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Questions tagged [spectral-density]

63 questions
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C++ - Complex Value mistake, computing Cross Spectral Density (CSD)

Dear community, I am facing a rather annoying problem. I am calculating the Cross Spectral Density (CSD) between two time signals, which were already proccessed with FFT to two complex frequency vectors(Singal1 =>freqvec, Signal2 =>…
Daniel Velden
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Using IFFT to get original signal and Parseval's Theorem

I have a current signal (extracted in csv) which I obtained from cadence simulation over 30ns time. I have removed DC offset and applied windowing function before FFT. And normalized FFT by sqrt(N). I have shift zero-frequency component to center of…
aguntuk
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FFT and PSD of current signal and analysis

I have a current signal which I obtained from cadence simulation over 30ns time but my current actually varies (which I call active region) over certain period. I extracted the data of current signal over 1ps fixed step and plotted the current. Then…
aguntuk
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window size and overlapping in pwelch function of matlab for PSD evaluations

Could anyone please suggest ideal Window size and overlapping samples for pwelch function in Matlab. I have several 200 ms EEG signals with sampling rate 1000 (signal length or number of samples = 200) to evaluate spectral power. By default pwelch…
user8020776
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Absolute/averaged spectral power of 128 channel EEG signal

I have a EEG signal with 128 channels and 500 samples as 128*500 matrix. I know we can calculate power spectral density using pmcov or pwelch in matlab for any discrete time signal. But is there any way in which I can calculate absolute or averaged…
user8020776
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Understanding frequency in time-series object R (spectral analysis)

I am trying to find out whether or not there is a 6-monthly seasonality in my data. I want to do it with spectral analysis, where I would look at the Ftest of the spectrum at a specific frequency. I am looking for help to understand what the x-axis…
Brigitte
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FFT output to PSD

I need some help understanding the output of the FFT. I'm working with GNU radio. I have a Signal source with output is Float type, after go through FFT transform, data will be send to my App using UDP. My App receives the data in a byte array and…
Bihex_26
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Plotting PSD in R

I'm making PSD plots of one minute recordings of white noise that I made underwater with a hydrophone. I have about 12 files to analyze. I made the plots, but my professor wants me to do a log transform of the data and make a plot of that. I am…
Emma Mccauley
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Is it appropriate to use PSD on the analysis of a plucked guitar string?

I'm using python 2.7 to compare tonal differences in guitar stings. I asked this same question in dsp.stackexchange.com but didn't have much luck so I figured I'd ask here, too. I've found that in matplotlib, there are some great built-in features…
Clayton Pipkin
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Python Calculating PSD and CSD of ONE Array

I got some problem in my signal analysis. I load an array in my script (x) with the shape of x(68, 815). 68 represent the number of signals in the array. So I want to perform PSD and CSD on it like. CSD: x[0] with x[1] .... x[0] with x[67] and…
Daniel Velden
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Computing power spectral density without averaging

I've been using psd() to compute power spectral density over a .wav file. I've shown it to my supervisor and he doesn't want it averaged to compute the Pxx: The |FFT(i)|^2 of each segment are averaged to compute Pxx He suggested I use PSD but…
Nanor
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Accurate frequency estimation with short time series data - maximum entropy methods or Yule Walker AR method?

I am using the Lomb-Scargle code to estimate some frequencies in a short time-series, the time series is shown in the first image. The results of the Lomb-Scargle analysis are shown in the second, and I have zoomed in on a prominent peak at about 2…
user2653752
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I need to calculate the average power spectral density after passing packets through a butterworth filter using MATLAB

I am trying to generate 100 packets(row vectors each of size 8192) of random bits(1,-1),filter them using butterworth filter and then plot their average power spectral density. I have to do this using MATLAB.My o/p should be a filtered sinc with a…
Samia
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spectral structure of sinusoidal model

let us consider following code function [ x ] = generate1(N,m,A3) f1 = 100; f2 = 200; T = 1./f1; t = (0:(N*T/m):(N*T))'; %' wn = randn(length(t),1); %zero mean variance 1 x = 20.*sin(2.*pi.*f1.*t) + 30.*cos(2.*pi.*f2.*t) + A3.*wn; %[pks,locs] =…
user466534
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Attempt to apply non-function on Spectral Density equation

I am trying to find the spectral density of an MA(2) model using R. This is the formula I came up with but R is telling me there is an "attempt to apply non-function" error. Can't find where I went wrong. Help. specdensity= (sigma^2 +…
Gru
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