The default sampling frequency for each channel is 200 Hz. Data are typically collected
for 20 to 60 seconds. The user is presented with a “Pre-Scan” panel to ensure that each signal
is calibrated and tracking appropriately. When the user is ready to collect and store data,
the “Cardiac DAQ” instrument is called (Figure 136-26). This sub-VI uses double-buffering
to collect and display each channel for the predefined time. In order to maintain high
temporal resolution, data are displayed in 10-second “sweeps.” An indicator is provided to
display the instantaneous and total collection time.
Once data are collected, the user is presented with the “Data Selection” sub-VI to
define a particular range of data to save to a file. This option allows the user to store only
the portion or subset of data that are useful among the entire collected data set (e.g., the
last 25 seconds of a 60-second array). The default setting will store the entire data set.
Interactive cursors are used to interactively set the initial and final indices of the data subset
for analysis, as illustrated in Figure 136-27