| 摘要 |
An improved apparatus for measuring conductivity or resistivity compensates for series capacitance (Cs) and parallel capacitance (Cp). A sine-wave potential excitation (14) is applied to a reference resistance (12) and a conductivity cell (10) connected in series. The voltages across the resistance (12) and the cell (10) are sampled. To compensate for series capacitance, both sampled voltages are synchronously rectified with respect to the phase of the sampled resistance voltage. To compensate for parallel capacitance, both sampled voltages are synchronously rectified with respect to the phase of the sampled cell voltage. The rectified voltages are integrated and the cell conductivity or resistivity is calculated from the ratio of the integrated voltages.
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