| 摘要 |
<p>PROBLEM TO BE SOLVED: To obtain a digital band-pass filter which is small in circuit scale and small in operation quantity as a filter which extracts signals of frequencies f1 and f2 from an input signal. SOLUTION: When f1 :f2 =1:2, an input signal is sampled at a frequency fs =6f1 and A/D-converted by an A/D converter 2, and then inputted to the comb filter 5 of the digital band-pass filter 4 to remove frequencies which are equal to and 1/6, 1/3, and 1/2 time as high as fs , so that the resulting signal is inputted to notch filters 6 and 7. The notch filter 6 further removes frequencies which are equal to and 1/3 and 1/2 time as high as fs , and then a signal of f1 is extracted. The notch filter 7, on the other hand, removes frequencies which are equal to and 1/6 and 1/2 time as high as fs to extract a signal of f2 .</p> |
