| 摘要 |
PURPOSE:To effectively reduce the unpleasant sound due to multipaths in a strong electric field area, by controlling the switch means provided at the post stage of the FM detection circuit by taking the output signal from the product detection circuit as the control signal. CONSTITUTION:When multipaths are developed, distortion is produced in the output signal of the FM detection circuit 6, that is, stereo signal, and low frequency components are produced in the output circuit of the product detection circuit 14, they are fed to the wave shape circuit 17 via LPF16, and the pulse shaped 17 is fed to the hold circuit 18 to output DC voltage. Accordingly, the presence of multipaths caused a DC voltage output at the circuit 18 to turn on the electronic switch 8 and to connect the capacitor C to grouond, allowing to attenuate the harmonics of audio signal and to reduce unpleasant sound due to multipaths. |
