| 摘要 |
An acoustic wave sensor includes an electromagnetic acoustic transducer to generate a resonant acoustic wave substantially trapped in an acoustic wave cavity. The acoustic wave cavity is defined by a radially symmetric raised surface. The electromagnetic acoustic transducer includes a spiral primary coil to generate the acoustic wave in the acoustic wave cavity and a concentric spiral pickup coil to pick up an electrical signal representing the acoustic wave in the cavity. A noise canceling coil portion is used to cancel spurious noise induced by the primary coil from the pickup coil to provide an output signal representing the acoustic wave energy in the cavity 12.
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