| 摘要 |
PURPOSE:To detect 'synchronizing step-out' and 'absence of signal' while distinguishing between them clearly by providing a synchronizing step-out detection means detecting frame synchronizing step-out and a signal absence detection means detecting the absence of signal. CONSTITUTION:The synchronizing step-out detection means 23 detects a violation in a reception input signal and when the effective violation 2 cannot be detected over 2-frame time, the out of synchronism signal is outputted. A gate circuit 24 outputs the synchronizing step-out detection signal when the synchronizing step-out detection means 23 outputs the synchronizing step-out signal and an INFO01 frame detection circuit 21 outputs no INFO01 signal. Thus, the detection of INFO0 and the detection of the synchronizing step-out are processed distinguishingly. |
