| 摘要 |
In a method for generating and/or for receiving ultrasonic signals by using a piezoelectric crystal, a higher resolution, improved location of faults and detection of the type of fault are achieved by arranging for the crystal to be predeformed continuously during measurement by a DC voltage. At the same time, bipolar pulses can be applied to the quartz crystal, resulting, e.g., in a simplification of the frequency analysis and of the phase shift.
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