AFC CIRCUIT, CARRIER REPRODUCING CIRCUIT, AND RECEIVER
    2.
    发明公开
    AFC CIRCUIT, CARRIER REPRODUCING CIRCUIT, AND RECEIVER 有权
    Schaltung zur automatischen Frequenzregelung,Schaltung zurTrägerrückgewinnung,undEmpfänger

    公开(公告)号:EP0940957A1

    公开(公告)日:1999-09-08

    申请号:EP98943037.6

    申请日:1998-09-18

    IPC分类号: H04L27/22 H04N5/455

    摘要: Stabilized carrier recovery is acheived even at the time of a low C/N ratio by measuring the phase of a signal and controlling VCO or NCO (Numerical Controlled Oscillator) using only a period having few constellation points. At this time, false lock phenomenon is avoided as follows. That is, relatively short SYNC modulated by an already-known pattern is entered into a modulation wave, VCO or NCO oscillation frequency is swept in a wide range and sweep is stopped at a frequency in which the SYNC can be received, thereby carrying out coarse control AFC. Further, a period having long to some extent, having few constellation points is provided in the modulation wave and then, a difference between the frequency of a received modulated signal and a local oscillation signal of VCO or NCO is obtained in this period. This frequency difference is analyzed according to the phase differential function method, self-correlation function method or count method, and the VCO or NCO is controlled based on this result of analysis.

    摘要翻译: 即使在C / N比较低的时候,通过测量信号的相位并且仅使用具有很少星座点的周期来控制VCO或NCO(数控振荡器),稳定的载波恢复也是可以实现的。 此时,如下所示避免假锁现象。 也就是说,通过已知的模式调制的相对较短的SYNC被输入到调制波中,VCO或NCO振荡频率在宽范围内被扫描,并且在可以接收SYNC的频率上停止扫描,从而执行粗略 控制AFC。 此外,在调制波中提供了具有很少的星座点的长时间段,然后在该周期中获得接收到的调制信号的频率与VCO或NCO的本地振荡信号之间的差。 根据相位差函数法,自相关函数法或计数法对该频差进行分析,并根据该分析结果对VCO或NCO进行控制。