| 摘要 |
PURPOSE:To enhance the S/N ratio of sound output to approximately the S/N ratio of a spectrum image, by removing the noise of an orthogonally detected ultrasonic Doppler signal and subjecting a part of the spectrum image thereof to inverse Fourier transform to convert a frequency series signal to a time series signal and, after conversion, removing the noise of said time series signal to convert the same to sound. CONSTITUTION:The processing in an IFFT processing part 8 may be performed by separately applying IFFT processing to an inputted USB signal and an inputted LSB signal and the inverse Fourier transform of the same content as that analyzed in an FFT operation part 4 is sufficient. These signals USBS3, LSBS3' receive noise removal processing, which is generated by signal processing for correcting the phase shift at the time of the coupling of a sampling signal, in a signal post-processing part 9. The output signals of the signal post-processing part 9 are converted to an analogue signal in D/A converters 10a, 10b to be outputted as sound signals S4, S4'. The sound signals are inputted to a noise removal processing part 5 as the spectra of an image signal to remove noise therefrom and converted to time axis signals by inverse transform to be outputted as sound signals and, therefore, the S/N ratio of the sound signals is enhanced to that of the image signal and the sound signals are regenerated as good ones.
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