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ECFt20 Probe User's Manual <br />4. Collecting Data <br />cable for all probes and all soil types. For example, the <br />standard calibrations for the EG20 and EG 10 probes do <br />not perform in soils with high sand or salt content. There- <br />fore, for added accuracy we encourage our customers to <br />perform soil -specific calibrations. <br />The calibration equation that you will use depends on <br />where you will be using it. If you will be using it with <br />probes connected to a non -Decagon datalogger OR using <br />the "SEN" value given from the ECH20 Check you will <br />need to use the 2500 ffiV calibration. If you use any Deca- <br />gon software (DataTrac, ECH20 Utility, etc.) or the user <br />calibration menu in the ECH20 Check, you will need to <br />use the RAW calibration. The difference between the two <br />is the slope constant. To increase the resolution of the <br />sensor output, Decagon uses all available increments of <br />the 12 -bit number (value of 4096) -where the measurement <br />is stored. Thus, the output of the sensors read by the <br />ECH20 Check and Decagon loggers must be multiplied <br />by 0.61 AND the 2500 ffiV slope to give the right value. <br />I <br />Following is a fist of the both the millivolt and RAW cali- <br />bration values for the ECH20 probes, where 0 is the vol- <br />umetric water content, W is the millivolt output of the <br />probe, and where x is the RAW probe output. <br />EG20 <br />2500mV. 0 (m3 3m3) = 0.000695mV - 0.29 <br />RAW 0 (m /m) =0.000424 x - 0.29 <br />EG10: <br />2500mV. 0 (m3/m3). = 0.000936mv - 0.376 <br />16 <br />H <br />H <br />I <br />Ell <br />L <br />L <br />j <br />LI <br />I <br />fl <br />j <br />U <br />r <br />