amplitude of the Power spectral density higher for shorter period of time as compared to a longer period of time when calculated for any vibration data?
1
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0answers
32 views
Effect of Background Radiation on a Transmitted Signal
I'm coding a basic simulation of using error correcting codes to transmit data from a satellite back to earth. I'm not sure what to set the "noise level" to. Let's say a satellite orbiting Mars ...
1
vote
0answers
34 views
How do you super impose two or more signals to occupy a fix area of space with the resultant summed wave?
Is it possible to super-impose two or more signals all sent from different directions as a standing wave with the resulting summed wave occupying a fix area of space that is also a complex area?
Do ...
0
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3answers
329 views
Magnitude of the Fourier Transform of White Noise
Say you have two white noise signals with different variation amplitudes A1 and A2 as shown in this beautiful Excel graph:
Ignoring the DC offset as it's been represented here, how do you relate ...
0
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0answers
44 views
Transfer functions of active filters
I've been looking for some straightforward method or trick to obtain the transfer functions of active filters (like the Sallen-Key filter, the butterworth or Cauer topology etc...) since KCL or KVL ...
0
votes
0answers
82 views
Wireless signal strength
My question is possibly somewhat misplaced, but I'll try to explain as best as I can. Suppose I have a transmitter with a frequency of 2500MHz and a power of 1W. It radiates uniformly in all ...
0
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0answers
29 views
What is the main downfall of using QPSK rather than DQPSK in fiber optics?
I've read that QPSK works theoretically in order to encode two bits depending on the phase of the signal. However, practically a reference for the carrier signal would be needed due to some ambiguity ...
0
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0answers
89 views
What should the amplitude be when plotting 1-sided Amplitude Spectrum?
I have a continuous signal $x(t)$ such that
$$x(t)=12\cos(6\pi t)+6\cos(24\pi t)+3\cos(30 \pi t)$$
and is asked to sketch a 1-sided Amplitude Spectrum of the signal $x(t)$ if sampled above the ...
0
votes
1answer
188 views
Sine wave with a constant period: what else is constant? [closed]
Which statistic that you can calculate on a window remains constant on a sine wave with a constant period? This is for a window function for a proprietary filter.
