摘要 |
The output of a VCO, a referenced frequency signal and an offset frequency signal are mixed to provide a control signal for the VCO and a double offset frequency signal which is mixed with an output of the offset frequency source to provide a DC component having a positive polarity if the signals are inphase and the VCO is locked on one sideband and a negative polarity if the signals are out of phase and the VCO is locked on the other sideband. A sweep signal is activated and applied to the VCO in response to the VCO being locked onto the wrong sideband.
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