Portable virtual instrumentation for soil infiltration and roughness measurements

A laptop computer with data acquisition cards installed in a docking station provided a reliable means of acquiring soil infiltration and surface roughness data in the field. The critical system requirements included: 1) field-use-rugged; 2) portable; and 3) an intuitive user interface. National Instruments LabWindows software provided the development environment necessary for creating a man-machine interface (MMI) that was graphical and intuitive. Creating the instrument interface with the personal computer (PC) software allowed the developers to create a ''virtual'' instrument that could be easily modified during development and provided the users a common look and feel across applications. The laptop display gives the user immediate detection of potential problems with the measurement system. The infiltration measurement system used one digital input to detect tipping bucket pulses. The roughness measurement system checked the status of 40 digital inputs after every pulse from a pulser that output 256 pulses per shaft revolution. More than 150 successful infiltration and soil roughness measurements were made on several studies from 1993 to 1995.