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Questions tagged [spectral-density]

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Understanding Decibel in a power spectral density plot

I wanted to plot the spectral content of my EEG data using MNE but I am unable to understand what this graph actually gives. I am having troubles in understanding the y-axis. From what I have gathered so far, a Decibel is calculated "relative" to…
Amelia
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Units of scipy.signal.stft

I am currently applying a short-term Fourier transform to some electrophysiological signal (variable 'my_signal', in mV/m^2). I would like to get the spectral amplitude in the same unit (mV/m^2/Hz). I did: f, t, Zxx = sg.stft(my_signal, fs = sf,…
user1363251
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Amplitude in Frequency domain not matching time domain signal after FFT in python. Explanation?

I am trying to create a Power spectral density function in python that outputs the amplitude spectral density and cumulative power spectral density graphs. I am using scipy.fft to compute the FFT of my output data. Then an operation to compute the…
mechPadawan
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Proper use of window parameter for Welch power spectral density (scipy)?

I am trying to calculate the Welch power spectral density over specific frequency bands for EEG signal processing ($\delta$ (0–4 Hz), $\theta$ (4–8 Hz), $\alpha$ (8–13 Hz), $\beta$ (13–30 Hz), $\gamma_1$ (30–60 Hz), and $\gamma_2$ (60–90 Hz)). I…
FM3
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Calculation of the power-law distribution (and exponent)

Aim: My aim is the calculation and display of a power-law distribution. Input to Phyton: The input files for Python provided by me are 1-column .txt files. Each .txt file has a column of numeric values extracted from time-series data. My script…
Philipp
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Power Spectrum Analysis for a very large set of data

I have a voltage signal that I am trying to denoise. The signal comes in very large files (524288 cells). When I take the whole file and make n equal to length of data set, I get two extremely large peaks at frequency 0 and max. sig =…
Ayub Sherif
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Using spectrum function to find peaks with same intervals

I have to analyze data and find instances that have higher values repeating through same intervals. Example: I am trying to use spectrum function but it gives me weird result. Here is my example data, I inserted outliers every 1 hour into…
Maxim
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Rotate PSD plot in Python by 90 degrees

I have generated a Power Spectral Density (PSD) plot using the command plt.psd(x,512,fs) I am attempting to duplicate this plot from a paper: I am able to get the spectrogram and the PSD graph. I however need to get the PSD rotated 90 degrees…
Joe
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How to get the amplitude spectrum function from the PSD or ASD?

I am sorry in advance for a bit clumsy question, but I am really stucked in the simple, but not trivial problem of finding the amplitude spectrum function from the given PSD or ASD. So, what I have initially is this ASD and PSD of the signal: What…
Abracadabra
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I am unable to get the psd range in R package psd to extend to a frequency of 1.5Hz

I have a timeseries for which I need PSD values using R. The data was sampled at non uniform intervals but I did a spline interpolation with the predict command to interpolate readings at exactly 0.01 seconds. I could obtain amplitude values from…
user2004198
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FFT for Spectral Analysis

Can someone explain me these lines of python code, and the role of each line ? thank you in advance. X_f = abs(sf.fft(x)) l = np.size(x) fr = (Fs/2)*np.linspace(0.1, l/2) xl_m = (2/l)*abs(X_f[0:np.size(fr)]);
Chamseddine
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Converting dimensions in power spectral density

I want to convert my data which is in Vpp/sqrt(Hz) to rad^2/sqrt(Hz) to compare with other data. So that I can go forward in my research work. How can I achieve this?
Sai Bharath
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Interpreting jTransform FFT results

I'm using Jtransforms java library to perform analysis on a give dataset. An example of the data is as follows: 980,988,1160,1080,928,1068,1156,1152,1176,1264 I'm using the DoubleFFT_1D funtion in jTransforms. The data output is as follows: 10952,…
Damon
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how to retrieve original signal from power spectrum

I have calculated power spectrum of signal. the steps are: FFT of time signal square of absolute value of FFT/length of signal i.e power spectrum Now I want to convert it into time domain. What steps should I follow.
user33584
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Converting spectral density values produced by spectrum() in R to values produced by SAS PROC SPECTRA

I am converting SAS programs that demonstrate temporal data analysis into R. I would like to reproduce SAS PROC SPECTRA output using R. So, my question is, can the spectral density values produced by the spectrum() function in R be converted into…
Timothy Schwinghamer
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