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2answers
31 views

Figure of merit for 'locality of power'

I have a raw signal which, if interpreted correctly with various 'tuning' parameters set to their optimum values, can be seen to consist of a relatively small (but a priori unknown) set of discrete ...
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0answers
26 views

How to normalize pwelch output and calculate band power using it ? . In matlab

I am using , [pxx,f] = pwelch(x,window,noverlap,f,fs) , to compute power spectrum of a EEG signal . I have to calculate band power in 1Hz frequency bands in 4-30Hz , using Hamming window , with 50% ...
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0answers
6 views

Spectrum density estimation in R. Plot scale

I used spec.pgram to estimate the spectrum of a sequence. It gives a plot, I wonder what exact does it plot? It is not spec in the return value it is not log of that, it is not log10 of that. I fail ...
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0answers
34 views

Relationship between values of frequency magnitude and values of time amplitude in an audio signal

I have an audio signal in wave format, with its time amplitude values located between -1 and 1. When I compute its fft (in respect to the whole signal) and then extract its absolute value to plot the ...
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1answer
29 views

Is there a closed form expression for noise other than white noise?

For white noise, where the PSD is constant, we can model that as a simple Gaussian. Is there any way to model the probability density function of other types of noise (pink noise, red noise, blue ...
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1answer
29 views

Deriving Time-Series Data from PSD when the Inverse Fourier Transform doesn't converge

So I'm trying to get some sample time-series data from pink noise (PSD: $S(f) = 1/f$). However, when I try to evaluate the Inverse Fourier Transform integral $\int \frac{1}{\omega} e^{j \omega t} dt$ ...
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1answer
33 views

Determining Power Spectral Density from Autocorrelation Function and Time-Series Data

So I think I've confused myself a bit here. I know that taking the FFT of time-series data (wind velocities, for example) yields a power spectral density. However, I just read that taking the Fourier ...
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1answer
47 views

why is the plot of the PSD of this autocorrelation function oscillating?

I was doing an exercise trying to compute the PSD of the following discrete autocorrelation function: \begin{equation} r_x(m) =(1/2)^{|m|} \end{equation} In this simple matlab code that I came up ...
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0answers
23 views

Determining the point in a temporal signal when a periodic behavior begins to occur

I'm a newcomer to digital signal processing, so I'm looking for some general advice and direction on this problem I have. I have a signal like that shown below. Starting around x=40000, you can see a ...
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1answer
47 views

WSS Ergodic Process with Power Spectrum

I was given a WSS ergodic process $x(t)$ with power spectrum : $$ \begin{array}{rcl} G_x(f) &=&1−\left|\frac{f}{B}\right| &\mbox{for } |f|<B\\ G_x(f) &=& 0 & ...
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0answers
17 views

“Normalizing” PSD of unequal window lengths

I am acquiring time-varying data with unequal sampling (nature of the source). When building a spectrogram, I have the algorithm choose sample blocks that are are -nearly- the same length -but, they ...
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1answer
27 views

Splitting of signal into different components for calculation of PSD

In BCI competition 3 dataset 5, It has been stated that we have to take 8-30 Hz frequency and break it with resolution of 2 Hz then it will result in 12 components but I am finding out only 11 ...
1
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1answer
127 views

Phase difference between two sinuisoidal signal

Currently, I have two signals, the main components of both signals are 60Hz, but both also have weaker response at 180Hz + small amount of noise. As shown in the photo below, I want to find the phase ...
1
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1answer
29 views

Is a negative Es/No for an SCPC RF signal possible, and what would such a value signify?

I apologize if this isn't the correct Stack on which to ask this question, but it seemed like the best fit. I've tried to Google an answer, but I haven't been able to find anything that applies ...
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0answers
9 views

can power density spectrum be used to evaluate filter performance?

