| 摘要 |
A feeble signal extracting circuit with a simple structure for extracting a feeble signal such as a pilot signal. A pilot signal extracting circuit 22 comprises a band elimination filter (BEF) 30, an analog subtracter 31, an amplifier 32, and a voltage comparator 33. The band elimination filter 30 removes only the frequency components at and near 19 kHz corresponding to the pilot signal and passes the other frequency components. The analog subtracter 31 receives a stereo composite signal inputted from an FM detection circuit 18 and the signal produced by removing the pilot signal from the stereo composite signal by passing the stereo composite signal through the band elimination filter 30, outputs the differential signal of the two signals, and thus extracts only the pilot signal.
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