| 摘要 |
A measurement system for capturing a transit time, phase, or frequency of energy waves propagating through a propagation medium is disclosed. The measurement system comprises two different closed-loop feedback paths. The first path includes a driver circuit (628), a transducer (604), a propagation medium (602), a transducer (606), and a zero-crossing receiver (640). The zero-crossing receiver (640) detects transition states of propagated energy waves in the propagation medium including the transition of each energy wave through a mid-point of a symmetrical or cyclical waveform. A second path includes the driver circuit (1228), a transducer (1204), a propagation medium (1202), a reflecting surface (1206), and an edge-detect receiver (1240). Energy waves in the propagating medium (1202) are reflected at least once. The edge-detect receiver (1240) detects a wave front of an energy wave. Each positive closed-loop path maintains the emission, propagation, and detection of energy waves in the propagation medium.
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