| 摘要 |
PURPOSE:To decide on an accurate surface water level by applying a voltage to electrodes of a measurement lever and making a scan on all the electrodes, measuring and storing flowing currents in a memory, and comparing them with previsouly stored values and performing arithmetics. CONSTITUTION:Sampling operation is repeated under the control of a control circuit 32. Namely, all water level detection electrodes E1-En of the measurement lever 10 are scanned successively at specific intervals of time and the voltage is applied to the respective electrodes to measure flowing currents, which are converted by an A/D converter 34 and stored temporarily in the memory. An arithmetic circuit 40 compares a stored measured value with the last stored measured value on every sampling operation to find the time variation value and increase/decrease polarity of each electrode current value, compares the obtained time variation value with a constant for deciding on the validity of electrode current variation to discriminate electrodes which relate to the up/down operation of the water level from others, and then compares the stored measured value of an electrode current with the underwater electrode current value of each electrode according to the increase/decrease polarity of the electrode current to find the difference, thereby deciding on the position of the electrode based upon the fluctuating water level and its state with time. |
