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The recording of voltages along the scalp for the purpose of monitoring brain wave activity and localizing sources of ionic currents

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21 views

How to remove ICA components from EEG?

I am doing my masters thesis on the analysis of EEG signals for various applications. Currently, I am doing the signal processing of the EEG data that I acquired using ICA method. I am using OpenBCI 8 ...
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0answers
18 views

Segment EEG signal into different lengths of epochs

My EEG data contains two types of events: event type 1: starts with trigger S100, ends with S102; event type 2: starts with S101, and ends with S103. I wish to segment the data in such a way that I ...
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0answers
40 views

How to use signal.lfilter?

I am processing EEG data(.tdsm) and i tried to implement the Ellipitic filter. But I can't manage to pass the signal through signal.lfilter, the end result doesnt seem correct because only the ...
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1answer
51 views

Manual filter or digital filter first for EEG?

I am getting conflicting advise regarding how to clean my EEG data: 1) Manually remove artefacts first and then apply digital filters OR 2) Apply digital filters first and then manually remove ...
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0answers
25 views

How to select Input parameters of FIR band pass filter (narrow band e.g Alpha (8-12 Hz)). A basic question?

I have to filter eeg data (500 samples) offline using a FIR bandpass filter for alpha rhythms (8-12 Hz) providing the fixed order of filter (i-e., 128). Can some one explain what should be the ...
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0answers
20 views

Remove artefact in signal, and then look at the PSD?

To note, I am using Matlab R2017a for my signal processing. I have filtered my EEG signal according to the frequencies I am interested in using butterworth (2Hz-30Hz). But there are some large ...
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0answers
72 views

Filter Bank Common Spatial Pattern (FBCSP) Algorithm

I know that for Common Spatial Pattern (CSP) algorithm i need two covariance matrices, for Filter Bank CSP algorithm i have filtered one trial of EEG signal into 9 frequency bands. My question is ...
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0answers
87 views

Wavelet transform and FFT using to extract feature power bands with EEG signals

I am using 5 channels [ fz , cz , c3 , c4 , pz] to detect drowsiness of driver My First Question is, what is the right input to get feature power band ( Theta , alpha , gamma , beta ) to wavelet ...
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1answer
36 views

Common Spatial Pattern for EEG Signals

I am having difficulty in understanding the use of CSP for EEG signal feature extraction and subsequently. Since I am using two classes, this query will be restricted to it. In essence CSP requires 2 ...
1
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1answer
78 views

Spatial spectrum of EEG data: non-uniform DFT?

I want to compute the spatial spectrum of EEG data collected using a non-uniformly sampled grid of sensors (as in the figure below). One way to do this would be to interpolate the data on a ...
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0answers
104 views

EEG Signal Preprocessing BCI Competition

I have downloaded a dataset from BCI Competition III(Dataset 3a). I wish to classify the data into given 4 classes. The signal array is a time X channel matrix of some 900000 values sampled as 250 ...
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0answers
70 views

output shape of STFT

I cant figure out why our output image is 257 * 32 , 32 I know why , but 257 I cant understand ? this is the exact word of this paper wich applied STFT on 3 channel of eeg signal : Short time Fourier ...
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0answers
42 views

Changing a filter as a function of different sampling rate or gain?

Dear fellow signal processors, my problem is the following, I have a butterworth filter (Matlab) applied to EEG data with which I already published and it is essential that only the most necessary ...
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1answer
211 views

How to apply Hamming Window and compute FFT?

I'm borrowing an EEG device whose accompanying software also computes the FFT of the data it collects. The software provides the user with a file of EEG values and a file of FFT values computed from ...
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1answer
41 views

EEG, PSI interpretation

My colleague and I started exploring EEG processing and, especially, functional connectivity. We decided to try the Phase Slope Index (PSI) and conducted a simple experiment as follows: it consists of ...
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0answers
58 views

EEG signal preprocessing

i have EEG data with 64 channels and a vector with 202 event timepoints in ms. How can i correlate the two vectors firstly for plotting and secondly to create epochs from each event [-1300ms +300ms] ...
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0answers
80 views

signal (EEG) segmentation and denoising, which one should done first?

