| 摘要 |
PURPOSE:To prevent mistracking of PLL by comparing the phase of the fundamental wave of the waveform received with the phase of the antenna scanning utilizing the nature that the phase changes depending on the incoming direction. CONSTITUTION:Delivered through switch S1, VCO control pulse is integrated by an integration circuit 6 to obtain a voltage corresponding to the phase step of the input whereby resetting is made prior to the arrival of the subsequent pulse. Upon the end of the integration, the switch S2 is closed momentarily to actuate the hold circuit 5 so that the result of the integration is maintained until the subsequent pulse integration is completed. When the result overlaps the PD output by an adder 7, the input signal remains unchanged in the phase. Thus the phase of the VCO changes and a PD output enough to offset the overlapped voltage develops. As a result, the PD output changes to offset the overlapped component and only PD signal is applied to the VCO. As the output changes in advance by a possible positive phase step, the actual phase step of VCO is reduced to a small level thereby preventing the malfunctioning of the apparatus. |