I have a noisy signal and filtered signal.I have got the filtered signal using various filtering techniques.I want to compare the various filters.Can power spectrum density be an evaluation metric ...
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0answers
44 views

Removing the mean in finding PSD

Does removing the mean value of the signal effect the estimation of power spectral density(PSD)? If it effects, how? What is the advantage we can get by removing the mean of the signal in estimating ...
1
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1answer
155 views

Dividing Audio signals into Barks Bands

I want to apply the following steps in matlab 1) Read the audio data 2) Apply window function on that data 3) Apply fft on the result of window function 4) Make power spectrum of fft 5) divide ...
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votes
1answer
63 views

Get a power spectral density from real random data

I am using real data of wind, which is a random one to get the power spectral density of these values. How can I do to get this PSD in matlab, and Can I get an analytical expression for this psd. ...
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1answer
227 views

cross power spectral density explanation in matlab

let us consider following code ...
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0answers
67 views

Python implementation of multidimensional power spectral density with Welch method

I have done my best to write Welch method implementation for python for multidimensional time series and still in the case of one dimensional time series I am getting inconsistent response compared to ...
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0answers
57 views

Python module request: Spectral density estimation for multivariate time series

I have worked with scipy.signal.welch and spectrum.pptm to calculate power spectral density with Welch and Multitaper methods. However as far as I can see these functions are meant for one dimensional ...
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0answers
106 views

how to compute the power spectral density matrix of the signal

I am implementing in Matlab a paper (*) which used the power spectral density matrix of the signal in the initial step. I will sum-up below. Suppose there are M channel measurements, and dividing ...
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1answer
111 views

Fourier transform properties. Spectral density function [closed]

I have the following signal for which amplitude and phase spectrums have to be computed: This exercise also has a solution which begins by deriving the signal twice. Next, they say the spectral ...
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0answers
72 views

Equivalence of FFT and PSD based output based on the Frequency Response Function

Correct me please if I am wrong... I have just started working in the domain of signal processing using the Fourier Transform ($\mathbf{FFT}$) and Power Spectral Density ($\mathbf{PSD}$). I am trying ...
2
votes
1answer
102 views

Segmenting a frequency series: do we need band-pass filtering?

I am trying to implement what's called the "second spectrum". Basically, you do this: Take a time series of length $N$. Divide it into $m$ segment, each of length $N'=N/m$. For each segment $m$, do ...
2
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1answer
92 views

How to average coherences estimated using Welch's method in MATLAB

I'm trying to estimate the average coherence of discontinuous snippets of a signal in MATLAB. For Welch's spectrum estimates, the following works: ...
0
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1answer
27 views

Signal Plus Weakly Stationary Noise

I was reading the book "Spectral Analysis of Time Series" By Herman Koopmans. On Page 55, he explains that a specific type of non-stationary signal which is the result of adding weakly stationary ...
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0answers
33 views

Power contained in a signal

Given a signal $$x(t)=16\cos(20\pi t+\frac\pi 4)+6\cos(30\pi t+\frac\pi 6)+4\cos(40\pi t+\frac\pi 3)$$how can I calculate the power contained in a frequency interval, say 12Hz to 22Hz. The total power ...
2
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1answer
178 views

Understanding the windowing method in PSD calculation

I have some issues understanding the use of a window (it doesn't matter which one) to calculate the Power Spectral Density of a signal. For example say I want to use the hann window, with $N = ...
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0answers
73 views

Problem calculating the average power of a vector?

I am calculating the average power of a vector. I would like to compare the final expression with the simulation. However, they are not equal. Please help me to point out which steps are wrong. Thank ...
2
votes
1answer
150 views

What is the relationship between the PSD of a continuous signal and the PSD of its periodically sampled one?

In Oppenheim's "discrete time signal processing", it says, How is the equation (10.65) derived? PS: you may try to derive it with Fourier transform of the original and the sampled signals. But i ...
2
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0answers
65 views

Noise analysis with periodogram. problem with different resolutions

I don't understand what happened in my simulation. I would like to perform a trade off between 2 ways to estimate power in frequency bands. I want to detect spurious frequencies. First method: I ...
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0answers
64 views

Looking for an algorithm that computes weighted average of frequencies intensity from narrow band in spectrograph

I am searching for the algorithm that takes (audio) signal as an input and outputs weighted intensity of the frequencies of some narrow band (axis X) in time (axis Y). Frequency in the middle of that ...
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0answers
58 views

Interpolation methods for radar and acoustic imaging [duplicate]

-----------------deleted by author to merge with valid account
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1answer
140 views

I have run an FFT now want to get the mean value in the 8hz - 13hz range?

