| 摘要 |
Level-holding circuits 16, 17 sample and hold the output of quadrature detecting circuit 11 at adjoining apertures of eye patterns of demodulated multi-level QAM signal components and at the middle point of the adjoining apertures, respectively. Thus, location information on a phase plane of demodulated signal such as (I0, Q0), (I1, Q1), and (I1/2, Q1/2) are obtained. Frequency deviation detecting circuit 18 calculates the amplitude and the direction of the frequency deviation of regenerated carrier based on the location information. The output of frequency deviation detecting circuit 18 is added to phase error signal in synthesizing circuit 20. The result of addition is applied to VCO 15.
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