| 摘要 |
PURPOSE:To make it possible to prevent erroneous frame synchronization of a PCM device by providing a frame synchronizing circuit and a means of detecting a multiframe synchronizing pattern of random frame phase, and then by putting them in specific operation. CONSTITUTION:The synchronizing circuit whose multiframe consists of 12 frames and which receives a primary group PCM signals, following CCITT advice G.733, having a prescribed frame synchronizing signal and multiframe pattern inserted into the initial bit of each frame is provided with a frame synchronizing circuit and a means of detecting multiframe synchronizing patterns of random frame phase. In the acquisition of synchronism, when a frame synchronizing pattern is discriminated and a multiframe synchronizing pattern is not detected, the retrieval of synchronizing bits is continued without maintaining the frame synchronism. |