I have a matrix [66 x 100,000] (it's some EEG data, across 66 electrodes) and want to find the mean power in the 8-13hz range. How can I do this? I have so far: ...
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2answers
47 views

Signal de-amplified before doing Power Spectral Density. Any effect?

I have a time-series signal (voltage, specifically) that was divided by 1000 before doing an FFT-based Power Spectral Density (PSD) (using LabView), giving the output in dB. Question: What is the ...
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0answers
107 views

What is OSNR in Fiber Optics?

I have seen that the SNR is measured for optical fibers "OSNR". What is the difference? Is there any equivalent?
1
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1answer
66 views

How to detect a spiky signal embedded in a periodic signal

Say I've got a signal that I know is composed of periodic components. However, I'm worried that there are "spiky" events that are embedded in this signal, and potentially occurring periodically. I ...
1
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0answers
65 views

Spectral estimation from noisy time-series data

This is the first time I'm posting a question on here so I hope I'm doing it right. I've tried searching on here for an answer but haven't found anything particularly relevant. I have some data ...
2
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1answer
519 views

1/3 Octave Analysis

Good Morning! I am new in signal processing and I am trying to do a work in noise control of an electronic steering lock device (ESL). My aim is to calculate the loudness (Zwicker Method- ISO 532 B) ...
1
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2answers
510 views

Parseval's theorem - Average Power

I want to calculate averaged power of a time-domain signal by means of its spectrum. I guess Parseval is the right tool. So I sample a sinus of 100 Hz 10000x within one second. Unfortunately the sum ...
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0answers
159 views

Autocorrelation Function and Power Spectrum

My aim is to determine the power spectrum of a signal of finite duration using Its autocorrelation function Performing FFT directly on the time-domain data The function is defined as follows in ...
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0answers
81 views

calculate variance of periodogram

I would like to know how to calculate the variance of periodogram? As I know variance is a big problem of periodogram. Namely increasing length of time series increases also variance of periodogram, ...
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2answers
695 views

PSD estimate using FFT - scaling and units

I know that similar questions have already been asked – I have read the answers, yet I am still not sure if I understand the topic properly at some points. I want to use FFT to calculate PSD ...
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1answer
56 views

Is the quantization noise white here?

If I have the following power spectral density of the quantization error can I tell that quantization noise is approximately white? Can you please provide some justification?
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1answer
400 views

Power spectral density interpretation

After reading this question: PSD (Power spectral density) explanation I am still a little confused as to what extra information the PSD gives us over simply taking the magnitude of the fourier ...
0
votes
2answers
163 views

What can we deduce about variance when we are given the noise spectral density?

Given the noise spectral density ${N_0\over 2} = a$, what can be deduced about the variance? In the case of a two-symbol canal(/cable), and when $T_0 = 1$. Is it that, $\sigma_X^2 = {N_0 \over 2} ...
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0answers
41 views

What is SNR of signal with additive white gaussian noise [duplicate]

Calculating the power of AWGN should be equal to infinity as PSD is constant and its integration is infinity over all frequencies. Hence for any signal with finite power mixed with AWGN, SNR should ...
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0answers
219 views

Analyzing an undersampled recording from an antenna with matlab?

I'm trying to analyze the power spectral density of a signal recorded from a Ham radio antenna. The signal is about 30 seconds long, recorded at a 48 kHz sample rate. The frequency is center frequency ...
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2answers
179 views

What assumptions should be used to invert spectrum into time domain data?

This question comes from a realistic problem that how to obtain a time domain wind pressure from known wind spectrum. Or similarly, gets rail surface curve from spatial rail spectrum. Obviously, ...