DPlot

I have a CSV file with samples of data taken at 300Hz. I import this data into DPlot with file format "D" and I select "0" for X-axis.

So far so good, I have the data and I can plot the graphs. The problem I have now, though, is that I can't seem to define the X-axis according to the sample rate. This is especially an issue when running the FFT function as it seems to make some assumptions as to the units for the X-axis.

My question is if there is a way to specify the time units for the X-axis. The Extents/Intervals/Size option doesn't seem to allow this. I know I can generate a secondary X-axis using multiple axes option but the FFT doesn't recognize that secondary axis in its' computations.

Am I missing something or can someone help me solve this problem? Thanks.

Daniel

Daniel,
If you do not have an X axis label, seconds are assumed.

If you DO have an X axis label and it contains "msec" or "millisec" then milliseconds are assumed. If it contains "microsec", "µsec", or "{\sm}sec" then microseconds are assumed. None of these searches are case-specific. If none of the above applies then seconds are assumed.

In your case your time units are 1/300th of a second. To get the correct frequency units for your FFT you'll need to first transform the X values using Edit>Operate on X, with X=X/300 for seconds or X=X/0.3 for milliseconds (and in the latter case add an X axis title containing "msec" or "millisec" so that DPlot will recognize the scale.)

Thanks. That fixed it but the FFT thing still isn't working out as well.

Daniel

Isn't working out in what way?