| 摘要 |
PURPOSE:To effectively eliminate ignition or fading noise, by limiting a slope (rate of change) of a demodulated output signal to a small value, when an input electric field level is low. CONSTITUTION:A reception signal amplified at an amplifier 1 is inputted to a slope limit circuit 3 at a demodulator 2 as an audio signal superimposed on noise. A slope limit circuit 3 controls the limit of slope limited with a reception electric field level detected at an electric field level detection section 5. For the control, the level of the amplitude limiter is made variable or the gain is varied. Since noise generally carries a sudden amplitude range, it is eliminated with the slope limiter 3. Even if the electric field level is decreased, the rate of change of an output signal reduced by controlling the limiter 3, allowing to reduce noise. |
