<div dir="ltr">Hi all,<br><br>I have been trying to convert ERSP estimates from dB units to uV or uV^2 but have so far been unsuccessful. I saw that a number of people have posted on this topic, but I haven't seen any conclusive replies and thought I'd send out another attempt.<br>
<br>Based on my own experience and the posts of others, the trouble seems to relate to the following:<br><br>1) There is a command - 'outputformat','old' - that is supposed to make this conversion (and is also said to convert ITC arrays into non-complex numbers) that I haven't gotten to work. The problem may be in the programming - matlab requires a "10.^" rather than the dot-less "10^" to do element-wise exponents on non-square matrices, and the below error suggests that this may be missing:<br>
<br>??? Error using ==> mpower<br>Matrix must be square.<br><br>Error in ==> newtimef at 1750<br> mbase = 10^(mbase/10);<br><br>2) Someone has suggested that the 'baseline','NaN' command may provide a uV output, though when I use it I get plots in units of uV/Hz. It was also suggested that these values must then be further converted to get absolute power or volts but I'm unsure as to how that would be done.<br>
<br>3) I considered the possibility of converting from dB to uV^2 directly in Matlab by using a formula for converting from dB to Volts. However, given that dB here are used as logarithmic voltage ratios (I think?), I don't know what value I would use as a reference voltage in the equation. Would I use the values given in the 'powbase' vector as reference values for the conversion? <br>
<br>Any help or insight into conversion of ERSP and ITC arrays would be very greatly appreciated!<br><br>Many thanks,<br><br>Zach Moran<br>Graduate Student<br>University of California-Los Angeles<br>Lab for Clinical Affective Psychophysiology<br>
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