Because of EEG nature, in EEG analysis often researcher use Windowing/segmentation method. As i currently work on sleep study, and in my study i need to analysis EEG data, i came to a problem. My ...
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0answers
37 views

How do I know if my EEG signal need denoising?

I recently started working on sleep study. For my research I download sleep EEG data from physionet. The EEG data has 100 Hz sampling rate and was recorded from 2 bipolar EEG site. When I start the ...
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3answers
2k views

How to correctly compute the EEG Frequency Bands with Python?

so I am trying to compute the EEG(25 channels, 512 sampling rate, 248832/channel) bands (alpha, beta, gamma, etc.) with Python. I managed to do so by: firstly filtering the signal with a butterworth ...
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0answers
35 views

How to generate scalp or topographical maps from EEG signals after obtaining ICA mixting matrix

I know that this can be done in EEGLAB and mne toolbox but I want to understand the process and implement it. I have original eeg channel data, independent components after applying ICA and mixing ...
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1answer
928 views

How to compute the power bands of an eeg signal using python?

so I have an eeg signal (edf format) that has 25 channels and 248832 entries, sampling frequency of 512Hz. I have to compute the frequency bands: – Delta: 0.1-4Hz – Theta: 4-8Hz – Alpha: 8-12Hz – ...
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1answer
167 views

DWT versus band-pass filter

Which technique gives better result in extracting a band from a signal, let's say the alpha band (8-13 Hz): using a band-pass-filter or a DWT (Discrete Wavelet Transformation)? P.S.: I am working in ...
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1answer
31 views

What is the meaning of negative second for a Morlet wavelet?

I kind of familiar with wavelet transform (I just used it in code but do not have a deep understanding about it). I've been reading an article and came across this sentence: where 4Fs is the ...
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1answer
559 views

why butterworth bandpass filter changes signal in the passband?

I want to apply a butterworth bandpass filter to EEG signals and it's not working so I tried with a simple signal: t=[0:0.01:10]; s3= 9*sin(2*pi*4*t); Still ...
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2answers
183 views

Compute absolute power spectrum in MATLAB

I have EEG signals. Is there a way to compute the absolute power spectrum in MATLAB within a frequency band? I know I have to use the fft function but I can't find any details about the absolute power ...
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1answer
911 views

Compute phase coherence between two eeg signals

I have two EEG signals/channels and I would like to compute phase coherence in MATLAB. I have this paper: https://www.nature.com/npp/journal/v39/n5/full/npp2013330a.html but it does not say what Sij ...
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2answers
5k views

What does epoch mean in EEG?

I need to understand the meaning of an epoch in EEG signal. I have an EEG signal. Then how can I get the epoch?
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0answers
218 views

How to choose notch frequencies for filtering line noise?

I'm using the function to filter out line noise at 60 Hz (and 120, 180 Hz) caused by electrical noise: ecogNotch In the case below I can effectively filter out the line noise with a notch filter at ...
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0answers
231 views

What's the suitable specifications for the FIR filter?

i have EEG signal,the sampling frequency is 256 HZ .The wavelet decomposition that i will use does not allow the extraction of specific frequency bands without additional filtering. Thus, in order to ...
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1answer
540 views

Low pass FIR filter for EEG signal

I'm trying to do Analysis of EEG Signal for the Detection of epileptic seizure so in the pre-processing of the EEG signal I use a low pass FIR filter ...
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0answers
32 views

Reduce impact of outliners for frequency analysis by increasing signal length?

I am working on a project to detect drivers drowsiness with EEG signals. I am using the frequency values retrieved by FFT. I have some outliners (artifacts) in my signals, which I don't want to remove ...
3
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1answer
99 views

What do certain terms mean in EEG processing describing frequency bands?

I've recently started a project about detecting driver drowsiness with an EEG and came across some terms I didn't quite understood: ...increase in theta activity occur... - ...low voltage theta ...
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1answer
615 views

Bandpass filter to get EEG frequency bands?

