| 摘要 |
PURPOSE:To obtain a stable IF output signal which has less distored component after demodulation by using a low-pass filter as a filter circuit following an amplitude limiting amplifier in a system for an IF signal of television on which reverse logarithmic and logarithmic amplitude demodulation is performed. CONSTITUTION:The IF input signal 1 of television is distributed by a distributor 2, and the carrier (FA) for a sound signal is selected by a band-pass filter 3 and sent to a detecting circuit 5 through an amplifying circuit 4 for FA; and the modulating signal of FA is detected there and its amplitude is limited by the amplitude limiting amplifier 6. The amplitude-limited modulated signal is passed through the low-pass filter 7-2 to remove its high frequency component, and inputted as a demodulating signal to a demodulating circuit 8. The circuit 8 demodulates the IF input signal of television after reverse logarithmic amplitude modulation from the distributor 2 with the demodulating signal passed through the low-pass filter 7-2 to obtain a normal television IF output signal. |
