| 摘要 |
PURPOSE:To decrease the noise component at the weak field region and to increase the articulation by increasing the de-emphasis constant in accordance with reduction of the detection level of the received wave. CONSTITUTION:At the reception time at the weak field region, the detection voltage of peak detection circuit 18 is lowered. And transistor 15 is turned off, and the collector features a high potential with transistor 13 and 14 turned on. Then the one end of capacitor 11 and 12 of de-emphasis adjusting circuit 6 is earthed to actuate circuit 6. Accordingly, the high band is attenuated according to the de-emphasis constant of circuit 6 for the aural signal of the output of detector circuit 4, and then the aural signal is supplied to the stereo demodulation part via capacitor 8. |
