Patent ID: 9002195
Filing Date: 2015-04-07
Classification: H04B

Abstract:
1. In an optical communication system containing a primary line card and backup line card, a method comprising the steps of: providing interfaces for said primary line card and backup line card, each line card including a transmitter and receiver; and selecting output from said transmitter from either said primary or back up line card including selecting said backup line card when said primary line card encounters a failure; using a frame alignment signal (FAS) for frame aligning by using a FAS starting point detected by the primary line card as a reference and using a plurality of FAS checking elements each detecting different offset with one bit difference between each; and logically naming checking elements E- wherein said interfaces are synchronous, frame based and comprise a start sequence for each frame, said receiver having a primary frame start detecting module and other frame start detecting modules to work in parallel when said receiver enters a normal working mode, said receiver switching to a point of a frame start detected by another module if said primary start detecting module encounters a frame start loss.