# Tagged Questions

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50 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 ...
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### 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 ...
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### 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 ...
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### 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 ...
460 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 ...
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### 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 ...
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### 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 ...
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### 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 ...
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### Normal distribution of x, xdot [closed]

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, ...
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### 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 ...
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### 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 ...
2k 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 ...
866 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 ...
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### 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 ...
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### 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 ...
211 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 ...
6k 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 ...
591 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 ...
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### 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. ...
3k 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 ...
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### 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?
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### 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 ...