| 摘要 |
<P>PROBLEM TO BE SOLVED: To enhance frequency resolution while enhancing resolution in a time range to be measured, and reduce an operation amount by reducing sample number through decrease of a sampling frequency in Fourier transform. <P>SOLUTION: The device executes steps of using: a modulator 5 to apply frequency conversion to a received signal; an A/D converter 61 to convert a frequency converted signal into a digital signal by oversampling through an analog filter 7; a digital BPF 62 to extract a component equivalent to an intended frequency bandwidth Δf<SB POS="POST">p</SB>; a downsampling part 63 to decrease a sampling frequency of the extracted signal to a lowest frequency bandwidth through conversion; a signal clipping gate 11 to clip out a digital data column from the downsampling part 63 within an intended duration, after the downsampling; a zero addition part 12 to add zero data so as to satisfy frequency resolution; and an FFT processing part 13 to apply fast Fourier transform to the zero-data-added digital data column. <P>COPYRIGHT: (C)2013,JPO&INPIT |
