| 摘要 |
PURPOSE:To set an operating point easily and efficiently and prevent the false opening of a squelch at the time of high-sensitive reception by opening the squelch only when a received wave is present. CONSTITUTION:The output of IFA6 is supplied to AFA8 via a detector 7 and given to a squelch circuit 11. In the circuit 11, the output of a detector 111 contains modulated component of a double frequency of a rotation frequency of a rotation modulator 2. This component is extracted by BPF112, and an output obtained through detection and amplification of the extracted component is proportional to an electric wave signal which arrives. When this DC output is larger than a reference value given by an operating-point setting unit 15, AFA8 is placed in an operating state by the output of a comparator 114. |
