[Eeglablist] Wrapped Phase Angle from newtimef?

Maria L. Stavrinou marial.stavrinou at gmail.com
Sat Apr 17 13:13:53 PDT 2010


Dear Zach,
You can use unwrap to un-wrap the phase that you calculate. To check if all
goes well, try this by having a simple sinusoid as input and check the
result, as shown in the image I am attaching. I would recommend, to do the
phase difference of the unwraped phase,  in radians of as they are now,
between -pi and pi. Using the function mod you can project them into [0,
2pi] interval.

Maria

2010/4/15 Zachary Moran <zdmoran at gmail.com>

> Hi Everyone,
>
> I'm currently investigating the relationship between phase angle and other
> EEG variables.  In order to get phase angle, I've been taking the angle(ITC)
> in Matlab which gives me phase angle estimates from -pi to pi radians.
> However, when I plot this data against time I find discontinuities at pi and
> -pi (see attached jpeg for an example), which has become problematic in
> using it as a predictor variable.
>
> Does this suggest that the phase information is "wrapped", and, if so, does
> Matlab's "unwrap(phase_angle_data)" function seem appropriate to anyone else
> as a means of making my phase angle data better suited as a predictor?
> Alternatively, I had initially wanted to constrain phase to between 0 and
> 2pi radians - does anyone have any advice for how to make this conversion?
> Any thoughts or ideas would be very greatly appreciated.
>
> Many thanks!
>
> Zach
>
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-- 
-- 
Maria L. Stavrinou
MSc. PhD.
Postdoc Researcher
Unit of Neurophysiology
Department of Physiology
School of Medicine,
University of Patras
Greece
tel. lab +30 - 2610-969153
cellular +30 -6938287930
http://physiology.med.upatras.gr/NU/

https://sites.google.com/site/marialstavrinou/
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