| 摘要 |
An aircraft fuel quantity gauging system has a number of probes within a tank to measure the height of fuel at different locations. Each probe includes a still well and an ultrasonic transducer mounted at the top and bottom of the still well. The lower transducer transmits pulses of acoustic energy upwardly through the fuel to its surface and measures the time of travel back of the reflected pulse back to the transducer. This is used to derive a first, bottom-up measure of fuel height. Similarly, the upper transducer transmits pulses down through air to the fuel surface to derive a second, top-down measurement. These are compared to check for correct operation of the probes.
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