[Eeglablist] Frequency resolution of newcrossf

[Bethel Osuagwu]

Dear All,

I am having a bit of confusion with the frequency resolution of of
'newcrossf' function.

I have:
srate=1926Hz
winlen=[0,1063]%i.e 2048 samples. So frequency resolution should be
1926/2048=0.9404

pop_newcrossf( EEG, 1, 1, 2, [0  1063], [0] ,'type', 'phasecoher',
'title','Channel 1-2 Phase Coherence','padratio',
1,'freqs',[1,70],'detrend','on','rmerp','on');

I was expecting to get a frequency resolution of about 1 or less but I am
getting 15; even after I add the option 'nfreqs'=70. Why is the frequency
resolution not ~1?

Increasing the 'padratio' option to 4 increases the frequency resolution
but I do not understand what padratio is, so I don't know how to report it.
Some how the following explanation of 'padratio' is not clear to me.

" 'padratio'  = FFT-length/winframes (2^k)                    {2}
                      Multiplies the number of output frequencies by
dividing
                      their spacing (standard FFT padding). When cycles~=0,
                      frequency spacing is divided by padratio."


What does it mean? Why can I not just rely on my window length to change
frequency resolution?
Thanks in advance.


-- 
*Bethel A. C. Osuagwu*
Clinical Research Fellow

*Stoke Mandeville Spinal Research*
National Spinal Injuries Centre
Mandeville Road
Aylesbury
Bucks
HP21 8AL
Tel: 01296 31 5963 (Applied NeuroLab)
*lifeafterparalysis.com <http://lifeafterparalysis.com/>*
​@lifeafterpara​

*justgiving.com/smsr <http://justgiving.com/smsr>*
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