| 摘要 |
PURPOSE:To execute measurement and decision in a real time by converting data outputted from a first (a second) power measuring means to a first (a second) signal-to-noise ratios, and deciding that a pulse code modulating circuit is not contained, in the case a difference of a first and a second signal-to-noise ratios is below a prescribed value. CONSTITUTION:An area deciding value of an area deciding device 14 and a signal level output value from an automatic equalizer 3 are inputted to a first SN ratio converter 15 and converted to a first SN ratio. A second analog-to- digital converter 16 measures a received signal level in a communication circuit, when a receiving carrier is detected, and measures a circuit white noise level, when the receiving carrier is not detected. Subsequently, it is converted to a second SN ratio and outputted, based on a second data table from a difference of a result of these measurements. Next, a subtracter 18 subtracts and compares a first SN ratio and a second SN ratio, and in the case they are equal to each other, it is decided that a PCM circuit is not contained in a circuit in present use, and in the case they are not equal, it is decided that the PCM circuit is contained. In such a way, whether the PCM circuit is contained or not is discriminated in a real time. |
