[Eeglablist] wavelet properties
Makoto Miyakoshi
mmiyakoshi at ucsd.edu
Wed Sep 2 11:40:11 PDT 2015
Dear Hendrik,
When you run newtimef(),
>> [ersp,itc,powbase,times,freqs,erspboot,itcboot] = ...
newtimef(data, frames, epochlim, srate, cycles,...
'key1',value1, 'key2',value2, ... );
The 5th output 'freqs' is the list of center frequencies. I think it uses
'freqresol' output from dftfilt3.
> The second point that I need to find out is the duration in the time
domain for each wavelet. Can anybody help how I can generate that
information to provide a table with the wavelet information?
When you run newtimef() it shows the length of the sliding window. You can
report the length there.
In EEGLAB's newtimef, by default the number of cycles increases linearly as
the central frequency increases, which may be tricky to explain. The
purpose of doing this is to adjust the ratio of time/frequency resolution
along with the frequency axis (if you use the fixed cycle numbers the
output image looks vertically stretched i.e. too much temporal resolution
with too less freq resolution at high freqs)
Makoto
On Mon, Aug 31, 2015 at 5:05 PM, Hendrik Enders <endersh at ucalgary.ca> wrote:
> Hello,
>
>
>
> I have finished my time-frequency analysis of my EEG data. Some people
> have asked me for some very specific information regarding the wavelet
> properties and I am unsure how to retrieve this information. I have a
> sampling frequency of 500 Hz and I used the input [3 0.5] for cycles and a
> pad ratio of 2.
>
>
>
> How can I calculate the center frequency of each individual wavelet that
> was generated between 3 – 50 Hz?
>
> I have tried the following:
>
>
>
> freqs = [3 50];
>
> cycles = [3 0.5];
>
> srate = 500;
>
> [wavelet,cycles,freqresol,timeresol] = dftfilt3( freqs, cycles, srate);
>
>
>
> This only returns two cells with wavelet information, time resolution and
> frequency resolution. How can I use the function to obtain center
> frequencies?
>
>
>
> The second point that I need to find out is the duration in the time
> domain for each wavelet. Can anybody help how I can generate that
> information to provide a table with the wavelet information?
>
>
>
> Thank you very much.
>
> Hendrik
>
>
>
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--
Makoto Miyakoshi
Swartz Center for Computational Neuroscience
Institute for Neural Computation, University of California San Diego
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