| 摘要 |
<p>PURPOSE:To reduce the trying again of a synchronous return action due to error detection by collating respective bit patterns of a detection synchronous word and a detection specific code word with a reception signal in a bit unit and preventing back up if both the synchronous word and the specific code word cannot be detected. CONSTITUTION:A counter is stepped and a detected number is counted whenever synchronous word detection information B-13 is inputted in a continuous period. With office identification code detection information A-41 (which is outputted only when an office identification code is not detected) outputted from an office identification code detection circuit A-4, the counter of a synchronous word detection protection circuit A-3 is reset. Namely, only when the synchronous word detection circuit shows the detection of the synchronous word, and the office identification code detection circuit A-4 shows the detection of an office identification code, the detected number is counted. Thus, the synchronous return action due to error detection can be prevented from being tried again and synchronous pull-in from being taken time.</p> |
