| 摘要 |
PURPOSE:To facilitate the discrimination of a reception level discriminating circuit with simple constitution by using two level detection circuits so as to detect the noise component of the upper side or the lower side frequency of the maximum frequency shift of an FM signal outputted from a limiter amplifier circuit. CONSTITUTION:A carrier level detection circuit 4 detecting the carrier level of the FM signal outputted from a limiter amplifier circuit 1 and a reception level discriminating circuit 7 discriminating the reception level from the output of the two level detecting circuits 4, 6, the latter detecting the noise level of the upper side frequency or the lower side frequency from the maximum frequency shift of the FM signal are provided. Thus, an output disconnecting circuit 8 is operated by the signal of the reception level discriminating circuit 7 to disconnected the output signal of the FM detecting circuit 2 and malfunction due to external noise is decreased.
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