| 摘要 |
A tracking filter system including a phase locked loop and a tracking filter is receptive of an input signal of frequency A and undesired frequency X from a signal source such as a frequency modulated/continuous wave radar range measuring system. The phase locked loop circuit receives the input signal and produces a control signal corresponding to a frequency intermediate frequencies A and X. The tracking filter is set by the control signal to pass frequencies above or below the intermediate frequency and thus to pass frequency A and to reject frequency X.
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