| 摘要 |
<p>A phase lock loop circuit (50) for removing abrupt changes in a received signal (33), such as those caused when an object tracking system's directional receiving antenna (10) becomes misaligned with the tracked object, uses a phase detector (60) to determine when an abrupt phase change has occurred, such as when a signal returned from the tracked object aligns with an antenna null and would reverse the phase of a control signal (37) fed to a phase locked oscillator (56). The received phase signal (37) is compared with a reference phase (57a) from the oscillator (56) and the difference signal (63) used to trigger a Schmidt trigger (66) that controls a phase-reversing circuit (70) interposed between the loop mixer (52) and the oscillator (56). A delaying low pass filter (54) ensures the control signal (77) is stable before it is fed to the phase locked oscillator (56).</p> |
