| 摘要 |
A positioning determining system using a delay element and driver transducer for producing a traveling wave in the delay element, the presence of a traveling wave being detectable by a receiver transducer for determining the relative positions of the driver and receiving transducers. In accordance with the invention, a driver transducer, the delay element, and a second transducer form a self-excited feedback loop oscillator, the frequency of oscillation of which is determined by the spatial filtering provided by the second transducer so as to generate a traveling wave having a selected wavelength. The system includes automatic frequency selection to compensate for position sensing errors due to changes in the velocity of propagation of elastic waves arising because of temperature effects on the delay medium.
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