| 摘要 |
PROBLEM TO BE SOLVED: To save power consumption. SOLUTION: A storage circuit 13 temporarily stores a DC level measurement value from a DC level measuring circuit 10, a noise pitch measurement value from a noise pitch measuring circuit 11 and a noise amplitude measurement value from a noise amplitude measuring circuit 12. A DC level comparing circuit 15, a noise pitch comparing circuit 16 and a noise amplitude comparing circuit 17 compare the DC level measurement value, the noise pitch measurement value and the noise pitch measurement value with a DC level reference value, a noise pitch reference value and a noise amplitude reference value and generate a DC level comparison result value, a noise pitch comparison result value and a noise amplitude comparison result value. An OR circuit 18 outputs the logical sum signal of the DC level comparison result value, the noise pitch comparison result value and the noise amplitude comparison result value. |
