| 摘要 |
<p>PURPOSE:To detect a synchronous signal with compact circuit configuration, by detecting the feature of each pattern without executing the coincidence of the pattern in all bits and detecting a synchronous pattern from the detected result. CONSTITUTION:Outputs Q0, Q1, Q2 of continuous three bits in a 4/8 modulation type conversion code are inputted to a pattern coincidence circuit 19 and whether the output of circuit 19 coincides with ''100'' or not can be detected. When counting up ''1'' by the prescribed number in every detection of ''100'', a counter 29 outputs ''1'' to the terminal Q3, and when the outputs are continued by the prescribed number, the output signal of the Q3 is held. When there is no ''100'' in the outputs Q2, Q1, Q0, the Q2 output of ''1'' is inputted to a terminal CE, counting is stopped and the counter 29 is reset. Therefore, the counter 29 can output ''1'' to the terminal Q3 only when the counting is continued by the prescribed number. Namely, the output of the Q3 at the continuous counting of ''100'' by the prescribed number and the output of an AND circuit 28 are inputted and the AND of these inputs is found by an AND circuit 22 to detect the synchronous signal.</p> |
