I am importing a .wav created in Matlab to use as a stimulus for current injection (through the Command input) in IGOR. In Matlab, the max value for the wav is 0.8, which if in Volts would correspond to about 320pA once passed through the Command input at 400pA/V. However, when I use SndLoadWav to import the stimulus into IGOR, V_max of the imported stimwav is 26155. Furthermore, when I try to scale it back down to 1V max using "stimwav /= V_max" it completely degrades the resolution so instead of a complex waveform it is just a binary wav. Do you have any insights into either of my problems (1: why the max/min values of the stimwav are arbitrarily at least 3 orders of magnitude bigger than the original stimulus file, and 2: why when i try to scale the amplitude of the stimwav, the sampling seems to also be affected).
I already use datawav /= [value] to scale the ADC input to appropriate pA and mV values and this seems to have worked fine. It is not obvious to me why it is not working with the stimwav I am trying to use?
Yes! Using Redimension/D allowed me to re-size the wav appropriately. Thanks John.
The stimulus is not one that I created, but one that I exported from a friend's database to use. I could ask them for the equations and implement it, but it seemed easier for now just to carry it around as a vector or text file, etc.
January 24, 2012 at 02:55 pm - Permalink
The D flag says to keep the values the same, but make the data in it into double-precision floating point.
But why not just create the wave in Igor in the first place? What sort of waveform is it?
John Weeks
WaveMetrics, Inc.
support@wavemetrics.com
January 24, 2012 at 02:58 pm - Permalink
The stimulus is not one that I created, but one that I exported from a friend's database to use. I could ask them for the equations and implement it, but it seemed easier for now just to carry it around as a vector or text file, etc.
January 24, 2012 at 03:10 pm - Permalink