(42S) … In Situ Measurement Soil Electric Properties

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An extract from Appendix A of A Prototype Microwave Probe and Reflectometer for In Situ Measurement of Soil Electrical Properties, USACE WES, Miscellaneous Paper EL-96-1, FEB 1996.

Calculation of Dielectric Constant and Conductivity
Since the actual calculation of the dielectric constant and conductivity from the DCSR probe measurements is quite involved and time-consuming when done by hand, it is recommended that a hand-held programmable calculator be used to do these calculations. What follows is a description of how such calculators have been used in past studies at WES when the original DICON probes were being utilized for electrical property measurements in the field. A similar approach might be taken for the DCSR device, or one might attach to it a microprocessor that would reduce data collection to a single pull of a trigger.
… calculator can be used … two programs that perform the soil electrical properties calculations … The programming steps for these programs ("CAL" and "SOILS") for a Hewlett-Packard HP-42S programmable calculator are shown on the following pages …
Once "CAL" and "SOIL" are programmed into the calculator, soil dielectric constant and conductivity calculations may be done by simply executing "CAL" and entering the calibration data and then executing "SOIL" and entering the soil data. The user will be prompted by the calculator for all input data. "CAL" need only be executed once for a given set of calibration data. If calibration measurements were taken both before and after the soil measurements were made, the average of the two measurements should be used in "CAL." After each soil measurement is entered, "SOIL" will calculate and display the dielectric constant and conductivity of the soil …
It should be noted that any programmable calculator or computer with sufficient memory can be used to do the dielectric constant and conductivity calculations. The principal advantage of using a small battery-powered calculator such as the HP-42S, however, is that the dielectric constant and conductivity of the soil can be calculated quickly and conveniently in the field as the DCSR probe measurements are taken. The "CAL" and "SOIL" programs for the HP-42S were originally developed for the HP-41CV/CX series calculators, which use essentially the same programming steps as the HP-42S.

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