Questions tagged [power-spectral-density]

The Power Spectral Density (PSD) is the distribution of signal power over frequencies.

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power spectral density estimation

I have an audio signal carols.wav. How do I obtain the PSD in Matlab using the inbuild pwelch function and also to write my own code.
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How to implement Matlab welch in python with the same result?

I want to implement Matlab pwelch function in python. The Matlab code is shown blew: [PSD,f] = pwelch(data,length(data),[],[],2000); which data is a row vector ...
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Plotting curved peaks on PSD graph

I am a PhD student with little engineering experience, currently attempting to recreate the signal processing techniques used in this paper: Monitoring Vital Signs and Postures During Sleep Using WiFi ...
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What are some of the disadvantages of parametric PSD estimation methods?

Roughly speaking, the methods of power-spectra estimation can be divided in two categories : parametric and non-parametric. From what I understood, parametric methods assumes that the signal can be ...
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why a limit on passband in spectral masks?

I was wondering why there is a usually flat limit on passband of every spectral masks. For sidebands it makes sense but for passband not so much.
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Correct comparison of FFT noise with FFT signal

I have a sensor which I am using to track a strong but noisy varying signal. When the signal is present there is a lot of energy in the FFT bins, when there is no signal the is much less energy - but ...
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Definitions of PSD, ESD and Autocorrelation

This question is going to encompass multiple areas and may not have a single answer but here it goes. I'm trying to conceptualize 3 different concepts and how they relate to each other. These 3 ...
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Difference of doing a PSD estimate of data and logarithmic transformed data?

What is the difference between doing a PSD estimate with data and the same data but which is logarithmically transformed before the estimate? Does it make the data more sinusoidal in nature? An ...
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PSD using MATLAB's $\tt pwelch$ algorithm window length and measure units

When using pwelch algorithm in MATLAB for a signal with $N$ samples, Is there a good rule of thumb for determining the length $L$ of the sections (second variable ...
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Can't seem to get welch function in scipy work correctly

I'm trying to learn DSP through using Python's scipy package. I have measure some 200Hz signal from a machine. Now I want to inspect the spectral density of the signal. Here's the signal plotted out: ...
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Relating Fourier and power-law descriptions of noise

I'm trying to understand this PDF, which is in English but has Polish authors, so there may be translation issues confusing me. The subject is the frequencies of sentence lengths in novels. Eq. (1), ...
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Prefactors computing PSD of a signal with numpy.fft VS. scipy.signal.welch

The power spectral density St of a signal u may be computed as the product of the FFT of the signal, ...
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Spectral density functions in NMR

A spectral density function (three of them depicted below) is 'power' vs frequency. These functions apparently inform us on the dynamics of spins in a protein somehow but I'm having the hardest time ...
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MATLAB & Power Spectral Density - Error - Getting the same range of values regardless of sound type?

I wrote code [attached at end of question] to take .wav files of child vocalizations and tried to see if there are valid ranges for the formants F1:F2:F3 for the 5 ...
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Computing differences between dynamic power spectrums to identify transient features

I have a few minutes of magnetic field data with a lot of noise and unwanted frequencies, and I'd like to be able to identify any transient waves that may appear in my data. To do this, I'm dividing ...
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Clip wav by PSD

I have the following two things. sequence_1: Sound file in the wave format. PSD_1: Some PSD (Power Spectral Density). I want that the PSD(sequence_1) < PSD_1 for all indices. How I think about ...
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Fluctuations of spectral density estimates

I have seen in a few papers things like : or Without ever seeing the assumptions which are made, and of course no justifications. Does somebody know why it is a valid approximation to make ?
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Test of statistical significance of power-spectrum against red-noise

I have a process which is most probably red-noise and my goal is to know if the peaks or pits are "real" or just due to random fluctuations. I would like to know if there is exists a test of ...
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PSD subtraction

I am interested seeing the difference between two power spectral densities (PSD) as a noise reduction exercise The blue line is the psd of my signal, and the the orange line is the psd of the ...
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power systems database

I'm having a hard time searching for a power systems database. I need some samples of a real wave form from a power source, like a residential power plug or an industrial one.
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Confusion about PSD and RMS

Let's say I have a noise power-spectral-density (PSD) which is not flat and ranges from 0 to $f_1$ Hz in frequency. As we know, the total area under the PSD is equal to the total average power of the ...
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A few questions about the output value of dsp.SpectrumAnalyzer

I am testing the output values of dsp.SpectrumAnalyzer for a sine wave mixed with white noise. The $\sigma^2$ of the white noise is 1e-4, so I use 0.01*randn(1024,1)...
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Calculate the harmonics in the power supply of $50\textrm{ Hz}$ using FFT

I need to calculate the harmonics in the power supply of $50\textrm{ Hz}$. If suppose I need to calculate up to 20 harmonics. Then my sampling frequency by Nyquist criteria should be : f_s \ge 2 ...
I want to calculate the channel power $P_\mathrm{x}$ of a given discrete and complex signal $x[n]$ (with a length of N) in a given bandwidth $B$. I'm aware, that I could probably apply a sharp ...