| 摘要 |
<p>PROBLEM TO BE SOLVED: To improve an accuracy of frequency calculation at the time of frequency calculation for an input signal based on amplitude of the input signal passed through a plurality of bandwidth filters.SOLUTION: An input signal inputted to a frequency calculation apparatus 1 is logarithmically amplified by an AMP3 after passing through each channel filter 2 and reference filters 7 and 8. A logarithmically amplified input signal is converted into a digital signal by an A-D converter 4. A comparator 5 compares amplitude values of digital signals on predetermined channels. A frequency calculation apparatus 6 calculates a frequency for an input signal based on a difference between an amplitude value of a digital signal corresponding to a channel filter 2 corresponding to a maximum value and an amplitude value of a digital signal corresponding to a channel filter 2 whose frequency domain pass band is adjacent to the channel filter 2 if the maximum value of a digital signal amplitude value corresponding to an input signal, passed through the channel filter 2, the reference filters 7 and 8, is equal to an amplitude value of a digital signal corresponding to the channel filter 2.</p> |
