| 摘要 |
PURPOSE:To eliminate malfunction against voice input or noise input by obtaining a power alpha1 of an input signal and a power alpha2 of a carrier for data communication and discriminating the data to be a data communication only when a ratio alpha2/alpha1 is larger than a prescribed value. CONSTITUTION:An input signal from an input terminal 1 is given to a power detection circuit 10 and the power alpha1 is outputted for each prescribed time t1. The input signal is inputted to a power detection circuit 11, from which the power alpha2 of a carrier signal for data communication is outputted for each prescribed time t1. A ratio detection circuit 12 obtain a ratio of the power a1 to the power alpha2 for each time t1 and gives it to a comparator circuit 13. The circuit 13 compares the output of the circuit 12 with a prescribed value betaand when the output of the circuit 12 is larger than the prescribed value beta, the data is discriminated to be the data communication and when the output of the circuit 12 is smaller than the prescribed value beta, it is discriminated to be a voice signal. Thus, malfunction against voice input or noise input is avoided. |
