| 摘要 |
<p>PURPOSE:To extract a basic frequency component at all times stably by extracting 1st and 2nd basic frequency components of a clock signal from a direct output of a demodulated base band signals and a multiplication output of the signals respectively and selecting a 2nd extraction component at a prescribed condition. CONSTITUTION:A multiplication output of demodulation base band signals 1 by a multiplier 2 is processed by a BPF 3, from which a basic frequency component of a 1st clock signal is extracted. On the other hand, the signal 1 is processed by a BPF 5 or the like, from which a basic frequency component of a 2nd clock signal is extracted. When a level of the 2nd basic frequency component is in excess of a threshold level set to a comparator 6, the 2nd basic frequency component is outputted while being selected by an output changeover device 8 and a timing recovery clock is not lost even at the transmission of 0,1 alternate codes and the basic frequency component is always extracted stably.</p> |
