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3
votes
1answer
48 views

Why are the systems equivalent?

Why are those two systems equivalent? System 1:$$\boxed{x[n]}\longrightarrow\boxed{\uparrow 3}\longrightarrow\boxed{\downarrow 4} \longrightarrow\boxed{y[n]}$$ System 2:$$\boxed{x[n]}\longrightarrow\...
5
votes
4answers
532 views

Why LTI system cannot generate any new frequencies?

Why $Y (\omega) = X(\omega)H(\omega)$ implies that an LTI system cannot generate any new frequencies? Why if a system generates new frequencies, then it is not LTI?
0
votes
0answers
25 views

Calculating frequency specific decay time of an echo/reverberation

How is it possible to calculate the decay times of specific frequencies utilizing the impulse response's frequency response? Such analysis is especially useful when analyzing reverberation and ...
0
votes
0answers
27 views

Wavelets: how to determine scales from frequencies?

(Reposted from StackOverflow) In the following code sample, I would expect the rows of the printed output to match each other, at least approximately. ...
0
votes
0answers
11 views

Time shift in DWT using Mallat algorithm over the $2^{10}$ scale

I am doing DWT on $2^{10}$ scale using the Mallat algorithm. As I know, DWT using the Mallat algorithm decimate sampling frequency 2 times at every next scale, it means $F_s$ is different for each ...
-2
votes
1answer
33 views

Listen to multi-dimensional data using FDM

This might be a duplicate because I can't imagine I'm the first one to have the idea, but I couldn't find similar posts by searching related titles (neither here nor on Google). Say I have a $C\times ...
1
vote
2answers
45 views

Compressing a time-domain signal in the frequency domain Matlab

I'm new to frequency domain analysis. Let's say I have a frequency domain representation from a time domain signal. What I want to do is taking frequencies with a low amplitude out of this frequency ...
0
votes
1answer
29 views

Confusion with regards to units in Sinc pulse

I am currently reading a section in the Handbook for MRI Pulse Sequence book where it says that the time-bandwidth product for a SINC pulse is given by: $$ T \Delta f = Z $$ where $T$ is the length ...
0
votes
2answers
59 views

Is this graph of Wigner-Ville distribution OK?

I am studying some code for smoothed Wigner-Ville distribution. update 3- solution, graph was over amplified in a 2d overdrive/oversaturation effect. if i divide by 20 only a line is visible. Update ...
0
votes
0answers
17 views

Application of the gabor limit to a time-frequency analysis

I want to do a time-frequency analysis for a signal containing several sinus signals with a frequency between $400\,\text{Hz}$ and $800\,\text{Hz}$, each with a frequency separation of $\Delta f$. The ...
1
vote
0answers
25 views

Does MATLAB have a FM discriminator [closed]

I'm wondering if MATLAB communications or DSP toolboxes has a FM discriminator? If so, what is the name of the function/object?
0
votes
0answers
20 views

Equalizers for controlled ISI and ICI

I am new to the physical layer and may not have all the necessary background. I have the following question on the design of Equalizers. Equalizers to combat the effect of ISI and ICI due to ...
0
votes
0answers
22 views

Extract the frequency range/mean from time series using Wavelet

I am working with Wavelet for the first time, and I need your help. I have time series of velocity collected for 2 min at 32 Hz: x = [n] where n = 120 (sec)*32 = 3840 counts. I am using Morlet ...
1
vote
1answer
66 views

Lowpass filter impulse response in frequency domain

A Linear Time-Invariant system with impulse response $h_1[n]$ is an ideal lowpass filter with cutoff frequency $\omega_c =\pi/2$. The frequency response of the system is $H_1\left(e^{j\omega}\right)$. ...
0
votes
0answers
49 views

Wavelet transform of time series(PyWavelets)

I am a newbie in wavelet transform and I would be glad if you help me. I have different time series(ECG with rate = 1000 points in second, length = 100 000 points). I need to classify them in two ...
1
vote
1answer
169 views

Matlab signal processing removing white noise from signal

What is the way to address the removal of white noise from a signal? Extra Details Hi I also agree the details are as follow: ...
0
votes
0answers
37 views

How to find the energy of a single frequency from its time-frequency distribution?

