| 摘要 |
<p>PURPOSE:To attain highly efficient data transmission by transiting the mode to the synchronization establishing mode when a frame synchronizing data is detected in the hunting mode and transiting the mode to the hunting mode when no frame synchronizing data is detected in the retrieval timing of the synchronization establishing mode. CONSTITUTION:A frame synchronization detection circuit 3 retrieves a frame synchronizing data comprising prescribed N-bit pattern and gives an active frame synchronization establishment detection signal in the case of the detection of the data, gives an active frame synchronizing step-out detection signal when no frame synchronization data is detected respectively to a 1/M frequency divider circuit 5 via a line 4 as a phase control signal of the frequency division clock. That is, as soon as the frame synchronizing data is detected, the mode is transited to the synchronization establishing mode and when no frame synchronization data is detected with the retrieval timing of the synchronization establishing mode, the mode is transited immediately into the hunting mode. Thus, the time till the synchronization establishment and the detection of out of synchronism is shortened and the data transmission efficiency is improved.</p> |
