GENERAL DESCRIPTION
The processing of path overhead bytes within the STS-1s or TUG-3s includes 64 bytes for storing the J1 bytes. Path overhead bytes can be accessed through the microprocessor interface or via serial interface. The XRT94L31 uses the internal E3/DS3 DeSynchronizer circuit with an internal pointer leak algorithm for clock smoothing as well as to remove the jitter due to mapping and pointer movements. These De-Synchronizer circuits do not need any external clock reference for its operation. The SONET/SDH transmit blocks allow flexible insertion of TOH and POH bytes through both Hardware and Software. Individual POH bytes for the transmitted SONET/SDH signal are mapped either from the XRT94L31 memory map or from external interface. A1, A2 framing pattern, C1 byte and H1, H2 pointer byte are generated. The SONET/SDH receive blocks receive SONET STS-3 signal or SDH STM-1 signal and perform the necessary transport and path overhead processing. The XRT94L31 provides a line side APS (Automatic Protection Switching) interface by offering redundant receive serial interface to be switched at the frame boundary.
Exar Corporation
