| 摘要 |
PURPOSE:To discriminate the presence or absence of a pilot signal in a quick and accurate way, by securing the setting of compromise between the responsiveness and the assuredness in the detection of the pilot signal in accordance with the receiving state. CONSTITUTION:A pulse formation circuit 1 converts a pilot signal into a pulse waveform. A period detecting circuit 2 detects whether or not the period of the input pulse signal is equal to a prescribed one. A duration detecting circuit 3 detects whether the detecting signal supplied to a terminal 6 has continued longer than N period of a pulse signal train which is supplied to a terminal 7. A level detector 10 delivers an N-value selection signal in accordance with the level of the supplied intermediate frequency signal. A selection signal control circuit 11 feeds the specific N value to a terminal group 8 in case a receiver is working for selection of channel and the demodulated signal is not stable and regardless of the output signal of the detector 10. In such constitution, both the responsiveness and the assuredness can be satisfied for the detection of a pilot signal. |
