| 摘要 |
PURPOSE:To eliminate the buzz sound be applying the delay AGC when the heavy field signal via the reception device of the double-super system, thus ensuring the sound reproduction free from the buzz sound, which is an advantage of the separate carrier system. CONSTITUTION:The 1st intermediate frequency signal is delivered form 1st mixer circuit 4 provided to tuner 2 of TV picture receiver and then applied to 2nd mixer circuit 7 via 1st intermediate frequency amplifier circuit 6 to be mixed with the output of 2nd local oscillation circuit 8. Thus the 2nd intermediate frequency signal is delivered. This signal is applied to FM detection circuit 11 via 2nd intermediate frequency amplifier circuit 9 to deliver the aural signal through output terminal 14. At the same time, the output of circuit 9 is applied to level detector 15, and the output of detector 15 is applied to AGC voltage amplifier circuit 16. And when the output of detector 15 is over the prescribed level, the delay AGC voltage is generated through detector 15 and circuit 16. The AGC voltage is applied to high frequency amplifier circuit 3 of circuit 2 as well as to circuit 6, thus preventing the occurrence of the buzz sound which is contained in the aural signal. |
