| 摘要 |
<P>PROBLEM TO BE SOLVED: To reduce sample number by decreasing a sampling frequency in Fourier transform while maintaining intended frequency resolution, and decrease the frequency of complex multiplication. <P>SOLUTION: A device for analyzing a frequency of a received signal within a predetermined frequency bandwidth Δf<SB POS="POST">p</SB>including a frequency f<SB POS="POST">c</SB>comprises: a modulator 3 that applies frequency conversion to the received signal; an analog filter 5 that is connected to output of the modulator 3; an A/D converter 6 that converts output of the analog filter 5 into a digital signal through oversampling; a digital BPF (bandpass filter ) 7 that extracts a component equivalent to the frequency bandwidth Δf<SB POS="POST">p</SB>from the output of the A/D converter 6; a downsampling part 8 that decreases a sampling frequency of a signal output from the digital BPF 7 through conversion so as to be arranged within a bandwidth equivalent to a range from a zero frequency to Δf<SB POS="POST">p</SB>; and an FFT processing part 9 that applies fast Fourier transform to the output of the downsampling part 8. <P>COPYRIGHT: (C)2013,JPO&INPIT |
