| 摘要 |
PURPOSE:To monitor the lock state properly by detecting whether or not a carrier recovery clock is locked based on the distribution state of an output of a phase comparator circuit on the phase plane. CONSTITUTION:A reception signal is demodulated and a phase of a symbol phase input 1 (input to terminal 6) obtained from a base band signal and an output phase of a VCO 2 are compared by a phase comparator circuit 3 and a phase error outputted from the phase comparator circuit 3 is inputted to a lock detection circuit 4. Moreover, the output of the phase comparator circuit 3 is smoothed by a loop filter 5 and fed back to the VCO 2. Then the output of the lock detection circuit 4 is monitored via a lock/unlock terminal 7. Thus, whether or not the carrier recovery circuit is locked is detected depending on the distribution state of the phase error being an output of the phase comparator circuit 3 on the phase plane to attain monitoring. |
