njit-etd2003-081 - New Jersey Institute of Technology

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As an example, the procedure of the cross-spectral analysis using a data file of a
COPD subject in text format acquired using the National Instrument data acquisition
system, saved as file name agu1baseline.txt is presented below:
1) Find the data acquisition sampling frequency, sf, of the data file. Use WinEdit or
Notepad to open the data file. A single integer number on line 1 of the data file is the
sampling frequency of the file. Record this number for reference. In all studies used for
this dissertation, the sampling frequency is 200 samples per second.
2) Next, the information of what signal on what channel is needed. Click on the
LabVIEW icon to start running LabVIEW. The National Instrument LabVIEW dialog
box opens. Click on Open VI bar to select the data file to load. The Choose the VI to
open: dialog box opens. Click on the down arrow of the Look in: bar to navigate the
windows directory and select the VI program. Double click to select 4dsp.vi. The
4dsp.vi front panel is displayed. Click on the right arrow on the command bar to run the
LabVIEW (4dsp.vi) program. The choose file to read dialog box appears. Use the down
arrow button in the Look in: bar to navigate the directory to select the data file to be
analyzed (in the example, the data file is agu1baseleine.txt). Double click on the data file
name to run the program.
3) In a few seconds, the plots of all four data signals are displayed. Resize the x-axis
on each plot to zoom in to a small section of the signal. Record the signals and their
channel numbers for reference. (In the example, the channels are shown below)
Signal Channel
CO2 0
BP 1
Resp 2
ECG 3