| 摘要 |
PURPOSE:To detect an error of a code rule of a CMI signal obtained by the conversion of an NRZ signal, by providing an NRZ/CMI code converting circuit, and an encoding error monitoring circuit for always monitoring an error in an encoding process in the converting circuit. CONSTITUTION:A clock signal 2-multiplying circuit 4, a CMI signal temporary storage circuit 7 and an encoding error deciding circuit 12 constitute an encoding error monitoring circuit. A clock signal which has been inputted through an input terminal 2 is converted to a clock signal of a frequency of two times by the clock signal 2-multiplying circuit 4. Subsequently, said signal is inputted to a clock input 35 of the temporary storage circuit 7 and a clock input 37 of the encoding error deciding circuit 12. A CMI signal from an NRZ/CMI code converting circuit 3 becomes an input of the temporary storage circuit 7, and read in by a clock which has been multiplied to two times by the two- multiplying circuit 4. As for the CMI code which has been read in, whether an error of a code rule exists or not is decided by the deciding circuit 12, and when the error exists, '1' is outputted to a terminal 20, and when no error exists, '0' is outputted.
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