SO on. DAQ task creation is accomplished using the DAQ Configuration Utility included in LabVIEW. Bluetooth Figure 12.29 Test configuration for mobile DAQ. Service Delivery Platforms DAQmx Base Task Name Samples per Channel ECG Waveform (bet) Analog 20 DBL status NChan NSamp spreadsheet string 10.00 timeout Figure 12.30 Data acquisition virtual instrument for the example of a bio- medical tele-monitoring (ECG_Graph.VI). A measurement cycle (Figure 12.30) consists of starting a specific DAQ task (using DAQmxBase Start Task.VI), reading data from the DAQ card (using DAQmxBase Read.VI) in a loop until the user stops the system or until an error occurs and then stopping the DAQ task (using DAQmxBase Stop Task.VI). The acquired data can be viewed both online, on the PDA screen using Waveform Chart (see the VI Panel on the screen, in Figure 12.31), or offline by log- ging the data into spreadsheet files (XLS format). A sampling rate of 250 S/s has been chosen (for many industrial or physiologic appliances). A relevant measure- ment cycle implies acquiring 1000 samples which can be stored in 10 kB spread- sheet files. The log file obtained after 24 h of continuous data acquisition (required for monitoring cardiac activity over a longer period of time) would then be 216 MB Pocket PC Figure 12.31 Acquired ECG (unfiltered)-in the LabVIEW Panel on PDA. Tele-Measurement Services for m-Learning large. Generated files which are as big as 10 kB, can be directly transferred over GPRS to a remote server. If the acquired signal needs to be monitored over a longer period of time, thus, resulting in larger files which are not fit for transfer over GPRS, these files can be stored on the SD card of the PDA and then "downloaded" to a PC in order to be analyzed offline. The transfer of the acquired data over Bluetooth to the mobile phone (which acts as a GPRS modem) is handled by a subVI (Figure 12.32) which opens a Bluetooth connection to that phone (using the LabVIEW function Bluetooth Open Connection. VI). The Bluetooth Open Connecti