| 摘要 |
PURPOSE:To allow the equipment to track a frequency of an audio signal such as a sound signal. CONSTITUTION:An A/D converter section 2 converts a transmission audio signal inputted from an input port 8 into a digital value based on a predetermined fixed frequency and A/D converter sections 3, 4 convert a transmission audio signal inputted from an input port 7 into a digital value based on a sampling frequency decided by a microprocessor 1. Whether a conversion data of the A/D converter section 2 is coincident with a conversion data of the A/D converter section 3 or a conversion data of the A/D converter section 2 is coincident with a conversion data of the A/D converter section 4 is discriminated, and when they are noncoincident, the sampling frequency used for the A/D converter section 3 is slightly increased and the sampling frequency used for the A/D converter section 4 is slightly decreased. The conversion data of the A/D converter section 3 or 4 is coincident with the conversion data of the A/D converter section 2 by varying gradually the sampling frequency so as to discriminate a change in the frequency. |
