[Eeglablist] Re: Noisy data for analysis(Husamsdu) - eeglablist Digest, Vol 5, Issue 3

Girish Kumar girishkumarm at gmail.com
Fri Mar 4 05:41:34 PST 2005


Hi,
    I'm Girish from India and i'm also working on eeg signal
processing and analysis as a part of my project for my UG degree. In
my case for initial analysis i used a combination of three to four
sinusoids corrupted with random noise, as a noisy signal. I calculated
the power spectral density of such a signal and obtained an estimate
which resulted in peaks only at the sinusoid frequencies. This noisy
signal is somewhat similar to a non-stationary and random signal such
as an EEG.. and I was able to obtain satisfactory results for my
cause.
     I generated this signal using MATLAB and have given the code for
the same below:

fs=1000;           %Sampling freq in Hz
f1=100;            %0.2pi in angular freq
f2=120;            %0.24pi in angular freq
f3=150;            %0.3pi
f4=250;            %0.5pi

t=0:1/fs:1;         %1000 sample values 

s=sin(2*pi*f1*t) + sin(2*pi*f2*t) + sin(2*pi*f3*t)+ sin(2*pi*f4*t)+
randn(size(t));


   This results in a noisy signal 's' that consists of four distinct
frequencies at 100Hz, 120Hz, 150Hz and 250Hz.

     Hope this helps.

GIRISH



On Thu, 3 Mar 2005 12:46:05 -0800, eeglablist-request at sccn.ucsd.edu
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>   1. (no subject) (husamsdu)
>   2. Power spectra and others (jingli at fmmu.edu.cn)
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> 
> ---------- Forwarded message ----------
> From: "husamsdu" <husamsdu at mynet.com>
> To: eeglablist at sccn.ucsd.edu
> Date: Thu, 3 Mar 2005 14:29:21 +0200 (EET)
> Subject: [Eeglablist] (no subject)
> hi research eeg signal analyse.but first i need a noisydata to anlyse.i can't find a good data on the net.i need your help.if you  have some data please send to : husam_sdu at yahoo.co.uk
> 
> 
> 
> 
> 
> 
> 
> 
> ____________________________________________________________________________ 
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> ---------- Forwarded message ----------
> From: "" <jingli at fmmu.edu.cn>
> To: eeglablist at sccn.ucsd.edu
> Date: Thu, 03 Mar 2005 23:17:25 +0800
> Subject: [Eeglablist] Power spectra and others
> Dear all:
> I am a beginner in matlab but I have to complete my PhD thesis that is about the
> analysis of rat EEG in matlab. I have acquired 10G data of rat EEG. I prefer the
> power spectra method. Would someone please tell me:
> 1. How to perform power spectra analysis of multichannel EEG(8 channels) in
> matlab? I hope the unit of the vertical axis is microV^2, but not dB ,nor
> 10*log10(microV^2/Hz).
> 2. How to calculate the absolute power and the relative power of EEG at a certain
> frequency band in matlab? is it possible to do it in EEGLAB
> 3. How to change the unit of the vertical axis from 10*log10(microV^2/Hz) to
> microV^2 in EEGLAB?
> 4.How to remove the ears from the figures because what I want to plot is not for
> human but for rat?
> 
> Thank you very much
> 
> Jing
> Jingli at fmmu.edu.cn
> 
> 
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