| 摘要 |
The invention relates to a phase locked loop for producing a reference carrier for a coherent detector, comprising a first phase detector (9) which compares the estimated carrier frequency of an incoming signal and the frequency of a local reference carrier oscillator (11) and produces a control signal proportional to the phase difference between said two frequencies. The oscillator (11) comprises a reference oscillator (1), a loop oscillator (5), a second phase detecting means (2) having inputs to which the output of the reference oscillator (1) and the output of the loop oscillator (5) are connected; and frequency adjusting means (6) which in response to said control signal adjust the frequency of the reference carrier oscillator (11) by simultaneously adjusting both the reference oscillator (1) and the loop oscillator (5). |