I have a non-stationary time series. I am interested in finding the energy content of a single frequency (actually the ratio of that single frequency over the total energy of the signal). The problem ...
0
votes
1answer
87 views

How does shifting a signal in the time domain affect its frequency domain?

Suppose the signal is shifted by dt (signal 'starts' later, say after 1s instead of 0s), does that correspond to a positive or a negative phase shift df in the frequency domain? There are certainly ...
0
votes
0answers
46 views

Multidimensional EMD - Problem Plotting Spectogram

I'm having difficulty plotting the famous Time vs Frequency plot of the Amplitude. What I did so far is  1. Simulated a three dimensional signal using ...
0
votes
1answer
46 views

Getting frequency content at different times from discrete wavelet transform coeffs

After being away from DSP for a long time, I am trying to familiarize myself with wavelet transform. Here is what I (think) have understood so far: Wavelet transform provides you high time ...
0
votes
1answer
85 views

Obtain the frequency response of a time domain chirp signal

I have simulation data in the time domain and I need to represent them in the frequency domain. The data have been obtained time integrating the following equation: $m \ddot{x} + c\dot{x} + kx = A \...
0
votes
0answers
20 views

Finding the original signal from the CWT Scalogram?

I have a Time-Frequency Representation (TFR) of a signal using Complex Wavelet transform with a half wavelet length of 6, I was wondering if there is a way to calculate the original time-domain data ! ...
1
vote
1answer
58 views

Doppler shift in time domain?

I have some clarifications required in this topic So initially I know that to shift a signal $X(f)$ by fo we need to take its inverse fourier transform and multiply it with a factor of $\exp(−j2\pi ...
1
vote
2answers
163 views

How does the Magnitude of an FFT relate back to the Time Series wave it was created from?

Alright, to start out I am a mechanical engineer with very little circuits and digital signal processing background. So please excuse my ignorance as this is far out of my usual territory. When ...
2
votes
1answer
137 views

Find time lag between two time series

I am trying to find the time lag between two time series over t = [0,1000] using MATLAB (not that it matters). The first time series is simply t^2. The second is (t-15)^2 which is, of course, shifted ...
0
votes
1answer
83 views

Is sub-sampling delay estimation possible without interpolation?

I want to estimate time delay between two complex narrow band signals. I can use any correlation method. There are several methods in the literature about sub-sample time delay estimation. Generally ...
1
vote
2answers
92 views

How can I accurately represent an mp3's wave form in respects to time?

I'm trying to programmatically plot a sound wave that I have placed in a 2d array, however, I cannot consistently get the sound wave to reach the end of the window. For example, when you load a sound ...
1
vote
0answers
25 views

Dividing a signal in channels

I have a signal in time domain, and I have to convert it into frequency domain and divide it into 100 channels, and find the center frequency of each channel. I am not good in "MATLAB" so how to do ...
1
vote
1answer
209 views

Spectrogram, time vs frequency localization, and length of signal

So I'm having some trouble conceptually and am hoping somebody can clear something up for me. This is long and I apologize for that but I want to provide as much information as possible so that the ...
0
votes
0answers
16 views

How to properly explain that computing wavelet at fine scale reveal localized high frequency component

I wonder if it is fair enough if I try to follow "Wavelet Tour of signal processing" which apply the Parseval formula: $$ Wf(u,s) = \langle f,\psi^{u,s}\rangle = \int f(t) \bar{\psi}^{u,s}(t)dt = \...
2
votes
1answer
57 views

Time-Frquency Resolution issues

While Im studying wavelet transform, I have this questions in my mind which can't find it's answer: I understand that when we take longer time windows and take the fourier transform we would suffer ...
0
votes
2answers
93 views

EEG Power at specific time points

I'm in the process of building features for an EEG machine learning problem and have been doing some reading about what features may be useful. Turns out, that alpha band (8-12Hz) power can make a ...
0
votes
1answer
594 views

Python - time frequency spectrogram

I have some 64 channel EEG data sampled at 256Hz and I'm trying to conduct a time frequency analysis for each channel and plot a spectrogram. The data is stored in a numpy 3d array, where one of the ...
0
votes
0answers
16 views

How accurate is Wavelet packet decomposition for emg signals with frequencies from 10 to 40 Hz?

