Questions tagged [signal-analysis]

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How can I shape my time channel response, in order to have Gaussian shaped Doppler Spread?

I know how to generate a Rayleigh fading channel but I have no clue how I can shape the Doppler spectrum to be Gaussian. Any help will be really appreciated. ps: I am coding on matlab
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Frequency Analysis of a Signal Without a Constant Sampling Frequency (Non Uniform Sampling in Time Domain)

I'm a stack exchange user for some time and now I'm registering to ask a simple question (I think!). I have a vibration signal with an amplitude and time (sampling frequency not constant) in a $...
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1answer
33 views

Questions about autocorrelation, correlation, and randomness

I'm learning about autocorrelation functions and trying to calculate some from a time series. Conceptually, what is the difference between the following two autocorrelation functions? $$g_{1}(\tau)=\...
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1answer
248 views

Phase Modulation and Intermodulation Anomaly ? (Spectrum plots inside - **Updated**)

I have a MATLAB script for modelling a two tone signal (a sum of two sinusoids) going through a non linear transfer function (such as an amplifier). The amplitude of a signal is amplified non linearly,...
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2answers
76 views

Getting the DTFT from the DFT samples

How would you get the DTFT from the DFT samples? How will the DFT indexes map to the discrete frequency and what kind of an interpolation would be required?
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3answers
93 views

Find the $\mathcal Z$-transform of this function?

I need to find the $\mathcal Z$-transform of $x(n)=a^{-n} u(n)$. Assume, $a$ is a positive constant , but the power of $a$ is negative. Looking at the transform table, I found that $\mathcal Z$-...
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11 views

How to separate EEG frequency band in python?

Sorry for stupid question! I am very new in EEG signal processing and python environment.I have started my a project work related to EEG signal analysis using MNE. I would like to separate EEG Bands ...
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3answers
33 views

Help with Audio Signal noise removing using FFT and IFFT in Matlab

I dont understand why my modified fft of a audio signal returns complex values after ifft. I modified my signal by zeroing out all the unnecessary freq. FFT: Fast fourier transfrom IFFT: Inverse ...
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1answer
41 views

Confusion regarding overshoot?

As shown underlined in attached photo Overshoot is mentioned as 9% I am confused in understanding it It is 9% of error or size of jump(1)?
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1answer
85 views

Audio from multiple microphones mixed to mono and ASR

I am trying to do speech recognition on an audio file which has 1 channel (mono). My problem is that the channel is comprised of the signal of 3 microphones which have captured the audio at different ...
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2answers
85 views

Augmentation for EEG signal classification using Deep Learning

Augmentation is a technique that we use in deep learning for expanding the training dataset. It includes different ways of modifying an image and adding it to the training dataset. My question is if ...
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32 views

How to Enhance the height difference of the experimental signal data?

I'm very new to signal processing. Is there any kind of method to enhance the signal of experimental data that I get from the experiment? Especially on the difference of y-axis. Thank you This signal ...
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Power line communication channel modelling [closed]

I am working on power line communication channel security. I am stuck on deriving the equation for the transmission of data from the transmitter to the receiver through the power line channel. the ...
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1answer
322 views

How to make sense of audio file's $\textrm{dBFS}$?

I'm trying to build a song visualizer using the FFT method. When I analyze the audio, I get the $\textrm{dBFS}$ value for each frequency range. From my understanding, $\textrm{dBFS}$ is in the range ...
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1answer
100 views

How to apply baseline methods to MNE preprocessed raw EEG signals?

