Questions tagged [signal-analysis]

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votes
2answers
381 views

Need to learn wavelet, suggest steps and resources [closed]

I am looking for a good introduction to wavelets and wavelet transforms. that covers the following: Vector Spaces – Properties– Dot Product – Basis – Dimension, Orthogonality and Orthonormality – ...
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1answer
569 views

Shifting / Permutation of an array taking a long time [closed]

I'm using matlab/octave and would like some help trying to improve the speed of my code. I've tried to vectorize the code but I run out of memory so I went back to for loops. What I'm trying to do ...
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0answers
19 views

Ergodic and non ergodic process [closed]

If I am given two random process (say x and y) are ergodic and their PDF is not given and the random process are periodic in time with period T1,T2 then xy will be periodic in time with period T4=LCM {...
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votes
1answer
30 views

Data Adaptive technique

I am doing data analysis. I used the wavelet transform and now I am trying the Hilbert–Huang transform (HHT). In the literature, I read that Hilbert–Huang transform (HHT) is an adaptive technique. I ...
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0answers
17 views

What is definition of cross correlation function?

I mean there are three different formulas for cross correlation that I have studied f and g are two functions whose correlation has to be found 1.For Energy signals 2.For Power signals 3.For ...
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1answer
43 views

What does this spectrogram mean?This is spectrogram of a multitone FM signal

! The spectrogram of FM signal has been generated by using Matlab.Now I want to what does these scratch like lined represent, though I have only two frequency components in my message signal(https://i....
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1answer
81 views

Signal Denoising Uniformly in Frequency Domain

I have a noisy sparse signal containing number of frequency components. Is there any method to uniformly denoise this signal. in other words, a method that estimated and eliminates the noise power ...
-1
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1answer
130 views

Why do we need the power spectral density?

Since the power spectral density is just the squared of the fourier transform, why is it useful ? Can't I just replace every solution that requires the psd with the fourier transform ?
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1answer
26 views

Is it possible to classify biosignal data based on feature extraction through multiple linear regression model? [closed]

i have 16 channel 2 class motor imaginary right hand ,right leg data.IS it possible to classify this through multiple linear regression model based on feature extraction?can i classify 3 class data ...
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votes
1answer
157 views

Spectral Subtraction python implementation error

I am trying to implement Spectral subtraction in python. I am new to DSP. I used this article as reference and below code is what I can come up with. Of course I did not get the expected output. I ...
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votes
1answer
64 views

Finding number of independent samples using autocorrelation

I have a pressure signal (y) with 512000 samples and with a sampling frequency ...
-1
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1answer
107 views

Weird noise floor slope when capturing with USRP E310

I'm experiencing a weird effect on my captures. It may just be due to my bad dsp understanding. I'm using an E310 SDR platform to capture a multitone (4 carriers) signal: Fc = 150 MHz Bw = 286 KHz ...
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1answer
28 views

Order of MR Imaging Encoding Steps

Why is it so important to have the phase gradient encoding step come before the frequency gradient encoding step when collecting MR Images? Currently, the phase encoding step is turned on briefly, ...
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votes
1answer
126 views

Quadtree decomposition of Discrete Wavelet Transform using bio4.4/CDF wavelet

My problem is pretty basic but fundamental. It relates to the way discrete wavelet transform behaves for biorothognal 4.4 or CDF wavelets. When using most wavelets (e.g., CDF 9/7 or bio4.4 or ...
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votes
1answer
90 views

signal saturation [duplicate]

My signal is an actuator displacement signal. It is a sinusoidal signal with the max amplitude of 10cm. I want to clip amplitude at 7 cm in Simulink. But with saturation block, I will get flat ...
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0answers
62 views

need help about DFT? [closed]

I am trying to get the answer from some of my questions: ...
-1
votes
1answer
236 views

Finding frequency of data given in time domain

Think there is an analog signal source and we are recording it with a data logger. Sampling rate isn't important in here. We know the analog signal is 0 mV when time 0 and goes to 1000mV in 1000 ...
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votes
1answer
43 views

How can dilation of a wavelet function lead to its sign reversal? [closed]

I am studying wavelets and it has been given that $$ \psi_{a,b} = \frac{1}{\sqrt{|a|}} \psi \left(\frac{t-b}{a}\right) $$ now the function $$ \psi(t)= \begin{cases} 1,& \text{if } 0\leq ...
-1
votes
1answer
102 views

Analyzing fluctuations within the Signal

I am trying to figure out how to analyze the signal shown below. It shows the fluctuation of number of review in for a product in Amazon, where positive means addition number of review while negative ...
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1answer
264 views

Alignment of signals for ensemble averaging? Something else?

