| 摘要 |
An aircraft ultrasonic fuel-gauging system has a processing unit that energizes probes and receives signals from transducers arising from energy reflected back from the fuel surface. In addition to determining the time between transmission of a signal from the transducer and reception of its reflection from the fuel surface, the processing unit also determines the time of reception of subsequent reflections caused by reflection back from the lower end of the probe. The processing unit determines whether the subsequent reflected signals are within predetermined limits of the time interval between transmission and reception of the first reflected signal in order to confirm the validity of the first signal. The processing unit also counts the number of subsequent reflected signals received within predetermined time intervals to assign a confidence level and this used to select between different incompatible signals, such as signals from that probe at different times or signals from different probes.
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