| 摘要 |
An ultrasonic liquid-level sensing system has a sensor (2) with a number of reflectors (101 to 105) mounted one above the other along the length of a tube (30) that extends upwardly from a transducer (68) and is filled with liquid to the same height as outside the tube. Liquid height is calculated from the ratio of the difference between the arrival times of the pulses reflected from the two uppermost submerged reflectors (104 and 103) and the difference between the arrival times of pulses reflected from the surface of the liquid (6) and the uppermost submerged reflector (104). <IMAGE>
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