I have been applying ensemble averaging (adding signals of different trials to obtain one signal) to improve Signal to noise ratio in my data. I have achieved good results in terms of classification ...
-1
votes
1answer
100 views

Exact formula for alias of Discrete Fourier transform for periodic sigals

Suppose that $f(t): \mathbb{R} \to \mathbb{C}$ is a $T$-periodic signal, with highest frequency $f_h$. Now suppose that our sampling rate frequency is lower than $f_h$, and is not any multiples of $1/...
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2answers
2k views

How do I identify CUTOFF frequency from my audio signal? [closed]

I was able to recorded an audio signal through the MIC and i applied FFT and Hanning window function to it. Now I want to know how do I identify CUTOFF frequency from it to apply the High Pass Filter. ...
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votes
1answer
364 views

Confusion when applying Hamming window to signal

I am writing some code which takes a signal of length $n$, and processes it in 20 ms chunks with 5 ms of overlap... So basically I have a buffer of 20 ms worth of sampled data, and I am trying to ...
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votes
1answer
238 views

BCI project using EEG signals

I want to make a BCI project, based on EEG signals, to control a robot using the brain's P300 wave. I have read a lot of papers, which give me a wide knowledge on how to deal with those signals, but ...
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votes
1answer
265 views

Describing Function for non-symmetric Saturation Model

Let's talk about a standard saturation model: with bounds $bound_{lower}$ and $bound_{upper}$. So in this example the output $y$ will be: \begin{equation} y(u) = \begin{cases} bound_{lower} ...
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votes
1answer
233 views

STFT Time Variance - Threshold

This is a follow up question to: Segment/Idenfication of signal from a spectrogram My main goal is to identify (segment) all of the calls from a given signal. The signal looks like the following (...
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votes
3answers
479 views

How we decide sample rate and number of samples while doing discrete Fourier transform

I solved a differential equation numerically and I want to find the frequencies present in the solution but I am not able to figure out sample rate/frequency and no. of samples that I should take.can ...
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votes
1answer
82 views

simulating noise with Yuler and burg

I want to simulate short term white noise with Yuler and Burg. It's said that it can give better results than Gauss-Markov. The problem is that each time the series diverge. Do you think that I made ...
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votes
1answer
96 views

Parameters for signal analysis

I am extremely new to signal analysis. And before posting I did a lot of reading on signal analysis, FFT and windowing. I am working on my thesis which involves comparison of speech signals lets say ...
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2answers
572 views

Is the system $h(t)=\frac{u(t)}{t+1}$ time-variant or time-invariant?

Following this answer , I tried like this $$h(t)=\frac{u(t)}{t+1}$$ where $u(t)$ is unit step function. I can write the input-output relation like this: \begin{align} y(t)&=\int_{-\infty}^{+\...
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1answer
310 views

Comparison using cross correlation [closed]

I have 2 stereo audio files to compare. Comparison of files include change in frequency, amplitude, phase shift Code: ...
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1answer
60 views

Signal reconstruction from sampled signal? [closed]

Can we construct exact analog signal at receiver as same as the source from the sampled signal?
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votes
1answer
79 views

classify the system if it's linear , non-linear , time variants or invariants [closed]

classify the system if it's linear , non-linear , time variants or invariants
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votes
1answer
28 views

Signal extraction [closed]

I have a receiver which receives several signals. The different signals are summed to the receiver. How can we find a signal in this sum? I know we can use PN (pseudo-random noise) codes but I do not ...
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votes
1answer
119 views

Can we find the skewness of Fourier coefficients?

Can I find skewness of the Fourier coefficients (the coefficients obtained after taking FFT of a 1D signal)?
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1answer
42 views

What happens to the fourier transform of sample result of $30kHz$ sinusoidal signal when sampled with sample frequency $44.1KHz$?

As the title says,w hat happens to the fourier transform of the sample output of $30KHz$ when sampled with sample frequency $44.1KHz$? I do not get how alias can appear, because fourier transform of ...
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votes
1answer
414 views

what is angular frequency ! what does it mean?

I know that $$ \omega = 2 \pi f $$ why do we use angular freq to expression about the instantaneous values of the wave?
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votes
1answer
93 views

Quantization of analog sound signals

I am using Librosa to detect pitch in a guitar audio signal. I have very little background in signal processing, and I was quite confused with the distinction between analog - digital signals and ...
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2answers
59 views

A question about the concept of the time

$\delta[n+1]$ equals to one only $n+1 = 0$ ? If the 1. is true, so what does a signal $x[n+1] $ stand for? Is this signal causal or anticausal? I mean, if 1. is true, $n = -1$, so is this signal ...
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0answers
25 views

Bandwidth of Time Division Multiplexing

Why is it said that bandwidth of output of a TDM transmitter is half of Sum of individual sampling frequencies.Is their a mathematical proof. I know that sampling frequency should be greater then ...
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votes
1answer
21 views

Signal with spectrum invariant under translation

Is there a signal with a spectrum limited in frequency and invariant by translation: $S(\nu)=S(\nu + \alpha), \alpha \in \mathbb{R}$?
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1answer
33 views

Frequency component not filtered properly

Are frequency components other than wanted signal present in the output? If yes then why does it not disturb the original signal? I think all practical filter responses are not ideal, so all frequency ...
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votes
1answer
494 views

FFT on Hamming Window Function [duplicate]

I want to apply Hamming window function the Audio sample then find out its fft.. ...
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votes
1answer
218 views

How Fourier decomposition is performed?

The Fourier decomposition explains a time series entirely as a weighted sum of sinusoidal functions and with the Fourier series,it is possible to do it. But I have some doubts Suppose ,for any ...
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0answers
27 views

PSD of Quantization noise [closed]

Psd of Quantization noise Psd of Granular noise Are above PSDs correct
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1answer
93 views

Causal question on a discrete signal

Given a signal with a list of discrete values 1,2,3 (t=0),0,1, Whether the signal is causal when the arrow is in 3 and why? I know the definition of causal is that the output will not depend on ...