| 摘要 |
PURPOSE:To ensure the perfect elimination of the FM noise and then omit the pilot signal processing circuit, by closing the gate for the fixed time when the pulsating noise is detected in the IF signal and then holding the frequency information immediately before the closing action to use it for the control signal of the oscillating circuit. CONSTITUTION:The reception signal is changed into the IF signal and then led to noise eliminating part 6 after receiving IF amplification 5. In this circuit 6, gate 61 is included along with frequency detector 62 which uses the gate output for the input and possesses the holding function plus control oscillator 63 the frequency of which is controlled in accordance with detector 62. Now if the pulsating noise is mixed into the IF signal, the gate signal is emitted from noise detecting part 7 to close gate 61 for a fixed time. Thus no IF signal is transmitted any more to detector 62. However, detector 62 holds the frequency information immediately before the closing action, and this holding signal is used for the frequency control signal of oscillating circuit 63 along with the oscillating output supplied to FM detector 9. As a result, the FM noise can be eliminated completely, thus omitting the pilot signal processing circuit. |