I am new at EEG preprocessing and classification. I have followed Clemens Brunner's blog https://cbrnr.github.io/2018/01/29/removing-eog-ica/ as a tutorial for MNE. This is how I have preprocessed ...
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2answers
23 views

Measuring Phase Difference at DC bin aliased frequency using FFT

I have a code in which two complex signals (I/Q) are created having same frequency but with phase difference. FFT of both signals is taken and atan2 is used to compute phase after which the difference ...
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2answers
36 views

Confused in Smoothing a signal in the Frequency domain

First of all i am new in DSP, so i have no solid education in the field. I have convert my time domain acceleration-seismic data to frequency using DFT and i am trying to smooth the DFT data, in ...
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1answer
31 views

Is there a way to break down a signal into its respective phases (4 in this case) to be later analysed individually

Is there a way to extract amplitude information but over 4 phases of the same frequency. That is, if the frequency is known could I extract amplitude peaks (between given values)in the time domain in ...
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1answer
64 views

What is issue in square wave reconstruction?

As shown in attached photo: What is the reason that the approximate square wave $$x_N (t)$$ at right side is not like the original $$x(t)$$ at left side .? Is the only reason is that number of ...
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2answers
50 views

Confusion regarding sinusoidal synthesis formula,

I am reading signal processing first by McClellan As shown in attached snapshot, we have formula of sinusoidal synthesis I am confused ,why in expression of x(t), there is a '2' in first line ...
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29 views

Wind turbine vibration analysis approach

This is going to be a bit of a long post. My questions are: Do the 5 signal processing steps look "correct"? Next steps could be to perform order analysis, and extract features from time, frequency, ...
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3answers
51 views

Confusion regarding calculation of fundamental period?

I am reading signal processing first and in chapter 3 ex3.8 i came across an example of fundamental period as shown in attached photo It apparently shows that signal $$x(t)=\cos^2(4\pi t)$$ has ...
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23 views

How to approach Feature Extraction and Feature Selection part in machone learning in python?

I am a bit new to machine learning and I have the following questions: Question 1: When dealing with feature extraction with signals from sensors, what is the typical approach to extract features ...
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1answer
41 views

Is it true that each and every signal has multiple frequency components?

Usually when we observe spectrum of a signal,we see multiple frequency components, each having different contribution to amplitude But is it true that each and every signal has multiple frequency ...
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48 views

Feature extraction for exponentially damped signals

I am looking into exponentially damped signals where it is a stationary signal (after implementing the Adfuller statistical test) and I would like to look into how can I extract meaningful features ...
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2answers
43 views

what is the difference between the convolution and differentiation over image in image processing?

In image processing the differentiation and convolution are the terms that are used interchangeably . what is the difference between applying convolution and differentiation over the image ?? How we ...
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2answers
59 views

Algorithm for detecting whether a signal stored in rolling buffer is Increasing, Decreasing or staying Constant

I have a data signal which is generated at constant time interval. It is a real world measurement and thus exhibits some noise in its value (it fluctuates approx + or - 20 units). The noise is fairly ...
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1answer
110 views

Detect Gradual Increase Before a Decrease in Noisy Data

I have data that'ss not too noisy and I am trying to detect a pattern where it gradually increases then decreases in a short period of time (20 ticks? it should be roughly similar per session but can ...
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1answer
63 views

Channel estimation and interpolation by vector in OFDM

I have V-OFDM system (Vector OFDM) where every symbol is organized as in below figure: The black cirles are pilots and white circles are data. First, iFFT operation it taken per column, and then ...
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1answer
106 views
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3answers
3k views

Type of filter, given difference equation?

Given a difference equation, how do we tell if it is an IIR filter or FIR filter? For example, y(n) = x(n-3)+y(n-1) . Is it FIR or IIR? Can you please give me a way to figure this out? Thanks! :)
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2answers
465 views

Convolution of an Image with a Kernel That Is a Product of Two Functions

Suppose that $G(i,j)$ is a Gaussian decay function on the distance between points $i$ and $j$ of an image. In addition, $D(i,j)$ is the difference between the VALUES of the image at those points. Now,...
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1answer
1k views

Ambiguous results of phase correlation in pattern recognition

We are using phase correlation to find pattern on image and what we get is 15% of results is spurious. Ours pattern has 32x32 pixels and image for research has 32x512 pixels. So we put Pattern to ...
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1answer
9k views

What does fir1 in matlab does?

