5.2.3. RX KR FEC Blocks
KR FEC Block Synchronization
You can obtain FEC block delineation for the RX KR FEC by locking onto correctly received FEC blocks with the KR FEC block synchronization.
KR FEC Descrambler
The KR FEC descrambler block descrambles received data to regenerate unscrambled data using the x58 + x39 +1 polynomial. Before the block boundary in the KR FEC sync block is detected, the data at the input of the descrambler is sent directly to the KR FEC decoder. When the boundary is detected, the aligned word from the KR FEC sync block is descrambled with the Pseudo Noise (PN) sequence and then sent to the KR FEC decoder.
KR FEC Decoder
The KR FEC decoder block performs the FEC (2112, 2080) decoding function by analyzing the received 32 65-bit blocks for errors. It can correct burst errors of 11 bits or less per FEC block.
KR FEC RX Gearbox
The KR FEC RX gearbox block adapts the PMA data width to the larger bus width of the PCS channel. It supports a 64:65 ratio.
The transcode decoder block performs the 65-bit to 64B/66B reconstruction function by regenerating the 64B/66B synchronization header.