I'm doing a project with an EEG to detect driver drowsiness and learned about EEG frequency bands (alpha, beta, gamma...). As the frequency bands are simple frequency ranges, I wonder if I can use ...
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1answer
64 views

What is QEEG technically, and how is it computed?

I've been working with EEG signals for a while. I wonder how to compute QEEG (or Brain Map) representation. I feel it is extracted from raw EEG and I want to know what is technical method for QEEg ...
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0answers
102 views

EOG artifacts turn up in several ICA source signals

I try to remove EOG artifacts from my EEG signals (I am using a EPOC+ for recording and MNE Python for processing). Therefore I've recorded test data with blinks every 5 seconds. The blinks can be ...
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2answers
1k views

Which order to perform downsampling and filtering?

I have EEG data recorded with 128Hz sampling rate. As my goal is to reduce the amount of data (and maybe noise), I want to downsample the data to 64Hz (I am only interested in range 0.5 - 30Hz). I ...
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1answer
3k views

Cross correlate a 2D array

I have a 2D array of eeg data with shape (64,512) - 64 electrodes, 512 timepoints I want to calculate the maximum cross correlation (irrespective of lag/time shift) between every single electrode, so ...
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1answer
1k views

How to segment frequency bands after FFT and calculate power?

I have been working with EEG signal. I have raw EEG data for a 2-second (i.e. $t=2$) duration. My objectives are: Transforming these raw data from time domain to frequency domain. Segmentation into ...
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1answer
968 views

How is the topo / scalp map from an EEG Signal with ICA created?

I am lately experimenting with an EEG and found this Library: MNE Python. I am using an ICA to find and correct artifacts - this is working fine. It's now possible to plot a topo / scalp map for the ...
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1answer
2k views

How do we use signal::filter and signal::butter in R for EEG data?

I am trying to design an experiment to determine the peak amplitude of an EEG signal in response to a stimulus. Till now, our team has been using MATLAB and since we wish to go open source, we are ...
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0answers
85 views

How to select the right wavelet for a wavelet based decomposition?

I am working with EEG signals and I would like to detect transients in the signal that have a special shape (epileptic spikes). And maybe enhance these patterns in the signal before thresholding. The ...
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1answer
235 views

Origin of artifacts 12 Hz away from electrical line noise (50 Hz)?

I made electroencephalographic measurements from people while they were sleeping. When plotting the frequencies, I see that I do not only have an expected 50 Hz (and 150 Hz and 250 Hz...) artifact (...
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0answers
821 views

Epilepsy seizure detection in EEG

I want to develop a method to detect the occurrence of epilepsy seizure in an EEG signal. I am using a large data set for number of patients so the algorithm has to detect the seizure in any of the ...
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1answer
76 views

What could be causing these humps every 10 Hz on my PSD estimate data?

I am working with EEG recordings about 1,000,000 data pts long, recorded at 4,000 Hz. I'm generating PSD estimates for these recordings using the matlab "periodogram" function like so: ...
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2answers
2k views

How to identify and differentiate frequency and time in EEG data using python?

I have an EEG data of 200 Hz and sampled at 4097. I have few doubts and questions related to this data: What does it mean by sampling in EEG data? I am getting the sample rate and the frequency when ...
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0answers
279 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 ...
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0answers
375 views

Autoregressive Model for EEG frequency analysis?

I want to do EEG frequency analysis in matlab using autoregressive models (e.g. Burg's method). How do I do this correctly? I just treated each channel individually (loop over channels), so I go ...
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1answer
273 views

AR model order selection for half second EEG fragments

I am using MATLAB to evaluate power spectral density estimates of half second EEG signals, using modified covariance method. Can anyone suggest me how to select the AR model order for this process? Is ...
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1answer
824 views

Python MNE - reading EEG data from array

I have EEG data that comes in the form of a 3D numpy array (epoch * channel * timepoint). timepoint is a 256 element array containing each sampled timepoint (1s total, at 256Hz). epoch is an ...
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3answers
2k views

Phase locking value / phase synchronization

I have pairs of EEG signals filtered to give me just alpha bands. For a machine learning problem I have found that calculating the phase locking value between the alpha signals of these 2 channels ...