| 摘要 |
PROBLEM TO BE SOLVED: To precisely detect bubbles by utilizing ultrasonic waves. SOLUTION: A frequency analysis part 24 performs FFT processing to a reception signal in a window set to a reception beam, and obtains the frequency distribution of the reception signal. For example, a power spectrum waveform 46 relative to the reception signal is formed. From the power spectrum waveform 46, a peak 48 corresponding to a second higher harmonic is detected. On the basis of whether a frequency distribution pattern corresponding to the vibration of a micro bubble is included in the power spectrum waveform 46 obtained by the frequency analysis part 24, a decision part 26 decides whether the reception signal corresponds to micro bubbles. In the case, the decision part 26 carries out decision processing on the basis of the peak 48 detected from the power spectrum waveform 46. COPYRIGHT: (C)2008,JPO&INPIT |
