I would like to measure the time ultrasound takes to travel through air (c = 1550m/s) with LabVIEW 7.1 and a NI PCI-6110 S DAQ card. I think that I have to use the internal 20MHz clock as a timebase for event counting. My problem is that I have no idea how to implement the code in LabVIEW for that purpose. Thanks for your help.