I have an electromyographic signal sampled at a frequency between 10 and 40 Hz in a time window of 300ms. Is wavelet packet decomposition adequate in order to perform features extraction for ...
0
votes
0answers
41 views

Variation of Pulse width with center frequency in Pulse Compression technique

Assume a chirp with BW = 1 Hz (frequency range 0-1 Hz) for a period of 700 sec. The pulse compression technique (obtained through auto correlation function) applied on the chirp generates a pulse ...
1
vote
2answers
52 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
2answers
68 views

How to find a certain frequency in a signal that varies in time?

I have an EEG signal. It is amplitude verses time. I want to find out how certain frequencies in that signal vary with time. One way I think I can do this is to do a short-time-Fourier-transform on ...
0
votes
1answer
39 views

2 points and instantaneous phase sufficient to estimate amplitude and frequency of sinusoid?

If you have 2 points (x1y1,x2y2) in a Cartesian grid, there are an infinite amount of sinusoids that pass through them. But if you are also given the instantaneous phase (Th0) in radians or degrees at ...
0
votes
1answer
111 views

How would I go about designing a difference equation for a given type of filter?

I have experience using design tools such as Xilinx's CoreGen and MatLab's DSP tool kit, but I have not really had much experience designing filters from the ground up. Reinventing the filter as it ...
0
votes
1answer
163 views

Teager-Kaiser Operator vs. Hilbert Transform

Since a couple of months I started working on the extraction (estimation) of signal frequency and amplitude components by means of two different time-frequency approaches, namely the Hilbert transform ...
0
votes
1answer
65 views

Signal Sampling

I am new in this field (junior year) and I have a question may a little lazy for the majority of the forum. I have a speech signal $ x(t)=0.4\cos(100πt)+0.3\cos(1800πt)+0.2\cos(980πt)$ and I know ...
0
votes
0answers
73 views

pattern recognition in a time series

I understand that the question I am asking seem the be somewhat related to another question which has been asked already. But I feel that this is an entirely different question. I have a huge (over ...
1
vote
2answers
91 views

What is a 'time-variant' signal?

I have found in the literature a "time-variant signal" term , but I could not understand what that's mean. I know that there is "time-variant systems", but this is the first time, which I see a time-...
2
votes
2answers
164 views

system response: time vs frequency. Why do I get different magnitudes?

I am simulating a linear system described by the following equation $m \ddot{x} + c \dot{x} + k x = A \sin(\omega t)$ ...
0
votes
1answer
232 views

Get data ready for IFFT

I am having troubles applying the IFFT function to some data I have. I already had a look here Complex conjugate and IFFT and here What assumptions should be used to invert spectrum into time domain ...
2
votes
1answer
174 views

Time Frequency Signal Analysis in Mathematica (MMA)

I want to know " Whether there is any Tool Box in Mathematica (MMA) for the Time-Frequency (TF) Signal Analysis". I am well-versed in MMA Programming, so want to do TF Signal Analysis in MMA. I think ...
1
vote
0answers
43 views

Time-frequency analysis

I had this question in the exam without any further explanation. Why the time translation invariance is an important feature for time-frequency distributions? I am writing to ask whether anyone can ...
0
votes
0answers
182 views

For discrete signals, why does phase change not correspond to time shift?

I'm going through a Signal Processing lecture where the professor mentions this fact and the argument given is: Suppose you have a sinusoidal signal: $Acos(\omega t)$ Now if you change the phase of ...
1
vote
1answer
207 views

Correct way to implement Discrete and Stationary Wavelet Transform?

Can someone please confirm if this is indeed the correct way to compute DWT: ...
0
votes
3answers
65 views

Introduction to Clustering and Classification of Linear Sequence

I'm a programmer/engineer that is getting into developing prototype wearable technology. I would like to be in a position to interpret raw accelerometer data and categorised the data into activities ...