May i know what does this function do in matlab? num = fir1(80, [5Hz, 50Hz]); I know that 5 Hz is the low cut-off freq and 50 Hz is the high cut-off freq. I'm ...
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Spectral kurtosis on non-stationary signal

I posted a question some weeks ago I still have not found an answer to. I updated the old question and am hoping someone could help. Link: Varying speed of shaft Spectral Kurtosis
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Varying speed of shaft Spectral Kurtosis

I want to perform Spectral Kurtosis (Kurtogram) on 10-second vibration signal of 25.6 kHz sample rate, where the shaft is varying in speed. Will a preprocessing step of resampling the signal be ...
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41 views

How to find if the signals are in sync or out of sync with each other?

Considering these are two signals over time, black and red.Following are some of the properties Every Second a new data point is added over time . There is no control on the generation of the ...
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1answer
1k views

Corner detection using Chris Harris & Mike Stephens [duplicate]

I am not able to understand the formula, What is $W$ (window) and intensity in the formula mean, I found this formula in opencv doc http://docs.opencv.org/trunk/doc/py_tutorials/py_feature2d/...
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Interest in adapting signal processing for reverse engineering principally from a biogenomic standpoint [closed]

NB: Cross-post to this post on reverseengineering.stackexchange.com. I am seeking any possible help for a problem I have devoted a quite protracted period of time exploring. I am total perm disabled, ...
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0answers
21 views

What steps and methods are recommended to process various signals of a IMU sensor [closed]

I'm new here because I'm making my degree final project. See more my profile for more information. I want you to recommend me what are the tools to analyse the sampled signals and process them in ...
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1answer
153 views

How to detect the maximum resolvable spatial frequency of camera?

I am trying to calculate the minimum line pixel width that can be distinguished from noise as shown in the camera test chart in Figure 1 where the thinner lines on the left are getting more and more ...
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4answers
2k views

How do I compare chords played on a guitar with a known sample?

I want to create a project that will recognized the chords that i played in guitar. I recorded a raw sound to be compare to the one that the user will input. Example I have a recorded sound chordA ...
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1answer
545 views

Detecting a frequency pattern in the frequency domain

I am looking to detect a combination of frequencies in the frequency domain. For example, here is my spectrum: And I'm trying to detect the pilot tone. I have the FFT of the pilot tone: which zoomed ...
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2answers
8k views

How to use low pass filter in Matlab for discrete data? [closed]

As see in the picture, there are high frequency noise in the signal. How to design a low-pass filter to eliminate the noise? How to apply this filter in Matlab?
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4answers
24k views

noise of zero mean and variance?

It might be a very silly question, however I'm facing problem with it. Now, the Gaussian noise is a signal with zero mean and variance. I understand what the mean and the variance mean however, I'm ...
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1answer
34 views

Determine reflections from received signal

I have a reference signal $r(t)$ and the correlation between that reference signal and the received signal : $C_{XR}(\tau)$. The signal I receive contains reflections on walls. I have to build a ...
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1answer
1k views

How can I find the actual frequency given a normalized frequency?

Suppose that we have some sample: ...
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2answers
535 views

Power of summation of two signals

Let $|A|$ denote the power of the analog signal $A$. Is that true to assume $|A+B|=|A|+|B|$, for two arbitrary signals $|A|$ and $|B|$? That is the power of the summation of two signals is -at least ...
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832 views

Ways to compute the n-the derivative of a discrete signal

This is a pretty general question about how to compute derivatives of a digital signal $x[n]$. I would like to know what are the different approaches (from naive to complex) and how are they compared ...
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2answers
238 views

Can I construct a linear system so that it results in a moving average?

I've just learned about linear systems and impulse response functions. I know that in a linear system consisting of $h_1[k]$ and $h_2[k]$, the impulse response of the system is $h_1[k] \ast h_2[k]$. ...

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