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0answers
11 views

WiFi and the sampling rate of spectrum analyzer

I'm trying to understand the correlation between RF analyzesrs and WiFi. Looking at the device's datasheet I see that it has a sample rate of (max.) 100msec. [to my understanding, the device can ...
0
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0answers
18 views

Estimation of latency for music played through a speaker

I need to estimate the latency for a music source that is played through stereo speakers but also transmitted wireless to the recipient. The music needs to be synced at the recipient by using a ...
-1
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0answers
8 views

How to estimate the power spectrum in yule walker method?

I'm trying to estimate the power spectrum using yule walker method in C++ . After finding the coefficient ,how to estimate the power spectrum ? Example: I got the coefficient up to 30 ...
0
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1answer
21 views

Defining an average in time for a density in time

I'm reading the text book "Time-Frequency Analysis" by Leon Cohen and I've made my way through a decent portion. There is however a conceptual issue I keep coming back to. The book states: If we ...
0
votes
1answer
20 views

Maximum Likelihood carrier phase estimation of $Acos(2\pi f_ct)$

This question refers to the example 5.2-1 of the book "Digital Communications, 5th Edition by John Proakis, Masoud Salehi" (example 6.2-1 in the 4th edition of the book) which asks for the estimate ...
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0answers
30 views

Fourier of a function in Matlab

I have a function describing a fourier transform of type : \begin{equation} \mathcal{F}(C(t)) = 1.42 \mathcal{F}\left( \exp^{-1.192t} u(t)\right) - 12.44 \mathcal{F}\left(\exp^{-1.192t} u(t)\right) ...
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0answers
57 views

Why is generating $1/f^\alpha$ noise so complicated?

Why can't I just take the square root of the power spectrum $P(f) = Cf^{-\alpha}$, multiply with $e^{i\theta_n}$ ($\theta_n$ being $N/2$ random phases in $[0, 2\pi]$), and then do an inverse Fourier ...
0
votes
1answer
35 views

Why does the specgram of this simple sine wave look strange?

I'm trying to test some intuition using the matplotlib specgram routine. I first generate a simple sine wave ...
0
votes
2answers
49 views

Fourier transform of a sum

I have a function : \begin{equation} C(t)=\left(1.42*\exp^{-1.192t}- 12.44*\exp^{-1.192t} +11.02 \right) u(t) \end{equation} where u(t) is a unit-step function What is its fourier transform? a step by ...
0
votes
1answer
21 views

Using pathloss in matlab

This is probably a very simple case but I am not sure where I am going wrong. In order to estimate the effect of path loss in Matlab, the function fspl(R,lambda) ...
0
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0answers
15 views

Received signal power when using multiple transmitters

If I have a two transmitter and one receiver system, with the transmitted power being $P_1 dBm$ for $Tx_1$ and $P_2 dBm$ for $Tx_2$. The signals from the two transmitters are added at the receiver ...
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0answers
9 views

computing the cross spectrum of two-dimensional matrice

I got stuck with the MATLAB syntax trying to compute the cross spectrum of two-dimensional matrices. I suppose that what I need is something like ...
0
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0answers
29 views

Frequency Spectrum through Wavelet Transform in Matlab

I have an EMG signal and trying to find out frequency domain features. I am using DWT for this purpose. It gives out coefficients in approximate and detail matrices. Now, I want to use detail coeffs ...
0
votes
3answers
67 views

EQ - Calculate the power per Octave of a signal through FFT

I'm working on a audio Equalizer, and I'm not sure if the way I obtain the power per octave of my signal is good. Here is the code I have : (I use the third octave bands, which is initialized earlier ...
0
votes
1answer
52 views

Spectral density of modulated noise process

Suppose we have a noise process $F(t)$. Suppose $F$ is stationary and we know its autocorrelation function $$\rho_F(\tau) \equiv \langle F(0)F(\tau) \rangle$$ where the average is over realizations of ...
0
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0answers
24 views

signal's spectrum energy

I have a signal with bandwidth between 0-2KHz. If i would like to know the signal's frequency spectrum energy, then I use Parseval's theorem and calculate it over time. Now it's my question: What if I ...
0
votes
1answer
51 views

How do I perform Specral Analysis (FFT, Windowing, Detrending) on Sonic Anemometer Data?

I am having trouble with all of the forums that I have looked at thus far. I have one day's worth of Sonic Anemometer data. I want to see the specral analysis of this data. When the anemometer data ...
0
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0answers
34 views

ًWhy we use fourier transform in most of spectrum estimation approaches?

I wonder why in all spectrum estimation techniques, the analysis depend on the Fourier transform? Why not deal with the signals in time domain?
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0answers
24 views

Classifying sleep stages from only EEG

I'm currently working on a project that requires me to classify sleep stages (Awake W, N1, N2, N3 and REM) based on only an EEG. Various algorithms and classifying standards (such as Rechtschaffen ...
0
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1answer
53 views

Spectral density of signal written as quadratures

Suppose I have a real-valued random signal $f(t)$ written as $$f(t) = I(t)\cos(\Omega t) - Q(t)\sin(\Omega t)\, .$$ What is the relationship between the spectral densities of $I$ and $Q$ and the ...
0
votes
1answer
60 views

Welch's Power Spectral Density - Time-Averaging Explanation

I am just branching out to taking the power spectrum of short-term audio frames ($20$ ms) in order to extract useful audio features. I have been reading about Welsh's method which states that after ...
0
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2answers
33 views

Getting wrong periodogram

I'm driving a white noise signal $e(n)$ through an AR random process: $$ x(n)=e(n)+\sum\limits_{k=1}^N \alpha_k x(n-k) $$ I got five values of $\alpha_k$ and plotted its power spectrum in Matlab for ...
2
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1answer
336 views

Is it only me or matlab's periodogram's function is confusing?

I am really confused with matlab's periodogram. First of all, it says in the documentation that its unit is "dB per unit frequency". What does that really mean? I just don't quite get it. Second of ...
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2answers
38 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 ...
0
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0answers
15 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
51 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 ...
0
votes
1answer
50 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 ...
0
votes
1answer
55 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 $\int \frac{1}{\omega} e^{j \omega t} dt$ ...
0
votes
1answer
132 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 ...
0
votes
1answer
98 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 ...
2
votes
0answers
26 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 ...
1
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1answer
59 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
30 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 ...
0
votes
1answer
42 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
vote
1answer
210 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
64 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
10 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
49 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
vote
1answer
196 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 ...
-1
votes
1answer
74 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. ...
-1
votes
1answer
392 views

cross power spectral density explanation in matlab

let us consider following code ...
0
votes
0answers
90 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 ...
0
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0answers
83 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
157 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 ...
-1
votes
1answer
118 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 ...
0
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0answers
85 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
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1answer
124 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 ...
3
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1answer
123 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
votes
1answer
30 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 ...
0
votes
0answers
35 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 ...