| 摘要 |
PURPOSE:To select the frequency haying the strongest electric field strength with simple circuit constitution by decreasing the reception sensitivity into plural stages in the reception of a broadcast station broadcasting one and the same program through plural frequencies simultaneously thereby selecting the frequency having been received in the lowest sensitivity. CONSTITUTION:The decision of electric field strength is started by a start signal through the application of power switch. At first, a frequency changeover signal 105 is used to set a frequency changeover circuit 104 to a 1st frequency. In this case, the sensitivity of the reception section 102 is set to a best state by using a reception sensitivity control signal 106. The signal received from an antenna 101 is detected and amplified by a reception section 102 and a reception detection signal 107 is outputted. The signal 107 is outputted when the S/N of the output of the reception section 102 reaches a specified value or over. The reception sensitivity is reduced by using the control signal 106 till the signal 107 is lost and the sensitivity and the frequency for the case are stored in a storage section 111. The sensitivity for plural frequencies is checked by the same procedure till the signal 107 is lost and the result is stored in the storage section 111 and the frequency having the signal 107 is received from the stored contents even if the sensitivity is lowered most.
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