| 摘要 |
PURPOSE:To perform spectrum analysis with a small number of multiplying circuits, by using (n+1) each digital low-pass or high-pass filters for sound recognition. CONSTITUTION:The input sound signal is supplied to LPFs 1-n+1 after converted from the analogue signal to a digital signal by A/D converter 6, and y1-yn+1 are obtained as outputs of LPFs. Outputs of LPFs 1 and 2 are seuared by squaring circuit 23 respectively, and respective outputs are supplied to subtracting circuit 24, and clear pulse 26 is used to obtain cumulative data in accumulator 25 after the subtraction processing. At this time, a BPF with fc1 as the upper limit and fc2 as the lower limit is constituted, and the cumulative value is output as spectrum analysis data. Similarly, outputs of LPFs 3-n+1 are processed, and similar results are obtained. |
