| 摘要 |
PURPOSE:To increase the S/N, by monitoring a reduction of the input field intensity and a deterioration of S/N due to the distortion noise and controlling the modulation factor. CONSTITUTION:The signal wave sent from the radio device 1' is demodulated by the demodulator 5. The noise detector 8 detects the voltage proportional to the S/N and sends it to the comparator 10 along with the AGC voltage of the IF amplifier 4. The comparator 10 decides whether the deterioration of S/N is mainly due to the heat noise or the distortion noise, and the control signal, which increases the modulation factor in case of the former and decreases the modulation factor in case of the latter, is sent to the device 1' via the data modulator 15. Thus the device 1' changes the modulation factor in accordance with the control signal to keep a good S/N. |
