Path test signal inspection circuit path and test signal generation circuit in a synchronous transmission equipment and digital transmission system

摘要

PROBLEM TO BE SOLVED: To perform a path test by effectively generating a path test signal. ;SOLUTION: An in-device frame counter 18 detects respective positions in an in-device frame according to an in-device clock and supplies results to respective circuits 14, 20, 22, 24, and 26. A test pattern generating circuit 20 generates a PN pattern continuously in a stoppable state, inserts a given logical value into a transmit frame at the positions of a section overhead and a path overhead, and continuously inserts the PN pattern over respective columns only at the position of a payload. A path overheat inserting circuit 22 rewrites the given logical value into the path overhead according to an AU pointer from an AU pointer processing circuit 14. Likewise, a multi-section terminating circuit 24 rewrites a multi-section overhead and a repeating section terminating circuit 26 rewrites a repeated-section overhead. Consequently, a synchronous transmission module STM-N which accommodates a path test signal having the PN pattern inserted into the payload continuously over respective columns is securely generated to perform the path test.;COPYRIGHT: (C)1998,JPO