| 摘要 |
PURPOSE:To eliminate a continuous disturbing wave, mixed in a pulse signal, automatically by controlling notch filters by a perturbation signal from a dither generator and an output signal from a voltage generator. CONSTITUTION:When a pulse signal and two continuous diturbing waves are inputted to a terminal 1, a dither generator 9 generates a perturbation signal of a repetitive frequency fD with wide pulse width, and the signal is superposed upon a DC voltage from a voltage generator 15 through a switch (SW) 13 and an adder 17 to control a notch filter (NF)2 by the resulting signal. At the output fo the NF2, the disturbing waves appear as being amplitude-modulated by the frequency fD and are detected 5 to pass through a band-pass filter BPF6 for the frequency fD. The output of the BPF6 is discriminated by a phase discriminator 8 from a signal from the generator 9, and the discriminator 8 sends a positive or negative signal to a controller 12 according to whether both the signals are in phase or out of phase. According to the input signal, the controller 12 controls the generator 15 to make the output of the BPF6 into a 0. At this time, the output of a BPF7 is applied to the controller 12 to stop its control. A timer 14 switches the SW13 a certain time later to control an NF3. |
